Efficacy of subcutaneous allergen immunotherapy in atopic dogs: A retrospective study of 664 cases.

BACKGROUND: Canine atopic dermatitis (cAD) is an allergic skin disease affecting approximately 10% of dogs. allergen-specific immunotherapy (ASIT) is currently the only treatment option able to induce tolerance to the causative allergens. OBJECTIVE: To retrospectively establish the efficacy of ASIT in atopic dogs. ANIMALS: Client-owned (n  = 664) dogs with cAD presented between 2008 and 2018 to two dermatology referral clinics. MATERIALS AND METHODS: Clinical records of atopic dogs were reviewed to obtain information including the results of the intradermal skin test and/or allergen-specific immunoglobulin (Ig)E serological results, the allergens included in the ASIT, concurrent symptomatic medications, and ASIT efficacy after at least 9 months. RESULTS: Excellent (ASIT alone controlled clinical signs), good (≥50% reduction of clinical signs) and poor (<50% improvement) responses were seen in 31.5%, 28.5% and 40.1% of the dogs, respectively. No significant differences in efficacy were associated with breed, sex, age at initiation of ASIT, type of allergens in ASIT, and between clinics. Dogs re-examined regularly responded significantly better to ASIT than dogs that did not (>50% improvement in 69.3% and 55.4% of the dogs, respectively). Dogs treated with ASIT and concomitant systemic glucocorticoids showed a significantly poorer response (success rate of >50% improvement of 38.5%). CONCLUSIONS AND CLINICAL IMPORTANCE: In 59.9% of atopic dogs, subcutaneous ASIT can improve clinical signs by ≥50%. The beneficial effect of ASIT is higher if dogs are re-examined regularly and if systemic long-term corticosteroids are avoided, at least during the first 9 months of ASIT.

Contexte - La dermatite atopique canine (DAC) est une maladie cutanée allergique qui touche environ 10 % des chiens. L'immunothérapie allergénique (ASIT) est actuellement la seule option thérapeutique capable d'induire une tolérance aux allergènes responsables. Objectif - Établir rétrospectivement l'efficacité de l'ASIT chez les chiens atopiques. Animaux - Chiens de clients (n = 664) atteints de DAC présentés entre 2008 et 2018 à deux cliniques de référé en dermatologie. Méthodes - Les dossiers cliniques des chiens atopiques ont été examinés pour obtenir des informations, notamment les résultats du test cutané intradermique et / ou les résultats sérologiques de l'immunoglobuline (Ig) E spécifique d'allergène, les allergènes inclus dans l'ASIT, les médicaments symptomatiques concomitants et l'efficacité de l'ASIT après au moins neuf mois. Résultats - Des réponses excellentes (signes cliniques contrôlés par l'ASIT seul), bonnes (réduction ≥ 50 % des signes cliniques) et médiocres (amélioration < 50 %) ont été observées chez 31,5 %, 28,5 % et 40,1 % des chiens, respectivement. Aucune différence significative d'efficacité n'a été associée à la race, au sexe, à l'âge au début de l'ASIT, au type d'allergènes dans l'ASIT et entre les cliniques. Les chiens réexaminés régulièrement ont répondu significativement mieux à l'ASIT que les chiens qui ne l'ont pas fait (amélioration > 50 % chez 69,3 % et 55,4 % des chiens, respectivement). Les chiens traités avec l'ASIT et des glucocorticoïdes systémiques concomitants ont montré une réponse significativement plus faible (taux de réussite > 50 % d'amélioration de 38,5 %). Conclusions et importance clinique - Chez 59,9 % des chiens atopiques, l'ASIT sous-cutanée peut améliorer les signes cliniques de ≥ 50 %. L'effet bénéfique de l'ASIT est plus élevé si les chiens sont réexaminés régulièrement et si les corticostéroïdes systémiques à long terme sont évités, au moins pendant les neuf premiers mois de l'ASIT.

Introducción- la dermatitis atópica canina (cAD) es una enfermedad alérgica de la piel que afecta aproximadamente al 10 % de los perros. La inmunoterapia con alérgenos (ASIT) es actualmente la única opción de tratamiento capaz de inducir tolerancia a los alérgenos causantes. Objetivo- establecer retrospectivamente la eficacia de ASIT en perros atópicos. Animales- perros de propietarios particulares (n=664) con cAD presentados entre 2008 y 2018 a dos clínicas de referencia de dermatología. Métodos- se revisaron las historias clínicas de los perros atópicos para obtener información, incluidos los resultados de la prueba cutánea intradérmica y/o los resultados serológicos de la inmunoglobulina (Ig)E específica para alérgenos, los alérgenos incluidos en el ASIT, los medicamentos sintomáticos concurrentes y la eficacia del ASIT después de al menos menos nueve meses. Resultados- se observaron respuestas excelentes (la ASIT sola controló los signos clínicos), buenas (≥50 % de reducción de los signos clínicos) y malas (<50 % de mejora) en el 31,5 %, 28,5 % y 40,1 % de los perros, respectivamente. No se asociaron diferencias significativas en la eficacia con la raza, el sexo, la edad al inicio de la ASIT, el tipo de alérgenos en la ASIT y entre las clínicas. Los perros reexaminados con regularidad respondieron significativamente mejor a la ASIT que los perros que no lo hicieron (>50 % de mejora en el 69,3 % y el 55,4 % de los perros, respectivamente). Los perros tratados con ASIT y glucocorticoides sistémicos concomitantes mostraron una respuesta significativamente peor (tasa de éxito de >50 % de mejora del 38,5 %). Conclusiones e importancia clínica - En el 59,9% de los perros atópicos, la ASIT subcutánea puede mejorar los signos clínicos en ≥50%. El efecto beneficioso de la ASIT es mayor si los perros se vuelven a examinar con regularidad y si se evitan los corticosteroides sistémicos a largo plazo, al menos durante los primeros nueve meses de la ASIT.

Contexto - A dermatite atópica canina (DAC) é uma doença alérgica que afeta aproximadamente 10% dos cães. A imunoterapia alérgeno-específica (ASIT) é atualmente a única opção terapêutica capaz de induzir tolerância aos alérgenos causadores. Objetivo - Estabelecer retrospectivamente a eficácia da ASIT em cães atópicos. Animais - Cães de proprietários (664) com DAC apresentados a duas clínicas de referência em dermatologia entre 2008 e 2018. Métodos - Os prontuários dos cães atópicos foram revisados para se obter informações incluindo os resultados dos testes intradérmicos e/ou sorológicos para anticorpos (IgE) alérgeno-específicos, os alérgenos incluídos na ASIT, medicações sintomáticas concomitantes, e a eficácia de ASIT após um mínimo de nove meses. Resultados - Resposta excelente (ASIT controlou os sinais clínicos sozinha), boa (redução ≥50% nos sinais clínicos) e pobre (<50% de melhora) foi observada em 31,5%, 28,5% e 40,1% dos cães, respectivamente. Não foram observadas diferenças significativas na eficácia em relação a raça, gênero, idade à iniciação da ASIT, tipo de alérgenos na ASIT e entre as clínicas. Os cães reavaliados periodicamente responderam significativamente melhor à ASIT que cães que não foram reavaliados com frequência (>50% de melhora em 69,3% e 55,4% dos cães, respectivamente). Cães tratados com ASIT e glicocorticoides sistêmicos concomitantemente demonstraram uma resposta significativamente mais pobre (a taxa de sucesso >50% ocorreu em 38,5%). Conclusões e importância clínica - Em 59,9% dos cães atópicos, ASIT subcutânea é capaz de melhorar os sinais clínicos em ≥50%. O efeito benéfico de ASIT foi maior se os cães fossem reavaliados regularmente e se corticoides sistêmicos a longo prazo fossem evitados, ao menos durante os primeiros meses de ASIT.

Hsp70 and NF-kB Mediated Control of Innate Inflammatory Responses in a Canine Macrophage Cell Line.

The pathogenesis of many inflammatory diseases is associated with the uncontrolled activation of nuclear factor kappa B (NF-κB) in macrophages. Previous studies have shown that in various cell types, heat shock protein 70 (Hsp70) plays a crucial role in controlling NF-κB activity. So far, little is known about the role of Hsp70 in canine inflammatory processes. In this study we investigated the potential anti-inflammatory effects of Hsp70 in canine macrophages as well as the mechanisms underlying these effects. To this end, a canine macrophage cell line was stressed with arsenite, a chemical stressor, which upregulated Hsp70 expression as detected by flow cytometry and qPCR. A gene-edited version of this macrophage cell line lacking inducible Hsp70 was generated using CRISPR-Cas9 technology. To determine the effects of Hsp70 on macrophage inflammatory properties, arsenite-stressed wild-type and Hsp70 knockout macrophages were exposed to lipopolysaccharide (LPS), and the expression of the inflammatory cytokines IL-6, IL-1ß and tumor necrosis factor-α (TNF-α) and levels of phosphorylated NF-κB were determined by qPCR and Western Blotting, respectively. Our results show that non-toxic concentrations of arsenite induced Hsp70 expression in canine macrophages; Hsp70 upregulation significantly inhibited the LPS-induced expression of the pro-inflammatory mediators TNF-α and IL-6, as well as NF-κB activation in canine macrophages. Furthermore, the gene editing of inducible Hsp70 by CRISPR-Cas9-mediated gene editing neutralized this inhibitory effect of cell stress on NF-κB activation and pro-inflammatory cytokine expression. Collectively, our study reveals that Hsp70 may regulate inflammatory responses through NF-κB activation and cytokine expression in canine macrophages.

Targeting of tolerogenic dendritic cells to heat-shock proteins in inflammatory arthritis.

BACKGROUND: Autologous tolerogenic dendritic cells (tolDC) are a promising therapeutic strategy for inflammatory arthritis (IA) as they can regulate autoantigen-specific T cell responses. Here, we investigated two outstanding priorities for clinical development: (i) the suitability of using heat-shock proteins (HSP), abundant in inflamed synovia, as surrogate autoantigens to be presented by tolDC and (ii) identification of functional biomarkers that confirm tolDC regulatory activity. METHODS: Cell proliferation dye-labelled human peripheral blood mononuclear cells of IA (rheumatoid arthritis (RA) and psoriatic arthritis (PsA)) patients or healthy donors were cultured with HSP40-, HSP60- and HSP70-derived peptides or recall antigens (e.g. tuberculin purified protein derivative (PPD)) in the presence or absence of tolDC or control DC for 9 days. Functional characteristics of proliferated antigen-specific T-cells were measured using flow cytometry, gene expression profiling and cytokine secretion immunoassays. Repeated measures analysis of variance (ANOVA) with Bonferroni correction for comparisons between multiple groups and paired Student t test for comparisons between two groups were used to determine significance. RESULTS: All groups showed robust CD4+ T-cell responses towards one or more HSP-derived peptide(s) as assessed by a stimulation index > 2 (healthy donors: 78%, RA: 73%, PsA: 90%) and production of the cytokines IFNγ, IL-17A and GM-CSF. Addition of tolDC but not control DC induced a type 1 regulatory (Tr1) phenotype in the antigen-specific CD4+ T-cell population, as identified by high expression of LAG3, CD49b and secretion of IL-10. Furthermore, tolDC inhibited bystander natural killer (NK) cell activation in a TGFß dependent manner. CONCLUSIONS: HSP-specific CD4+ T-cells are detectable in the majority of RA and PsA patients and can be converted into Tr1 cells by tolDC. HSP-loaded tolDC may therefore be suitable for directing T regulatory responses to antigens in inflamed synovia of IA patients. Tr1 markers LAG3, CD49b and IL-10 are suitable biomarkers for future tolDC clinical trials.

Immunization of young heifers with staphylococcal immune evasion proteins before natural exposure to Staphylococcus aureus induces a humoral immune response in serum and milk.

BACKGROUND: Staphylococcus aureus, a leading cause of mastitis in dairy cattle, causes severe mastitis and/or chronic persistent infections with detrimental effects on the cows' wellbeing, lifespan and milk production. Despite years of research there is no effective vaccine against S. aureus mastitis. Boosting of non-protective pre-existing immunity to S. aureus, induced by natural exposure to S. aureus, by vaccination may interfere with vaccine efficacy. The aim was to assess whether experimental immunization of S. aureus naïve animals results in an immune response that differs from immunity following natural exposure to S. aureus. RESULTS: First, to define the period during which calves are immunologically naïve for S. aureus, Efb, LukM, and whole-cell S. aureus specific serum antibodies were measured in a cohort of newborn calves by ELISA. Rising S. aureus specific antibodies indicated that from week 12 onward calves mounted an immune response to S. aureus due to natural exposure. Next, an experimental immunization trial was set up using 8-week-old heifer calves (n = 16), half of which were immunized with the immune evasion molecules Efb and LukM. Immunization was repeated after one year and before parturition and humoral and cellular immunity specific for Efb and LukM was determined throughout the study. Post-partum, antibody levels against LukM and EfB were significantly higher in serum, colostrum and milk in the experimentally immunized animals compared to animals naturally exposed to S. aureus. LukM specific IL17a responses were also significantly higher in the immunized cows post-partum. CONCLUSIONS: Experimental immunization with staphylococcal immune evasion molecules starting before natural exposure resulted in significantly higher antibody levels against Efb and LukM around parturition in serum as well as the site of infection, i.e. in colostrum and milk, compared to natural exposure to S. aureus. This study showed that it is practically feasible to vaccinate S. aureus naïve cattle and that experimental immunization induced a humoral immune response that differed from that after natural exposure only.

Targeting of tolerogenic dendritic cells towards heat-shock proteins: a novel therapeutic strategy for autoimmune diseases?

Tolerogenic dendritic cells (tolDCs) are a promising therapeutic tool to restore immune tolerance in autoimmune diseases. The rationale of using tolDCs is that they can specifically target the pathogenic T-cell response while leaving other, protective, T-cell responses intact. Several ways of generating therapeutic tolDCs have been described, but whether these tolDCs should be loaded with autoantigen(s), and if so, with which autoantigen(s), remains unclear. Autoimmune diseases, such as rheumatoid arthritis, are not commonly defined by a single, universal, autoantigen. A possible solution is to use surrogate autoantigens for loading of tolDCs. We propose that heat-shock proteins may be a relevant surrogate antigen, as they are evolutionarily conserved between species, ubiquitously expressed in inflamed tissues and have been shown to induce regulatory T cells, ameliorating disease in various arthritis mouse models. In this review, we provide an overview on how immune tolerance may be restored by tolDCs, the problem of selecting relevant autoantigens for loading of tolDCs, and why heat-shock proteins could be used as surrogate autoantigens.

Altered lipid properties of the stratum corneum in Canine Atopic Dermatitis.

Skin barrier disruption plays a role in the pathogenesis of atopic dermatitis (AD) in humans. However, little is known about skin barrier (dys-) function in Canine Atopic Dermatitis. The properties of lipids located in the outermost layer of the skin, the stratum corneum (SC) are considered to be important for the barrier. In the present study the lipid composition and lipid organization of the SC of AD dogs and control dogs were examined. The lipid composition of lesional AD skin as compared to control skin, showed a reduced free fatty acid level and a decreased ratio of ceramide[NS] C44/C34, in which C44 and C34 are the total numbers of carbon atoms of the sphingosine (S) and non-hydroxy (N) acyl chains. As a consequence of the observed changes in lipid composition in AD lesional skin the lamellar organization of lipids altered and a shift from orthorhombic to hexagonal lipid packing was monitored. Simultaneously an increased conformational disordering occurred. These changes are expected to compromise the integrity of the skin barrier. The C44/C34 chain length ratio of ceramide[NS] also showed a decreasing nonlinear relationship with the AD severity score (CADESI). Taken together, canine atopic skin showed alterations in SC lipid properties, similar to the changes observed in atopic dermatitis in humans, that correlated with a disruption of the skin barrier. Hence lipids play an important role in the pathogenesis of Canine Atopic Dermatitis.

Autologous stem cell transplantation aids autoimmune patients by functional renewal and TCR diversification of regulatory T cells.

Autologous hematopoietic stem cell transplantation (HSCT) is increasingly considered for patients with severe autoimmune diseases whose prognosis is poor with standard treatments. Regulatory T cells (Tregs) are thought to be important for disease remission after HSCT. However, eliciting the role of donor and host Tregs in autologous HSCT is not possible in humans due to the autologous nature of the intervention. Therefore, we investigated their role during immune reconstitution and re-establishment of immune tolerance and their therapeutic potential following congenic bone marrow transplantation (BMT) in a proteoglycan-induced arthritis (PGIA) mouse model. In addition, we determined Treg T-cell receptor (TCR) CDR3 diversity before and after HSCT in patients with juvenile idiopathic arthritis and juvenile dermatomyositis. In the PGIA BMT model, after an initial predominance of host Tregs, graft-derived Tregs started dominating and displayed a more stable phenotype with better suppressive capacity. Patient samples revealed a striking lack of diversity of the Treg repertoire before HSCT. This ameliorated after HSCT, confirming reset of the Treg compartment following HSCT. In the mouse model, a therapeutic approach was initiated by infusing extra Foxp3(GFP+) Tregs during BMT. Infusion of Foxp3(GFP+) Tregs did not elicit additional clinical improvement but conversely delayed reconstitution of the graft-derived T-cell compartment. These data indicate that HSCT-mediated amelioration of autoimmune disease involves renewal of the Treg pool. In addition, infusion of extra Tregs during BMT results in a delayed reconstitution of T-cell compartments. Therefore, Treg therapy may hamper development of long-term tolerance and should be approached with caution in the clinical autologous setting.

DEC205+ Dendritic Cell-Targeted Tolerogenic Vaccination Promotes Immune Tolerance in Experimental Autoimmune Arthritis.

Previous studies in mouse models of autoimmune diabetes and encephalomyelitis have indicated that the selective delivery of self-antigen to the endocytic receptor DEC205 on steady-state dendritic cells (DCs) may represent a suitable approach to induce Ag-specific immune tolerance. In this study, we aimed to examine whether DEC205(+) DC targeting of a single immunodominant peptide derived from human cartilage proteoglycan (PG) can promote immune tolerance in PG-induced arthritis (PGIA). Besides disease induction by immunization with whole PG protein with a high degree of antigenic complexity, PGIA substantially differs from previously studied autoimmune models not only in the target tissue of autoimmune destruction but also in the nature of pathogenic immune effector cells. Our results show that DEC205(+) DC targeting of the PG peptide 70-84 is sufficient to efficiently protect against PGIA development. Complementary mechanistic studies support a model in which DEC205(+) DC targeting leads to insufficient germinal center B cell support by PG-specific follicular helper T cells. Consequently, impaired germinal center formation results in lower Ab titers, severely compromising the development of PGIA. Overall, this study further corroborates the potential of prospective tolerogenic DEC205(+) DC vaccination to interfere with autoimmune diseases, such as rheumatoid arthritis.

Distribution patterns of mucosally applied particles and characterization of the antigen presenting cells.

Mucosal application is the most common route of vaccination to prevent outbreaks of infectious diseases like Newcastle disease virus (NDV). To gain more knowledge about distribution and uptake of a vaccine after mucosal vaccination, we studied the distribution pattern of antigens after different mucosal routes of administration. Chickens were intranasally (i.n.), intratracheally (i.t.) or intraocularly (i.o.) inoculated with fluorescent beads and presence of beads in nasal-associated lymphoid tissue (NALT), Harderian gland (HG), conjunctiva-associated lymphoid tissue (CALT), trachea, lungs, air sacs, oesophagus and blood was characterized. The distribution patterns differed significantly between the three inoculation routes. After i.t. inoculation, the beads were mainly retrieved from trachea, NALT and lung. I.n. inoculation resulted in beads found mainly in NALT but detectable in all organs sampled. Finally, after i.o. inoculation, the beads were detected in NALT, CALT, HG and trachea. The highest number of beads was retrieved after i.n. inoculation. Development of novel vaccines requires a comprehensive knowledge of the mucosal immune system in birds in order to target vaccines appropriately and to provide efficient adjuvants. The NALT is likely important for the induction of mucosal immune responses. We therefore studied the phenotype of antigen-presenting cells isolated from NALT after i.n. inoculation with uncoated beads or with NDV-coated beads. Both types of beads were efficiently taken up and low numbers of bead+ cells were detected in all organs sampled. Inoculation with NDV-coated beads resulted in a preferential uptake by NALT antigen-presenting cells as indicated by high percentages of KUL01+-, MHC II+ and CD40+ bead+ cells.

Regulatory T cells that recognize a ubiquitous stress-inducible self-antigen are long-lived suppressors of autoimmune arthritis.

Reestablishing self-tolerance in autoimmunity is thought to depend on self-reactive regulatory T cells (Tregs). Exploiting these antigen-specific regulators is hampered by the obscure nature of disease-relevant autoantigens. We have uncovered potent disease-suppressive Tregs recognizing Heat Shock Protein (Hsp) 70 self-antigens, enabling selective activity in inflamed tissues. Hsp70 is a major contributor to the MHC class II ligandome. Here we show that a conserved Hsp70 epitope (B29) is present in murine MHC class II and that upon transfer, B29-induced CD4(+)CD25(+)Foxp3(+) T cells suppress established proteoglycan-induced arthritis in mice. These self-antigen-specific Tregs were activated in vivo, and when using Lymphocyte Activation Gene-3 as a selection marker, as few as 4,000 cells sufficed. Furthermore, depletion of transferred Tregs abrogated disease suppression. Transferred cells exhibited a stable phenotype and were found in joints and draining lymph nodes up to 2 mo after transfer. Given that (i) B29 administration by itself suppressed disease, (ii) our findings were made with wild-type (T-cell receptor nontransgenic) Tregs, and (iii) the B29 human homolog is presented by HLA class II, we are nearing translation of antigen-specific Treg activation as a promising intervention for chronic inflammatory diseases.

Peritoneal cavity B-1a cells promote peripheral CD4+ T-cell activation.

Innate-like murine B-1a cells are well known for their ability to secrete natural IgM. Their non-Ab mediated functions, including Ag presentation to CD4(+) T cells, are less well explored. Using combined adoptive transfer experiments with peptide-pulsed peritoneal cavity (PerC)-derived B-1a cells and CFSE-labeled T cells, we show that B-1a cells present Ag to CD4(+) T cells from the periphery in vivo. In vitro characterization, using co-cultures in which B-1a or splenic B cells presented whole OVA protein to OVA-specific Tg T cells, shows that B-1a cells differentially promote intracellular cytokine-expressing T cells. PerC-derived B-1a cells increase the percentage of IL-10-producing T cells along with IL-4- and IFN-γ-producing CD4(+) T cells. These data suggest that B cells in the PerC have the potential to influence peripheral immune responses without the necessity to migrate out of this location. This, to our knowledge previously undescribed, immuno-logical pathway potentially plays a role in the presentation of gut microbiota-derived Ags to peripheral T cells.

CD4+ and CD8+ skin-associated T lymphocytes in canine atopic dermatitis produce interleukin-13, interleukin-22 and interferon-γ and contain a CD25+ FoxP3+ subset.

BACKGROUND: T Cells play a major role in the immunopathogenesis of canine atopic dermatitis (cAD). However, the significance of cutaneous regulatory T cells (Tregs) and CD8(+) T cells is currently unclear. HYPOTHESIS/OBJECTIVES: The study aimed to evaluate the presence and distribution of Tregs in cAD and healthy skin and to determine the cytokine production of cutaneous CD4(+) and CD8(+) T cells. ANIMALS: Biopsies were taken from four dogs with cAD (lesional and nonlesional skin) and four healthy control dogs. METHODS: Distribution patterns of T-cell subtypes in cAD lesional, nonlesional and control skin were evaluated by immunohistochemistry. Phenotypic characterization of T cells from skin explant cultures and enzymatic digestions was performed using flow cytometry. Cytokine production of sorted CD4(+) and CD8(+) explant-derived T cells was measured by RT-qPCR. RESULTS: Regulatory T cells phenotypically characterized by CD25(+) FoxP3(+) were found in both CD4(+) and CD8(+) subsets of skin explant and digestion samples. The percentages of CD4(+) CD25(+) cells that were FoxP3(+) were similar in cAD and control skin. In atopic lesional and nonlesional explant samples, lower FoxP3(+) percentages of CD8(+) CD25(+) cells were seen compared with control skin. The presence of predominantly periadnexal CD25(+) FoxP3(+) cells was confirmed by immunohistochemistry in lesional, nonlesional and control skin. The CD4(+) /CD8(+) ratio was less than one in cAD skin with both skin explant and digestion methods. CD4(+) and CD8(+) T-cell subsets of lesional and nonlesional cAD skin were capable of producing interleukin-13, interleukin-22 and interferon-γ. CONCLUSIONS AND CLINICAL IMPORTANCE: Both CD4(+) and CD8(+) T cells are likely to contribute to the immunopathogenesis of cAD through the production of interleukin-13, interleukin-22 and interferon-γ. In both subsets, functional analysis of FoxP3(+) cells is essential to determine their role.

Owners' experiences of administering meglumine antimoniate injections to dogs with leishmaniosis: An online questionnaire study.

BACKGROUND: This study examined the experiences of owners of dogs with leishmaniosis who treated their dogs with daily subcutaneous meglumine antimoniate injections. The owners' perceived ease of administering the injections, the occurrence of problems and the effects on the owners and on the dog‒owner bond were evaluated. METHODS: Dogs prescribed meglumine antimoniate as a treatment for leishmaniosis were identified using the database of the veterinary pharmacy of the Faculty of Veterinary Medicine, Utrecht University. An online questionnaire was sent to the owners of these dogs to evaluate the perceived ease of administering the injections, the occurrence of problems and the effects on the owner and the dog-owner bond. RESULTS: Responses were received from 64 dog owners. Most respondents (78%) reported that administering the injections was not difficult. Pain or the development of nodules at the injection site was reported in 50% and 40% of the dogs, respectively. Polyuria was reported in 44% of the dogs. Some owners reported that administering the injections had a negative impact on their psychological wellbeing (20%), and some would have liked more veterinary support (11%). LIMITATIONS: Some questions were answered by a limited number of people, and their responses may not be representative. CONCLUSION: Dog owners remain highly motivated to persevere with meglumine antimoniate treatment and are willing to administer the injections themselves. The availability of active support when needed during the therapy cycle may further improve their acceptance of and confidence in giving the injections.

Autoantigen-Dexamethasone Conjugate-Loaded Liposomes Halt Arthritis Development in Mice.

There is no curative treatment for chronic auto-inflammatory diseases including rheumatoid arthritis, and current treatments can induce off-target side effects due to systemic immune suppression. This work has previously shown that dexamethasone-pulsed tolerogenic dendritic cells loaded with the arthritis-specific antigen human proteoglycan can suppress arthritis development in a proteoglycan-induced arthritis mouse model. To circumvent ex vivo dendritic cell culture, and enhance antigen-specific effects, drug delivery vehicles, such as liposomes, provide an interesting approach. Here, this work uses anionic 1,2-distearoyl-sn-glycero-3-phosphoglycerol liposomes with enhanced loading of human proteoglycan-dexamethasone conjugates by cationic lysine tetramer addition. Antigen-pulsed tolerogenic dendritic cells induced by liposomal dexamethasone in vitro enhanced antigen-specific regulatory T cells to a similar extent as dexamethasone-induced tolerogenic dendritic cells. In an inflammatory adoptive transfer model, mice injected with antigen-dexamethasone liposomes have significantly higher antigen-specific type 1 regulatory T cells than mice injected with antigen only. The liposomes significantly inhibit the progression of arthritis compared to controls in preventative and therapeutic proteoglycan-induced arthritis mouse models. This coincides with systemic tolerance induction and an increase in IL10 expression in the paws of mice. In conclusion, a single administration of autoantigen and dexamethasone-loaded liposomes seems to be a promising antigen-specific treatment strategy for arthritis in mice.

Deciphering metabolic crosstalk in context: lessons from inflammatory diseases.

Metabolism plays a crucial role in regulating the function of immune cells in both health and disease, with altered metabolism contributing to the pathogenesis of cancer and many inflammatory diseases. The local microenvironment has a profound impact on the metabolism of immune cells. Therefore, immunological and metabolic heterogeneity as well as the spatial organization of cells in tissues should be taken into account when studying immunometabolism. Here, we highlight challenges of investigating metabolic communication. Additionally, we review the capabilities and limitations of current technologies for studying metabolism in inflamed microenvironments, including single-cell omics techniques, flow cytometry-based methods (Met-Flow, single-cell energetic metabolism by profiling translation inhibition (SCENITH)), cytometry by time of flight (CyTOF), cellular indexing of transcriptomes and epitopes by sequencing (CITE-Seq), and mass spectrometry imaging. Considering the importance of metabolism in regulating immune cells in diseased states, we also discuss the applications of metabolomics in clinical research, as well as some hurdles to overcome to implement these techniques in standard clinical practice. Finally, we provide a flowchart to assist scientists in designing effective strategies to unravel immunometabolism in disease-relevant contexts.

Heat shock proteins can be targets of regulatory T cells for therapeutic intervention in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterised by excessive immune responses resulting in inflammation of the joints. Although current therapies can be successful in dampening inflammation, a long-lived state of tolerance is seldom achieved. Therefore, novel therapies are needed that restore and maintain tolerance in patients with RA. Targeting regulatory T cells (Tregs) is a successful strategy to achieve tolerance, as was shown in studies performed in animal models and in human clinical trials. The antigen-specificity of Tregs is crucial for their effectiveness and allows for very specific targeting of these cells. However, which antigen is suitable for autoimmune diseases such as RA, for which the autoantigens are largely unknown? Heat shock proteins (HSPs) are ubiquitously expressed and can be up-regulated during inflammation. Additionally, HSPs, or HSP-derived peptides are immunogenic and can be recognised by a variety of immune cells, including Tregs. Therefore, this review highlights the potential of HSP-specific Tregs to control inflammatory immune responses. Targeting HSP-specific Tregs in RA can be achieved via the administration of HSPs (derived peptides), thereby controlling inflammatory responses. This makes HSPs attractive candidates for therapeutic intervention in chronic autoimmune diseases, with the ultimate goal of inducing long-lasting tolerance.

Survival time and prognostic factors in canine leishmaniosis in a non-endemic country treated with a two-phase protocol including initial allopurinol monotherapy.

BACKGROUND: Leishmania infantum is an intracellular protozoan parasite which is endemic in countries of the Mediterranean Basin. Leishmaniosis is increasingly diagnosed in non-endemic areas due to the relocation of dogs from endemic areas and the travel of dogs to and from these areas. The prognosis of leishmaniosis in these dogs may differ from that of those in endemic areas. The aims of this study were (1) to determine the Kaplan-Meier estimated survival time for dogs with leishmaniosis in the Netherlands (a non-endemic country), (2) to determine if clinicopathological variables at the time of diagnosis predicted the survival of these dogs, and (3) to evaluate the effect of a two-phase therapy protocol of allopurinol monotherapy followed by meglumine antimoniate and/or miltefosine in the case of incomplete remission or relapse. METHODS: The database of the Department of Clinical Sciences of Companion Animals of the Faculty of Veterinary Medicine, Utrecht University was investigated for leishmaniosis patients. Patient records were reviewed for signalment and clinicopathological data at the time of diagnosis. Only treatment-naive patients were included. Follow-up was performed during the study by phone contact and included treatment received and date and cause of death. Univariate analysis was performed using the Cox proportional hazards regression model. RESULTS: The estimated median Kaplan-Meier survival time was 6.4 years. In the univariate analysis, increases in monocyte, plasma urea and creatinine concentrations, and urine protein to creatinine ratio were all significantly associated with decreased survival time. The majority of patients only received allopurinol monotherapy. CONCLUSIONS: Canine leishmaniosis patients in our study population in the Netherlands, which is non-endemic for the disease, had an estimated Kaplan-Meier median survival time of 6.4 years, which is comparable to the outcome of other reported therapy protocols. Increased plasma urea and creatinine concentrations and monocyte concentration were statistically associated with an increased risk of death. We conclude that initial allopurinol monotherapy for 3 months should be effective in more than half of canine leishmaniosis cases, provided there is adequate follow-up, and that meglumine antimoniate or miltefosine therapy should be started as the second phase of the protocol in cases where remission is incomplete or there is a relapse.

Perforin and granzyme A release as novel tool to measure NK cell activation in chickens.

Natural killer (NK) cells are cytotoxic lymphocytes that are present in the circulation but also in many organs including spleen and gut, where they play an important role in the defense against infections. Interaction of NK cells with target cells leads to degranulation, which results in the release of perforin and granzymes in the direct vicinity of the target cell. Chicken NK cells have many characteristics similar to their mammalian counterparts and based on similarities with studies on human NK cells, surface expression of CD107 was always presumed to correlate with granule release. However, proof of this degranulation or in fact the actual presence of perforin (PFN) and granzyme A (GrA) in chicken NK cells and their release upon activation is lacking. Therefore, the purpose of the present study was to determine the presence of perforin and granzyme A in primary chicken NK cells and to measure their release upon degranulation, as an additional tool to study the function of chicken NK cells. Using human specific antibodies against PFN and GrA in fluorescent and confocal microscopy resulted in staining in chicken NK cells. The presence of PFN and GrA was also confirmed by Western blot analyses and its gene expression by PCR. Stimulation of NK cells with the pectin SPE6 followed by flow cytometry resulted in reduced levels of intracellular PFN and GrA, suggesting release of PFN and GrA. Expression of PFN and GrA reversely correlated with increased surface expression of the lysosomal marker CD107. Finally it was shown that the supernatant of activated NK cells, containing the NK cell granule content including PFN and GrA, was able to kill Escherichia coli. This study correlates PFN and GrA release to activation of chicken NK cells and establishes an additional tool to study activity of cytotoxic lymphocytes in chickens.

Chimeric Peptidomimetic Antibiotic Efficiently Neutralizes Lipopolysaccharides (LPS) and Bacteria-Induced Activation of RAW Macrophages.

Peptide antibiotics have gathered attention given the urgent need to discover antimicrobials with new mechanisms of action. Their extended role as immunomodulators makes them interesting candidates for the development of compounds with dual mode of action. The objective of this study was to test the anti-inflammatory capacity of a recently reported chimeric peptidomimetic antibiotic (CPA) composed of polymyxin B nonapeptide (PMBN) and a macrocyclic ß-hairpin motif (MHM). We investigated the potential of CPA to inhibit lipopolysaccharide (LPS)-induced activation of RAW264.7 macrophages. In addition, we elucidated which structural motif was responsible for this activity by testing CPA, its building blocks, and their parent compounds separately. CPA showed excellent LPS neutralizing activity for both smooth and rough LPSs. At nanomolar concentrations, CPA completely inhibited LPS-induced nitric oxide, TNF-α, and IL-10 secretion. Murepavadin, MHM, and PMBN were incapable of neutralizing LPS in this assay, while PMB was less active compared to CPA. Isothermal titration calorimetry showed strong binding between the CPA and LPS with similar binding characteristics also found for the other compounds, indicating that binding does not necessarily correlate with neutralization of LPS. Finally, we showed that CPA-killed bacteria caused significantly less macrophage activation than bacteria killed with gentamicin, heat, or any of the other compounds. This indicates that the combined killing activity and LPS neutralization of CPA can prevent unwanted inflammation, which could be a major advantage over conventional antibiotics. Our data suggests that immunomodulatory activity can further strengthen the therapeutic potential of peptide antibiotics and should be included in the characterization of novel compounds.

Cellular and humoral immune responsiveness to inactivated Leptospira interrogans in dogs vaccinated with a tetravalent Leptospira vaccine.

Vaccination is commonly used to protect dogs against leptospirosis, however, memory immune responses induced by canine Leptospira vaccines have not been studied. In the present study, antibody and T cell mediated responses were assessed in dogs before and 2 weeks after annual revaccination with a commercial tetravalent Leptospira vaccine containing serogroups Canicola and Australis. Vaccination significantly increased average log2 IgG titers from 6.50 to 8.41 in year 1, from 5.99 to 7.32 in year 2, from 5.32 to 8.32 in year 3 and from 5.32 to 7.82 in year 4. The CXCL-10 levels, induced by in vitro stimulation of PBMC with Canicola and Australis, respectively, significantly increased from 1039.05 pg/ml and 1037.38 pg/ml before vaccination to 2547.73 pg/ml and 2730.38 pg/ml after vaccination. IFN-γ levels increased from 85.60 pg/ml and 178.13 pg/ml before vaccination to 538.62 pg/ml and 210.97 pg/ml after vaccination. The percentage of proliferating CD4+ T cells in response to respective Leptospira strains significantly increased from 1.43 % and 1.25 % before vaccination to 24.11 % and 14.64 % after vaccination. Similar responses were also found in the CD8+ T cell subset. Vaccination also significantly enhanced the percentages of central memory CD4+ T cells from 12 % to 26.97 % and 27.65 %, central memory CD8+ T cells from 3 % to 9.47 % and 7.55 %, and effector CD8+ T cells from 3 % to 7.6 % and 6.42 %, as defined by the expression of CD45RA and CD62L, following stimulation with Canicola and Australis, respectively. Lastly, enhanced expression of the activation marker CD25 on T cells after vaccination was found. Together, our results show that next to IgG responses, also T cell responses are induced in dogs upon annual revaccination with a tetravalent Leptospira vaccine, potentially contributing to protection.