Caracterización de aislamientos de Klebsiella pneumoniae doble productores de carbapenemasas en un hospital universitario / Phenotypic and genotypic characterization of double carbapenemase producing Klebsiella pneumoniaeisolates in a University Hospital

La emergencia de aislamientos de Klebsiella pneumoniaedoble productores de carbapenemasas (KPC y NDM) es una de las consecuencias de la pandemia causada por SARS-CoV-2 que ha causado un impacto significativo en las tasas de resistencia a los antimicrobianos en las infecciones intrahospitalarias por esta enterobacteria. Estos aislamientos representan un desafío para los servicios de salud, por su detección y caracterización y posterior tratamiento. En este trabajo se describen los aislamientos portadores de KPC y NDM recuperados durante 2022 aislados de distintas muestras clínicas de pacientes internados en un hospital universitario de la Ciudad de Buenos Aires, se los caracteriza fenotípicamente y genotípicamente como portadores de ambas carbapenemasas y se destaca la excelente actividad in vitro de la combinación ceftazidima-avibactam y aztreonam en el tratamiento de estas infecciones en donde las alternativas terapéuticas estarían limitadas a antibióticos no ß-lactámicos con porcentajes de resistencia que superan el 70%

The emergence of double-carbapenemase (KPC and NDM) producing Klebsiella pneumoniae isolates is one of the consequences derived from the SARS CoV-2 pandemic, which has caused significant impact on the antimicrobial resistance rates in hospital acquired infections. These isolates represent a real challenge for Health Services due to their difficult detection and characterization and subsequent treatment. In the present work we describe the double carbapenemase producing isolates recovered during the year 2022 from clinical samples belonging to hospitalized patients at a University Hospital in Buenos Aires city, we report their phenotypic and genotypic characterization and the excellent "in vitro" activity of the ceftazidime-avibactam-aztreonam combination in the treatment of infections in which the therapeutical options are restricted to non ß- lactamic antimicrobials which hold resistance rates higher than 70%

Actinomyces europaeus (Gleimia europaea) asociado con absceso cerebral: comunicación de tres casos / Actinomyces europaeus (Gleimia europaea) associated with brain abscess: A reportof three cases

Resumen El absceso cerebral es una infección focal caracterizada por acumulación de pus enel parénquima cerebral; su diagnóstico es de urgencia debido a la alta mortalidad que acarrea.Presentamos tres casos de pacientes con abscesos cerebrales con foco otogénico de origen poli-microbiano, que presentaron en común el aislamiento de Actinomyces europaeus, agente nodescrito hasta el momento en esta localización. A. europaeus fue identificado por la metodo-logía convencional, por espectrometría de masas por desorción/ionización asistida por matriz(MALDI-TOF MS) y por secuenciación del gen ARNr 16S. La sensibilidad antibiótica se evaluó porel método epsilométrico. Todos los aislados presentaron sensibilidad a penicilina, vancomicinay linezolid, mientras que la sensibilidad a clindamicina y eritromicina fue variable. La iden-tificación por MALDI-TOF MS permitió arribar a nivel de especie de forma rápida y confiabley dar una respuesta oportuna y efectiva, evitando el retraso en el tratamiento, lo que sueleincrementar la morbimortalidad del cuadro clínico.

Inflammation on the Waiting List Is a Risk Factor for New-Onset Prediabetes and Post-Transplant Diabetes Mellitus: A Prospective Study.

INTRODUCTION: Inflammation is a risk factor for diabetes in the general population. The role of inflammation in prediabetes or post-transplant diabetes mellitus (PTDM) is not clear. We evaluated the association between inflammatory markers in patients on the waiting list for renal transplantation and the onset of prediabetes and PTDM 12 months after transplantation. METHODS: This is a post hoc analysis of a prospective study that included nondiabetic patients on the waiting list for kidney transplantation who underwent an oral glucose tolerance test (OGTT) and were followed up to 12 months after transplantation. At this time, those patients without PTDM underwent another OGTT. At pre-transplantation, five cytokines: TNFα, IL6, IL1ß, CRP, MCP1 were determined. The association between inflammation and prediabetes/PTDM was evaluated using multiple regression models. RESULTS: 110 patients on the waiting list were enrolled: 74 had normal glucose metabolism and 36 had prediabetes or occult diabetes. At 12 months, 53 patients had normal glucose metabolism, 25 prediabetes, and 32 PTDM. In multiple regression analysis, pre-transplant inflammation was not a risk factor for prediabetes or PTDM. This was attributed to the high interrelation between obesity, prediabetes, and inflammation: about 75% of the cases had these conditions. In a sub-analysis, we analyzed only patients without prediabetes and occult diabetes on the waiting list and found that TNFα levels and BMI at pre-transplantation were independently associated with the onset of prediabetes or PTDM 1 year after transplantation. CONCLUSIONS: Pre-transplant inflammation and BMI are risk factors for prediabetes and PTDM in patients without glucose metabolism alterations.

Fusobacterium nucleatum dissemination by neutrophils.

Recent studies uncovered that Fusobacterium nucleatum (Fn), a common, opportunistic bacterium in the oral cavity, is associated with a growing number of systemic diseases, ranging from colon cancer to Alzheimer's disease. However, the pathological mechanisms responsible for this association are still poorly understood. Here, we leverage recent technological advances to study the interactions between Fn and neutrophils. We show that Fn survives within human neutrophils after phagocytosis. Using in vitro microfluidic devices, we determine that human neutrophils can protect and transport Fn over large distances. Moreover, we validate these observations in vivo by showing that neutrophils disseminate Fn using a zebrafish model. Our data support the emerging hypothesis that bacterial dissemination by neutrophils is a mechanistic link between oral and systemic diseases. Furthermore, our results may ultimately lead to therapeutic approaches that target specific host-bacteria interactions, including the dissemination process.

Soluble epoxide hydrolase inhibition enhances production of specialized pro-resolving lipid mediator and promotes macrophage plasticity.

BACKGROUND AND PURPOSE: Epoxyeicosatrienoic acids (EETs) and other epoxy fatty acids (EpFA) are lipid mediators that are rapidly inactivated by soluble epoxide hydrolase (sEH). Uncontrolled and chronic inflammatory disorders fail to sufficiently activate endogenous regulatory pathways, including the production of specialized pro-resolving mediators (SPMs). Here, we addressed the relationship between SPMs and the EET/sEH axis and explored the effects of sEH inhibition on resolving macrophage phenotype. EXPERIMENTAL APPROACH: Mice were treated with a sEH inhibitor, EETs, or sEH inhibitor + EETs (combination) before ligature placement to induce experimental periodontitis. Using RT-qPCR, gingival samples were used to examine SPM receptors and osteolytic and inflammatory biomarkers. Maxillary alveolar bone loss was quantified by micro-CT and methylene blue staining. SPM levels were analysed by salivary metabolo-lipidomics. Gingival macrophage phenotype plasticity was determined by RT-qPCR and flow cytometry. Effects of sEH inhibition on macrophage polarization and SPM production were assessed with bone marrow-derived macrophages (BMDMs). KEY RESULTS: Pharmacological inhibition of sEH suppressed bone resorption and the inflammatory cytokine storm in experimental periodontitis. Lipidomic analysis revealed that sEH inhibition augmented levels of LXA4, RvE1, RvE2, and 4-HDoHE, concomitant with up-regulation of LTB4R1, CMKLR1/ChemR23, and ALX/FPR2 SPM receptors. Notably, there is an impact on gingival macrophage plasticity was affected suggesting an inflammation resolving phenotype with sEH inhibition. In BMDMs, sEH inhibition reduced inflammatory macrophage activation, and resolving macrophages were triggered to produce SPMs. CONCLUSION AND IMPLICATIONS: Pharmacological sEH inhibition increased SPM synthesis associated with resolving macrophages, suggesting a potential target to control osteolytic inflammatory disorders.

Post-transplant diabetes mellitus and renal cell cancer after renal transplantation.

BACKGROUND: Diabetes is a risk factor for cancer in the general population. However, few data are available on the association between post-transplant diabetes mellitus (PTDM) and cancer after transplantation. METHODS: We analyzed this issue in a Spanish cohort of patients without diabetes before transplantation. PTDM was diagnosed with consensus criteria at 12 months after transplantation and 12 months before the diagnosis of cancer. The association between PTDM and cancer (overall and specific types) was evaluated with regression analysis. RESULTS: During a follow-up of 12 years (interquartile range 8-14), 85 cases of 603 developed cancer (829/100 000/year) and 164 (27%) PTDM. The most frequent cancers were renal cell cancer (RCC) n = 15, 146/cases/100 000/year), lung (n = 12, 117/cases/100 000/year), colon (n = 9, 88/cases/100 000/year) and prostate (n = 9, 88/cases/100 000/year). In logistic regression, PTDM was not associated with cancer. Eight of the 164 patients with PTDM (4.9%) vs 7 of the 439 without PTDM developed RCC (1.6%) (P = .027). In multivariate analysis, PTDM was independently associated with RCC [odds ratio (OR) 2.92, confidence interval (CI) 1.03-8.27], adjusting for smoking (OR 4.020, 95% CI 1.34-12.02) and other covariates. PTDM was not associated with other types of cancer. CONCLUSIONS: Patients with PTDM must be considered a population at risk for RCC and accordingly, the subject of active surveillance.

Incidencia de hipocalcemia e hipoparatiroidismo en cirugías de cuello / Hypocalcaemia and hypoparathyroidism' incidence in neck surgeries

INTRODUCCIÓN: el hipoparatiroidismo es la alteración causada por hipofunción de las glándulas paratiroides y la causa más común es la posquirúrgica. OBJETIVO: conocer la incidencia de hipocalcemia dentro de las 72 horas del postoperatorio y de hipoparatiroidismo permanente de tiroidectomías en nueve años. SUJETOS Y MÉTODO: estudio observacional, descriptivo y retrospectivo de pacientes con tiroidectomías entre enero de 2011 y diciembre de 2019 en el Hospital de Clínicas. Se dividió la muestra por grupos etarios, se consideró hipocalcemia a valores ≤8,5 mg/dl e hipoparatiroidismo permanente cuando persistían por lo menos un año luego de cirugía. RESULTADOS: fueron 202 pacientes, 182 mujeres y 20 hombres, media de edad ± ES para mujeres 47.3±1.2 años y para hombres 55.1±3.4. El 61,5% presentó hipocalcemia en las primeras 72 horas del postoperatorio: 60,2% de mujeres y 71,4% de hombres (p=0.42). El 79% fueron hipocalcemias asintomáticas, 7,5% tuvo síntomas y 13,5% sin datos. El signo de Trousseau fue negativo 68% y positivo en 9%. Respecto a la patología hubo 107 resultados benignos, 94 malignos. CONCLUSIONES: el 90% fueron mujeres, 6 de cada 10 presentaron hipocalcemia en las primeras 72hs, en la gran mayoría fueron asintomáticas y tuvieron signo de Trousseau negativo. No hubo correlación entre hipocalcemia con edad, sexo, duración o tiempo de la cirugía, ni resultado de patología. La incidencia de hipoparatiroidismo transitorio fue 75,7% y permanente 7,3%. Cuando no hubo hipoparatiroidismo transitorio tampoco hubo hipoparatiroidismo permanente.

INTRODUCTION: hypoparathyroidism is the alteration caused by hypofunction of the parathyroid glands and the most common cause is post-surgery. OBJECTIVE: to know the incidence of hypocalcaemia within 72 hours of the postoperative period and of permanent hypoparathyroidism of thyroidectomies in nine years. SUBJECTS AND METHOD: observational, descriptive and retrospective study of patients with thyroidectomies between January 2011 and December 2019 at Clinical's Hospital. The sample was divided by age groups, hypocalcemia was considered at values ≤8.5 mg/dl and permanent hypoparathyroidism when they persisted for at least one year after surgery. RESULTS: there were 202 patients, 182 women and 20 men, mean age ± SE for women 47.3±1.2 years and for men 55.1±3.4. 61.5% presented hypocalcaemia in the first 72 hours after surgery: 60.2% of women and 71.4% of men (p=0.42). 79% were asymptomatic hypocalcemia, 7.5% had symptoms and 13.5% without data. Trousseau's sign was negative in 68% and positive in 9%. Regarding the pathology, there were 107 benign results, 94 malignant. CONCLUSIONS: 90% were women, 6 out of 10 presented hypocalcemia in the first 72 hours, the vast majority were asymptomatic and had a negative Trousseau sign. There was no correlation between hypocalcaemia with age, sex, duration or time of surgery, or pathology result. The incidence of transient hypoparathyroidism was 75.7% and permanent 7.3%. When there was no transient hypoparathyroidism, there was also no permanent hypoparathyroidism.

Immunoprotection evaluation of the recombinant N-terminal domain of Cys-loop receptors against Rhipicephalus (Boophilus) microplus tick infestation.

Rhipicephalus (Boophilus) microplus ticks are obligatory hematophagous ectoparasites of cattle and act as vectors for disease-causing microorganisms. Conventional tick control is based on the application of chemical acaricides; however, their uncontrolled use has increased resistant tick populations, as well as food and environmental contamination. Alternative immunological tick control has shown to be partially effective. Therefore, there is a need to characterize novel antigens in order to improve immunological protection. The aim of this work was to evaluate Cys-loop receptors as vaccine candidates. N-terminal domains of a glutamate receptor and of a glycine-like receptor were recombinantly produced in Escherichia coli. Groups of BALB/c mice were independently immunized with four doses of each recombinant protein emulsified with Freund's adjuvant. Both vaccine candidates were immunogenic in mice as demonstrated by western blot analysis. Next, recombinant proteins were independently formulated with the adjuvant Montanide ISA 50 V2 and evaluated in cattle infested with Rhipicephalus microplus tick larvae. Groups of three European crossbred calves were immunized with three doses of each adjuvanted protein. ELISA test was used to evaluate the IgG immune response elicited against the recombinant proteins. Results showed that vaccine candidates generated a moderate humoral response on vaccinated cattle. Vaccination significantly affected the number of engorged adult female ticks, having no significant effects on tick weight, egg weight and egg fertility values. Vaccine efficacies of 33% and 25% were calculated for the glutamate receptor and the glycine-like receptor, respectively.

TITLE: Évaluation de l'immunoprotection du domaine N-terminal recombinant des récepteurs Cys-loop contre l'infestation par les tiques Rhipicephalus (Boophilus) microplus. ABSTRACT: Les tiques Rhipicephalus (Boophilus) microplus sont des ectoparasites hématophages obligatoires des bovins et agissent comme vecteurs de micro-organismes pathogènes. Le contrôle conventionnel des tiques est basé sur l'application d'acaricides chimiques, mais leur utilisation incontrôlée a augmenté les populations de tiques résistantes ainsi que la contamination des aliments et de l'environnement. Le contrôle immunologique alternatif des tiques s'est avéré partiellement efficace. Par conséquent, il est nécessaire de caractériser de nouveaux antigènes afin d'améliorer la protection immunologique. Le but de ce travail était d'évaluer les récepteurs Cys-loop comme candidats vaccins. Les domaines N-terminaux d'un récepteur du glutamate et d'un récepteur de type glycine ont été produits par recombinaison chez Escherichia coli. Des groupes de souris BALB/c ont été immunisés indépendamment avec quatre doses de chaque protéine recombinante émulsionnée avec l'adjuvant de Freund. Les deux vaccins candidats étaient immunogènes chez la souris, comme l'a démontré l'analyse par transfert Western. Ensuite, des protéines recombinantes ont été formulées indépendamment avec l'adjuvant Montanide ISA 50 V2 et évaluées chez des bovins infestés de larves de tiques Rhipicephalus microplus. Des groupes de trois veaux croisés européens ont été immunisés avec trois doses de chaque protéine avec adjuvant. Le test ELISA a été utilisé pour évaluer la réponse immunitaire IgG induite contre les protéines recombinantes. Les résultats ont montré que les candidats vaccins généraient une réponse humorale modérée sur les bovins vaccinés. La vaccination a affecté de manière significative le nombre de tiques femelles adultes engorgées mais n'a eu aucun effet significatif sur le poids des tiques, le poids des œufs et les valeurs de fertilité des œufs. Des efficacités vaccinales de 33 % et 25 % ont été calculées pour le récepteur du glutamate et le récepteur de type glycine, respectivement.

Resolvin E1 Regulates Th17 Function and T Cell Activation.

Resolvin E1 (RvE1) is a specialized pro-resolving lipid mediator derived from eicosapentaenoic acid and plays a critical role in resolving inflammation and tissue homeostasis. Th17 cells are a distinct group of T helper (Th) cells with tissue-destructive functions in autoimmune and chronic inflammatory diseases via the secretion of IL-17. Dendritic cell (DC)-mediated antigen presentation regulates the Th17-induced progression of inflammation and tissue destruction. In this study, we hypothesized that the RvE1 would restore homeostatic balance and inflammation by targeting the Th17 function. We designed three experiments to investigate the impact of RvE1 on different phases of Th17 response and the potential role of DCs: First CD4+ T cells were induced by IL-6/TGFß to measure the effect of RvE1 on Th17 differentiation in an inflammatory milieu. Second, we measured the impact of RvE1 on DC-stimulated Th17 differentiation in a co-culture model. Third, we measured the effect of RvE1 on DC maturation. RvE1 blocked the CD25, CCR6 and IL-17 expression; IL-17, IL-21, IL-10, and IL-2 production, suggesting inhibition of T cell activation, Th17 stimulation and chemoattraction. RvE1 also suppressed the activation of DCs by limiting their pro-inflammatory cytokine production. Our findings collectively demonstrated that the RvE1 targeted the Th17 activation and the DC function as a potential mechanism for inflammatory resolution and acquired immune response.

Hexavalent chromium: Regulation and health effects.

Despite the knowledge about heavy metals toxicity on humans, its use is widely spread mainly for industrial processes. Chromium is an element that belongs to this group and although it is present in our daily diet, it can also be harmful for humans, causing skin allergies and increasing the risk of lung cancer, among other health effects reported. In this review, we highlight its nutritional role, its toxicokinetic and toxicodynamic in humans, its regulation in the industry and the biomonitoring proposal of this element in blood and urine samples with the aim to control the level of exposure of the workers in military industry and also of the general population.

COVID-19: enfoque básico para entender sus tratamientos / COVID-19: a basic approach to understanding potential treatments

Resumen El virus SARS-CoV-2 ha sido identificado como el agente patológico causante de la pandemia de COVID-19. Aun cuando no se cuenta con un tratamiento estándar, se han probado antivirales como remdesivir y otros fármacos como cloroquina e ivermectina, que interfieren con la replicación del virus. También se han intentado algunas estrategias encaminadas a disminuir los mecanismos inmunitarios, como el uso de tocilizumab y antioxidantes naturales. Los fármacos relacionados con el sistema renina-angiotensina han resultado controversiales. Aún se debe estudiar con detalle los mecanismos de patogenicidad, así como los tratamientos controlados para proponer alguna opción terapéutica viable que evite la entrada y replicación del virus o que aumente los sistemas inmunitarios del huésped.

Abstract SARS-CoV-2 virus has been identified as the causative agent of the COVID-19 pandemic. Even when no standard treatment is available, antivirals such as remdesivir and other drugs such as chloroquine and ivermectin, which interfere with viral replication, have been assayed. Some strategies aimed to reduce immune mechanisms, such as the use of tocilizumab and natural antioxidants, have also been tested. The use of drugs related to the renin-angiotensin system has been controversial. Pathogenicity mechanisms, as well as controlled treatments, still have to be studied in detail in order to propose a viable therapeutic option that prevents the entry and replication of the virus or enhances the host immune system.

Regulatory T cell phenotype and anti-osteoclastogenic function in experimental periodontitis.

The alveolar bone resorption is a distinctive feature of periodontitis progression and determinant for tooth loss. Regulatory T lymphocytes (Tregs) display immuno-suppressive mechanisms and tissue repairing functions, which are critical to support periodontal health. Tregs may become unstable and dysfunctional under inflammatory conditions, which can even accelerate tissue destruction. In this study, experimental periodontitis was associated with the progressive and increased presence of Th17 and Treg-related mediators in the gingiva (IL-6, IL-17A, IL-17F, RANKL, IL-10, TGF-ß and GITR; P < 0.05), and the proliferation of both Treg and Th17 cells in cervical lymph nodes. Tregs from cervical lymph nodes had reduced Foxp3 expression (> 25% MFI loss) and increased IL-17A expression (> 15%), compared with Tregs from spleen and healthy controls. Tregs gene expression analysis showed a differential signature between health and disease, with increased expression of Th17-associated factors in periodontitis-derived Tregs. The ex vivo suppression capacity of Tregs on osteoclastic differentiation was significantly lower in Tregs obtained from periodontally diseased animals compared to controls (P < 0.05), as identified by the increased number of TRAP+ osteoclasts (P < 0.01) in the Tregs/pre-osteoclast co-cultures. Taken together, these results demonstrate that Tregs become phenotypically unstable and lose anti-osteoclastogenic properties during experimental periodontitis; thus, further promoting the Th17-driven bone loss.

Macrophages skew towards M1 profile through reduced CD163 expression in symptomatic apical periodontitis.

OBJECTIVES: To explore the macrophage profiles in symptomatic and asymptomatic forms of AP through phenotypic and functional analyses. MATERIAL AND METHODS: Cross-sectional study. Apical tissue/lesion samples were collected from patients with clinical diagnosis of AAP (n = 51) or SAP (n = 45) and healthy periodontal ligament (HPL) from healthy patients as controls (n = 14), all with indication of tooth extraction. Samples were digested, cells were stained for CD14, M1 (CD64, CD80), and M2 (CD163, CD206) phenotypic surface markers and analyzed by flow cytometry. Functional cytokine profiles L-6, IL-12, TNF-α, IL-23 (M1), IL-10, and TGF-ß (M2) were determined by qPCR. RESULTS: Higher macrophage M1/M2 ratio (CD64+CD80+/CD163+CD206+) along with lower CD163 mean fluorescence intensity (MFI) were found in SAP compared to AAP and controls (p < 0.05). IL-6, IL-12, TNF-α, IL-23 (M1), and IL-10 mRNA (M2) were upregulated, whereas TGF-ß mRNA (M2) was downregulated in apical lesions compared to controls. Specifically, IL-6 and IL-23 (M1) were upregulated in SAP compared with AAP and controls (p < 0.05). The data were analyzed with Kruskal-Wallis test. CONCLUSIONS: Macrophages exhibited a polarization switch towards M1 in AL. SAP exhibited a reduced M2 differentiation profile based on a reduction of CD163 expression levels in SAP over AAP. Specifically, IL-6 and IL-23 were augmented SAP over AAP, suggesting a role in the severity of apical lesions. CLINICAL RELEVANCE: Deciphering the macrophage polarization and functions in apical periodontitis can contribute to explain AP dynamics, its clinical presentation and systemic impact.

IL-22-expressing CD4+ AhR+ T lymphocytes are associated with RANKL-mediated alveolar bone resorption during experimental periodontitis.

BACKGROUND AND OBJECTIVE: Over the past few years, the importance of interleukin-22 (IL-22) and T-helper (Th)22 lymphocytes in the pathogenesis of periodontitis has become apparent; however, there are still aspects that are not addressed yet. Cells expressing IL-22 and aryl hydrocarbon receptor (AhR), transcription factor master switch gene implicated in the differentiation and function of Th22 lymphocytes, have been detected in periodontal tissues of periodontitis-affected patients. In addition, IL-22 has been associated with osteoclast differentiation and their bone resorptive activity in vitro. However, the destructive potential of IL-22-expressing AhR+ Th22 lymphocytes over periodontal tissues during periodontitis has not been demonstrated in vivo yet. Therefore, this study aimed to analyze whether IL-22-expressing CD4+ AhR+ T lymphocytes detected in periodontal lesions are associated with alveolar bone resorption during experimental periodontitis. MATERIAL AND METHODS: Using a murine model of periodontitis, the expression levels of IL-22 and AhR, as well as the Th1-, Th2-, Th17- and T regulatory-associated cytokines, were analyzed in periodontal lesions using qPCR. The detection of CD4+ IL-22+ AhR+ T lymphocytes was analyzed in periodontal lesions and cervical lymph nodes that drain these periodontal lesions using flow cytometry. In addition, the expression of the osteoclastogenic mediator called receptor activator of nuclear factor-κB ligand (RANKL) was analyzed by qPCR, western blot, and immunohistochemistry. Finally, alveolar bone resorption was analyzed using micro-computed tomography and scanning electron microscopy, and the bone resorption levels were correlated with IL-22 and RANKL expression. RESULTS: Higher levels of IL-22, AhR, and RANKL, as well as IL-1ß, IL-6, IL-12, IL-17, IL-23, and TNF-α, were expressed in periodontal lesions of infected mice compared with periodontal tissues of sham-infected and non-infected controls. Similarly, high RANKL immunoreaction was observed in periodontal tissues of infected mice; however, few or absent RANKL immunoreaction was observed in controls. This association between RANKL and periodontal infection was ratified by western blot. Furthermore, a higher detection of CD4+ IL-22+ AhR+ T lymphocytes was found in periodontal lesions and cervical lymph nodes that drain these periodontal lesions in infected mice compared with non-infected controls. Finally, the increased IL-22 and RANKL expression showed positive correlation between them and with the augmented alveolar bone resorption observed in experimental periodontal lesions. CONCLUSION: This study demonstrates the increase of IL-22-expressing CD4+ AhR+ T lymphocytes in periodontitis-affected tissues and shows a positive correlation between IL-22, RANKL expression, and alveolar bone resorption.

Immunostimulatory activity of low-molecular-weight hyaluronan on dendritic cells stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis.

OBJECTIVES: Periodontitis is a chronic inflammatory disease characterized by tooth-supporting tissue destruction, which is elicited by the host's immune response triggered against periodonto-pathogen bacteria. During periodontal tissue destruction, extracellular matrix components are metabolized and fragmented. Some extracellular matrix component-derived fragments, such as low-molecular-weight hyaluronan (LMW-HA), have potent immunogenic potential, playing a role as damage-associated molecular patterns (DAMPs) during activation of immune cells. Dendritic cells (DCs) play a central role in the host's immune response displayed during periodontitis; thus, this study aimed to analyze whether LMW-HA has an immunostimulatory activity on DCs when stimulated with periodonto-pathogen bacteria. MATERIALS AND METHODS: LMW-HA-treated and non-treated DCs were stimulated with Aggregatibacter actinomycetemcomitans or Porphyromonas gingivalis and the mRNA expression for cytokines tumor necrosis factor-α (TNF-alpha), interleukin-1ß (IL-1B), interleukin-6 (IL-6), and interleukin-23 (IL-23A) was quantified by RT-qPCR. In addition, transcription factors interferon regulatory factor 4 (IRF4), interferon regulatory factor 8 (IRF8), neurogenic locus notch homolog protein 2 (NOTCH2), and basic leucine zipper ATF-like transcription factor 3 (BATF3), involved in DC activation, were analyzed. RESULTS: Higher expression levels of TNF-alpha, IL-1B, IL-6, and IL-23A were detected in LMW-HA-treated DCs after bacterial infection, as compared with non-treated DCs. When LMW-HA-treated DCs were infected with A. actinomycetemcomitans, higher levels of IRF4, NOTCH2, and BATF3 were detected compared with non-treated cells; whereas against P. gingivalis infection, increased levels of IRF4 and NOTCH2 were detected. CONCLUSION: LMW-HA plays an immunostimulatory role on the immune response triggered by DCs during infection with A. actinomycetemcomitans or P. gingivalis. CLINICAL RELEVANCE: Detection of extracellular matrix component-derived fragments produced during periodontal tissue destruction, such as LMW-HA, could explain at least partly unsuccessful periodontal treatment and the chronicity of the disease.

Regulatory T Lymphocytes in Periodontitis: A Translational View.

Periodontitis is a chronic immuno-inflammatory disease in which the disruption of the balance between host and microbiota interactions is key to the onset and progression of the disease. The immune homeostasis associated with periodontal health requires a regulated immuno-inflammatory response, during which the presence of regulatory T cells (Tregs) is essential to ensure a controlled response that minimizes collateral tissue damage. Since Tregs modulate both innate and adaptive immunity, pathological conditions that may resolve by the acquisition of immuno-tolerance, such as periodontitis, may benefit by the use of Treg immunotherapy. In recent years, many strategies have been proposed to take advantage of the immuno-suppressive capabilities of Tregs as immunotherapy, including the ex vivo and in vivo manipulation of the Treg compartment. Ongoing research in both basic and translational studies let us gain a better understanding of the diversity of Treg subsets, their phenotypic plasticity, and suppressive functions, which can be used as a substrate for new immunotherapies. Certainly, as our knowledge of Treg biology increases, we will be capable to develop new therapies designed to enhance the stability and function of Tregs during periodontitis.

Mesenchymal stem cells and their immunosuppressive role in transplantation tolerance.

Since they were first described, mesenchymal stem cells (MSCs) have been shown to have important effector mechanisms and the potential for use in cell therapy. A great deal of research has been focused on unveiling how MSCs contribute to anti-inflammatory responses, including describing several cell populations involved and identifying soluble and other effector molecules. In this review, we discuss some of the contemporary evidence for use of MSCs in the field of immune tolerance, with a special emphasis on transplantation. Although considerable effort has been devoted to understanding the biological function of MSCs, additional resources are required to clarify the mechanisms of their induction of immune tolerance, which will undoubtedly lead to improved clinical outcomes for MSC-based therapies.