Breast milk-mediated exposure to dioxins and antigen in infancy enhances antigen-specific antibody production capacity in adulthood in mice.

The immune system is sensitive to many chemicals. Among dioxin compounds, 2,3,7,8-tetrachlorodizenzo-p-dioxin (TCDD) is the most toxic environmental pollutant. The effects of perinatal maternal exposure to dioxins may persist into childhood. However, there have been no reports to date on the effects of exposure to dioxins during infancy, when the immune organs are developing. Therefore, we investigated the effects of TCDD and antigen exposure during lactation on immune function, especially antibody production capacity, in adult mice. Beginning the day after delivery, lactating mothers were orally administered TCDD or a mixture of TCDD and ovalbumin (OVA) daily for 4 weeks, until the pups were weaned. At 6 weeks of age, progeny mice were orally administered OVA daily for 10 weeks, while non-progeny mice were orally administered OVA or a mixture of TCDD and OVA daily for 10 weeks. Production of serum OVA-specific IgG was examined weekly. The amount of TCDD transferred from the mother to the progeny via breast milk was determined by measuring TCDD in the gastric contents of the progeny. A trend toward increasing IgA titer was observed in TCDD-treated mice, and production of IgE was observed only in progeny whose mothers were treated with TCDD and OVA. The results suggest that exposure to TCDD and OVA in breast milk can affect immune function in newborns.

Disulfiram treatment suppresses antibody-producing reactions by inhibiting macrophage activation and B cell pyrimidine metabolism.

Antibody responses, involving B cells, CD4 + T cells, and macrophages, are implicated in autoimmune diseases and organ transplant rejection. We have previously shown that inhibiting FROUNT with disulfiram (DSF) suppresses macrophage activation and migration, effectively treating inflammatory diseases. In this study, we investigated the effectiveness of DSF in antibody-producing reactions. Using a heart transplantation mouse model with antibody-mediated rejection, we administered anti-CD8 antibody to exclude cellular rejection. DSF directly inhibited B cell responses in vitro and significantly reduced plasma donor-specific antibodies and graft antibody deposition in vivo, resulting in prolonged survival of the heart graft. DSF also mediated various effects, including decreased macrophage infiltration and increased Foxp3+ regulatory T-cells in the grafts. Additionally, DSF inhibited pyrimidine metabolism-related gene expression induced by B-cell stimulation. These findings demonstrate that DSF modulates antibody production in the immune response complexity by regulating B-cell and macrophage responses.

Sleep deprivation reduced LPS-induced IgG2b production by up-regulating BMAL1 and CLOCK expression.

Sleep deprivation (SD) weakens the immune system and leads to increased susceptibility to infectious or inflammatory diseases. However, it is still unclear how SD affects humoral immunity. In the present study, sleep disturbance was conducted using an sleep deprivation instrument, and the bacterial endotoxin lipopolysaccharide (LPS) was used to activate the immune response. It was found that SD-pretreatment reduced LPS-induced IgG2b+ B cells and IgG2b isotype antibody production in lymphocytes of spleen. And, SD-pretreatment decreased the proportion of CD4+T cells, production of CD4+T cells derived TGF-ß1 and its contribution in helping IgG2b production. Additionally, BMAL1 and CLOCK were selectively up-regulated in lymphocytes after SD. Importantly, BMAL1 and CLOCK deficiency contributed to TGF-ß1 expression and production of IgG2b+ B cells. Thus, our results provide a novel insight to explain the involvement of BMAL1 and CLOCK under SD stress condition, and their roles in inhibiting TGF-ß1 expression and contributing to reduction of LPS induced IgG2b production.

Comparison of antibody responses after the 1st and 2nd doses of COVID-19 vaccine with those of patients with mild or severe COVID-19.

BACKGROUND/AIMS: Data comparing the antibody responses of different coronavirus disease 2019 (COVID-19) vaccine platforms according to dose with natural severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection-induced antibody responses are limited. METHODS: Blood samples from adult patients with mild and severe COVID-19 and healthcare workers who received ChAdOx1 nCoV-19 vaccine (2nd dose at 12-week intervals) and BNT162b2 vaccine (2nd dose at 3-week intervals) were collected and compared by immunoglobulin G immune responses to SARS-CoV-2 specific spike protein using an in-house-developed enzyme-linked immunosorbent assay. RESULTS: A total of 53 patients, including 12 and 41 with mild and severe COVID-19, respectively, were analyzed. In addition, a total of 73 healthcare workers, including 37 who received ChAdOx1 nCoV-19 and 36 who received BNT162b2, were enrolled. Antibody responses after the first and second doses of the ChAdOx1 nCoV-19 vaccine or the first dose of the BNT162b2 vaccine were similar to those in convalescent patients with mild COVID-19, but lower than those in convalescent patients with severe COVID-19, respectively. However, after the second dose of the BNT162b2 vaccine, the antibody response was comparable to that in convalescent patients with severe COVID-19. CONCLUSION: Our data suggest that the second dose of mRNA vaccination may be more beneficial in terms of long-term immunity and prevention of SARS-CoV-2 variant infection than a single dose of COVID-19 vaccination or homologous second challenge ChAdOx1 nCoV-19.

Mucosal Vaccination With Recombinant Tm-WAP49 Protein Induces Protective Humoral and Cellular Immunity Against Experimental Trichuriasis in AKR Mice.

Trichuriasis is one of the most common neglected tropical diseases of the world's poorest people. A recombinant vaccine composed of Tm-WAP49, an immunodominant antigen secreted by adult Trichuris stichocytes into the mucosa of the cecum to which the parasite attaches, is under development. The prototype is being evaluated in a mouse model of Trichuris muris infection, with the ultimate goal of producing a mucosal vaccine through intranasal delivery. Intranasal immunization of mice with Tm-WAP49 formulated with the adjuvant OCH, a truncated analog of alpha-GalCer with adjuvanticity to stimulate natural killer T cells (NKT) and mucosal immunity, induced significantly high levels of IgG and its subclasses (IgG1 and IgG2a) in immunized mice. This also resulted in a significant reduction of worm burden after challenge with T. muris-infective eggs. The addition of QS-21 adjuvant to this vaccine formulation further reduced worm counts. The improved protection from the dual-adjuvanted vaccine correlated with higher serum antibody responses (IgG, IgG1, IgG2a, IgA) as well as with the induction of antigen-specific IgA in the nasal mucosa. It was also associated with the robust cellular responses including functional subsets of CD4 T cells producing IL-4, and cytotoxic CD8 T cells expressing granzyme B. The worm reduction achieved by mucosal immunization was higher than that induced by subcutaneous immunization. Intranasal immunization also induced a significantly higher nasal mucosa-secreted antigen-specific IgA response, as well as higher functional cellular responses including CD4+IL4+ (Th1) and CD8+GnzB+ (Th2) T cells, and antigen-specific INFγ-producing T cells in both spleen and MLNs and antibody-producing B cells (CD19+B220+/B220+GL7+). Mucosal immunization further induced long-term T lymphocyte memory with increased central (CD62L+CD44+) and effector (CD62L-CD44+) memory subsets of both CD4 and CD8 T cells at 60 days after the last immunization. In summary, intranasal immunization with recombinant Tm-WAP49 protein induced strong protection versus murine trichuriasis. It represents a promising vaccination approach against intestinal nematodes.

Toxicity of high-molecular-weight polyethylene glycols in Sprague Dawley rats.

Polyethylene glycol (PEG) is present in a variety of products. Little is known regarding the accumulation of high-molecular-weight PEGs or the long-term effects resulting from PEG accumulation in certain tissues, especially the choroid plexus. We evaluated the toxicity of high-molecular-weight PEGs administered to Sprague Dawley rats. Groups of 12 rats per sex were administered subcutaneous injections of 20, 40, or 60 kDa PEG or intravenous injections of 60 kDa PEG at 100 mg PEG/kg body weight/injection once a week for 24 weeks. A significant decrease in triglycerides occurred in the 60 kDa PEG groups. PEG treatment led to a molecular-weight-related increase in PEG in plasma and a low level of PEG in cerebrospinal fluid. PEG was excreted in urine and feces, with a molecular-weight-related decrease in the urinary excretion. A higher prevalence of anti-PEG IgM was observed in PEG groups; anti-PEG IgG was not detected. PEG treatment produced a molecular-weight-related increase in vacuolation in the spleen, lymph nodes, lungs, and ovaries/testes, without an inflammatory response. Mast cell infiltration at the application site was noted in all PEG-treated groups. These data indicate that subcutaneous and intravenous exposure to high-molecular-weight PEGs produces anti-PEG IgM antibody responses and tissue vacuolation without inflammation.

Determinants of early antibody responses to COVID-19 mRNA vaccines in a cohort of exposed and naïve healthcare workers.

BACKGROUND: Two doses of mRNA vaccination have shown >94% efficacy at preventing COVID-19 mostly in naïve adults, but it is not clear if the second dose is needed to maximize effectiveness in those previously exposed to SARS-CoV-2 and what other factors affect responsiveness. METHODS: We measured IgA, IgG and IgM levels against SARS-CoV-2 spike (S) and nucleocapsid (N) antigens from the wild-type and S from the Alpha, Beta and Gamma variants of concern, after BNT162b2 (Pfizer/BioNTech) or mRNA-1273 (Moderna) vaccination in a cohort of health care workers (N=578). Neutralizing capacity and antibody avidity were evaluated. Data were analyzed in relation to COVID-19 history, comorbidities, vaccine doses, brand and adverse events. FINDINGS: Vaccination induced robust IgA and IgG levels against all S antigens. Neutralization capacity and S IgA and IgG levels were higher in mRNA-1273 vaccinees, previously SARS-CoV-2 exposed, particularly if symptomatic, and in those experiencing systemic adverse effects (p<0·05). A second dose in pre-exposed did not increase antibody levels. Smoking and comorbidities were associated with 43% (95% CI, 19-59) and 45% (95% CI, 63-18) lower neutralization, respectively, and 35% (95% CI, 3-57%) and 55% (95% CI, 33-70%) lower antibody levels, respectively. Among fully vaccinated, 6·3% breakthroughs were detected up to 189 days post-vaccination. Among pre-exposed non-vaccinated, 90% were IgG seropositive more than 300 days post-infection. INTERPRETATION: Our data support administering a single-dose in pre-exposed healthy individuals as primary vaccination. However, heterogeneity of responses suggests that personalized recommendations may be necessary depending on COVID-19 history and life-style. Higher mRNA-1273 immunogenicity would be beneficial for those expected to respond worse to vaccination and in face of variants that escape immunity such as Omicron. Persistence of antibody levels in pre-exposed unvaccinated indicates maintenance of immunity up to one year. FUNDING: This work was supported by Institut de Salut Global de Barcelona (ISGlobal) internal funds, in-kind contributions from Hospital Clínic de Barcelona, the Fundació Privada Daniel Bravo Andreu, and European Institute of Innovation and Technology (EIT) Health (grant number 20877), supported by the European Institute of Innovation and Technology, a body of the European Union receiving support from the H2020 Research and Innovation Programme. We acknowledge support from the Spanish Ministry of Science and Innovation and State Research Agency through the "Centro de Excelencia Severo Ochoa 2019-2023" Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program. L. I. work was supported by PID2019-110810RB-I00 grant from the Spanish Ministry of Science & Innovation. Development of SARS-CoV-2 reagents was partially supported by the National Institute of Allergy and Infectious Diseases Centers of Excellence for Influenza Research and Surveillance (contract number HHSN272201400008C). The funders had no role in study design, data collection and analysis, the decision to publish, or the preparation of the manuscript.

Oligosaccharide equine feed supplement, Immulix, has minor impact on vaccine responses in mice.

Several mammalian species are vaccinated in early life, but little is known about the effect of diet on vaccine response. Oligosaccharides are increasingly proposed as dietary supplement for young individuals due to their anti-inflammatory potential elicited through modulation of gut microbiota (GM). Also, diet, e.g. the size of the fat fraction, is known to modulate the GM. We tested if an oligosaccharide diet (Immulix) and/or increased dietary fat content affected antibody titers to a tetanus vaccine in 48 BALB/cJTac mice through GM modulation. Female mice had significantly higher IgG titers with higher variation compared to male mice. The effects of Immulix and/or increased fat content were minor. Immulix negatively affected IgG titers in male mice four weeks after secondary vaccination but upregulated Il1b gene expression in the spleen. Immulix had a downregulating effect on expression of Cd4 and Foxp3 in ileum only if the mice were fed the diet with increased fat. The diet with increased dietary fat increased Il1b but decreased Cd8a gene expression in the spleen. Immulix and diet affected GM composition significantly. Increased dietary fat content upregulated Lactobacillus animalis but downregulated an unclassified Prevotella spp. Immulix decreased Lactobacillales, Streptococcaceae and Prevotellaceae but increased Bacteroides. It is concluded that in spite of some minor influences on immune cell markers, cytokines and IgG titers Immulix feeding or increased dietary fat content did not have any biologically relevant effects on tetanus vaccine responses in this experiment in mice.

Antibiotic use differentially affects the risk of anti-drug antibody formation during anti-TNFα therapy in inflammatory bowel disease patients: a report from the epi-IIRN.

OBJECTIVE: Anti-drug antibodies (ADA) to anti-tumour necrosis factor (anti-TNF) therapy drive treatment loss of response. An association between intestinal microbial composition and response to anti-TNF therapy was noted. We therefore aimed to assess the implications of antibiotic treatments on ADA formation in patients with inflammatory bowel disease (IBD). DESIGN: We analysed data from the epi-IIRN (epidemiology group of the Israeli IBD research nucleus), a nationwide registry of all patients with IBD in Israel. We included all patients treated with anti-TNF who had available ADA levels. Survival analysis with drug use as time varying covariates were used to assess the association between antibiotic use and ADA development. Next, specific pathogen and germ-free C57BL mice were treated with respective antibiotics and challenged with infliximab. ADA were assessed after 14 days. RESULTS: Among 1946 eligible patients, with a median follow-up of 651 days from initiation of therapy, 363 had positive ADA. Cox proportional hazard model demonstrated an increased risk of ADA development in patients who used cephalosporins (HR=1.97, 95% CI 1.58 to 2.44), or penicillins with ß-lactamase inhibitors (penicillin-BLI, HR=1.4, 95% CI 1.13 to 1.74), whereas a reduced risk was noted in patients treated with macrolides (HR=0.38, 95% CI 0.16 to 0.86) or fluoroquinolones (HR=0.20, 95% CI 0.12 to 0.35). In mice exposed to infliximab, significantly increased ADA production was observed in cephalosporin as compared with macrolide pretreated mice. Germ-free mice produced no ADA. CONCLUSION: ADA production is associated with the microbial composition. The risk of ADA development during anti-TNF therapy can possibly be reduced by avoidance of cephalosporins and penicillin-BLIs, or by treatment with fluoroquinolones or macrolides.

Quercetin ameliorates ochratoxin A-Induced immunotoxicity in broiler chickens by modulation of PI3K/AKT pathway.

Ochratoxin A (OTA) is a fungal secondary metabolite produced by certain species of Aspergillus and Penicillium, and exerts immunosuppressive effect on humans and animals. Quercetin (QUE) is one of the flavonoids produced as a plant-secondary metabolite. The present study was designed to evaluate the efficacy of QUE against the immunotoxic hazard of OTA in broiler chickens. Forty one-day-old broiler chicks were randomly and equally allocated into four groups; control, OTA (0.5 mg/kg feed), QUE (0.5 g/kg feed) and OTA + QUE (0.5 mg/kg OTA + 0.5 g/kg QUE). The results revealed that dietary OTA induced a significant decrease in the antibody response to Newcastle Disease (ND), Infectious Bronchitis (IB) and Avian Influenza (AI) vaccination and in the lymphoproliferative response to Phytohemagglutinin-P (PHA-P). Ochratoxin A also induced oxidative stress and lipid peroxidation in the bursa of Fabricius, spleen and thymus tissues of chickens as demonstrated by decreased CAT and GSH levels and increased TBARS content. In addition, administration of OTA resulted in apoptosis, which was evident by the increased expression level of PTEN, Bax and Caspase-3 genes and decreased expression level of PI3K, AKT and Bcl-2 genes. Furthermore, exposure to OTA resulted in various pathological lesions in the bursa of Fabricius, spleen and thymus of chickens. On the other hand, administration of QUE ameliorated most of the immunotoxic effects of OTAby its immunomodulatory, antioxidant and anti-apoptotic activities. Taken together, the results suggested that QUE potentially alleviated the OTA-induced immunotoxicity in broiler chickens, probably through amelioration of oxidative stress and activation of the PI3K/AKT signaling pathway.

An analysis of antibody responses and clinical sequalae of the Sinopharm HB02 COVID19 vaccine in dialysis patients in the United Arab Emirates.

AIM: To establish the responses to the Sinopharm HB02 COVID-19 vaccination in the dialysis population, which are not well established. We examined the humoral responses to the Sinopharm COVID vaccine in haemodialysis patients. METHODS: Standard vaccinations (two doses at interval of ~21 days) were given to all consenting haemodialysis patients on dialysis (n = 1296). We measured the antibody responses at 14-21 days after the second vaccine to define the development of anti-spike antibodies >15 AU/ml after vaccination and observed the clinical effects of vaccination. RESULTS: Vaccination was very well tolerated with few side-effects. In those who consented to antibody measurements, (n = 446) baseline sampling showed 77 had positive antibodies, yet received full vaccination without any apparent adverse events. Positive anti-spike antibodies developed in 50% of the 270 baseline negative patients who had full sampling, compared with 78.1% in the general population. COVID infection continues to occur in both vaccinated and unvaccinated individuals, but in the whole group vaccination appears to have been associated with a reduction in the case fatality rate. CONCLUSION: The humoral immune responses to standard HB02 vaccination schedules are attenuated in a haemodialysis cohort, but likely the vaccine saves lives. We suggest that an enhanced HB02 vaccination course or antibody checking may be prudent to protect this vulnerable group of patients. We suggest a booster dose of this vaccine at 3 months should be given to all dialysis patients, on the grounds that it is well tolerated even in those with good antibody levels and there may be a survival advantage.

Efficacy and safety of heterologous booster vaccination with Ad26.COV2.S after BNT162b2 mRNA COVID-19 vaccine in haemato-oncological patients with no antibody response.

Patients with haemato-oncological malignancies are one of the high-risk groups for a severe course in case of COVID-19 infections. Furthermore, vaccination results in significantly lower response rates in haematological malignancies and lower antibody levels in patients with solid cancer. We investigated efficacy and safety of a heterologous booster vaccination with Ad26.COV2.S DNA vector vaccine in haemato-oncological patients without antibody response after double-dose BNT162b2 messenger (m-)RNA COVID-19 vaccine. A total of 32 haemato-oncological non-responders to double-dose BNT162b2 received a heterologous booster vaccination with Ad26.COV2.S. Blood samples were assessed directly before the vaccination (T0) and four weeks after (T1). Safety assessment was performed using a standardised questionnaire. The overall response rate was 31%, with a mean (SD) antibody titre of 693·79 (1 096·99) binding activity units (BAU)/ml. Patients with chronic lymphocytic leukaemia or lymphoma showed a significantly lower response rate (P = 0·048). Adverse events were reported in 29·6% of patients, of which 7·1% were graded as severe, including grade III and IV events following the Common Terminology Criteria of Adverse Events (CTCAE). The heterologous booster vaccination with Ad26.COV2.S led to a serological response in nine out of 29 patients without response after double-dose BNT162b2. Furthermore, the vaccination was safe in our cohort, leading to mainly mild local and systemic reactions. Overall, this vaccination regimen should be further evaluated to increase the response rate in the highly vulnerable population of haemato-oncological patients.

The immunomodulatory effect of koumine on B cells under dependent and independent responses by T cells.

Dysregulated activation of polyclonal B cells and production of pathogenic antibodies are involved in the development of rheumatoid arthritis (RA). Therefore, targeted B cell therapy is effective against RA. Gelsemium elegans (Gardn. & Champ.) Benth., a toxic plant widely distributed in Southeast Asia, has been used for treating rheumatoid pain, neuropathic pain, spasticity, skin ulcers, and cancers for many years in traditional Chinese medicine. Koumine, an alkaloid monomer from Gelsemium elegans Benth., exerts therapeutic effects against RA. However, whether koumine affects B cells remains unknown. In this study, the effect of koumine on B cells under T cell-independent (TI) and T cell-dependent (TD) immune responses is investigated in vitro and in vivo. Mouse primary B cells were obtained by immunomagnetic bead sorting, and immunomodulatory effects of koumine on the activation, proliferation, and differentiation of B cells were determined in TI and TD models induced by lipopolysaccharide (LPS) and anti-CD40 antibodies in vitro, respectively. The humoral immune responses of TI and TD were established using NP-AECM-FICOLL and NP-CGG in C57BL/6J mice, respectively. We found that koumine inhibited B cell differentiation in the TI model and inhibited B cell activation and proliferation in the TD model in vitro. Koumine also inhibited antibody secretion in TI immune response, TD initial immune response, and in TD secondary immune response. Our results reveal that koumine has a direct and indirect immune regulatory effect on B cells, showing that it can directly inhibit the differentiation and secretion of autoantibodies after abnormal activation of B cells, and indirectly inhibit the activation and proliferation of TD B cells to reduce the secretion of antibodies. It may be an important mechanism for its anti-RA effect in mice, providing a rationale and laboratory data support for the application of koumine in anti-human RA therapy.

Different adjuvanted pediatric HIV envelope vaccines induced distinct plasma antibody responses despite similar B cell receptor repertoires in infant rhesus macaques.

Different HIV vaccine regimens elicit distinct plasma antibody responses in both human and nonhuman primate models. Previous studies in human and non-human primate infants showed that adjuvants influenced the quality of plasma antibody responses induced by pediatric HIV envelope vaccine regimens. We recently reported that use of the 3M052-SE adjuvant and longer intervals between vaccinations are associated with higher magnitude of antibody responses in infant rhesus macaques. However, the impact of different adjuvants in HIV vaccine regimens on the developing infant B cell receptor (BCR) repertoire has not been studied. This study evaluated whether pediatric HIV envelope vaccine regimens with different adjuvants induced distinct antigen-specific memory B cell repertoires and whether specific immunoglobulin (Ig) immunogenetic characteristics are associated with higher magnitude of plasma antibody responses in vaccinated infant rhesus macaques. We utilized archived preclinical pediatric HIV vaccine studies PBMCs and tissue samples from 19 infant rhesus macaques immunized either with (i) HIV Env protein with a squalene adjuvant, (ii) MVA-HIV and Env protein co-administered using a 3-week interval, (iii) MVA-HIV prime/ protein boost with an extended 6-week interval between immunizations, or (iv) with HIV Env administered with 3M-052-SE adjuvant. Frequencies of vaccine-elicited HIV Env-specific memory B cells from PBMCs and tissues were similar across vaccination groups (frequency range of 0.06-1.72%). There was no association between vaccine-elicited antigen-specific memory B cell frequencies and plasma antibody titer or avidity. Moreover, the epitope specificity and Ig immunogenetic features of vaccine-elicited monoclonal antibodies did not differ between the different vaccine regimens. These data suggest that pediatric HIV envelope vaccine candidates with different adjuvants that previously induced higher magnitude and quality of plasma antibody responses in infant rhesus macaques were not driven by distinct antigen-specific memory BCR repertoires.

Assessment of the Optimum Linker Tethering Site of Alternariol Haptens for Antibody Generation and Immunoassay Development.

Immunochemical methods for mycotoxin analysis require antigens with well-defined structures and antibodies with outstanding binding properties. Immunoreagents for the mycotoxins alternariol and/or alternariol monomethyl ether have typically been obtained with chemically uncharacterized haptens, and antigen conjugates have most likely been prepared with mixtures of functionalized molecules. For the first time, total synthesis was performed, in the present study, to obtain two haptens with opposite linker attachment locations. The functionalized synthetic haptens were purified and deeply characterized by different spectrometric methods, allowing the preparation of bioconjugates with unequivocal structures. Direct and indirect competitive enzyme-linked immunosorbent assays, using homologous and heterologous conjugates, were employed to extensively evaluate the generated immunoreagents. Antibodies with high affinity were raised from conjugates of both haptens, and a structure-activity relationship between the synthetic haptens and the specificity of the generated antibodies could be established. These results pave the way for the development of novel highly sensitive immunoassays selective of one or two of these Alternaria mycotoxins.

Design, Synthesis, and Biological Evaluation of Desmuramyl Dipeptides Modified by Adamantyl-1,2,3-triazole.

Muramyl dipeptide (MDP) is the smallest peptidoglycan fragment able to trigger the immune response. Structural modification of MDP can lead to the preparation of analogs with improved immunostimulant properties, including desmuramyl peptides (DMPs). The aim of this work was to prepare the desmuramyl peptide (L-Ala-D-Glu)-containing adamantyl-triazole moiety and its mannosylated derivative in order to study their immunomodulatory activities in vivo. The adjuvant activity of the prepared compounds was evaluated in a murine model using ovalbumin as an antigen, and compared to the reference adjuvant ManAdDMP. The results showed that the introduction of the lipophilic adamantyl-triazole moiety at the C-terminus of L-Ala-D-Glu contributes to the immunostimulant activity of DMP, and that mannosylation of DMP modified with adamantyl-triazole causes the amplification of its immunostimulant activity.

Role of interleukin-6 in antigen-specific mucosal immunoglobulin A induction by cationic liposomes.

The COVID-19 pandemic, caused by a highly virulent and transmissible pathogen, has proven to be devastating to society. Mucosal vaccines that can induce antigen-specific immune responses in both the systemic and mucosal compartments are considered an effective measure to overcome infectious diseases caused by pathogenic microbes. We have recently developed a nasal vaccine system using cationic liposomes composed of 1,2-dioleoyl-3-trimethylammonium-propane and cholesteryl 3ß-N-(dimethylaminoethyl)carbamate in mice. However, the comprehensive molecular mechanism(s), especially the host soluble mediator involved in this process, by which cationic liposomes promote antigen-specific mucosal immune responses, remain to be elucidated. Herein, we show that intranasal administration of cationic liposomes elicited interleukin-6 (IL-6) expression at the site of administration. Additionally, both nasal passages and splenocytes from mice nasally immunized with cationic liposomes plus ovalbumin (OVA) were polarized to produce IL-6 when re-stimulated with OVA in vitro. Furthermore, pretreatment with anti-IL-6R antibody, which blocks the biological activities of IL-6, attenuated the production of OVA-specific nasal immunoglobulin A (IgA) but not OVA-specific serum immunoglobulin G (IgG) responses. In this study, we demonstrated that IL-6, exerted by nasally administered cationic liposomes, plays a crucial role in antigen-specific IgA induction.

Production and persistence of specific antibodies in COVID-19 patients with hematologic malignancies: role of rituximab.

The ability of patients with hematologic malignancies (HM) to develop an effective humoral immune response after COVID-19 is unknown. A prospective study was performed to monitor the immune response to SARS-CoV-2 of patients with follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), chronic lymphoproliferative disorders (CLD), multiple myeloma (MM), or myelodysplastic/myeloproliferative syndromes (MDS/MPN). Antibody (Ab) levels to the SARS-CoV-2 nucleocapsid (N) and spike (S) protein were measured at +1, +3, +6 months after nasal swabs became PCR-negative. Forty-five patients (9 FL, 8 DLBCL, 8 CLD, 10 MM, 10 MDS/MPS) and 18 controls were studied. Mean anti-N and anti-S-Ab levels were similar between HM patients and controls, and shared the same behavior, with anti-N Ab levels declining at +6 months and anti-S-Ab remaining stable. Seroconversion rates were lower in HM patients than in controls. In lymphoma patients mean Ab levels and seroconversion rates were lower than in other HM patients, primarily because all nine patients who had received rituximab within 6 months before COVID-19 failed to produce anti-N and anti-S-Ab. Only one patient requiring hematological treatment after COVID-19 lost seropositivity after 6 months. No reinfections were observed. These results may inform vaccination policies and clinical management of HM patients.

Safety, immunogenicity and efficacy of PfSPZ Vaccine against malaria in infants in western Kenya: a double-blind, randomized, placebo-controlled phase 2 trial.

The radiation-attenuated Plasmodium falciparum sporozoite (PfSPZ) vaccine provides protection against P. falciparum infection in malaria-naïve adults. Preclinical studies show that T cell-mediated immunity is required for protection and is readily induced in humans after vaccination. However, previous malaria exposure can limit immune responses and vaccine efficacy (VE) in adults. We hypothesized that infants with less previous exposure to malaria would have improved immunity and protection. We conducted a multi-arm, randomized, double-blind, placebo-controlled trial in 336 infants aged 5-12 months to determine the safety, tolerability, immunogenicity and efficacy of the PfSPZ Vaccine in infants in a high-transmission malaria setting in western Kenya ( NCT02687373 ). Groups of 84 infants each received 4.5 × 105, 9.0 × 105 or 1.8 × 106 PfSPZ Vaccine or saline three times at 8-week intervals. The vaccine was well tolerated; 52 (20.6%) children in the vaccine groups and 20 (23.8%) in the placebo group experienced related solicited adverse events (AEs) within 28 d postvaccination and most were mild. There was 1 grade 3-related solicited AE in the vaccine group (0.4%) and 2 in the placebo group (2.4%). Seizures were more common in the highest-dose group (14.3%) compared to 6.0% of controls, with most being attributed to malaria. There was no significant protection against P. falciparum infection in any dose group at 6 months (VE in the 9.0 × 105 dose group = -6.5%, P = 0.598, the primary statistical end point of the study). VE against clinical malaria 3 months after the last dose in the highest-dose group was 45.8% (P = 0.027), an exploratory end point. There was a dose-dependent increase in antibody responses that correlated with VE at 6 months in the lowest- and highest-dose groups. T cell responses were undetectable across all dose groups. Detection of Vδ2+Vγ9+ T cells, which have been correlated with induction of PfSPZ Vaccine T cell immunity and protection in adults, were infrequent. These data suggest that PfSPZ Vaccine-induced T cell immunity is age-dependent and may be influenced by Vδ2+Vγ9+ T cell frequency. Since there was no significant VE at 6 months in these infants, these vaccine regimens will likely not be pursued further in this age group.