Primary Antibody Response Research Articles

Local Inflammatory and Systemic Antibody Responses Initiated by a First Intradermal Administration of Autogenous Salmonella-Killed Vaccines and Their Components in Pullets

Vaccination strategies are used to manage Salmonella in chickens. Salmonella-killed vaccines are considered safer since they are inactivated. However, little is known regarding the cellular immune activities at the site of vaccine administration of Salmonella-killed vaccines. The growing feather (GF) cutaneous test has been shown to be an effective bioassay to monitor local tissue/cellular responses. We assessed local and systemic antibody responses initiated by intradermal injection of Salmonella-killed vaccines into GF-pulps of 14–15-week-old pullets. Treatments consisted of two autogenous Salmonella-killed vaccines (SV1 and SV2), S. Enteritidis (SE) lipopolysaccharide (SE-LPS), and the water-oil-water (WOW) emulsion vehicle. GF-pulps were collected before (0 h) and at 6, 24, 48, and 72 h post-GF-pulp injection for leukocyte population analysis, while heparinized blood samples were collected before (0 d) and at 3, 5, 7, 10, 14, 21, and 28 d after GF-pulp injections to assess plasma levels (a.u.) of SE-specific IgM, avian IgY (IgG), and IgA antibodies using an ELISA. Injection of GF-pulps with SV1, SV2, or SE-LPS, all in a WOW vehicle, initiated inflammatory responses characterized by the recruitment of heterophils, monocytes/macrophages, and a few lymphocytes. The WOW vehicle emulsion alone recruited more lymphocytes than vaccines or SE-LPS. The SV1 and SV2 vaccines stimulated Salmonella-specific IgM and IgA early, while IgG levels were greatly elevated later during the primary response. Overall, SV1 and SV2 stimulated a heterophil and macrophage-dominated local inflammatory- and SE-specific humoral response with an isotype switch from IgM to IgG, characteristic of a T-dependent primary antibody response. This study provides comprehensive information on innate and adaptive immune responses to autogenous Salmonella-killed vaccines and their components that will find application in the management of Salmonella in poultry.

The ICF2 gene Zbtb24 specifically regulates the differentiation of B1 cells via promoting heme synthesis

BackgroundLoss-of-function mutations of ZBTB24 cause immunodeficiency, centromeric instability, and facial anomalies syndrome 2 (ICF2). ICF2 is a rare autosomal recessive disorder with immunological defects in serum antibodies and circulating memory B cells, resulting in recurrent and sometimes fatal respiratory and gastrointestinal infections. The genotype–phenotype correlation in patients with ICF2 indicates an essential role of ZBTB24 in the terminal differentiation of B cells.MethodsWe used the clustered regularly interspaced short palindromic repeats (CRISPER)/Cas9 technology to generate B cell specific Zbtb24-deficient mice and verified the deletion specificity and efficiency by quantitative polymerase chain reaction (Q-PCR) and western blotting analyses in fluorescence-activated cell sorting (FACS)-sorted cells. The development, phenotype of B cells and in vivo responses to T cell dependent or independent antigens post immunization were analyzed by flow cytometry and enzyme-linked immunosorbent assay (ELISA). Adoptive transfer experiment in combination with in vitro cultures of FACS-purified B cells and RNA-Seq analysis were utilized to specifically determine the impact of Zbtb24 on B cell biology as well as the underlying mechanisms.ResultsZbtb24 is dispensable for B cell development and maintenance in naive mice. Surprisingly, B cell specific deletion of Zbtb24 does not evidently compromise germinal center reactions and the resulting primary and secondary antibody responses induced by T cell dependent antigens (TD-Ags), but significantly inhibits T cell independent antigen-elicited antibody productions in vivo. At the cellular level, Zbtb24-deficiency specifically impedes the plasma cell differentiation of B1 cells without impairing their survival, activation and proliferation in vitro. Mechanistically, Zbtb24-ablation attenuates heme biosynthesis partially through mTORC1 in B1 cells, and addition of exogenous hemin abrogates the differentiation defects of Zbtb24-null B1 cells.ConclusionsZbtb24 seems to regulate antibody responses against TD-Ags B cell extrinsically, but it specifically promotes the plasma cell differentiation of B1 cells via heme synthesis in mice. Our study also suggests that defected B1 functions contribute to recurrent infections in patients with ICF2.

EFFECT OF LEAD AND CADMIUM ON IMMUNITY OF TWO VACCINES

This study was performed to investigate the effect of lead exposure on resistance of mice immunized against haemorrhagic septicaemia and challenged with virulent organisms. Lead treated mice showed greater susceptibility to challenge with P. multucida than control especially if lead nitrate is administered orally. this result showed that treatment with lead initials resistance of mice and might interferes with the vaccination programs. Cadmium chloride (cd) injected into rabbits at various time intervals in relation to tetanus toxoid injection was found to have some effect on the immune response. A reduction in the primary immune response was detected in case if (cd) is given two weeks prior to toxoid injection. On the other hand, enhancement of secondary antibody titers was detected. Cadmium reduced both primary and secondary antibody response if it is given seven days before immunization.

TRPV1 nociceptors are required to optimize antigen-specific primary antibody responses to novel antigens

BackgroundKey to the advancement of the field of bioelectronic medicine is the identification of novel pathways of neural regulation of immune function. Sensory neurons (termed nociceptors) recognize harmful stimuli and initiate a protective response by eliciting pain and defensive behavior. Nociceptors also interact with immune cells to regulate host defense and inflammatory responses. However, it is still unclear whether nociceptors participate in regulating primary IgG antibody responses to novel antigens.MethodsTo understand the role of transient receptor potential vanilloid 1 (TRPV1)-expressing neurons in IgG responses, we generated TRPV1-Cre/Rosa-ChannelRhodopsin2 mice for precise optogenetic activation of TRPV1 + neurons and TRPV1-Cre/Lox-diphtheria toxin A mice for targeted ablation of TRPV1-expressing neurons. Antigen-specific antibody responses were longitudinally monitored for 28 days.ResultsHere we show that TRPV1 expressing neurons are required to develop an antigen-specific immune response. We demonstrate that selective optogenetic stimulation of TRPV1+ nociceptors during immunization significantly enhances primary IgG antibody responses to novel antigens. Further, mice rendered deficient in TRPV1- expressing nociceptors fail to develop primary IgG antibody responses to keyhole limpet hemocyanin or haptenated antigen.ConclusionThis functional and genetic evidence indicates a critical role for nociceptor TRPV1 in antigen-specific primary antibody responses to novel antigens. These results also support consideration of potential therapeutic manipulation of nociceptor pathways using bioelectronic devices to enhance immune responses to foreign antigens.

Endogenous complement-activating IgM is not required for primary antibody responses but promotes plasma cell differentiation and secondary antibody responses to a large particulate antigen in mice.

Lack of complement factor C1q of the classical pathway results in severely impaired primary antibody responses. This is a paradox because antibodies, especially IgM, are the most efficient activators of the classical pathway and very little specific IgM will be present at priming. A possible explanation would be that natural IgM, binding with low affinity to the antigen, may suffice to activate complement. In support of this, mice lacking secretory IgM have an impaired antibody response, which can be rescued by transfer of non-immune IgM. Moreover, passive administration of specific IgM together with antigen enhances the antibody response in a complement-dependent fashion. To test the idea, we have used a knock-in mouse strain (Cμ13) carrying a point mutation in the IgM heavy chain, rendering the IgM unable to activate complement. Mutant mice backcrossed to BALB/c or C57BL/6 background were primed and boosted with a low dose of sheep red blood cells. Confirming earlier data, no impairment in early, primary IgM- or IgG-responses were seen in either of the Cμ13 strains. However, in one of the mutant strains, late primary IgG responses were impaired. A more pronounced effect was observed after boost, when the IgG response, the number of germinal center B cells and antibody secreting cells as well as the opsonization of antigen were impaired in mutant mice. We conclude that complement activation by natural IgM cannot explain the role of C1q in primary antibody responses, but that endogenous, specific, wildtype IgM generated after immunization feedback-enhances the response to a booster dose of antigen. Importantly, this mechanism can only partially explain the role of complement in the generation of antibody responses because the IgG response was much lower in C3- or complement receptor 1 and 2-deficient mice than in Cμ13 mice.

Quantifying the impact of PFOA Exposure on B cell development and antibody production.

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals; the vast majority are environmentally and biologically persistent, and some have demonstrated toxicity, including cancer, effects on metabolism, endocrine disruption, and immune dysfunction. Suppression of T-cell dependent antibody responses (TDAR) has been observed in numerous studies of PFAS but mechanisms remain elusive. Evidence from our work suggests that B cells and how they use energy are impacted by PFAS exposure. We hypothesize that a well-studied and immunotoxic PFAS, perfluorooctanoic acid (PFOA), alters B cell subclasses and markers of their metabolism. Adult male and female C57BL/6 mice were given PFOA (0 or 7.5 mg/kg) via gavage for 15 days, a duration and dose sufficient to suppress the TDAR. After dosing and immunization of subgroups, spleens were prepared to quantify B cell subsets. Flow cytometric analysis revealed decreased numbers of plasmablasts, follicular, naïve, and overall B cell subclasses in female PFOA-exposed groups. Male PFOA-exposed groups had a significant increase in follicular B cells and other subsets had decreases, including in the overall number of B cells. Twenty-four hours after naïve B cell isolation and ex vivo activation, metabolic measurements revealed a five-fold increase in metabolic markers in response to stimulation in PFOA-exposed groups compared to controls. These findings suggest that B cell development and survival may be hindered by PFOA exposure, but that activation of the remaining B cells was not. Based on these findings, PFOA mediated suppression of the primary IgM antibody response results changes to specific subsets of B cells.

T cell immunity following COVID-19 vaccination in adult patients with primary antibody deficiency - a 22-month follow-up.

Primary antibody deficiencies, such as common variable immunodeficiency (CVID), are heterogenous disease entities consisting of primary hypogammaglobulinemia and impaired antibody responses to vaccination and natural infection. CVID is the most common primary immunodeficiency in adults, presenting with recurrent bacterial infections, enteropathy, autoimmune disorders, interstitial lung diseases and increased risk of malignancies. Patients with CVID are recommended to be vaccinated against SARS-CoV-2, but there are relatively few studies investigating humoral and cellular responses to immunization. We studied the dynamics of humoral and cell-mediated immunity responses up to 22 months in 28 patients with primary immunodeficiency and three patients with secondary immunodeficiency receiving ChAdOx1, BNT162b2 and mRNA-1273 COVID-19 vaccines. Despite inadequate humoral response to immunization, we demonstrate a robust T cell activation likely protecting from severe COVID-19.

Characterization of the primary antibody response to Plasmodium falciparum antigens in infants living in a malaria-endemic area

BackgroundThe primary antibody (Ab) response to Plasmodium falciparum is a critical step in developing immunity to malaria. Information on the initial Ab responses of babies in malaria-endemic areas is incomplete, in part, because babies receive maternal IgG via transplacental-transfer and usually become infected before maternal IgG wanes. The study aimed to identify the primary IgM and IgG Ab responses to malarial antigens in Cameroonian babies.MethodsInfants (n = 70) living in a high malaria transmission area were followed from birth throughout the first year of life (mean 341 ± 42 days, an average of 8.5 time points per infant). Malaria infection was assessed by microscopy and PCR, and IgM and IgG antibodies (Abs) were measured using a multiplex immunoassay to AMA1, EBA-175, MSP1-42, MSP2, MSP3, RESA, LSA1, and CSP.ResultsThe half-life of maternal IgG varied among the antigens, ranging from 0.7 to 2.5 months. The first infection of 41% of the babies was sub-microscopic and only 11 to 44% of the babies produced IgM to the above antigens; however, when the first infection was detected by microscopy, 59–82% of the infants made IgM Abs to the antigens. Infants were able to produce IgM even when maternal IgG was present, suggesting maternal Abs did not suppress the baby’s initial Ab response. Using longitudinal regression models that incorporated time-varying covariates, infants were found to produce IgG Ab to only AMA-1 when the first infection was sub-microscopic, but they produced IgG Abs to MSP1-42 (3D7, FVO), AMA1 (3D7, FVO) MSP2-FC27, MSP3, RESA, and LSA1, but not MSP 2-3D7, EBA-175, and CSP during their first slide-positive infection. Notably, the primary and secondary IgG responses were short-lived with little evidence of boosting.ConclusionsThe primary Ab response of babies who had maternal IgG was similar to that reported for primary infections in malaria-naïve adults.

Primary antibody response after influenza virus infection is first dominated by low-mutated HA-stem antibodies followed by higher-mutated HA-head antibodies.

Several studies have shown that the first encounter with influenza virus shapes the immune response to future infections or vaccinations. However, a detailed analysis of the primary antibody response is lacking as this is difficult to study in humans. It is therefore not known what the frequency and dynamics of the strain-specific hemagglutinin (HA) head- and stem-directed antibody responses are directly after primary influenza virus infection. Here, sera of twelve H1N1pdm2009 influenza virus-infected cynomolgus macaques were evaluated for HA-head and HA-stem domain antibody responses. We observed an early induction of HA-stem antibody responses, which was already decreased by day 56. In contrast, responses against the HA-head domain were low early after infection and increased at later timepoint. The HA-specific B cell repertoires in each animal showed diverse VH-gene usage with preferred VH-gene and JH-gene family usage for HA-head or HA-stem B cells but a highly diverse allelic variation within the VH-usage. HA-head B cells had shorter CDRH3s and higher VH-gene somatic hyper mutation levels relative to HA-stem B cells. In conclusion, our data suggest that HA-stem antibodies are the first to react to the infection while HA-head antibodies show a delayed response, but a greater propensity to enter the germinal center and undergo affinity maturation.

Infant Antibody Repertoires during the First Two Years of Influenza Vaccination.

The first encounter with influenza virus biases later immune responses. This "immune imprinting," formerly from infection within a few years of birth, is in the United States now largely from immunization with a quadrivalent, split vaccine (IIV4 [quadrivalent inactivated influenza vaccine]). In a pilot study of IIV4 imprinting, we used single-cell cultures, next-generation sequencing, and plasma antibody proteomics to characterize the primary antibody responses to influenza in two infants during their first 2 years of seasonal influenza vaccination. One infant, who received only a single vaccination in year 1, contracted an influenza B virus (IBV) infection between the 2 years, allowing us to compare imprinting by infection and vaccination. That infant had a shift in hemagglutinin (HA)-reactive B cell specificity from largely influenza A virus (IAV) specific in year 1 to IBV specific in year 2, both before and after the year 2 vaccination. HA-reactive B cells from the other infant maintained a more evenly distributed specificity. In year 2, class-switched HA-specific B cell IGHV somatic hypermutation (SHM) levels reached the average levels seen in adults. The HA-reactive plasma antibody repertoires of both infants comprised a relatively small number of antibody clonotypes, with one or two very abundant clonotypes. Thus, after the year 2 boost, both infants had overall B cell profiles that resembled those of adult controls. IMPORTANCE Influenza virus is a moving target for the immune system. Variants emerge that escape protection from antibodies elicited by a previously circulating variant ("antigenic drift"). The immune system usually responds to a drifted influenza virus by mutating existing antibodies rather than by producing entirely new ones. Thus, immune memory of the earliest influenza virus exposure has a major influence on later responses to infection or vaccination ("immune imprinting"). In the many studies of influenza immunity in adult subjects, imprinting has been from an early infection, since only in the past 2 decades have infants received influenza immunizations. The work reported in this paper is a pilot study of imprinting by the flu vaccine in two infants, who received the vaccine before experiencing an influenza virus infection. The results suggest that a quadrivalent (four-subtype) vaccine may provide an immune imprint less dominated by one subtype than does a monovalent infection.

Adjuvant effect of mesoporous silica SBA-15 on anti-diphtheria and anti-tetanus humoral immune response

Routine immunization against diphtheria and tetanus has drastically reduced the incidence of these diseases worldwide. Anti-diphtheria/tetanus vaccine has in general aluminum salt as adjuvant in its formulation that can produce several adverse effects. There is a growing interest in developing new adjuvants. In this study, we evaluated the efficiency of SBA-15 as an adjuvant in subcutaneous immunization in mice with diphtheria (dANA) and tetanus (tANA) anatoxins as well as with the mixture of them (dtANA). The tANA molecules and their encapsulation in SBA-15 were characterized using Small-Angle X-ray Scattering (SAXS), Dynamical Light Scattering (DLS), Nitrogen Adsorption Isotherm (NAI), Conventional Circular Dichroism (CD)/Synchrotron Radiation Circular Dichroism (SRCD) Spectroscopy, and Tryptophan Fluorescence Spectroscopy (FS). The primary and secondary antibody response elicited by subcutaneous immunization of High (HIII) and Low (LIII) antibody responder mice with dANA, tANA, or dtANA encapsulated in the SBA-15 were determined. We demonstrated that SBA-15 increases the immunogenicity of dANA and tANA antigens, especially when administered in combination. We also verified that SBA-15 modulates the antibody response of LIII mice, turning them into high antibody responder. Thus, these results suggest that SBA-15 may be an effective adjuvant for different vaccine formulations.

Early human B cell signatures of the primary antibody response to mRNA vaccination

Messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are highly effective at inducing protective immunity. However, weak antibody responses are seen in some individuals, and cellular correlates of immunity remain poorly defined, especially for B cells. Here we used unbiased approaches to longitudinally dissect primary antibody, plasmablast, and memory B cell (MBC) responses to the two-dose mRNA-1273 vaccine in SARS-CoV-2-naive adults. Coordinated immunoglobulin A (IgA) and IgG antibody responses were preceded by bursts of spike-specific plasmablasts after both doses but earlier and more intensely after dose 2. While antibody and B cell cellular responses were generally robust, they also varied within the cohort and decreased over time after a dose-2 peak. Both antigen-nonspecific postvaccination plasmablast frequency after dose 1 and their spike-specific counterparts early after dose 2 correlated with subsequent antibody levels. This correlation between early plasmablasts and antibodies remained for titers measured at 6 months after vaccination. Several distinct antigen-specific MBC populations emerged postvaccination with varying kinetics, including two MBC populations that correlated with 2- and 6-month antibody titers. Both were IgG-expressing MBCs: one less mature, appearing as a correlate after the first dose, while the other MBC correlate showed a more mature and resting phenotype, emerging as a correlate later after dose 2. This latter MBC was also a major contributor to the sustained spike-specific MBC response observed at month 6. Thus, these plasmablasts and MBCs that emerged after both the first and second doses with distinct kinetics are potential determinants of the magnitude and durability of antibodies in response to mRNA-based vaccination.

Innate Immune Responses and P. falciparum CS Repeat-Specific Neutralizing Antibodies Following Vaccination by Skin Scarification.

The skin is the site of host invasion by the mosquito-borne Plasmodium parasite, which caused an estimated 229 million infections and 409,000 deaths in 2019 according to WHO World Malaria report 2020. In our previous studies, we have shown that skin scarification (SS) with a P. falciparum circumsporozoite (CS) peptide in the oil-in-water adjuvant AddaVax containing a combination of TLR 7/8 and TLR 9 agonists can elicit sporozoite neutralizing antibodies. SS with AddaVax + TLR agonists, but not AddaVax alone, elicited CD4+ Th1 cells and IgG2a/c anti-repeat antibody. To explore the innate immune responses that may contribute to development of adaptive immunity following SS, we examined the skin at 4h and 24h post priming with CS peptide in AddaVax with or without TLR agonists. H&E stained and IHC-labeled dorsal skin sections obtained 24h post SS demonstrated a marked difference in the pattern of infiltration with F4/80+, CD11b+ and Ly6G+ cells at the immunization site, with the lowest intensity noted following SS with AddaVax + TLR agonists. Serum collected at 4h post SS, had reproducible increases in IL-6, MIP-3α, IL-22 and IP-10 (CXCL10) following SS with AddaVax + TLR agonists, but not with AddaVax alone. To begin to decipher the complex roles of these pro-inflammatory cytokines/chemokines, we utilized IP-10 deficient (IP-10 -/-) mice to examine the role of this chemokine in the development of anti-repeat antibody response following SS. In the absence of IP-10, the levels of Th1-type IgG2a/c antibody and kinetics of the primary anti-repeat antibody response were reduced following prime and boost. The IP-10 chemokine, present as early as 4h post prime, may provide an early serological marker for rapid screening of adjuvant formulations and delivery platforms to optimize SS-induced humoral immunity to CS repeats as well as other pathogens.

The Effect of Rapamycin and Ibrutinib on Antibody Responses to Adeno-Associated Virus Vector-Mediated Gene Transfer.

Adeno-associated virus (AAV) vector-mediated gene transfer is lessening the impact of monogenetic disorders. Human AAV gene therapy recipients commonly mount immune responses to AAV or the encoded therapeutic protein, which requires transient immunosuppression. Most efforts to date have focused on blunting AAV capsid-specific T cell responses, which have been implicated in elimination of AAV-transduced cells. Here, we explore the use of immunosuppressants, rapamycin given alone or in combination with ibrutinib to inhibit AAV vector- or transgene product-specific antibody responses. Our results show that rapamycin or ibrutinib given alone reduces primary antibody responses against AAV capsid, but the combination of rapamycin and ibrutinib is more effective, blunts recall responses, and reduces numbers of circulating antibody-secreting plasma cells. The drugs fail to lower B cell memory formation or to reduce the inhibitory effects of pre-existing AAV capsid-specific antibodies on transduction efficiency.

Preclinical Immunopharmacologic Assessment of KPL-404, a Novel, Humanized, Non-Depleting Antagonistic Anti-CD40 Monoclonal Antibody

The CD40/CD40L pathway plays a major role in multiple inflammatory processes involving different immune and stromal cells. Abnormal activation of this pathway has been implicated in pathogenesis of complex autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, Graves' disease, and Sjogren's Syndrome. We completed in vitro and in vivo preclinical characterization of KPL-404, a novel humanized anti-CD40 IgG4 monoclonal antibody, to demonstrate its potency, efficacy, and pharmacokinetic profile; safety was also assessed. In vitro, KPL-404 bound recombinant human and cynomolgus monkey CD40 with comparable affinity in the nanomolar range. KPL-404 binding to cell surface CD40 did not induce antibody- or complement-mediated cytotoxicity of CD40-expressing cells. Pharmacological antagonistic activity of KPL-404 was demonstrated in vitro by inhibition of CD40-mediated downstream NF-kB activation. In the in vivo study with cynomolgus monkeys, KPL-404, administered intravenously as a single dose (10 mg/kg) or two monthly doses of 1 or 5 mg/kg, did not elicit observable safety findings, including thrombocytopenia over 8 weeks. KPL-404 engaged CD40 expressed on peripheral B cells for 2 and 4 weeks after a single administration of 5 or 10 mg/kg IV, respectively, without depletion of peripheral B cells. At 5 mg/kg IV, KPL-404 blocked both primary and secondary responses to T-cell dependent antibody responses to test antigens, KLH, and tetanus toxoid. These data illustrated the relationship between KPL-404 serum concentration and pharmacodynamic effects of CD40-targeting in circulation and in lymphoid tissues. These data support clinical development of KPL-404 in autoimmune diseases. SIGNIFICANCE STATEMENT: We aimed to develop a potent and efficacious CD40 antagonist. In vitro and in vivo findings show that KPL-404 blocks the anti-CD40 antibody that potently inhibits primary and secondary antibody responses at pharmacologically relevant concentrations, has a favorable pharmacokinetic profile, and does not deplete B cells by antibody-dependent cellular cytotoxicity or apoptosis ("nondepleting"). These findings support clinical development of KPL-404 as a potential therapeutic in autoimmune diseases.

Primary Immune Responses and Affinity Maturation Are Controlled by IgD.

Mature B cells co-express IgM and IgD B cell antigen receptors (BCR) on their surface. While IgM BCR expression is already essential at early stages of development, the role of the IgD-class BCR remains unclear as most B cell functions appeared unchanged in IgD-deficient mice. Here, we show that IgD-deficient mice have an accelerated rate of B cell responsiveness as they activate antibody production within 24h after immunization, whereas wildtype (WT) animals required 3 days to activate primary antibody responses. Strikingly, soluble monovalent antigen suppresses IgG antibody production induced by multivalent antigen in WT mice. In contrast, IgD-deficient mice were not able to modulate IgG responses suggesting that IgD controls the activation rate of B cells and subsequent antibody production by sensing and distinguishing antigen-valences. Using an insulin-derived peptide we tested the role of IgD in autoimmunity. We show that primary autoreactive antibody responses are generated in WT and in IgD-deficient mice. However, insulin-specific autoantibodies were detected earlier and caused more severe symptoms of autoimmune diabetes in IgD-deficient mice as compared to WT mice. The rapid control of autoimmune diabetes in WT animals was associated with the generation of high-affinity IgM that protects insulin from autoimmune degradation. In IgD-deficient mice, however, the generation of high-affinity protective IgM is delayed resulting in prolonged autoimmune diabetes. Our data suggest that IgD is required for the transition from primary, highly autoreactive, to secondary antigen-specific antibody responses generated by affinity maturation.

Environmental exposure to cadmium reduces the primary antibody-mediated response of wood mice (Apodemus sylvaticus) from differentially polluted locations in the Netherlands

The Wood mouse (Apodemus sylvaticus) is a widespread mammalian species that acts as a reservoir host for multiple infections, including zoonotic diseases. Exposure to immunotoxins, like for instance trace metals, may reduce the ability of the host to mount proper responses to pathogens, potentially increasing the transmission and prevalence of infections. Antibody-mediated responses are crucial in preventing and limiting infections, and the quantification of the primary antibody response is considered a sensitive predictor of immunosuppression. The current study aims to investigate effects of cadmium exposure on the antibody-mediated responses of wood mice inhabiting polluted and non-polluted areas in the Netherlands. Wood mice were captured alive at different locations and immunized to sheep red blood cells (SRBC) to induce a primary antibody response. SRBC-specific antibody-producing cells, or plaque forming cells (PFC), were quantified and related to kidney cadmium levels. Differential circulating main leukocyte populations were also characterised. Cadmium concentrations in mice kidneys differed between mice captured at different locations, and increased with individual body mass, likely associated with age-related time of exposure. Effect of cadmium was apparent on the percentages of B cell counts in blood. Because of potential natural immune heterogeneity between wild rodent populations, mice immune responses were analysed and compared grouped by captured locations. Capture location had significant effect on the total counts of white blood cells. Increasing cadmium exposure in wood mice captured from polluted sites was associated with a decrease of splenic PFC counts. This field research shows that wood mice antibody responses can be impaired by cadmium exposure, even at low environmental levels, by affecting B cell functioning mainly. Impaired B cell function can make exposed mice more susceptible to infections, potentially increasing the reservoir function of their populations. It also shows that immunomodulatory effects in the field should be assessed site specifically.

Effect of Abelmoschus ficulneus (L.) Wight & Arn. on immunomodulation: in vivo experimental animal models

BackgroundAbelmoschus ficulneus (L.) Wight & Arn. (Malvaceae) commonly known as herb in the Ayurveda, Indian traditional medicine system. Herb is reported as a Rasayana that has the potential to produce immunomodulatory effects. In the present study, the immunomodulatory effect of aqueous (AEAF) and ethanolic (EEAF) leaves extract of A. ficulneus (L.) Wight & Arn. in different experimental animal models were evaluated.ResultsAcute oral toxicity shows that both extracts have wide range of safety as per OECD 420 guidelines. Quantitative and qualitative analysis was evaluated by performing preliminary phytochemical screening, thin layer chromatography and high-performance thin layer chromatography developed for simultaneous quantification of flavonoids (quercetin) in both the extracts. Oral administration of A. ficulneus L. extracts showed a significant increase in the primary and secondary humoral antibody responses against cyclophosamide (100 mg/kg) induced immunosuppression, by significantly increasing (p < 0.05) the hemagglutinating antibody titre at dose of 200 mg/kg/p.o. and also significantly (p < 0.05) potentiated delayed type hypersensitivity reaction induced by sheep red blood cells. There was a significant (p < 0.05) increase in the phagocytic index, percentage neutrophil adhesion and significantly prevented the mortality induced by bovine Pasteurella multocida in mice when compared with control group. Result findings shows that both the extracts have ability to inhibit immunosuppression induced by cyclophosamide.ConclusionStudy finding shows that AEAF and EEAF (at dose 200 mg/kg) extracts exerts immunostimulatory effects on specific and nonspecific immune system thus chemical constituents of herbal extracts may have applications as an effective immunotherapeutic agent and its potential application in the treatment of immune-related diseases.

Formulation Approach that Enables the Coating of a Stable Influenza Vaccine on a Transdermal Microneedle Patch.

A trivalent influenza split vaccine was formulated at high concentration for coating on the transdermal microneedle system. Monovalent vaccine bulks of three influenza strains, two influenza A strains, and one B strain were diafiltrated, concentrated, and lyophilized. The lyophilized powder of each vaccine strain was separately reconstituted and subsequently combined into a coating formulation of high concentration trivalent vaccine. The formulation process converted the monovalent vaccine bulks with low hemagglutinin (HA) concentrations 0.1 mg/mL into a viscous, emulsion containing HA at ~50 mg/mL. This physically stable emulsion demonstrated viscosity 1 poise and 30° contact angle for effective, homogeneous coating on each microneedle. Evaluation of the vaccine antigen HA by SRID and SDS-PAGE/Western blot showed that HA remained stable throughout the vaccine transdermal microneedle system manufacturing process and 1-year ambient storage (25°C). Anti-influenza antibody responses were evaluated by ELISA and hemagglutination inhibition (HAI) assay after primary and booster immunization with the vaccine-coated transdermal microneedle systems at either 25-μg or 40-μg total HA. The results showed the induction of serum anti-influenza IgG and anti-HA neutralizing antibodies after primary immunization and significant titer rises after booster immunization for both doses, indicating the dry-coated trivalent vaccine delivered by transdermal microneedle system elicited both primary and recall antibody responses against all three antigen strains. The study demonstrates that the transdermal microneedle system provides an attractive alternative for influenza vaccine delivery with key advantages such as preservative-free and room-temperature storage.

TRPV1+ Neurons are Required for Antigen‐Specific Immune Responses

The lung is densely innervated by sensory neurons expressing nociceptors including transient receptor potential vanilloid channel 1 (TRPV1+). Nociceptors detect and respond to pathogen-associated molecular patterns and other inflammatory mediators. However, the function of nociceptors in regulating lung antigen-specific immune responses is unknown. Here, using chemogenetic mice we reveal sensory nociceptor fibers expressing TRPV1+ are required for efficient antigen-specific immune responses. Chemogenetics enable temporal control of neuron activity using Designer Receptors Exclusively Activated by Designer Drugs (DREADD). Inhibitory G protein (Gi-DREADD) is a modified muscarinic acetylcholine receptor that binds the ligand, clozapine-N-oxide (CNO), which triggers inhibitory G protein signaling to inhibit neuronal excitability. To selectively silence TRPV1+ nociceptors, we generated TRPV1-Gi-DREADD mice to transiently inhibit neuronal activity specifically in TRPV1+ neurons. CNO or Vehicle was administered intraperitoneally to TRPV1-Gi-DREADD mice 30 minutes prior to intratracheal immunization with 4-Hydroxy-3-nitrophenylacetyl hapten coupled to ovalbumin (NP27-OVA). Chemogenetic inhibition of TRPV1+ neurons, before primary immunization, significantly diminishes NP-specific antibody responses. We observe a significant reduction in NP-specific IgG in mice receiving CNO as compared to vehicle controls at 14 days post-immunization (Anti-NP IgG1 U/mL, Mean ± SEM, D14: vehicle, 120,877 ± 29,519, n=10 versus CNO, 42,525 ± 14,641, n=11, ** p=0.0017). These results indicate TRPV1+ sensory neurons are required to initiate primary antibody responses to novel antigens. These findings offer significant new insights into the biological mechanisms of vaccination.