Search

Each year, up to one fifth of the United States population is infected with influenza virus. Although mortality rates are low, hundreds of thousands are hospitalized each year in the United States. Specific high risk groups, such as those with suppressed or dysregulated immune systems, are at greater danger for influenza complications. Respiratory infections are a common cause of hospitalizations and early mortality in patients with systemic lupus erythematosus (SLE); however, whether this increased infection risk is a consequence of the underlying dysregulated immune background and/or immunosuppressing drugs is unknown. To evaluate the influenza immune response in the context of lupus, as well as assess the effect of infection on autoimmune disease in a controlled setting, we infected lupus-prone MRL/MpJ-Fas(lpr) mice with influenza virus A PR/8/34 H1N1. Interestingly, we found that Fas(lpr) mice generated more influenza A virus specific T cells with less neutrophil accumulation in the lung during acute infection. Moreover, Fas(lpr) mice produced fewer flu-specific IgG and IgM antibodies, but effectively cleared the virus. Further, increased extrinsic apoptosis during influenza infection led to a delay in autoimmune disease pathology with decreased severity of splenomegaly and kidney disease. Following primary influenza A infection, Fas(lpr) mice had severe complications during the contraction and resolution phase with widespread severe pulmonary inflammation. Our findings suggest that influenza infection may not exacerbate autoimmune pathology in mice during acute infection as a direct result of virus induced apoptosis. Additionally, autoimmunity drives an enhanced antigen-specific T cell response to clear the virus, but persisting pulmonary inflammation following viral clearance may cause complications in this lupus animal model.

Roughly half of U.S. adults do not receive recommended booster vaccinations, but protective antibody levels are rarely measured in adults. Demographic factors, vaccination history, and responses to other vaccinations could help identify at-risk individuals. We sought to characterize rates of seroconversion and determine associations of humoral responses to multiple vaccinations in healthy adults.Humoral responses toward measles, mumps, tetanus toxoid, pertussis, hepatitis B surface antigen, and anthrax protective antigen were measured by ELISA in post-immunization samples from 1465 healthy U.S. military members. We examined the effects of demographic and clinical factors on immunization responses, as well as assessed correlations between vaccination responses.Subsets of boosted adults did not have seroprotective levels of antibodies toward measles (10.4%), mumps (9.4%), pertussis (4.7%), hepatitis B (8.6%) or protective antigen (14.4%) detected. Half-lives of antibody responses were generally long (30 years). Measles and mumps antibody levels were correlated (r=0.31, p0.001), but not associated with select demographic features or vaccination history. Measles and mumps antibody levels also correlated with tetanus antibody response (r=0.11, p0.001).Vaccination responses are predominantly robust and vaccine specific. However, a small but significant portion of the vaccinated adult population may not have quantitative seroprotective antibody to common vaccine-preventable infections.

In order to identify the combination of antibody-mediated mechanisms of neutralization that result from vaccination with anthrax vaccine adsorbed (AVA), we isolated antibody secreting cells from a single donor seven days after booster vaccination with AVA and generated nine fully human monoclonal antibodies (hmAb) with high specificity for protective antigen (PA). Two of the antibodies were able to neutralize lethal toxin in vitro at low concentrations (IC(50): p6C01, 0.12 μg/ml and p6F01, 0.45 μg/ml). Passive transfer of either of these hmAbs to A/J mice prior to challenge with lethal toxin conferred 80-90% protection. We demonstrate that hmAb p6C01 is neutralizing by preventing furin cleavage of PA in a dose-dependent manner, but the mechanism of p6F01 is unclear. Three additional antibodies were found to bind to domain 3 of PA and prevent oligomerization, although they did not confer significant protection in vivo and showed a significant prozone-like effect in vitro. These fully human antibodies provide insight into the neutralizing response to AVA for future subunit vaccine and passive immunotherapeutic cocktail design.

Background: Antiphospholipid syndrome is characterized by autoantibodies against cardiolipins (aCL), lupus anticoagulant, and independent β2-glycoprotein (β2GPI). Controversy exists as to whether vaccination triggers the development of antiphospholipid antibodies (aPL) in patients with systemic lupus erythematosus (SLE). Methods: Patients with SLE (101) and matched controls (101) were enrolled from 2005–2009 and received seasonal influenza vaccinations. Sera were tested by ELISA for aCL at baseline, 2, 6, and 12 weeks after vaccination. Vaccine responses were ranked according to an overall anti-influenza antibody response index. Individuals with positive aCL were further tested for β2GPI antibodies. Results: Patients with SLE and healthy controls can develop new-onset aCL post vaccination, although at rates which do not differ between patients and controls (12/101 cases and 7/101 controls, OR 1.81, p = 0.34). New-onset moderate aCL are slightly enriched in African American SLE patients (5/36 cases; p = 0.094). The optical density measurements for aCL reactivity in patients were significantly higher than baseline at 2 weeks ( p Conclusions: This study shows transient increases in aCL, but not anti-β2GPI responses, after influenza vaccination.

Vitamin D deficiency is widespread and has been associated with many chronic diseases, including autoimmune disorders. A study was undertaken to explore the impact of low vitamin D levels on autoantibody production in healthy individuals, as well as B cell hyperactivity and interferon α (IFNα) activity in patients with systemic lupus erythematosus (SLE).Serum samples from 32 European American female patients with SLE and 32 matched controls were tested for 25-hydroxyvitamin D (25(OH)D) levels, lupus-associated autoantibodies and serum IFNα activity. Isolated peripheral blood mononuclear cells were tested for intracellular phospho-ERK 1/2 as a measure of B cell activation status.Vitamin D deficiency (25(OH)D20 ng/ml) was significantly more frequent among patients with SLE (n=32, 69%) and antinuclear antibody (ANA)-positive controls (n=14, 71%) compared with ANA-negative controls (n=18, 22%) (OR 7.7, 95% CI 2.0 to 29.4, p=0.003 and OR 8.8, 95% CI 1.8 to 43.6, p=0.011, respectively). Patients with high B cell activation had lower mean (SD) 25(OH)D levels than patients with low B cell activation (17.2 (5.1) vs 24.2 (3.9) ng/ml; p=0.009). Patients with vitamin D deficiency also had higher mean (SD) serum IFNα activity than patients without vitamin D deficiency (3.5 (6.6) vs 0.3 (0.3); p=0.02).The observation that ANA-positive healthy controls are significantly more likely to be deficient in vitamin D than ANA-negative healthy controls, together with the finding that vitamin D deficiency is associated with certain immune abnormalities in SLE, suggests that vitamin D plays an important role in autoantibody production and SLE pathogenesis.

B lymphocyte stimulator (BLyS, also known as TNFSF13B and BAFF) is a type II transmembrane protein and a member of the TNF superfamily (1, 2). BLyS is produced by several different cell types, including monocytes, activated neutrophils, T cells, and dendritic cells (3–5), and is expressed as a cell surface protein which can be furin-cleaved and released into the circulation. Although BLyS has been shown to be constitutively expressed, certain inflammatory cytokines such as IL-2, TNF-α, IFN-γ, and IFN-α can enhance its production and secretion (3, 4, 6, 7). BLyS binds to 3 receptors found primarily on B cells (8). Activation of these receptors leads to B cell proliferation, differentiation, survival, and IgG class switching (1, 4, 9). BLyS has been shown to play an important role in primary immune responses, as anti-BLyS treated mice show profoundly reduced numbers of naive B cells with accompanying attenuated responses to both T-dependent and T-independent antigens (10). Transgenic mice that overexpress BLyS display a myriad of autoimmune features, such as high levels of rheumatoid factor, anti-DNA, circulating immune complexes, and immunoglobulin deposition in the kidneys (9). Mice treated with exogenous BLyS develop an increase in B cell numbers, particularly those directed against chromatin (11), and autoreactive cells encountering transitional B cell checkpoints in the spleen require higher concentrations of BLyS to survive than do non-autoreactive B cells (8, 9, 12). Mouse models have also demonstrated that deletion of either BLyS or its receptor severely impairs B cell development beyond the transitional stage with a resulting decrease in peripheral B cell populations (9, 13–15). Elevated circulating BLyS levels have been found in patients with systemic autoimmune disorders such as SLE, rheumatoid arthritis (RA), and Sjoren’s syndrome (16–18). Early reports found increased serum BLyS levels in SLE patients compared to healthy individuals that correlated with anti-dsDNA titers, but not disease activity (16, 17, 19). BLyS levels did, however, decrease following high-dose corticosteroid treatment (19). Other studies found that peripheral blood leukocyte BLyS mRNA levels correlated with SLE disease activity (20, 21). While most of these initial studies, which were performed in mainly Hispanic SLE patients, failed to demonstrate a correlation between serum BLyS levels and disease activity, a later longitudinal study undertaken at 4 different clinical centers that contained ancestral diversity, found an association between increases in plasma BLyS levels from a previous visit and increases in SELENA-SLEDAI scores at the next visit (22). Additionally, another study involving Norwegian SLE patients, also found a correlation with serum BLyS levels and SLEDAI scores (23). A study examining plasma BLyS protein levels in pediatric SLE also demonstrated an association between elevated BLyS levels and increased disease activity (24). IFN-α has proven to be a key cytokine in SLE pathogenesis, and has been shown to increase BLyS expression in antigen-presenting cells (4). Therefore, it is possible that IFN-α plays a role in driving BLyS production in SLE, although a direct correlation between circulating BLyS levels and serum IFN-α activity has yet to be demonstrated in SLE patients. Additionally, several environmental factors have been implicated in the pathogenesis of SLE (25), including vitamin D deficiency (26). As vitamin D has been shown to suppress the expression of the IFN signature in myeloid-derived dendritic cells, as well as suppress B cell activation and immunoglobulin production (27, 28), it is of interest to assess the relationship between vitamin D and BLyS levels. Belimumab is a fully human monoclonal antibody that binds BLyS and inhibits its activity. Two recent large randomized, double-blind, placebo-controlled, multicenter phase 3 trials, BLISS-52 and BLISS-76, evaluated the efficacy of belimumab plus standard of care compared to placebo plus standard of care; positive results were obtained with both studies reaching their primary efficacy endpoints of reductions in disease activity without ancillary organ flares (29, 30). Taken together, these data suggest that excessive BLyS may be an important mechanism underlying SLE pathogenesis and that BLyS targeted therapies seem promising. However, normal B cell function requires some BLyS activity. To date no studies have evaluated whether specific levels of BLyS are required to mount appropriate vaccination responses or whether BLyS levels change after vaccination. The primary objective of this study is to investigate the relationship between circulating BLyS levels and humoral responses made to influenza vaccination, as well as the effect of influenza vaccination on BLyS production in SLE. The current study also examines select demographic, environmental, and clinical features of SLE for association with elevated BLyS levels in an effort to better understand the mechanisms of elevated BLyS in a heterogeneous SLE population.

The efficacy biomarker of the currently licensed anthrax vaccine (AVA) is based on quantity and neutralizing capacity of anti-protective antigen (anti-PA) antibodies. However, animal studies have demonstrated that antibodies to lethal factor (LF) can provide protection against in vivo bacterial spore challenges. Improved understanding of the fine specificities of humoral immune responses that provide optimum neutralization capacity may enhance the efficacy of future passive immune globulin preparations to treat and prevent inhalation anthrax morbidity and mortality. This study ( n = 1000) was designed to identify AVA vaccinated individuals who generate neutralizing antibodies and to determine what specificities correlate with protection. The number of vaccine doses, years post vaccination, and PA titer were associated with in vitro neutralization, reinforcing previous reports. In addition, African American individuals had lower serologic neutralizing activity than European Americans, suggesting a genetic role in the generation of these neutralizing antibodies. Of the vaccinated individuals, only 69 (6.9%) had moderate levels of anti-LF IgG compared to 244 (24.4%) with low and 687 (68.7%) with extremely low levels of IgG antibodies to LF. Using overlapping decapeptide analysis, we identified six common LF antigenic regions targeted by those individuals with moderate levels of antibodies to LF and high in vitro toxin neutralizing activity. Affinity purified antibodies directed against antigenic epitopes within the PA binding and ADP-ribotransferase-like domains of LF were able to protect mice against lethal toxin challenge. Findings from these studies have important implications for vaccine design and immunotherapeutic development.

Bacillus anthracis remains a serious bioterrorism concern, and the currently licensed vaccine remains an incomplete solution for population protection from inhalation anthrax and has been associated with concerns regarding efficacy and safety. Thus, understanding how to generate long lasting protective immunity with reduced immunizations or providing protection through post exposure immunotherapeutics are long sought goals. Through evaluation of a large military cohort, we characterized the levels of antibodies against protective antigen and found that over half of anthrax vaccinees had low levels of in vitro toxin neutralization capacity in their sera. Using solid phase epitope mapping and confirmatory assays, we identified several neutralization-associated humoral epitopes and demonstrated that select anti-peptide responses mediated protection in vitro. Finally, passively transferred antibodies specific for select epitopes provided protection in an in vivo lethal toxin mouse model. Identification of these antigenic regions has important implications for vaccine design and the development of directed immunotherapeutics.

Recent studies have identified distinct populations of memory T cells that persist in the lungs following respiratory virus infections, and contribute to the control of secondary virus infections. Here we discuss the establishment, maintenance and recall of memory T cells in the lung.