Production Of IgM Antibodies Research Articles

The effect of Sea urchin (Diadema setosum) gonad extract on IgM and IgG antibodies production in BALB/c mice infected by Salmonella typhi

Background: Salmonella typhi infection decreases of the immune system and influences the adaptive antibodies among malnourished children. The gonad of Diadema setosum (D. setosum) is one of food sources from marine biota that contains high-quality nutrients and potentially can be used as a dietary supplement for typhoid fever condition.Objective: This study aimed to determine the effect of gonad D. setosum extract on the production of antibody IgM and IgG in an animal model.Method: This experimental study was used BALB/c mice before and after infected Salmonella typhi through intraperitoneally at 0.2 mL x the unit 103 CFU/mL. The level of IgM and IgG production was measured by Enzyme Linked Immune Sorbent Assay (ELISA). Experimental animals were divided into 2 groups. The control group was only fed with standard diets, while at the intervention group received the extract of D. setosum gonad in two doses (100 and 200 mg/kg body weight).Results: Production of IgM antibodies in the control group significantly increased twofold (p=0.001) whereas the intervention group received the extracts of D. setosum gonad (200 mg/kg body weight) could suppress the increase in IgM antibody production and indicate the highest increase of IgG antibody significantly (p<0.05) at day 7.Conclusion: The gonad of Diadema setosum extracts (200 mg/kg body weight) could suppress the increase in IgM antibody productions and indicate the highest increase of IgG antibody titers in mice infected with Salmonella typhi. The role of anti-microbial substances of the gonad of Diadema setosum, is potential to be utilized as dietary supplement to increase body immune system among patients infected by Salmonella typhi.

Differential effects of experimental hyperthyroidism on declined immunity of broiler chicken.

Thyroid hormones (THs) are involved in the development of lymphoid organs and regulation of immune function in birds. However, their role as an immune-modulator in the hyperthyroid state is still debatable. To explore the interrelationship of thyroxine (T4 ) and the immune system, chicks were divided into three groups. Group I was comprised of control birds, who received the basal diet while group II and III were given diets supplemented with 5μg and 10μg thyroxine/kg feed, respectively, from 15 to 28days of age. Cell-mediated immune response was evaluated through in vitro abdominal macrophage phagocytosis assay, macrophage nitric oxide (NO) production, heterophil-to-lymphocyte (H:L) ratio and delayed-type hypersensitivity response against phytohemagglutinin (PHA). Humoural immune response was assessed through serum IgG and IgM antibody production against sheep red blood cells (SRBCs) and antibody production against infectious bronchitis virus (IBV). Sampling was carried out at 7, 14 and 21days of treatment. Results have shown higher levels (p<.001) of circulating T4 in both treatment groups compared to the control group. There was a lower (p<.05) macrophage engulfment percentage, an increase in H:L ratio (p<.001) in treated birds, while their NO production remained higher (p<.05) in thyroxine supplemented groups after bacterial lipopolysaccharide stimulation. The humoural immune response revealed a significant decline (p<.001) in IgG, IgM antibody production against SRBCs but IBV circulating antibodies increased with age. In conclusion, hyperthyroidism has a strong co-relation with decreased immune performance of birds.

Immunization with gingipain A hemagglutinin domain of Porphyromonas gingivalis induces IgM antibodies binding to malondialdehyde-acetaldehyde modified low-density lipoprotein.

Treatment of periodontitis has beneficial effects on systemic inflammation markers that relate to progression of atherosclerosis. We aimed to investigate whether immunization with A hemagglutinin domain (Rgp44) of Porphyromonas gingivalis (Pg), a major etiologic agent of periodontitis, would lead to an antibody response cross-reacting with oxidized low-density lipoprotein (OxLDL) and how it would affect the progression of atherosclerosis in low-density lipoprotein receptor-deficient (LDLR-/-) mice. The data revealed a prominent IgM but not IgG response to malondialdehyde-acetaldehyde modified LDL (MAA-LDL) after Rgp44 and Pg immunizations, implying that Rgp44/Pg and MAA adducts may share cross-reactive epitopes that prompt IgM antibody production and consequently confer atheroprotection. A significant negative association was observed between atherosclerotic lesion and plasma IgA to Rgp44 in Rgp44 immunized mice, supporting further the anti-atherogenic effect of Rgp44 immunization. Plasma IgA levels to Rgp44 and to Pg in both Rgp44- and Pg-immunized mice were significantly higher than those in saline control, suggesting that IgA to Rgp44 could be a surrogate marker of immunization in Pg-immunized mice. Distinct antibody responses in plasma IgA levels to MAA-LDL, to Pg lipopolysaccharides (Pg-LPS), and to phosphocholine (PCho) were observed after Rgp44 and Pg immunizations, indicating that different immunogenic components between Rpg44 and Pg may behave differently in regard of their roles in the development of atherosclerosis. Immunization with Rgp44 also displayed atheroprotective features in modulation of plaque size through association with plasma levels of IL-1α whereas whole Pg bacteria achieved through regulation of anti-inflammatory cytokine levels of IL-5 and IL-10. The present study may contribute to refining therapeutic approaches aiming to modulate immune responses and inflammatory/anti-inflammatory processes in atherosclerosis.

Nevada desert dust with heavy metals suppresses IgM antibody production.

Systemic health effects from exposure to a complex natural dust containing heavy metals from the Nellis Dunes Recreation Area (NDRA) near Las Vegas, NV, were evaluated. Several toxicological parameters were examined following lung exposure to emissive dust from three geologic sediment types heavily used for recreational off-road activities: yellow sand very rich in arsenic (termed CBN 5); a shallow cover of loose dune sand overlying a gravelly subsoil bordering dune fields (termed CBN 6); and brown claystone and siltstone (termed CBN 7). Adult female B6C3F1 mice were exposed by oropharyngeal administration to these three types of geogenic dusts at 0.01-100 mg of dust/kg of body weight, once per week for four weeks. The median grain sizes were 4.6, 3.1, and 4.4 μm, for CBN 5, 6, and 7, respectively. Each type of dust contained quantifiable amounts of aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Descriptive markers of immunotoxicity, neurotoxicity, hematology, and clinical chemistry parameters were assessed. Notable among all three CBN units was a systemic, dose-responsive decrease in antigen-specific IgM antibody responses. Geogenic dust from CBN 5 produced more than a 70% suppression in IgM responses, establishing a lowest adverse effect level (LOAEL) of 0.01 mg/kg. A suppression in IgM responses and a corresponding increase in serum creatinine determined a LOAEL of 0.01 mg/kg for CBN 6. The LOAEL for CBN 7 was 0.1 mg/kg and also was identified from suppression in IgM responses. These results are of concern given the frequent off-road vehicle traffic and high visitor rates at the NDRA, estimated at 300,000 each year.

Canonical Stimulation of the NLRP3 Inflammasome by Fungal Antigens Links Innate and Adaptive B-Lymphocyte Responses by Modulating IL-1β and IgM Production.

The NLRP3 inflammasome is activated in response to different bacterial, viral, and fungal pathogens and serves as modulator of different pattern recognition receptors signaling pathways. One of the main functions of NLRP3 is to participate in IL-1β maturation which is important in the host defense against Pneumocystis and other fungal infections. However, dysregulation of NLRP3 and IL-1β secretion are also implicated in the pathophysiology of many auto-inflammatory disorders. Often time’s inflammatory flares are preceded by infectious illnesses questioning the role of infection in autoimmune exacerbations. However, we still do not fully understand the exact role that infection or even colonization plays as a trigger of inflammation. Herein, we investigated the role of NLRP3 in circulating B-lymphocytes following activation with two major microbial antigens (β-glucan and CpG). NLRP3 was determined essential in two independent B-lymphocytes processes: pro-inflammatory cytokine secretion and antibody regulation. Our results show that the β-glucan fungal cell wall carbohydrate stimulated B-lymphocytes to secrete IL-1β in a process partially mediated by Dectin-1 activation via SYK and the transcription factors NF-κB and AP-1. This IL-1β secretion was regulated by the NLRP3 inflammasome and was dependent on potassium efflux and Caspase-1. Interestingly, B-lymphocytes activated by unmethylated CpG motifs, found in bacterial and fungal DNA, failed to induce IL-1β. However, B-lymphocyte stimulation by CpG resulted in NLRP3 and Caspase-1 activation and the production and secretion of IgM antibodies. Furthermore, CpG-stimulated IgM secretion, unlike β-glucan-mediated IL-1β production, was mediated by the mammalian target of rapamycin (mTOR). Inhibition of NLRP3 and the mTOR pathway in CpG activated B-lymphocytes resulted in impaired IgM secretion suggesting their participation in antibody regulation. In conclusion, this study describes a differential response of NLRP3 to β-glucan and CpG antigens and identifies the NLRP3 inflammasome of human circulating B-lymphocytes as a modulator of the innate and adaptive immune systems.

Lack of immunotoxic effects of repeated exposure to atrazine associated with the adaptation of adrenal gland activation

T cell-dependent IgM antibody production and natural killer cell (NKC) activity were assessed in SD rats orally administered atrazine for 28 days to males (0, 6.5, 25, or 100 mg/kg/day) or females (0, 3, 6, or 50 mg/kg/day), or 30 or 500 ppm in diet (3 or 51 mg/kg/day). Anti-asialo GM1 antibodies (NKC) and cyclophosphamide (antibody-forming cell assay [AFC]) served as positive controls. Pituitary (ACTH, prolactin), adrenal (corticosterone, progesterone, aldosterone), and gonadal (androgens, estrogens) hormones were assessed after 1, 7, and/or 28 days of treatment. Food intake and body weights were significantly reduced in the highest dosed males, and transiently affected in females. Urinary corticosterone levels were not increased in atrazine-treated groups in either sex at any time point measured (10, 22, or 24 days). Corticosterone and progesterone were elevated in males after a single atrazine dose ≥6.5 mg/kg/day, but not after 7, 14, or 28 doses. There were no effects on adrenal, pituitary, or gonadal hormones in females. Atrazine did not suppress the AFC response or decrease NKC function after 28 days in males or females. Atrazine had no effect on spleen weights or spleen cell numbers in males or females, although thymus weights were elevated in males receiving the highest dose. The lack of immunotoxic effect of atrazine was associated with diminished adrenal activation over time in males, and no effects on adrenal hormones in females.

Abstract 223: CXCR4 Regulates B1 Cell Localization, Proliferation, Survival, and Atheroprotective IgM Production

Background: B1 cells exert protective effects in atherosclerosis through production of anti-inflammatory natural IgM antibodies that recognize oxidation-specific epitopes, such as MDA-LDL, present in diseased arteries. The bone marrow, spleen, and omental fat are known niches for B1 antibody production. However, the mechanisms underlying B1 localization to these sites and B1 antibody production are currently unclear. Methods and Results: To identify key immune mediators that may be relevant to atherosclerosis, our lab has correlated surface marker expression on peripheral blood mononuclear cells with clinical markers of atherosclerosis in a human cohort. Expression of the chemokine receptor CXCR4 on circulating B1 cells associates with decreased plaque burden in coronary arteries and increased plasma levels of anti-MDA-LDL IgM antibodies. To study the role of CXCR4 in modulating B1 cell function, we generated mice with B cell-specific loss of CXCR4 on the atherogenic ApoE -/- background (CXCR4 BKO ). Chow-fed, 8-week-old CXCR4 BKO mice demonstrate fewer B1 cells (N=6-8, p&lt;0.0001) and IgM antibody-secreting cells (N=6, p=0.004) in the bone marrow, and reduced plasma total IgM levels (N=6-8, p=0.04), relative to littermate controls (CXCR4 WT ). To determine the role of CXCR4 on the B1 cell subset specifically, we adoptively transferred CXCR4 WT or CXCR4 BKO B1 cells into lymphocyte-deficient Rag1 -/- ApoE -/- mice. After 16 weeks of Western diet feeding, recipient mice given CXCR4 BKO B1 cells demonstrate significantly reduced plasma IgM levels (n=5-7, p=0.02), and fewer donor B1 cells in the spleen, peritoneal cavity, and omental fat compared to recipients given CXCR4 WT B1 cells. Few to no donor cells were detected in the bone marrow. To determine whether CXCR4 has a role in B1 cell proliferation or survival, BrdU incorporation and expression of the death receptor FasR were assayed in CXCR4 WT and CXCR4 BKO B1 cells. B1 cells from CXCR4 BKO mice display heightened BrdU incorporation (n=4, p=0.005), yet have increased expression of FasR (n=4, p=0.01) relative to CXCR4 WT B1 cells. Conclusion: Our data demonstrate novel roles for CXCR4 in regulating several processes in B1 cells, including proliferation and survival, consequently impacting production of IgM.

Correction: The soluble pattern recognition receptor PTX3 links humoral innate and adaptive immune responses by helping marginal zone B cells.

Pentraxin 3 (PTX3) is a fluid-phase pattern recognition receptor of the humoral innate immune system with ancestral antibody-like properties but unknown antibody-inducing function. In this study, we found binding of PTX3 to splenic marginal zone (MZ) B cells, an innate-like subset of antibody-producing lymphocytes strategically positioned at the interface between the circulation and the adaptive immune system. PTX3 was released by a subset of neutrophils that surrounded the splenic MZ and expressed an immune activation–related gene signature distinct from that of circulating neutrophils. Binding of PTX3 promoted homeostatic production of IgM and class-switched IgG antibodies to microbial capsular polysaccharides, which decreased in PTX3-deficient mice and humans. In addition, PTX3 increased IgM and IgG production after infection with blood-borne encapsulated bacteria or immunization with bacterial carbohydrates. This immunogenic effect stemmed from the activation of MZ B cells through a neutrophil-regulated pathway that elicited class switching and plasmablast expansion via a combination of T cell–independent and T cell–dependent signals. Thus, PTX3 may bridge the humoral arms of the innate and adaptive immune systems by serving as an endogenous adjuvant for MZ B cells. This property could be harnessed to develop more effective vaccines against encapsulated pathogens.

Multivalent Fusion DNA Vaccine against Brucella abortus.

As an alternative brucellosis prevention method, we evaluated the immunogenicity induced by new multivalent DNA vaccines in BALB/c mice. We constructed the vaccines by fusion of BAB1_0273 and/or BAB1_0278 open reading frames (ORFs) from genomic island 3 (GI-3) and the Brucella abortus 2308 sodC gene with a link based on prolines and alanines (pV273-sod, pV278-sod, and pV273-278-sod, resp.). Results show that immunization with all tested multivalent DNA vaccines induced a specific humoral and cellular immune response. These novel multivalent vaccines significantly increased the production of IgM, IgG, and IgG2a antibodies as well as IFN-γ levels and the lymphoproliferative response of splenocytes. Although immunization with these multivalent vaccines induced a typical T-helper 1- (Th1-) dominated immune response, such immunogenicity conferred low protection levels in mice challenged with the B. abortus 2308 pathogenic strain. Our results demonstrated that the expression of BAB1_0273 and/or BABl_0278 antigens conjugated to SOD protein can polarize mice immunity to a Th1-type phenotype, conferring low levels of protection.

Myasthenia gravis: a pathologic approach

Our immune system protects us from all kinds of pathogens our body faces every day. However, the immune system can also initiate an immune response against our own proteins. This is called autoimmunity. Myasthenia gravis (MG) is a rare autoimmune disease in which patients show severe muscle weakness, due to antibody production against proteins of the neuromuscular junction, which is the connection between nerve and muscle. At this moment, three different forms of myasthenia gravis are identified. Muscle-specific tyrosine kinase (MuSK)-MG is a form of MG in which patients produce antibodies, predominantly immunoglobulin (Ig)G4, against MuSK. This paper is a summary of a B cell immortalization project, in which antibodies produced by MuSK-MG patients are investigated. The aim of this study was to sequence and generate antibodies produced by these patients in vitro to learn more about the pathological mechanism of MuSK-MG. Blood-derived B cells of MuSK-MG patients were immortalized by the Epstein Bar Virus and stimulated to grow and produce antibodies in culture. Genes of these antibodies were amplified and analyzed. These amplification products were cloned in vectors and will be transfected in a human embryonic kidney (HEK)-cell line. This study showed that the B cell immortalization method worked and that MuSK-MG patients predominantly produce IgM antibodies against MuSK. This is very striking as literature states that these patients predominantly produce IgG4 against MuSK. It is suggested that this high production of IgM is due to the absence of the heavy chain isotype switch from IgM to IgG. Moreover, as the pathologic mechanism of MuSK-MG is still unknown, IgM may play an important pathological role.

Pneumococcal Polysaccharide Vaccination Elicits IgG Anti-A/B Blood Group Antibodies in Healthy Individuals and Patients with Type I Diabetes Mellitus.

Blood group antibodies are natural antibodies that develop early in life in response to cross-reactive environmental antigens in the absence of antigen encounter. Even later in life structural similarities in saccharide composition between environmental antigens such as bacterial polysaccharides and blood group A/B antigens could lead to changes in serum levels, IgM/IgG isotype, and affinity maturation of blood group anti-A/B antibodies. We addressed the question whether immunization with pneumococcal polysaccharide (PnP) vaccine Pneumo 23 Vaccine "Pasteur Merieux" (Pn23) could have such an effect in patients with type I diabetes mellitus (DM I), an autoimmune disease where an aberrant immune response to microbial antigens likely plays a role. Anti-PnP IgM and IgG responses were determined by ELISA, and the DiaMed-ID Micro Typing System was used to screen anti-A/B antibody titer before and after Pn23 immunization in 28 healthy individuals and 16 patients with DM I. In addition, surface plasmon resonance (SPR) technology using the Biacore® device and a synthetic blood group A/B trisaccharide as the antigen was applied to investigate IgM and IgG anti-A/B antibodies and to measure antibody binding dynamics. All healthy individuals and DM I patients responded with anti-PnP IgM and IgG antibody production 4-6 weeks after Pn23 immunization, while no increase in blood group anti-A/B antibody titer was observed when measured by the DiaMed-ID Micro Typing System. Interestingly, isotype-specific testing by SPR technology revealed an increase in blood group anti-A/B IgG, but not IgM, following Pn23 immunization in both patients and controls. No change in binding characteristics of blood group anti-A/B antibodies could be detected following Pn23 vaccination, supporting the assumption of an increase in IgG antibody titer with no or very little affinity maturation. The study provides evidence for epitope sharing between pneumococcal polysaccharides and blood group ABO antigens, which leads to a booster of blood group anti-A/B antibodies of the IgG isotype after Pn23 immunization in healthy individuals. Manifest autoimmunity such as present in DM I patients has no additional effect on the cross-reactive antibody response against pneumococcal polysaccharides and blood group antigens.

FcμR in human B cell subsets in primary selective IgM deficiency, and regulation of FcμR and production of natural IgM antibodies by IGIV

IgMFcR (FcμR) are expressed on B cell and B cell subsets. Mice deficient in secreted IgM and FcμR share properties of impaired specific antibody response and autoimmunity with patient with selective IgM deficiency (SIGMD). Intravenous immunoglobulin (IGIV) regulates immune response, including modulation of IgGFc receptors. However, there are no data on the expression of FcμR in patients with SIGMD, and the effects of IGIV on FcμR. In this study, we investigated FcμR expression in naïve marginal zone (MZ), IgM memory, and class-switched memory B cells in patients with selective IgM deficiency and healthy controls. Furthermore, we examined the direct effect of IGIV on FcμR expression and on the upregulation of FcμR by TLR2 agonist (Pam3). Finally, we examined the effect of IVIG on spontaneously produced IgM and natural IgM anti-phosphorylcholine (PC) antibodies by B cells and B1 cells. FcμR expression is significantly decreased in MZ B cells in patients with SIGMD as compared to control. IGIV, at immunomodulatory concentrations, inhibited FcμR upregulation by Pam3 in MZ B cells, and IgM-depleted IGIV inhibited spontaneous secretion of natural IgM anti-PC antibodies and not total IgM by B1 cells. These data suggest that decreased FcμR expression on MZ B cells may play a role in the pathogenesis of SIGMD, and an inhibition of TLR-2-induced upregulation of FcμR by IGIV may be one of the mechanisms of its anti-inflammatory action. IGIV-induced inhibition of natural IgM antibodies may be one of the mechanisms of IGIV-induced immunoregulation.

The soluble pattern recognition receptor PTX3 links humoral innate and adaptive immune responses by helping marginal zone B cells.

Pentraxin 3 (PTX3) is a fluid-phase pattern recognition receptor of the humoral innate immune system with ancestral antibody-like properties but unknown antibody-inducing function. In this study, we found binding of PTX3 to splenic marginal zone (MZ) B cells, an innate-like subset of antibody-producing lymphocytes strategically positioned at the interface between the circulation and the adaptive immune system. PTX3 was released by a subset of neutrophils that surrounded the splenic MZ and expressed an immune activation-related gene signature distinct from that of circulating neutrophils. Binding of PTX3 promoted homeostatic production of IgM and class-switched IgG antibodies to microbial capsular polysaccharides, which decreased in PTX3-deficient mice and humans. In addition, PTX3 increased IgM and IgG production after infection with blood-borne encapsulated bacteria or immunization with bacterial carbohydrates. This immunogenic effect stemmed from the activation of MZ B cells through a neutrophil-regulated pathway that elicited class switching and plasmablast expansion via a combination of T cell-independent and T cell-dependent signals. Thus, PTX3 may bridge the humoral arms of the innate and adaptive immune systems by serving as an endogenous adjuvant for MZ B cells. This property could be harnessed to develop more effective vaccines against encapsulated pathogens.

Humoral response against myelin associated glycoprotein reflects oligodendroglial degeneration in Parkinson's disease.

Identification of disease-specific diagnostic and prognostic biomarkers which would enable early detection and follow-up of Parkinson's disease (PD) is a crucial problem. Recently, we confirmed the presence of adaptive immune response against different glial-derived antigens in PD. The aim of the study was to assess humoral response against myelin-associated glycoprotein (MAG) on a larger group of PD patients. IgM autoantibodies against MAG were measured by an ELISA system in 66 PD patients and 66 control subjects. The study confirmed a significantly increased production of anti-MAG IgM antibodies in parkinsonian patients (p<0.05). No correlations were found between anti-MAG IgM antibody titers and disease severity measured on the Hoehn-Yahr scale, MMSE or age of PD onset (p>0.05). The results provide evidence for activation of humoral response against MAG in PD patients, but argue against the utility of anti-MAG antibodies as biomarkers of disease severity. The results additionally indicate the potential protective role of autoimmunity in maintaining the body's homeostasis, which may involve the clearance of abnormal proteins. Further studies are necessary to confirm the role of anti-MAG antibodies as biomarkers of PD, especially in relation to other neurodegenerative disorders.

Abstract 464: Chemokine Receptor CCR6 Expression on B Cells Augments Local IgM Production and Atheroprotection

Background: CCR6 mediates immune cell recruitment to inflammatory sites and has cell type-specific effects on diet-induced atherosclerosis in mice. Recent studies implicate the local immune responses in the adventitia/perivascular adipose tissue (PVAT) in atherosclerosis development. We have previously demonstrated that adoptive transfer of CD43 - splenocytes (B cells) into B cell deficient μMT -/- ApoE -/- mice results in reduced diet-induced atherosclerosis in a CCR6-dependent manner. Notably, there were significantly greater numbers of B cells in the aorta including PVAT of μMT -/- ApoE -/- mice which received splenic B cells from CCR6 +/+ mice compared to CCR6 -/- mice, despite no difference in B cell numbers in blood, spleen and peritoneal cavity, suggesting that CCR6 expression on B cells is important in B cell aortic homing. Production of IgM antibodies is thought to be a major mechanism whereby B cells limit atherosclerosis development. Yet whether B cells produce IgM locally in the PVAT and whether this is regulated by chemokine receptors such as CCR6 is unknown. Methods and Results: FACS experiments demonstrated high numbers of B cells available in the PVAT than aorta of young ApoE -/- (49121±11190 and 80±11; p&lt;0.001, n=7) mice. ELISPOT experiments demonstrated significantly fewer IgM secreting cells were in the PVAT of ApoE -/- CCR6 -/- mice compared to ApoE -/- CCR6 +/+ mice (100±25 vs 850±150, p&lt;0.05, n=5), despite no differences in IgM secreting cell numbers in spleen and bone marrow. Adoptive transfer of CD43 - splenic B cells from ApoE -/- CCR6 -/- and ApoE -/- CCR6 +/+ mice into secretory IgM deficient ApoE -/- sIgM -/- mice demonstrated significantly reduced atherosclerosis in mice that received B cells from ApoE -/- CCR6 +/+ mice compared to those that received B cells from ApoE -/- CCR6 -/- mice. Moreover, the B cells from ApoE -/- CCR6 +/+ mice attenuated atherosclerosis only when they were capable of secreting IgM. FACS data from human blood demonstrated that circulating B and T cells but not monocytes express CCR6, suggesting potential human relevance to our murine findings. Conclusion: Results provide evidence that CCR6 expression on B cells mediates B cell recruitment into aorta and/or PVAT to provide atheroprotection via IgM secretion.

CXCR4 mediates B-1 cell localization to the bone marrow and production of atheroprotective IgM antibody

Abstract Existing evidence demonstrates that B1 cells exert protective effects in atherosclerosis through production of anti-inflammatory natural IgM antibodies that recognize oxidation-specific epitopes (OSE), such as MDA-LDL, present in diseased arteries. The bone marrow is a known niche for B1 antibody production. However, the mechanisms underlying B1 localization to the bone marrow and B1 antibody production are currently unclear. Our lab has correlated surface marker expression on peripheral blood mononuclear cells with clinical markers of atherosclerosis in a human cohort. Expression of the chemokine receptor CXCR4 on circulating B1 cells associates with decreased plaque burden in coronary arteries and increased plasma levels of anti-MDA-LDL IgM antibodies. To study the role of CXCR4 in modulating B1 cell function more directly, we generated mice with B cell-specific loss of CXCR4 (CXCR4BKO). 8-week-old CXCR4BKO mice demonstrate a significant reduction in B1 number in the bone marrow relative to littermate controls (CXCR4WT). No significant changes in B1 number were seen in the aorta, peritoneal cavity, or spleen. Using ELISA and ELISPOT, CXCR4BKO mice were demonstrated to have decreased circulating IgM levels and fewer IgM antibody-secreting cells (ASC) in the bone marrow, but not in spleen. CXCR4BKO and CXCR4WT mice were placed on 9 weeks Western diet (WD) or control chow diet and then analyzed for IgM ASC number. CXCR4WT WD-fed mice have increased IgM ASC’s in the bone marrow relative to CXCR4WTchow-fed controls. This increase did not occur in WD-fed CXCR4BKO mice. Our data demonstrate that CXCR4 mediates B1 localization to the bone marrow and IgM production in mice, and indicate an atheroprotective role for CXCR4 on B1 cells.

The natural history of acute Q fever: a prospective Australian cohort.

A detailed description of the natural history of acute Q fever, caused by infection with Coxiella burnetii, AIM: : To significantly increase understanding of the illness. Subjects with provisional acute Q fever (n = 115) were recruited from primary care in rural Australia, and followed prospectively by interview and blood collection including for serological confirmation. A nested series of subjects with prolonged illness (cases), and those without (controls), were investigated in detail. Total phase I and phase II anti-C. burnetii antibodies were detected by complement fixation test; and IgG, IgM and IgA phase I and phase II titres by immunofluorescence. Flow cytometric analysis was conducted to enumerate circulating T cells subsets, B cells, monocytes and natural killer cells. Serological testing confirmed acute Q fever in 73 subjects (63%). The acute illness featured fever, headache, sweats, fatigue and anorexia; and varied widely in severity, causing an average of 8 days in bed and 15 days out of work or other role in the first month of illness. The illness course varied from 2 days to greater than a year. No cases of chronic, localized Q fever infection, such as endocarditis, were identified. Neither severe nor prolonged illness were associated with persistence of C. burnetii DNA, altered patterns of C. burnetii-specific IgG, IgM or IgA antibody production, or altered leucocyte subsets. The severity of acute Q fever alone predicted prolonged duration. Further studies are warranted to better understand the pathophysiology of prolonged illness after acute Q fever.

Virulence of representative Japanese Francisella tularensis and immunologic consequences of infection in mice.

Francisella tularensis, which causes tularemia, is widely distributed in the Northern hemisphere. F. tularensis strains isolated in Japan are genetically unique from non-Japanese strains; however, their phenotypic properties have not been well studied. Thus, mice were infected with representative Japanese strains of F. tularensis and their virulence and mouse immune responses to them assessed. Of four representative Japanese strains, the Ebina, Jap and Tsuchiya strains were susceptible to H2 O2 and did not grow well intracellularly. Only Yama strain grew intracellularly and was lethal to mice. Infection with Yama strain resulted in drastic increases in IFN-γ, CD4 and CD8 double-positive T cells and Th1 cells (CD3, CD4 and Tim3-positive cells), and a decrease in the ratio of CD8-positive CD4-negative T cells in mice. C57BL/6J mice that survived infection produced IgM antibodies to LPS and IgG2c antibodies to 43, 19 and 17 kDa proteinase K-sensitive components. These data are valuable for understanding the phenotypic properties of F. tularensis in Japan.

The Effect of High Carbohydrate Consumption on Glucose Levels and Antibody Production in Nonobese Diabetic Mice

The aim of this study was to evaluate the effect of chronic treatment with diets rich in carbohydrates on the IgM and IgG antibody production and the seric glucose concentration in diabetes. Nonobese diabetic (NOD) mice received, ad libitum, by oral route, the diet consisting of an aqueous extract (20 mg/mL) of the following flours: babassu mesocarp, manioc, corn or rice, during 120 days. The diet intake was monitored throughout this period. At the end, the weight variation, blood glucose, serum IgG and IgM antibody and IgM anti-insulin titers, were determined. The babassu and manioc flour extracts altered Purina chow intake and these animals also presented a significant increase in body weight. In contrast, treatment with rice flour resulted in a significant weight loss. Moderate to severe hyperglycemia was observed in the groups receiving rice and manioc, whereas treatment with babassu mesocarp flour and cornmeal resulted in hypoglycemia. The extracts did not alter the IgG concentration. On the other hand, the cornmeal extract caused a marked reduction in both total IgM and anti-insulin IgM antibody production. Although babassu mesocarp flour, cornmeal and manioc flour caused important variations in the parameters studied, only treatment with the rice flour extract anticipated the onset of diabetes in male mice genetically predisposed to the disease.

Protection Against Necrotic Enteritis in Broiler Chickens by Regulated Delayed Lysis Salmonella Vaccines.

Necrotic enteritis (NE), caused by Gram-positive Clostridium perfringens type A strains, has gained more attention in the broiler industry due to governmental restrictions affecting the use of growth-promoting antibiotics in feed. To date, there is only one commercial NE vaccine available, based on the C. perfringens alpha toxin. However, recent work has suggested that the NetB toxin, not alpha toxin, is the most critical virulence factor for causing NE. These findings notwithstanding, it is clear from prior research that immune responses against both toxins can provide some protection against NE. In this study, we delivered a carboxyl-terminal fragment of alpha toxin and a GST-NetB fusion protein using a novel attenuated Salmonella vaccine strain designed to lyse after 6-10 rounds of replication in the chicken host. We immunized birds with vaccine strains producing each protein individually, a mixture of the two strains, or with a single vaccine strain that produced both proteins. Immunization with strains producing either of the single proteins was not protective, but immunization with a mixture of the two or with a single strain producing both proteins resulted in protective immunity. The vaccine strain synthesizing both PlcC and GST-NetB was able to elicit strong production of intestinal IgA, IgY, and IgM antibodies and significantly protect broilers against C. perfringens challenge against both mild and severe challenges. Although not part of our experimental plan, the broiler chicks we obtained for these studies were apparently contaminated during transit from the hatchery with group D Salmonella. Despite this drawback, the vaccines worked well, indicating applicability to real-world conditions.