Autoantibodies in nonautoimmune individuals during infections

The Onset of Antinuclear Antibodies (ANAs) as a Potential Risk Factor for Mortality and Morbidity in COVID-19 Patients: A Single-Center Retrospective Study

The immune system's amplified response to SARS-CoV-2 may lead to the production of autoantibodies, but their specific impact on disease severity and outcome remains unclear. This study aims to assess if hospitalized COVID-19 patients face a worse prognosis based on ANA presence, even without autoimmune diseases. We performed a retrospective, single-center, observational cohort study, enrolling 638 COVID-19 patients hospitalized from April 2020 to March 2021 at Hospital "Policlinico Riuniti" of Foggia (Italy). COVID-19 patients with a positive ANA test exhibited a significantly lower 30-day survival rate (64.4% vs. 83.0%) and a higher likelihood of severe respiratory complications during hospitalization than those with negative ANA screening (35.4% vs. 17.0%) (p < 0.001). The association between poor prognosis and ANA status was identified by calculating the HALP score (Hemoglobin-Albumin-Lymphocyte-Platelet), which was lower in COVID-19 patients with a positive ANA test compared to ANA-negative patients (108.1 ± 7.4 vs. 218.6 ± 11.2 AU; p < 0.011). In detail, COVID-19 patients with a low HALP showed a lower 30-day survival rate (99.1% vs. 83.6% vs. 55.2% for high, medium, and low HALP, respectively; p < 0.001) and a higher incidence of adverse respiratory events compared to those with high and medium HALP (13.1% vs. 35.2% vs. 64.6% for high, medium, and low HALP, respectively; p < 0.001). In summary, ANA positivity in COVID-19 patients appears to be linked to a more aggressive disease phenotype with a reduced survival rate. Furthermore, we propose that the HALP score could serve as a valuable parameter to assess prognosis for COVID-19 patients.

High-throughput autoantibody profiling of different stages of Schistosomiasis japonica

Infection by the Schistosoma japonicum can result in acute, chronic and late-stage manifestations. The latter often presents with severe organ failures and premature death. Importantly, infection can also produce autoimmune phenomena reflected by the development of autoantibodies. We wished to explore and profile the presence of autoantibodies in sera of patients with different stages of S. japonicum infection with the added aim of providing a reference assisting diagnosis. Blood samples from 55 patients with chronic and 20 patients with late-stage schistosomiasis japonica together, with a control group of 50 healthy people were randomly investigated against a microarray of 121 different autoantigens. In addition, the frequency of antibodies against Schistosoma egg antigen (SEA) was examined. In the sera from patients with chronic schistosomiasis japonica, 14 different highly expressed autoantibodies were detected, while patients with late-stage schistosomiasis were found to express as many as 43 autoantibody specificities together with a significantly higher frequency of antibodies against SEA compared to the control group. The findings presented suggest that autoantibody-based classification of schistosomiasis japonica represents a promising approach for the elucidation of subtypes of the disease. This approach may reflect differential disease mechanisms, which could ultimately lead to better treatment.

Case report: Coxiella burnetii endocarditis in the absence of evident exposure

Q fever is a worldwide zoonotic disease caused by Coxiella burnetii. In humans, it can manifest clinically as an acute or chronic disease and endocarditis, the most frequent complication of chronic Q fever is associated with the greatest morbidity and mortality. We report a severe case of endocarditis in a 55-year-old man with a history of aortic valve replacement affected by monoclonal gammopathy of undetermined significance (MGUS), and living in a non-endemic area for C. burnetii. After two episodes of fever of unknown origin (FUO), occurring 2 years apart and characterized by negative blood cultures, a serological diagnosis of Q fever endocarditis was performed even though the patient did not refer to possible past exposure to C. burnetii. Since people with preexisting valvular heart disease, when infected with C. burnetii, have reported a 40% risk of Q fever endocarditis, clinicians should maintain a high index of suspicion for infective endocarditis in all patients with FUO even when the exposure to C. burnetii appears to be unlikely.

B cells in the balance: Offsetting self-reactivity avoidance with protection against foreign

Antibodies are theoretically limitless in their diversity and specificity to foreign antigens; however they are constrained by the need to avoid binding to self. Germinal centers (GC) allow diversification and maturation of the antibody response towards the foreign antigen. While self-tolerance mechanisms controlling self-reactivity during B cell maturation are well recognized, the mechanisms by which GCs balance self-tolerance and foreign binding especially in the face of cross-reactivity between self and foreign, remain much less well defined. In this review we explore the extent to which GC self-tolerance restricts affinity maturation. We present studies suggesting that the outcome is situationally dependent, affected by affinity and avidity to self-antigen, and the extent to which self-binding and foreign-binding are interdependent. While auto-reactive GC B cells can mutate away from self while maturing towards the foreign antigen, if no mutational trajectories allow for self-reactive redemption, self-tolerance prevails and GC responses to the foreign pathogen are restricted, except when self-tolerance checkpoints are relaxed. Finally, we consider whether polyreactivity is subject to the same level of restriction in GC responses, especially if polyreactivity is linked to an increase in foreign protection, as occurs in certain broadly neutralizing antibodies. Overall, the outcomes for GC B cells that bind self-antigen can range from redemption, transient relaxation in self-tolerance or restriction of the antibody response to the foreign pathogen.

Autoimmune anti-DNA and anti-phosphatidylserine antibodies predict development of severe COVID-19

COVID-19 induces high levels of autoimmune anti-DNA and anti-phosphatidylserine antibodies that are detected in some patients upon hospital admission and predict later development of severe disease.

High levels of autoimmune antibodies are observed in COVID-19 patients but their specific contribution to disease severity and clinical manifestations remains poorly understood. We performed a retrospective study of 115 COVID-19 hospitalized patients with different degrees of severity to analyze the generation of autoimmune antibodies to common antigens: a lysate of erythrocytes, the lipid phosphatidylserine (PS) and DNA. High levels of IgG autoantibodies against erythrocyte lysates were observed in a large percentage (up to 36%) of patients. Anti-DNA and anti-PS antibodies determined upon hospital admission correlated strongly with later development of severe disease, showing a positive predictive value of 85.7% and 92.8%, respectively. Patients with positive values for at least one of the two autoantibodies accounted for 24% of total severe cases. Statistical analysis identified strong correlations between anti-DNA antibodies and markers of cell injury, coagulation, neutrophil levels and erythrocyte size. Anti-DNA and anti-PS autoantibodies may play an important role in the pathogenesis of COVID-19 and could be developed as predictive biomarkers for disease severity and specific clinical manifestations.

Matrix lumican endocytosed by immune cells controls receptor ligand trafficking to promote TLR4 and restrict TLR9 in sepsis

Infections and inflammation are profoundly influenced by the extracellular matrix (ECM), but their molecular underpinnings are ill defined. Here, we demonstrate that lumican, an ECM protein normally associated with collagens, is elevated in sepsis patients' blood, while lumican-null mice resolve polymicrobial sepsis poorly, with reduced bacterial clearance and greater body weight loss. Secreted by activated fibroblasts, lumican promotes Toll-like receptor (TLR) 4 response to bacterial lipopolysaccharides (LPS) but restricts nucleic acid-specific TLR9 in macrophages and dendritic cells. The underlying mechanism involves lumican attachment to the common TLR coreceptor CD14 and caveolin 1 (Cav1) in lipid rafts on immune cell surfaces via two epitopes, which may be cryptic in collagen-associated lumican. The Cav1 binding epitope alone is sufficient for cell surface enrichment of Cav1, while both are required for lumican to increase cell surface TLR4, CD14, and proinflammatory cytokines in response to LPS. Endocytosed lumican colocalizes with TLR4 and LPS and promotes endosomal induction of type I interferons. Lumican-null macrophages show elevated TLR9 in signal-permissive endolysosomes and increased response, while wild types show lumican colocalization with CpG DNA but not TLR9, consistent with a ligand sequestering, restrictive role for lumican in TLR9 signaling. In vitro, lumican competes with CD14 to bind CpG DNA; biglycan, a lumican paralog, also binds CpG DNA and suppresses TLR9 response. Thus, lumican and other ECM proteins, synthesized de novo or released from collagen association during ECM remodeling, may be internalized by immune cells to regulate their transcriptional programs and effector responses that may be harnessed in future therapeutics.

The Metabolic Clock Model of B Cell Activation and Differentiation

Recent advancements in the field of B cell immunometabolism have provided mechanistic insights to B cell activation and fate determination. Here, in this short article, I will explain the main principles of our novel metabolic clock model and how it may reshape our perspective on longstanding immunological questions related to pathologies arising from out of context B cell activation.

Autoantibodies Among HIV-1 Infected Individuals and the Effect of Anti-Retroviral Therapy (ART) on It

BACKGROUND

Antiretroviral therapy (ART) has led to a decline in autoimmune diseases but lacks studies on its effect on autoantibodies.

METHODS

It is a cross-sectional study with archived samples from 100 paired HIV-1 infected ART naïve and experienced individuals and 100 prospectively collected matched blood-donor controls. Antinuclear antibody, IgG anticardiolipin antibody, IgM and IgG β2 glycoprotein-1 antibodies, and total IgG levels were detected. Results are expressed as mean with standard deviation (SD), median, percentage positivity, and a p<0.05 is considered significant. The study was approved by the Institutional Review Board.

RESULTS

The median viral load of the treatment naïve samples was 4.34 Log copies/mL, while all were virally suppressed post ART with a median duration of treatment for 12 months (range: 3-36 months). The percentage of antinuclear antibody positivity was 5% among ART naïve and controls, with a decrease of 2% post ART (p= 0.441). The positivity for anti-cardiolipin antibody was 15% among ART naïve while none of the ART experienced or controls were positive (p<0.05). IgM β2 glycoprotein-1 were 4%, 1% and 3% among ART naïve, treated and controls, respectively (p<0.05). IgG β2 glycoprotein-1 was 2% among ART naïve while none of the treated and controls were positive (p<0.05). The mean total IgG level among ART naïve, experienced, and controls were 21.82 (SD 6.67), 16.91 (SD 3.38), 13.70 (SD 2.24) grams/Litre, respectively (p<0.05).

CONCLUSION

ART has a significant effect on IgG anti-cardiolipin antibody and total IgG but only a marginal effect on ANA, IgM, and IgG β2 glycoprotein-1 antibodies.

Management of pernio-like cutaneous manifestations in children during the outbreak of COVID-19

During the outbreak of COVID‐19 many pernio‐like lesions have been increasingly reported. The aim of the study is to describe our management of these skin manifestations and to evaluate a possible correlation to SARS‐CoV‐2 infection. All patients underwent clinical and laboratory tests to detect a possible underlying connective disease and also to specific SARS‐CoV‐2 investigations such as oropharyngeal swab and IgG‐IgM serology. Nine patients aged between 5 and 15 years old were evaluated. Skin lesions observed were purplish, erythematous and oedematous, in some cases painful and itchy. Six out of nine had respiratory and systemic symptoms (cough, nasal congestion, chills, fever, and asthenia) that preceded cutaneous findings of approximately 2 weeks. Concerning blood exams, three out of nine had D‐dimer weakly increased, four had ANA positivity: two with a title 1:160, one with 1:320, and one with 1:5120 and a speckled pattern. The latter patient had also ENA SS‐A positive and RF positivity, confirmed at a second check, so as to allow us to make a diagnosis of connective tissue disease. Four out of nine had aPL positivity (IgM). Reactants acute phase were all negative. Oropharyngeal swabs and serology tests for SARS‐CoV‐2 was negative (borderline in one patient for IgM). No treatment was needed. Even if we do not have enough data to prove it, we hypothesize a correlation between pernio‐like lesions and SARS‐CoV‐2 infection for an increased number of these lesions described during the pandemic and also because such manifestations appeared when temperatures were mild and patients were at home in isolation for the lockdown. Many questions remain open about interaction host‐virus.

Antinuclear Antibody Tests

The presence of antinuclear antibodies (ANAs), which include autoantibodies to extractable nuclear antigens (ENAs), in the sera of patients with connective tissue diseases provides useful immunologic and pathophysiologic insight into the nature of their disease. This article discusses the most commonly used diagnostic modalities for detecting and quantitating the presence of ANA: indirect immunofluorescence assay, enzyme-linked immunosorbent assay, and multiplex bead technology, which serve as useful screening tests. We also review testing for autoantibodies to ENAs, which are often helpful to confirm the diagnosis of a specific connective tissue disease.

Autoantibody levels are associated with acute kidney injury, anemia and post-discharge morbidity and mortality in Ugandan children with severe malaria

Autoantibodies targeting host antigens contribute to autoimmune disorders, frequently occur during and after infections and have been proposed to contribute to malaria-induced anemia. We measured anti-phosphatidylserine (PS) and anti-DNA antibody levels in 382 Ugandan children prospectively recruited in a study of severe malaria (SM). High antibody levels were defined as antibody levels greater than the mean plus 3 standard deviations of community children (CC). We observed increases in median levels of anti-PS and anti-DNA antibodies in children with SM compared to CC (p < 0.0001 for both). Children with severe malarial anemia were more likely to have high anti-PS antibodies than children with cerebral malaria (16.4% vs. 7.4%), p = 0.02. Increases in anti-PS and anti-DNA antibodies were associated with decreased hemoglobin (p < 0.05). A one-unit increase in anti-DNA antibodies was associated with a 2.99 (95% CI, 1.68, 5.31) increase odds of acute kidney injury (AKI) (p < 0.0001). Elevated anti-PS and anti-DNA antibodies were associated with post-discharge mortality (p = 0.031 and p = 0.042, respectively). Children with high anti-PS antibodies were more likely to have multiple hospital readmissions compared to children with normal anti-PS antibody levels (p < 0.05). SM is associated with increased autoantibodies against PS and DNA. Autoantibodies were associated with anemia, AKI, post-discharge mortality, and hospital readmission.

Potential Involvement of Salmonella Infection in Autoimmunity

In this work, we investigated the potential effects of nontyphoidal Salmonella infection on autoantibody (AA) formation. The titer and profiles of autoantibodies in the sera of patients with acute salmonellosis due to Salmonella enterica serovar Typhimurium (S. Typhimurium) or Salmonella enterica serovar Enteritidis (S. Enteritidis) infection, as well as in convalescent patients, were determined with indirect immunofluorescence. A significant increase of autoantibodies in acute diseases caused by both serotypes of Salmonella and during post infection by S. Enteritidis was detected. Antibody profile analysis by multivariate statistics revealed that this increase was non-specific and was not dependent on the infectious agent or disease stage. The results obtained suggest that nontyphoidal Salmonella infection contributes to the generation of autoantibodies and may play a role in autoimmune disease.

A comparison of a fluorescence enzyme immunoassay versus indirect immunofluorescence for initial screening of connective tissue diseases: Systematic literature review and meta-analysis of diagnostic test accuracy studies

The aim was to compare indirect immunofluorescence (IIF) and fluorescence enzyme immunoassay (FEIA) for initial screening of connective tissue diseases (CTDs) and to evaluate whether combining IIF with FEIA adds value. A comprehensive systematic literature review was conducted to identify fully paired, cross-sectional or case-control studies on ANA screening of CTD reporting results for IIF and FEIA. Study quality was assessed using the QUADAS-2 checklist. The reference standard was assessed against established classification criteria. The meta-analysis used hierarchical, bivariate and mixed-effects models to allow test results to vary within and across studies. Eighteen studies of good to fair quality were included in the review. IIF had a higher sensitivity than FEIA [cut-off 1:160, 7 studies, 3251 patients, 0.83 (95% CI 0.75-0.89) versus 0.73 (95% CI 0.64-0.80); cut-off 1:80, 7 studies, 12,311 patients, 0.89 (95% CI 0.84-0.93) versus 0.78 (95% CI 0.71-0.84)] but lower specificity [1:160, 0.81 (95% CI 0.73-0.87) versus 0.94 (95% CI 0.91-0.95); 1:80, 0.72 (95% CI 0.62-0.81) versus 0.94 (95% CI 0.90-0.96)]. A double-positive test had a higher likelihood ratio (LR) for CTD (26.2 (95% CI 23.0-29.9)) than a single positive test (14.4 (95% CI 13.1-15.9) FEIA+, 5.1 (95% CI 4.8-5.4) IIF+). A double-negative test result had more clinical value for ruling out CTD than a single negative test (LR 0.15 (95% CI 0.12-0.18) versus 0.21 (95% CI 0.18-0.25) IIF; 0.33 (95% CI 0.29-0.37) FEIA-). A FEIA+/IIF- discordant result had a higher LR than an IIF+/FEIA- discordant result (LR 2.4 (95% CI 1.7-3.4) versus 1.4 (95% CI 1.2-1.7)). Because of the comparatively higher specificity of FEIA and higher sensitivity of IIF, the combination of FEIA and IIF increases the diagnostic value. Clinicians should be acquainted with the clinical presentation of CTD and aware of the advantages and disadvantages of FEIA and IIF to avoid misinterpretation.

Divergent Roles of Antiself Antibodies during Infection

Antiself antibodies are most commonly associated with autoimmune disorders, but a large body of evidence indicates that they are also present in numerous infectious diseases. These autoimmune antibodies appear transiently during infection with a number of viruses, bacteria, and parasites and in some cases have been associated with the development of autoimmune disorders that develop after infection has been cleared. Traditionally these infection-associated autoantibodies are considered an erroneous byproduct of a legitimate immune response, but their possible role in the clearance of microbes and infected cells or inhibition of host-cell invasion suggests that they may be present because of their beneficial protective role against various infections.

Plasmodium DNA-mediated TLR9 activation of T-bet+ B cells contributes to autoimmune anaemia during malaria

Infectious pathogens contribute to the development of autoimmune disorders, but the mechanisms connecting these processes are incompletely understood. Here we show that Plasmodium DNA induces autoreactive responses against erythrocytes by activating a population of B cells expressing CD11c and the transcription factor T-bet, which become major producers of autoantibodies that promote malarial anaemia. Additionally, we identify parasite DNA-sensing through Toll-like receptor 9 (TLR9) along with inflammatory cytokine receptor IFN-γ receptor (IFN-γR) as essential signals that synergize to promote the development and appearance of these autoreactive T-bet+ B cells. The lack of any of these signals ameliorates malarial anaemia during infection in a mouse model. We also identify both expansion of T-bet+ B cells and production of anti-erythrocyte antibodies in ex vivo cultures of naive human peripheral blood mononuclear cells (PBMC) exposed to P. falciprum infected erythrocyte lysates. We propose that synergistic TLR9/IFN-γR activation of T-bet+ B cells is a mechanism underlying infection-induced autoimmune-like responses.

Anticeramide antibody and butyrylcholinesterase in peripheral neuropathies

Ceramide is a glycosphingolipid, a component of nerve and non neuronal cell membrane and plays a role in maintaining the integrity of neuronal tissue. Butyrylcholinesterase (BChE) is a multifunctional enzyme, its involvement in neurodegenerative diseases has been well established. Anticeramide antibody (Ab-Cer) and enzyme BChE have been implicated in peripheral neuropathies. The present study investigates whether there is an association between Ab-Cer and BChE activities and peripheral neuropathies. Patients included: human immunodeficiency virus associated peripheral neuropathy (HIV-PN, n=39), paucibacillary leprosy (PB-L, n=36), multibacillary leprosy (MB-L, n=52), diabetic neuropathy (DN, n=22), demyelinating sensory motor polyneuropathy (DSMN, n=13) and chronic inflammatory demyelinating polyneuropathy (CIDP, n=10). Plasma Ab-Cer was measured by indirect enzyme linked immune assay (ELISA) and BChE activity in plasma was measured by colorimetric method. Ab-Cer levels were significantly elevated in MB-L and DN as compared to healthy subjects (HS). BChE levels were significantly higher in MB-L and DN as well as in HIV and HIV-PN. There is no significant difference in either Ab-Cer or BChE levels in DSMN and CIDP. Elevated plasma Ab-Cer and BChE levels may be considered significant in the pathogenesis of neuropathies. The variation in concurrent involvement of both the molecules in the neuropathies of the study, suggest their unique involvement in neurodegenerative pathways.

Autoantibodies other than Anti-desmogleins in Pemphigus Vulgaris Patients

Background:

Pemphigus vulgaris (PV) is an immunoglobulin G-mediated autoimmune bullous skin disease. Nonorgan-specific antibodies were detected in Tunisian and Brazilian pemphigus patients with different prevalence.

Materials and Methods:

Fifty PV patients and fifty controls were screened for antinuclear antibodies (ANAs), anti-smooth muscle antibodies (ASMAs), anti-parietal antibodies (APAs), anti-mitochondrial antibodies, and Anti-nuclear cytoplasmic antibodies (ANCA) by indirect immunofluorescence.

Results:

Thirty-nine patients were female and 11 were male. Fifteen patients did not receive treatment before while 35 patients were on systemic steroid treatment ± azathioprine. Twenty (40%) of the PV patients and 1 (2%) control had positive ANA. ANA was significantly higher in PV patients than controls, P < 0.0001. ASMAs were detected in 20 (40%) PV patients and none of the controls. ASMA was significantly higher in PV patients than controls, P < 0.0001. No significant difference was detected between treated and untreated regarding ANA, P - 0.11. However, there was a significant difference between treated and untreated regarding ASMA, P - 0.03. Six patients (12%) and none of the controls had positive APA. There was a significant difference between the patients and the controls in APA. P - 0.027.

Conclusion:

Egyptian PV patients showed more prevalent ANA, ASMA, and APA than normal controls. Follow-up of those patients is essential to detect the early development of concomitant autoimmune disease. Environmental factors might account for the variability of the nonorgan-specific antibodies among different populations.

Autoantibody presentation in drug-induced liver injury and idiopathic autoimmune hepatitis: the influence of human leucocyte antigen alleles

OBJECTIVES

Positive autoantibody (AAB) titres are commonly encountered in autoimmune hepatitis (AIH) and in a proportion of drug-induced liver injury (DILI) patients. The underlying mechanism for selective AAB occurrence in DILI is unknown, but could be associated with variations in immune-associated genes. Hence, we aimed to analyse human leucocyte antigen (HLA) allele compositions in DILI with positive (+) and negative (-) AAB titres and in AIH patients.

METHODS

High-resolution genotyping of HLA class I (A, B, C) and II (DRB1, DQB1) loci was performed on 207 DILI and 50 idiopathic AIH patients and compared with 885 healthy Spanish controls.

RESULTS

Compared with controls, HLA-B*08:01 [44 vs. 9.7%, P=3.7E-13/corrected P-value (Pc)=1.0E-11], C*07:01 (46 vs. 24%, P=6.4E-04/Pc=0.012), DRB1*03:01 (58 vs. 21.5%, P=5.0E-09/Pc=1.0E-07) and DQB1*02:01 (56 vs. 22%, P=6.8E-08/Pc=9.0E-07) were significantly more frequent in AIH patients. The HLA-A*01:01 frequency was increased in the same population, but did not reach significance after Bonferroni's correction (34 vs. 19%, P=0.02/Pc=0.37). Fifty-eight of 207 DILI patients presented positive titres for at least one AAB (predominantly antinuclear antibody 76% and antismooth muscle antibody 28%). There was a tendency towards higher representation of DRB1*14:01 and DQB1*05:03 in DILI AAB+ compared with DILI AAB- (13.8 vs. 4.0%, P=0.02/Pc=0.5; 13.8 vs. 4.7%, P=0.04/Pc=0.5).

CONCLUSION

The presence of HLA alleles B*08:01, C*07:01, DRB1*03:01, DQB1*02:01 and possibly A*01:01 enhances the risk of AIH (type 1) in Spanish patients. These alleles form part of the ancestral haplotype 8.1. HLA-DRB1*14:01 and DQB1*05:03 could potentially increase the risk of positive AAB (particularly antinuclear antibody) in Spanish DILI patients.

Autoimmunity against laminins

Laminins are ubiquitous constituents of the basement membranes with major architectural and functional role as supported by the fact that absence or mutations of laminins lead to either lethal or severely impairing phenotypes. Besides genetic defects, laminins are involved in a wide range of human diseases including cancer, infections, and inflammatory diseases, as well as autoimmune disorders. A growing body of evidence implicates several laminin chains as autoantigens in blistering skin diseases, collagenoses, vasculitis, or post-infectious autoimmunity. The current paper reviews the existing knowledge on autoimmunity against laminins referring to both experimental and clinical data, and on therapeutic implications of anti-laminin antibodies. Further investigation of relevant laminin epitopes in pathogenic autoimmunity would facilitate the development of appropriate diagnostic tools for thorough characterization of patients' antibody specificities and should decisively contribute to designing more specific therapeutic interventions.

Infectomics and autoinfectomics: a tool to study infectious-induced autoimmunity

The exposome represents all exogenous and endogenous environmental exposures that begin at preconception and carry on throughout life, while the microbiome reflects the microbial component of the exposome. We recently introduced the concept of infectome and autoinfectome as a means of studying the totality of infections throughout life that participate in the induction as well as the progression of autoimmune diseases in an affected individual. The investigation of the autoinfectome could help us understand why some patients develop more than one autoimmune disease, a phenomenon also known as mosaic of autoimmunity. It could also explain the infectious and autoantibody burden of various autoimmune rheumatic diseases. The close interplay between infections and the immune system should be studied over time, long before the onset of autoaggression and autoimmunity. Tracking down each individual's exposure to infectious agents (as defined by the autoinfectome) would be important for the establishment of a causative link between infection and autoimmunity.

Aging-dependent decline of IL-10 producing B cells coincides with production of antinuclear antibodies but not rheumatoid factors

Aging is associated with development of autoimmunity. Loss of B cell tolerance in the elderly is suggested by an increased prevalence of anti-nuclear antibodies (ANAs) and rheumatoid factors (RFs). Accumulating evidence indicates that B cells also impact autoimmunity via secretion of cytokines. So far, few studies have directly assessed the effect of aging on the latter B cell function. Here, we determined if and how human aging influences the production of cytokines by B cells. In a cross-sectional study, we found that absolute numbers of circulating B cells were similar in 31 young (ages 19-39) and 73 old (age ≥ 60) individuals. Numbers of transitional B cells (CD19(+)CD27(-)CD38(High)CD24(High)) were decreased in old individuals, whereas numbers of naive and memory B cell subsets were comparable in young and old individuals. Short-term in vitro stimulation of whole blood samples revealed that numbers of B cells capable of producing TNF-α were similar in young and old individuals. In contrast, B cells capable of IL-10 production were decreased in old subjects. This decline of IL-10(+) B cells was observed in old individuals that were ANA positive, and in those that were negative for both ANAs and RFs. However, IL-10(+) B cells were remarkably well retained in the circulation of old subjects that were RF positive. Thus, pro-inflammatory TNF-α(+) B cells are retained in the elderly, whereas IL-10(+) B cells generally decline. In addition, our findings indicate that IL-10(+) B cells may differentially impact the development of ANAs and RFs in the elderly.

The transcription, translation, transport-trail and autoimmunity: Guilt by association

The autoimmune connective tissue diseases (ACTD) are a group of diseases which share clinical features and genetic inheritance. They are characterized by systemic autoimmunity and autoantibody production with a striking predilection for cellular components involved in transcription, translation and cellular transport. Although multiple triggers of autoimmunity have been proposed for this group of diseases including microbial agents such as viruses and bacteria, drugs, ultraviolet light, environmental toxins, stress, hormones and heavy metals, the prominence of autoantibodies to components of the transcription, translation, cellular transport-trail (TTTT) suggests that the agent(s) triggering the autoimmune response potentially utilize the TTTT. For the ACTD, viruses and viral agents are the likely triggers of autoimmunity as a result of aberrant viral latency with the production of autoantibodies to the components of the cellular TTTT machinery through multiple mechanisms, perhaps including molecular mimicry, bystander activation and epitope spreading.

Regulatory T cells resist virus infection-induced apoptosis

Regulatory T (Treg) cells are important in the maintenance of self-tolerance, and the depletion of Treg cells correlates with autoimmune development. It has been shown that type I interferon (IFN) responses induced early in the infection of mice can drive memory (CD44hi) CD8 and CD4 T cells into apoptosis, and we questioned here whether the apoptosis of CD44-expressing Treg cells might be involved in the infection-associated autoimmune development. Instead, we found that Treg cells were much more resistant to apoptosis than CD44hi CD8 and CD4 T cells at days 2 to 3 after lymphocytic choriomeningitis virus infection, when type I IFN levels are high. The infection caused a downregulation of the interleukin-7 (IL-7) receptor, needed for survival of conventional T cells, while increasing on Treg cells the expression of the high-affinity IL-2 receptor, needed for STAT5-dependent survival of Treg cells. The stably maintained Treg cells early during infection may explain the relatively low incidence of autoimmune manifestations among infected patients.

IMPORTANCE

Autoimmune diseases are controlled in part by regulatory T cells (Treg) and are thought to sometimes be initiated by viral infections. We tested the hypothesis that Treg may die off at early stages of infection, when virus-induced factors kill other lymphocyte types. Instead, we found that Treg resisted this cell death, perhaps reducing the tendency of viral infections to cause immune dysfunction and induce autoimmunity.

Inflammation and vitamin D: the infection connection

INTRODUCTION

Inflammation is believed to be a contributing factor to many chronic diseases. The influence of vitamin D deficiency on inflammation is being explored but studies have not demonstrated a causative effect.

METHODS

Low serum 25(OH)D is also found in healthy persons exposed to adequate sunlight. Despite increased vitamin D supplementation inflammatory diseases are increasing. The current method of determining vitamin D status may be at fault. The level of 25(OH)D does not always reflect the level of 1,25(OH)2D. Assessment of both metabolites often reveals elevated 1,25(OH)2D, indicating abnormal vitamin D endocrine function.

FINDINGS

This article reviews vitamin D's influence on the immune system, examines the myths regarding vitamin D photosynthesis, discusses ways to accurately assess vitamin D status, describes the risks of supplementation, explains the effect of persistent infection on vitamin D metabolism and presents a novel immunotherapy which provides evidence of an infection connection to inflammation.

CONCLUSION

Some authorities now believe that low 25(OH)D is a consequence of chronic inflammation rather than the cause. Research points to a bacterial etiology pathogenesis for an inflammatory disease process which results in high 1,25(OH)2D and low 25(OH)D. Immunotherapy, directed at eradicating persistent intracellular pathogens, corrects dysregulated vitamin D metabolism and resolves inflammatory symptoms.

Toxoplasmosis--a global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries

BACKGROUND

Toxoplasmosis is becoming a global health hazard as it infects 30-50% of the world human population. Clinically, the life-long presence of the parasite in tissues of a majority of infected individuals is usually considered asymptomatic. However, a number of studies show that this 'asymptomatic infection' may also lead to development of other human pathologies.

AIMS OF THE STUDY

The purpose of the study was to collect available geoepidemiological data on seroprevalence of toxoplasmosis and search for its relationship with mortality and disability rates in different countries.

METHODS AND FINDINGS

Prevalence data published between 1995-2008 for women in child-bearing age were collected for 88 countries (29 European). The association between prevalence of toxoplasmosis and specific disease burden estimated with age-standardized Disability Adjusted Life Year (DALY) or with mortality, was calculated using General Linear Method with Gross Domestic Product per capita (GDP), geolatitude and humidity as covariates, and also using nonparametric partial Kendall correlation test with GDP as a covariate. The prevalence of toxoplasmosis correlated with specific disease burden in particular countries explaining 23% of variability in disease burden in Europe. The analyses revealed that for example, DALY of 23 of 128 analyzed diseases and disease categories on the WHO list showed correlations (18 positive, 5 negative) with prevalence of toxoplasmosis and another 12 diseases showed positive trends (p<0.1). For several obtained significant correlations between the seroprevalence of toxoplasmosis and specific diseases/clinical entities, possible pathophysiological, biochemical and molecular explanations are presented.

CONCLUSIONS

The seroprevalence of toxoplasmosis correlated with various disease burden. Statistical associations does not necessarily mean causality. The precautionary principle suggests however that possible role of toxoplasmosis as a triggering factor responsible for development of several clinical entities deserves much more attention and financial support both in everyday medical practice and future clinical research.

Tracing environmental markers of autoimmunity: introducing the infectome

We recently introduced the concept of the infectome as a means of studying all infectious factors which contribute to the development of autoimmune disease. It forms the infectious part of the exposome, which collates all environmental factors contributing to the development of disease and studies the sum total of burden which leads to the loss of adaptive mechanisms in the body. These studies complement genome-wide association studies, which establish the genetic predisposition to disease. The infectome is a component which spans the whole life and may begin at the earliest stages right up to the time when the first symptoms manifest, and may thus contribute to the understanding of the pathogenesis of autoimmunity at the prodromal/asymptomatic stages. We provide practical examples and research tools as to how we can investigate disease-specific infectomes, using laboratory approaches employed from projects studying the “immunome” and “microbiome”. It is envisioned that an understanding of the infectome and the environmental factors that affect it will allow for earlier patient-specific intervention by clinicians, through the possible treatment of infectious agents as well as other compounding factors, and hence slowing or preventing disease development.

Immunostimulation in the treatment for chronic fatigue syndrome/myalgic encephalomyelitis

Chronic fatigue syndrome (CFS)/myalgic encephalomyelitis (ME) has long been associated with the presence of infectious agents, but no single pathogen has been reliably identified in all patients with the disease. Recent studies using metagenomic techniques have demonstrated the presence of thousands of microbes in the human body that were previously undetected and unknown to science. More importantly, such species interact together by sharing genes and genetic function within communities. It follows that searching for a singular pathogen may greatly underestimate the microbial complexity potentially driving a complex disease like CFS/ME. Intracellular microbes alter the expression of human genes in order to facilitate their survival. We have put forth a model describing how multiple species-bacterial, viral, and fungal-can cumulatively dysregulate expression by the VDR nuclear receptor in order to survive and thus drive a disease process. Based on this model, we have developed an immunostimulatory therapy that is showing promise inducing both subjective and objective improvement in patients suffering from CFS/ME.

The human microbiome and autoimmunity

PURPOSE OF REVIEW

To demonstrate how dysbiosis of the human microbiome can drive autoimmune disease.

RECENT FINDINGS

Humans are superorganisms. The human body harbors an extensive microbiome, which has been shown to differ in patients with autoimmune diagnoses. Intracellular microbes slow innate immune defenses by dysregulating the vitamin D nuclear receptor, allowing pathogens to accumulate in tissue and blood. Molecular mimicry between pathogen and host causes further dysfunction by interfering with human protein interactions. Autoantibodies may well be created in response to pathogens.

SUMMARY

The catastrophic failure of human metabolism observed in autoimmune disease results from a common underlying pathogenesis - the successive accumulation of pathogens into the microbiome over time, and the ability of such pathogens to dysregulate gene transcription, translation, and human metabolic processes. Autoimmune diseases are more likely passed in families because of the inheritance of a familial microbiome, rather than Mendelian inheritance of genetic abnormalities. We can stimulate innate immune defenses and allow patients to target pathogens, but cell death results in immunopathology.

Infectome: a platform to trace infectious triggers of autoimmunity

The "exposome" is a term recently used to describe all environmental factors, both exogenous and endogenous, which we are exposed to in a lifetime. It represents an important tool in the study of autoimmunity, complementing classical immunological research tools and cutting-edge genome wide association studies (GWAS). Recently, environmental wide association studies (EWAS) investigated the effect of environment in the development of diseases. Environmental triggers are largely subdivided into infectious and non-infectious agents. In this review, we introduce the concept of the "infectome", which is the part of the exposome referring to the collection of an individual's exposures to infectious agents. The infectome directly relates to geoepidemiological, serological and molecular evidence of the co-occurrence of several infectious agents associated with autoimmune diseases that may provide hints for the triggering factors responsible for the pathogenesis of autoimmunity. We discuss the implications that the investigation of the infectome may have for the understanding of microbial/host interactions in autoimmune diseases with long, pre-clinical phases. It may also contribute to the concept of the human body as a superorganism where the microbiome is part of the whole organism, as can be seen with mitochondria which existed as microbes prior to becoming organelles in eukaryotic cells of multicellular organisms over time. A similar argument can now be made in regard to normal intestinal flora, living in symbiosis within the host. We also provide practical examples as to how we can characterise and measure the totality of a disease-specific infectome, based on the experimental approaches employed from the "immunome" and "microbiome" projects.

Geographical differences in autoantibodies and anti-infectious agents antibodies among healthy adults

Much is known about the geoepidemiology of defined autoimmune diseases (AD); however, there is currently limited data regarding the prevalence of autoantibodies among healthy populations of different geographical areas. The aim of this study was to evaluate a large profile of autoantibodies in healthy adults from distinct global regions as well as the prevalence of anti-infectious agents antibodies in those regions. Sera samples from 557 healthy donors were obtained at six centers located in different countries (i.e., Italy, Netherlands, Israel, Mexico, Columbia, Papua New Guinea (Kitavans)). Sera were tested for the presence of antinuclear antibodies (ANA) and autoantibodies associated with thrombophilia, vasculitis, and gastrointestinal (GI) disease. Sera samples were also screened for antibodies against infectious agents (i.e., EBV, CMV, HBV, Helicobacter pylori, Treponema pallidum, and Toxoplasma gondii). Tests were performed using the BioPlex 2200 or ELISA kits (Bio-Rad Laboratories, USA). We found a significant gradient of ANA positivity among the groups: 45% of Columbians, 38% of Kitavans, 26% of Mexicans, 12% of Italians, 12% of Dutch, and 11% of Israelis were ANA positive. Geographical differences were also observed regarding the prevalence of specific autoantibodies, namely ANA: anti-dsDNA, chromatin, SmRNP, Ro/SSA, La/SSB, Scl70; GI associated: antigliadin; and thrombophilia-associated: anti-β2GP1 and prothrombin. Additionally, significant differences were observed regarding serological markers of all infectious agents screened. The observed variance between healthy ethno-geographical distinct populations in prevalence of autoantibodies may represent different genetic or environmental (e.g., prior exposure to infection) influences. Thus may illuminate possible causes of geoepidemiological differences in AD.

Binding of hepatitis A virus to its cellular receptor 1 inhibits T-regulatory cell functions in humans

BACKGROUND & AIMS

CD4+ T-regulatory (Treg) cells suppress immune responses and control self-tolerance and immunity to pathogens, cancer, and alloantigens. Most pathogens activate Treg cells to minimize immune-mediated tissue damage and prevent clearance, which promotes chronic infections. However, hepatitis A virus (HAV) temporarily inhibits Treg-cell functions. We investigated whether the interaction of HAV with its cellular receptor 1 (HAVCR1), a T-cell co-stimulatory molecule, inhibits the function of Treg cells to control HAV infection.

METHODS

We studied the effects of HAV interaction with HAVCR1 on human T cells using binding, signal transduction, apoptosis, activation, suppression, cytokine production, and confocal microscopy analyses. Cytokines were analyzed in sera from 14 patients with HAV infection using bead arrays.

RESULTS

Human Treg cells constitutively express HAVCR1. Binding of HAV to HAVCR1 blocked phosphorylation of Akt, prevented activation of the T-cell receptor, and inhibited function of Treg cells. At the peak viremia, patients with acute HAV infection had no Treg-cell suppression function, produced low levels of transforming growth factor-β , which limited leukocyte recruitment and survival, and produced high levels of interleukin-22, which prevented liver damage.

CONCLUSIONS

Interaction between HAV and its receptor HAVCR1 inhibits Treg-cell function, resulting in an immune imbalance that allows viral expansion with limited hepatocellular damage during early stages of infection-a characteristic of HAV pathogenesis. The mechanism by which HAV is cleared in the absence of Treg-cell function could be used as a model to develop anticancer therapies, modulate autoimmune and allergic responses, and prevent transplant rejection.

[Prevalence and diagnostic value of antinuclear antibodies without identified antigenic target: a retrospective study of 90 patients]

PURPOSE

The objective of this study was to determine the clinical relevance and the diagnostic significance of positive antinuclear antibodies (ANA) without identified antigenic target by the usual characterization technique.

PATIENTS AND METHODS

Retrospective study conducted in the Laboratory of Immunology of Habib Bourguiba Hospital (Sfax, Tunisia) during 18 months. The inclusion criteria were the presence of an ANA titer greater or equal to 1/320 with negative characterization result. ANA screening was performed by indirect immunofluorescence (IIF) on Hep2 cells. Each positive serum was tested by IIF on Crithidia luciliae (anti-native DNA) and by immunodot (anti-nucleosome, anti-histone, anti-Sm, anti-RNP, anti-SSA, anti-SSB, anti-Scl 70, anti-PM-Scl, anti-Jo1, anti-PCNA and anti-ribosomal protein). Sera of systemic lupus erythematosus (SLE), myositis, and scleroderma patients were tested for anti-Ku, anti-PL7, anti-PL12 and anti-Ro-52 using dot myositis.

RESULTS

Sera of 90 patients were studied: 18 men and 72 women (average age: 44 years). Drug-induced ANA was found in eight patients. The most frequent clinical symptoms were joint (56.7%), cutaneous (54.4%) and constitutional symptoms (45.6%). The diagnosis of an autoimmune disease was suspected in 49 patients (54.5%) and confirmed in 30 (33.3%) including 20 cases of connective tissue disease: myositis (n=6), scleroderma (n=5), Sjögren's syndrome (n=3), SLE (n=4), rheumatoid arthritis (n=6) and antiphospholipid syndrome (n=4). Other autoimmune diseases were less frequent. The anti-Ku antibody was detected in the majority of patients with connective tissue disease. The diagnosis of non-autoimmune diseases was established in 25.5% of patients. Eighteen patients (20%) had no diagnosis orientation.

CONCLUSION

Our study demonstrated the diagnostic value of the presence of ANA even in the absence of known antigenic target, confirmed the role of the IIF as "gold standard" test for ANA screening, and suggested the usefulness of the addition of Ku antigen in the immunodot classic profile.

Using the antinuclear antibody test to diagnose rheumatic diseases: when does a positive test warrant further investigation?

The anti-nuclear antibody (ANA) test is ordered commonly as a screening test for rheumatic diseases. Although ANA positivity is highly sensitive for certain rheumatic diseases, the presence of ANA is nonspecific and can be associated with numerous nonrheumatic factors, including environmental exposures, malignancies, drugs, and infections. This article describes a practical approach for physicians when evaluating patients using a positive ANA test. In the absence of connective tissue disease symptoms, the ANA test has minimal clinical significance in diagnosing rheumatic diseases. Understanding how to use ANA test results appropriately may reduce unnecessary referrals and costly workups.

Clinical significance of the detection of antinuclear antibodies in patients with acute hepatitis a

Background/Aims

The findings of several recent studies suggest that antinuclear antibodies (ANAs) are frequently detected in patients with acute hepatitis A (AHA). However, the clinical significance of a positive ANA test remains uncertain. This study was performed to evaluate the clinical significance of ANAs in AHA patients.

Methods

All patients admitted with AHA were consecutively enrolled in this study. An ANA assay was performed by indirect immunofluorescence during hospitalization. ANA positivity was defined as an ANA titer ≥1:80. The peak international normalized ratio (INR), peak alanine aminotransferase (ALT) and peak bilirubin levels were assessed over the duration of the hospitalization, and the incidence of AHA complications was evaluated.

Results

A total of 422 patients were enrolled in this study (age, 31±7 years), of which 260 (61.6%) were men. ANAs were detected in 179 AHA patients (42.4%). The proportion of ANA-positive patients varied significantly with AHA status on the day of the ANA assay (4.7% during the prodromal period vs 52.1% during the icteric or recovery period, p<0.001) and sex (56.2% in women vs 33.8% in men, p<0.001). The ANAs became undetectable in all ANA-positive patients within 3 months. The incidence of complications, including mortality, fulminant hepatic failure, renal dysfunction, relapse, and cholestatic hepatitis, did not differ significantly between ANA-positive and ANA-negative patients.

Conclusions

ANAs were detected frequently and transiently in patients with AHA, especially after their peak-ALT day. The presence of ANAs may not be associated with the clinical outcome of AHA, but simply with AHA status on the ANA assay day.

Current and future role of biomarkers in Crohn's disease risk assessment and treatment

BACKGROUND

Crohn's disease (CD), a chronic inflammatory bowel disease (IBD), occurs in genetically susceptible individuals who develop aberrant immune responses to endoluminal bacteria. Recurrent inflammation increases the risk of several complications. Despite use of a traditional "step-up" therapy with corticosteroids and immunomodulators, most CD patients eventually require surgery at some time in their disease course. Newer biologic agents have been remarkably effective in controlling severe disease. Thus, "top-down," early aggressive therapy has been proposed to yield better outcomes, especially in complicated disease. However, safety and cost issues mandate the need for careful patient selection. Identification of high-risk candidates who may benefit from aggressive therapy is becoming increasingly relevant. Serologic and genetic markers of CD have great potential in this regard. The aim of this review is to highlight the clinical relevance of these markers for diagnostics and prognostication.

METHODS

A current PubMed literature search identified articles regarding the role of biomarkers in IBD diagnosis, severity prediction, and stratification. Studies were also reviewed on the presence of IBD markers in non-IBD diseases.

RESULTS

Several IBD seromarkers and genetic markers appear to be associated with complex CD phenotypes. Qualitative and quantitative serum immune reactivity to microbial antigens may be predictive of disease progression and complications.

CONCLUSION

The cumulative evidence provided by serologic and genetic testing has the potential to enhance clinical decision-making when formulating individualized IBD therapeutic plans.

Immunostimulation in the era of the metagenome

Microbes are increasingly being implicated in autoimmune disease. This calls for a re-evaluation of how these chronic inflammatory illnesses are routinely treated. The standard of care for autoimmune disease remains the use of medications that slow the immune response, while treatments aimed at eradicating microbes seek the exact opposite-stimulation of the innate immune response. Immunostimulation is complicated by a cascade of sequelae, including exacerbated inflammation, which occurs in response to microbial death. Over the past 8 years, we have collaborated with American and international clinical professionals to research a model-based treatment for inflammatory disease. This intervention, designed to stimulate the innate immune response, has required a reevaluation of disease progression and amelioration. Paramount is the inherent conflict between palliation and microbicidal efficacy. Increased microbicidal activity was experienced as immunopathology-a temporary worsening of symptoms. Further studies are needed, but they will require careful planning to manage this immunopathology.

Exposure to Epstein-Barr virus infection is associated with mild systemic lupus erythematosus disease

Infections may act as environmental triggers for the induction of systemic lupus erythematosus (SLE). In this study, we determine the relationship between disease manifestations of SLE patients and the titers of five Epstein-Barr virus (EBV) Abs. We evaluated the titers of early antigen IgG (EAG), nuclear antigen IgG, viral capsid antigen (VCA) IgG and IgM, and heterophile IgM, using the BioPlex 2200 multiplexed immunoassay method in 260 sera (120 SLE patients and 140 controls). EAG titers were significantly elevated (P < 0.024) in patients with cutaneous symptoms and increased anti-Ro antibody titers (P < 0.005). VCA IgG titers were significantly elevated (P < 0.003) in patients with joint involvement. None of the titers differed by central nervous system or renal involvement or antiphospholipid syndrome. We conclude that exposure to EBV infection may predict a disease phenotype of mild SLE disease with cutaneous and joint manifestations and elevated titers of anti-Ro Abs.

Autoimmunity and HIV

PURPOSE OF REVIEW

This review focuses on some of the recent advances in the understanding of HIV immunopathogenesis and the diagnosis and treatment of several autoimmune conditions associated with HIV in the era of potent antiretroviral therapy.

RECENT FINDINGS

Chronic immune activation with progressive immune exhaustion are central features of HIV pathogenesis. The role of self-reactive T cells in the generation and maintenance of this process has recently been described. The understanding of the impact of immune dysregulation on the generation of autoimmune phenomena in HIV infection remains incomplete. The diagnosis of autoimmune diseases in the context of HIV is often difficult due to similarities in clinical presentations and laboratory markers. The antiretroviral therapy-associated immune reconstitution syndrome can present as autoimmune disease.

SUMMARY

The cause, frequency and prognosis of autoimmune conditions associated with HIV infection remain somewhat uncertain. Their management is often empirical with the use of novel immunosuppressive medication.

Identification of cross-reactive epitopes on the conserved 47-kilodalton antigen of Orientia tsutsugamushi and human serine protease

Orientia tsutsugamushi is the causative agent of scrub typhus. One of the protein antigens of this species, the conserved 47-kDa protein (HtrA), has been shown to induce an antibody response in patients and can provide protective immunity against live challenge by Orientia in mice. Pepscan experiments identified many peptide epitope clusters in different parts of this protein. The majority of the most reactive epitopes are located at the C terminus of the protein (from amino acid 333 to amino acid 430). Protein sequence analysis revealed that the 47-kDa protein contains a trypsin domain and has sequence homology to human serine protease HtrA1 (hHtrA1). As the 47-kDa protein is a potential vaccine candidate and its ability to induce autoimmunity is a concern, the reactivity of scrub typhus patient sera with purified recombinant 47-kDa and hHtrA1 proteins was tested. A significant percentage (>20%) of scrub typhus patient sera reacted strongly with recombinant hHTRA1 and two of the antigenic polypeptide epitopes in hHtrA1. These findings suggest that the safety of the full-length 47-kDa antigen as a vaccine candidate is a significant issue due to its cross-reactivity with a human protein, which may also contribute to autoimmune responses or enhanced pathology in some scrub typhus patients.