Higher IgA Research Articles

Noninvasively measured immune responses reflect current parasite infections in a wild carnivore and are linked to longevity.

Host immune defenses are important components of host–parasite interactions that affect the outcome of infection and may have fitness consequences for hosts when increased allocation of resources to immune responses undermines other essential life processes. Research on host–parasite interactions in large free‐ranging wild mammals is currently hampered by a lack of verified noninvasive assays. We successfully adapted existing assays to measure innate and adaptive immune responses produced by the gastrointestinal mucosa in spotted hyena (Crocuta crocuta) feces, including enzyme‐linked immunosorbent assays (ELISAs), to quantify fecal immunoglobulins (total IgA, total IgG) and total fecal O‐linked oligosaccharides (mucin). We investigated the effect of infection load by an energetically costly hookworm (Ancylostoma), parasite richness, host age, sex, year of sampling, and clan membership on immune responses and asked whether high investment in immune responses during early life affects longevity in individually known spotted hyenas in the Serengeti National Park, Tanzania. Fecal concentrations of IgA, IgG, and mucin increased with Ancylostoma egg load and were higher in juveniles than in adults. Females had higher mucin concentrations than males. Juvenile females had higher IgG concentrations than juvenile males, whereas adult females had lower IgG concentrations than adult males. High IgA concentrations during the first year of life were linked to reduced longevity after controlling for age at sampling and Ancylostoma egg load. Our study demonstrates that the use of noninvasive methods can increase knowledge on the complex relationship between gastrointestinal parasites and host local immune responses in wild large mammals and reveal fitness‐relevant effects of these responses.

40 Dietary Saccharomyces cerevisiae fermentate affects mucosal immunity in young stress-challenged horses in training

Competition horses are under pressure from a wide range of stressors putting them at higher risk of infectious disease. Ingestion of Saccharomyces cerevisiae fermentate (SCF) products have been shown to improve immunocompetence in humans and other species, and we hypothesized it would provide similar benefits for horses. Yeast fermentate contains cellular components that can bind to pathogens and stimulate host immune cells, as well as bioactive fermentation byproducts (e.g., short chain fatty acids, vitamins, antioxidants) that can augment gut and other mucosal defenses. This study aimed to evaluate the effect of SCF on mucosal immunity in young horses in training. Two-year-old Quarter Horses (mean ± SEM; initial age 22 ± 0.3 mo and BW 439 ± 3 kg) were paired by age and sex and randomly assigned to receive SCF (Diamond V, Cedar Rapids, IA; 21 g/d; n = 10) or no supplement (CON; n = 10) added to their diet (60% hay, 40% concentrate) for 60 d. Horses were exercised 4 d/wk for 30–45 min/d at light to moderate intensity. On d 57, horses were placed in individual stalls and tethered with their heads elevated 35 cm above wither height for 12 h to induce mild upper respiratory tract inflammation. Feces, whole blood, and nasopharyngeal flush (NPF) samples were obtained at study initiation and before and up to 72 h after stress induction to evaluate immune responses. Data were compared using mixed model ANOVA with time as a repeated measure. Prolonged head elevation resulted in greater ( P < 0.0001) serum cortisol and increases ( P < 0.05) in mucus, total leukocytes, neutrophils, lymphocytes, monocytes, and ratio of neutrophils to lymphocytes in NPF, indicative of an inflammatory response that was mostly resolved by h 72. A similar leukogram was observed in whole blood, though it was delayed 12 h compared with NPF. Neutrophils and lymphocytes were lower ( P < 0.05) and monocytes greater ( P < 0.05) in NPF from horses fed SCF than CON. Immunoglobulin (Ig) A in NPF exhibited a time × treatment effect ( P = 0.05) with an increased response to head elevation in SCF horses but no change in CON. Head elevation increased ( P < 0.05) IgA, IgG and IgM in feces, and fecal concentrations of IgA and IgG were greater ( P < 0.05) for CON than SCF. Serum IgA, IgG, and IgM were not affected by head elevation nor treatment. Changes in leukocytes and IgG in mucosal secretions suggest a stronger inflammatory response to head elevation in CON horses. Higher IgA in NPF from SCF horses may have helped attenuate local inflammation. Further study is needed to determine if SCF could improve other markers of disease resistance.

Determinants of Serum Immunoglobulin Levels: A Systematic Review and Meta-Analysis.

BackgroundAn up-to-date overview of determinants of serum immunoglobulins in adults is pivotal for clinical practice and research, but currently lacking. We therefore performed a systematic review and meta-analysis to identify determinants of serum immunoglobulin levels.MethodsEmbase, Web of Science, Medline, Cochrane, and Google Scholar were searched from inception to July 11th, 2019 for articles reporting on determinants of serum immunoglobulin A, G or M (IgA, IgG or IgM) in adult humans. Random and fixed effect models were applied to obtain pooled mean differences (MDs) and 95% confidence intervals (CIs) for the association of age and sex with serum immunoglobulins.ResultsWe retrieved 117 articles reporting on determinants of serum immunoglobulins, of which 28 could be meta-analyzed. Older compared to younger individuals had higher IgA (MD: 0.38; CI: 0.18 – 0.58), but lower IgM levels (MD: -0.40; 95%: -0.66 – -0.14). Men had higher IgA (MD: 0.22; CI: 0.03 – 0.42), but lower IgM levels (MD: -0.21; CI: -0.32 – -0.10) than women. Age and sex did not influence IgG. Caucasian ethnicity was associated with lower IgA, IgG, and IgM. Smoking and corticosteroid use were associated with lower IgG. Positive associations were reported of probiotics with IgG, alcohol with IgA, hypertension with IgA and IgG, and acute psychological stress with IgA, IgG, and IgM.ConclusionsOlder age and male sex are associated with higher IgA, but lower IgM, and urge investigation of age- and sex-specific reference ranges of immunoglobulins. Other identified determinants were ethnicity, diet, lifestyle and cardio-metabolic factors.

Gut Microbiome Homeostasis and the CD4 T- Follicular Helper Cell IgA Axis in Human Immunodeficiency Virus Infection.

Human Immunodeficiency Virus (HIV) and Simian Immunodeficiency Virus (SIV) are associated with severe perturbations in the gut mucosal environment characterized by massive viral replication and depletion of CD4 T cells leading to dysbiosis, breakdown of the epithelial barrier, microbial translocation, immune activation and disease progression. Multiple mechanisms play a role in maintaining homeostasis in the gut mucosa and protecting the integrity of the epithelial barrier. Among these are the secretory IgA (sIgA) that are produced daily in vast quantities throughout the mucosa and play a pivotal role in preventing commensal microbes from breaching the epithelial barrier. These microbe specific, high affinity IgA are produced by IgA+ plasma cells that are present within the Peyer’s Patches, mesenteric lymph nodes and the isolated lymphoid follicles that are prevalent in the lamina propria of the gastrointestinal tract (GIT). Differentiation, maturation and class switching to IgA producing plasma cells requires help from T follicular helper (Tfh) cells that are present within these lymphoid tissues. HIV replication and CD4 T cell depletion is accompanied by severe dysregulation of Tfh cell responses that compromises the generation of mucosal IgA that in turn alters barrier integrity leading to commensal bacteria readily breaching the epithelial barrier and causing mucosal pathology. Here we review the effect of HIV infection on Tfh cells and mucosal IgA responses in the GIT and the consequences these have for gut dysbiosis and mucosal immunopathogenesis.

Early Viral Clearance and Antibody Kinetics of COVID-19 Among Asymptomatic Carriers.

Asymptomatic carriers contribute to the spread of Coronavirus Disease 2019 (COVID-19), but their clinical characteristics, viral kinetics, and antibody responses remain unclear. A total of 56 COVID-19 patients without symptoms at admission and 19 age-matched symptomatic patients were enrolled. RNA of SARS-CoV-2 was tested using transcriptase quantitative PCR, and the total antibodies (Ab), IgG, IgA, and IgM against the SARS-CoV-2 were tested using Chemiluminescence Microparticle Immuno Assay. Among 56 patients without symptoms at admission, 33 cases displayed symptoms and 23 remained asymptomatic throughout the follow-up period. 43.8% of the asymptomatic carriers were children and none of the asymptomatic cases had recognizable changes in C-reactive protein or interleukin-6, except one 64-year-old patient. The initial threshold cycle value of nasopharyngeal SARS-CoV-2 in asymptomatic carriers was similar to that in pre-symptomatic and symptomatic patients, but the positive viral nucleic acid detection period of asymptomatic carriers (9.63 days) was shorter than pre-symptomatic patients (13.6 days). There were no obvious differences in the seropositive conversion rate of total Ab, IgG, and IgA among the three groups, though the rates of IgM varied largely. The average peak IgG and IgM COI of asymptomatic cases was 3.5 and 0.8, respectively, which is also lower than those in symptomatic patients with peaked IgG and IgM COI of 4.5 and 2.4 (p < 0.05). Young COVID-19 patients seem to be asymptomatic cases with early clearance of SARS-CoV-2 and low levels of IgM generation but high total Ab, IgG, and IgA. Our findings provide empirical information for viral clearance and antibody kinetics of asymptomatic COVID-19 patients.

High serum IgA and activated Th17 and Treg predict the efficacy of abatacept in patients with early, seropositive rheumatoid arthritis

To identify the predictive biomarkers for achieving remission with abatacept in patients with seropositive rheumatoid arthritis (RA). We enrolled patients with RA who were treated with abatacept. We compared the baseline laboratory results and longitudinal immune-phenotyping data between patients who achieved remission and those who did not achieve remission at 6months according to the clinical disease activity index. One hundred and twenty RA patients were enrolled. In the seropositive patients with early RA (n = 24), high serum IgA levels, anti-citrullinated peptide (CCP) titers, and neutrophil counts before treatment were predictors of remission (area under the curve [AUC], 0.659, 0.741, and 0.704, respectively). Additionally, activated Th17 (aTh17) cells and activated Treg (aTreg) cells before treatment were found to be significantly higher in patients with remission compared to those without remission (2.9% vs 1.1%, P = 0.02; 34.3% vs 17%, P = 0.03, respectively). The measurement of longitudinal cell subpopulation revealed a decrease in the effector CD4 T cell population after abatacept treatment, which correlated with anti-CCP titers and neutrophil counts, and was associated with remission achievement. In seropositive patients with established RA (n = 79), high RF titers and low IFN-γ levels were associated with the good response to abatacept. Our study has shown that serum IgA levels, anti-CCP titer, and neutrophil counts are predictive biomarkers for predicting the response to abatacept in patients with seropositive and early RA and may reflect the inhibition of effector CD4 T cell subpopulations by abatacept. Key Points • Serum IgA levels and neutrophil counts are novel biomarkers for predicting the efficacy of abatacept. • Those may reflect the inhibition of effector CD4 T cell subpopulations by abatacept.

Induction of mucosal immunity by pulmonary administration of a cell-targeting nanoparticle

We previously found that a nanoparticle constructed with an antigen, benzalkonium chloride (BK) and γ-polyglutamic acid (γ-PGA) showed high Th1 and Th2-type immune induction after subcutaneous administration. For prophylaxis of respiratory infections, however, mucosal immunity should be induced. In this study, we investigated the effect of pulmonary administration of a nanoparticle comprising ovalbumin (OVA) as a model antigen, BK, and γ-PGA on induction of mucosal immunity in the lungs and serum. The complex was strongly taken up by RAW264.7 and DC2.4cells. After pulmonary administration, lung retention was longer for the OVA/BK/γ-PGA complex than for OVA alone. OVA-specific serum immunoglobulin (Ig)G was highly induced by the complex. High IgG and IgA levels were also induced in the bronchoalveolar lavage fluid, and in vivo toxicities were not observed. In conclusion, we effectively and safely induced mucosal immunity by pulmonary administration of an OVA/BK/γ-PGA complex.

IgA Levels Are Associated with Coronary Artery Lesions in Kawasaki Disease.

Background and ObjectivesKawasaki disease (KD) is an acute systemic vasculitis that affects the coronary arteries. Abnormal immune reactions are thought to contribute to disease pathogenesis. The effect of immunoglobulin (Ig) isotype (IgG, IgA, IgM, and IgE) on inflammatory data and clinical outcomes of patients with KD was examined.MethodsIg levels in 241 patients with KD were measured during the acute, subacute, convalescent, and normal phases of the disease.ResultsCompared with reference Ig values, IgG, IgA, and IgM levels were significantly higher in the subacute phase, while IgE levels were elevated in 73.9% (178/241) of patients with KD in all clinical phases. However, high IgE levels were not associated with clinical outcomes, including intravenous immunoglobulin unresponsiveness and coronary artery lesions (CALs). Significantly more CALs were observed in the high IgA group than in the normal IgA group (44.7% vs. 20.8%, respectively; p<0.01). In addition, IgA levels in the acute phase (p=0.038) were 2.2-fold higher, and those in the subacute phase were 1.7-fold higher (p <0.001), in the CAL group than in the non-CAL group. IgA concentrations increased along with the size of the coronary artery aneurysm (p <0.001). Furthermore, there was a strong correlation between IgA levels and CAL size (r=0.435, p<0.001), with a high odds ratio of 2.58 (p=0.022).ConclusionsHigh IgA levels in patients with KD are prognostic for the risk of CALs.

Systemic and mucosal antibody responses specific to SARS-CoV-2 during mild versus severe COVID-19

BackgroundWhereas severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody tests are increasingly being used to estimate the prevalence of SARS-CoV-2 infection, the determinants of these antibody responses remain unclear.ObjectivesOur aim was to evaluate systemic and mucosal antibody responses toward SARS-CoV-2 in mild versus severe coronavirus disease 2019 (COVID-19) cases.MethodsUsing immunoassays specific for SARS-CoV-2 spike proteins, we determined SARS-CoV-2–specific IgA and IgG in sera and mucosal fluids of 2 cohorts, including SARS-CoV-2 PCR-positive patients (n = 64) and PCR-positive and PCR-negtive health care workers (n = 109).ResultsSARS-CoV-2–specific serum IgA titers in patients with mild COVID-19 were often transiently positive, whereas serum IgG titers remained negative or became positive 12 to 14 days after symptom onset. Conversely, patients with severe COVID-19 showed a highly significant increase of SARS-CoV-2–specific serum IgA and IgG titers after symptom onset. Very high titers of SARS-CoV-2–specific serum IgA were correlated with severe acute respiratory distress syndrome. Interestingly, some health care workers with negative SARS-CoV-2–specific serum antibody titers showed SARS-CoV-2–specific IgA in mucosal fluids with virus-neutralizing capacity in some cases. SARS-CoV-2–specific IgA titers in nasal fluids were inversely correlated with age.ConclusionsSystemic antibody production against SARS-CoV-2 develops mainly in patients with severe COVID-19, with very high IgA titers seen in patients with severe acute respiratory distress syndrome, whereas mild disease may be associated with transient production of SARS-CoV-2–specific antibodies but may stimulate mucosal SARS-CoV-2–specific IgA secretion.

Characterization of ShigETEC, a Novel Live Attenuated Combined Vaccine against Shigellae and ETEC.

Background: Shigella spp. and enterotoxigenic Escherichia coli (ETEC) remain the two leading bacterial causes of diarrheal diseases worldwide. Attempts to develop preventive vaccines against Shigella and ETEC have not yet been successful. The major challenge for a broad Shigella vaccine is the serotype-specific immune response to the otherwise protective LPS O-antigen. ETEC vaccines mainly rely on the heat-labile enterotoxin (LT), while heat-stable toxin (ST) has also been shown to be an important virulence factor. Methods: We constructed a combined Shigella and ETEC vaccine (ShigETEC) based on a live attenuated Shigella strain rendered rough and non-invasive with heterologous expression of two ETEC antigens, LTB and a detoxified version of ST (STN12S). This new vaccine strain was characterized and tested for immunogenicity in relevant animal models. Results: Immunization with ShigETEC resulted in serotype independent protection in the mouse lung shigellosis model and induced high titer IgG and IgA antibodies against bacterial lysates, and anti-ETEC toxin antibodies with neutralizing capacity. Conclusions: ShigETEC is a promising oral vaccine candidate against Shigella and ETEC infections and currently in Phase 1 testing.

The possible double-edged sword effects of vitamin D on COVID-19: A hypothesis.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) gains access to host cells by attaching to angiotensin-converting enzyme 2 (ACE2). Vitamin D (VitD) can upregulate ACE2 and has an antagonistic effect on Renin, which exerts a vasodilatation and anti-inflammatory effect against coronavirus disease (COVID-19). However, it may also facilitate viral entry by increasing ACE2 as the main SARS-CoV-2 receptor and mediates ROS production through NADPH oxidase, as a double-edged sword effect. Lung function and the immune system are also influenced by VitD through several mechanisms, including increased natural antibiotics (Defensin and Cathelicidin) and upregulated transforming growth factor-β. A higher IgA, Th2/Th1 ratio, and T-regulatory cells are attributable to VitD effects on the immune cells, while these changes may also be a double-edged sword in COVID-19. Although VitD supplementation might be highly recommended in COVID-19, the administration's dosage and route could be challenging. Furthermore, this issue has not been mentioned in various studies so far. So, the report aimed to explain the current challenges with the application of VitD in COVID-19.

Identification of risk features for complication in Gaucher\u2019s disease patients: a machine learning analysis of the Spanish registry of Gaucher disease

BackgroundSince enzyme replacement therapy for Gaucher disease (MIM#230800) has become available, both awareness of and the natural history of the disease have changed. However, there remain unmet needs such as the identification of patients at risk of developing bone crisis during therapy and late complications such as cancer or parkinsonism. The Spanish Gaucher Disease Registry has worked since 1993 to compile demographic, clinical, genetic, analytical, imaging and follow-up data from more than 400 patients. The aims of this study were to discover correlations between patients’ characteristics at diagnosis and to identify risk features for the development of late complications; for this a machine learning approach involving correlation networks and decision trees analyses was applied.ResultsA total of 358 patients, 340 type 1 Gaucher disease and 18 type 3 cases were selected. 18% were splenectomyzed and 39% had advanced bone disease. 81% of cases carried heterozygous genotype. 47% of them were diagnosed before the year 2000. Mean age at diagnosis and therapy were 28 and 31.5 years old (y.o.) respectively. 4% developed monoclonal gammopathy undetermined significance or Parkinson Disease, 6% cancer, and 10% died before this study. Previous splenectomy correlates with the development of skeletal complications and severe bone disease (p = 0.005); serum levels of IgA, delayed age at start therapy (> 9.5 y.o. since diagnosis) also correlates with severe bone disease at diagnosis and with the incidence of bone crisis during therapy. High IgG (> 1750 mg/dL) levels and age over 60 y.o. at diagnosis were found to be related with the development of cancer. When modelling the decision tree, patients with a delayed diagnosis and therapy were the most severe and with higher risk of complications.ConclusionsOur work confirms previous observations, highlights the importance of early diagnosis and therapy and identifies new risk features such as high IgA and IgG levels for long-term complications.

Antibodies Against Glycoprotein 2 Are Specific Biomarkers for Pediatric Crohn's Disease.

Serological markers can assist in accurate differentiation between Crohn's disease (CD) and ulcerative colitis (UC). One such marker is anti-glycoprotein 2 (anti-GP2) which was shown to be a specific marker for CD in adult patients. The aim of our study was to assess the utility of anti-GP2 and GP2 as biomarkers for pediatric CD, and determine whether they correlate with disease activity. Serum samples were tested by ELISA for anti-GP2 isoform 4 IgG and IgA, and also for GP2. Results were correlated with demographic and clinical data. The cohort consisted of 53 pediatric patients with CD, 42 with UC, and 53 controls. Levels of anti-GP2 were significantly increased in pediatric patients with CD in comparison with patients with UC, and control subjects, with high positive predictive value for both IgG and IgA (97.9% and 82.6%, respectively). While specificity of anti-GP2 IgG and IgA was very high (98.7% and 90.0%, respectively), sensitivity was low (42.0% and 35.5% for IgG and IgA, respectively). In CD, anti-GP2 correlated with disease activity, and decreased in treatment-naïve patients following successful induction therapy. A higher IgA anti-GP2 was also demonstrated in patients with ileo-colonic involvement, and was associated with a younger age. Finally, positive GP2 level was identified in only 1/211 serum samples. A positive anti-GP2 level is highly associated with CD, while a negative result does not exclude CD. Additional studies are required to determine whether these markers can be used in pediatric patients with CD for risk stratification.

Reverse Angle: Immunological Evaluation of Patients with Bronchiectasis

Objective: Bronchiectasis is a chronic debilitating disease of the airways that results in chronic cough and production of viscous sputum due to dilatation of the airways and bronchial wall thickening. Although bronchiectasis is a common problem in immunodeficiencies and a well-known complication of these disorders, there are a limited number of studies on the frequency of immune abnormalities in adult patients with bronchiectasis. Materials and Methods: The records of adult patients who visited the Pulmonology Outpatient Clinic and whose immune system was assessed due to bronchiectasis at the Immunology Outpatient Clinic until June 2018 were retrospectively evaluated. The data of 84 patients with bronchiectasis (mean age: 48.5 ± 17.9 years, female: 45 [53.6%], male: 39 [46.4%]) were analyzed. Results: Six patients (7.1%) had at least one antibody deficiency. Four patients (4.8%) had low IgG levels, one (1.2%) had low IgA level, and one (1.2%) had low IgM level. Fourteen patients (16.7%) had high IgG (16-22 g/l), 10 (11.9%) high IgA (4.08 - 6.60 g/l) and one (1.2%) high IgM (8.87 g/l). Thirty-five patients (41.7%) had at least one abnormality in the peripheral lymphocyte subset analyses. Conclusion: Adult patients with bronchiectasis may have a variety of immunological abnormalities in addition to hypogammaglobulinemia. Therefore, clinicians should not overlook immunological evaluation in the etiological investigation of bronchiectasis, and patients with immunological abnormalities should be closely monitored.

Identification of Prognostic Markers in Patients with Primary Vitreoretinal Lymphoma by Clustering Analysis Using Clinical Data.

(1) Purpose: Primary vitreoretinal lymphoma (PVRL) is associated with poor prognosis because most of the patients with PVRL develop central nerve system lymphoma. The prognostic biomarker of PVRL is largely unknown. Cluster analysis has been used to identify phenotypic groups within various diseases. In this study, we aimed to describe clinical features of patients with PVRL grouped by clustering analysis and to identify biomarkers for predicting survival prognosis in patients with PVRL. (2) Materials and Methods: Forty patients with PVRL were divided into two groups by clustering analysis using clinical data. Clinical features of the two groups were compared. (3) Result: Clustering analysis classified patients into groups A and B. The survival rate during the follow-up period was significantly lower in group B than in group A (p = 0.03). Serum IgG, serum IgA, vitreous IL-10 and vitreous IL-10 to IL-6 ratio were significantly different between groups A and B (p = 0.03, 0.005, 0.008 and 0.03, respectively). Receiver operating characteristic (ROC) curves generated for the four variables indicated that serum IgA was most suitable for the prediction of prognosis. Patients with serum IgA below 184 mg/dL obtained from the ROC curve had a lower three-year survival rate (p = 0.03) and more episodes of recurrence of lymphoma (3.2 times versus 1.8 times, p = 0.02) compared with patients with serum IgA above 184 mg/dL. (4) Conclusion: The survival rate was significantly different in PVRL patients classified into two groups by clustering analysis. Patients with lower serum IgA had more recurrences and poorer survival than patients with higher IgA.

BREASTMILK AND COVID-19

After the New Corona Virus epidemic emerged in China at the beginning of December 2019, authorities announced the appearance of cases in our country in March 2020. This epidemic reminds us of the importance of preventive healthcare. Breastfeeding is very important for child health. The anti-infective and immunomodulatory properties of breast milk play an important role in protection against infections. Passive immunity is provided especially by the high secretory IgA concentration and other antipathogen factors in breastmilk. During emergency situations, protection and promotion of breastfeeding is very important. The COVID-19 pandemic is also an emergency situation, and it is recommended that mothers should continue breastfeeding or giving expressed milk by wearing a mask, and taking necessary hygiene measurements during this epidemic.&nbsp;

Assessment of European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines in an Australian paediatric population

Coeliac disease (CD) diagnosis is based on clinical assessment, detection of specific autoantibodies and histological examination of small intestinal biopsies. The European Society of Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) guidelines have recently been updated and recommend CD may be diagnosed without a biopsy or HLA typing in symptomatic patients with high titre IgA tissue transglutaminase antibodies (aTTG) and positive endomysial antibodies (EMA). However, the need for EMA in patients with high level aTTG has been questioned. We aimed to determine the diagnostic benefit of HLA typing, EMA and IgG antibodies to deamidated gliadin (DGP) in children with high level aTTG. We prospectively evaluated children presenting for assessment of possible CD. All patients underwent small bowel biopsy, serological testing and HLA typing. Results were analysed and correlated with histopathological diagnosis. A total of 209 children were assessed; 61.5% were found to have CD and 29% could have avoided biopsy as per 2020 ESPGHAN guidelines. Titres of aTTG ≥60 U/mL or DGP ≥28 U/mL gave 100% specificity and 100% positive predictive value (PPV) for CD. HLA typing and EMA did not improve the PPV of patients with aTTG ≥60 U/mL, but addition of DGP ≥28 U/mL improved diagnostic sensitivity whilst retaining 100% specificity. Addition of HLA and EMA testing in patients with high titre aTTG antibodies does not improve diagnostic performance and may possibly be omitted from the serological workup in these patients. Our data support combining aTTG and DGP testing and optimising cut-offs to maximise specificity as an alternative biopsy-free diagnostic approach.

Characterization of Tear Immunoglobulins in a Small-Cohort of Keratoconus Patients

Keratoconus (KC) is classically considered a non-inflammatory condition caused by central corneal thinning that leads to astigmatism and reduced visual acuity. Previous studies have identified increased systemic levels of pro-inflammatory factors, including interleukin-6, tumor necrosis factor-α, and matrix metalloproteinase-9, suggesting that KC may have an inflammatory component in at least a subset of patients. In this study, we evaluated the levels of different immunoglobulins (light and heavy chains) based on Ig α, Ig λ, Ig κ, Ig µ, and Ig heavy chain subunits in non-KC tears (n = 7 control individuals) and KC tears (n = 7 KC patients) using tandem-liquid chromatography mass spectrometry. The most abundant Ig heavy chains detected in both control individuals and KC patients were Ig α-1 and Ig α-2 likely correlating to the higher IgA levels reported in human tears. We identified significant differences in immunoglobulin κ-chain V-II levels in KC patients compared to control individuals with no significant difference in Ig κ/Ig λ ratios or heavy chain levels. Our study supports previous findings suggesting that KC possesses a systemic component that may contribute to the KC pathology. Further studies are required to define causality and establish a role for systemic immune system-dependent factors and pro-inflammatory processes in KC development or progression.

Specific microbiota enhances intestinal IgA levels by inducing TGF-β in T follicular helper cells of Peyer's patches in mice.

In humans and mice, mucosal immune responses are dominated by IgA antibodies and the cytokine TGF-β, suppressing unwanted immune reactions but also targeting Ig class switching to IgA. It had been suggested that eosinophils promote the generation and maintenance of mucosal IgA-expressing plasma cells. Here, we demonstrate that not eosinophils, but specific bacteria determine mucosal IgA production. Co-housing of eosinophil-deficient mice with mice having high intestinal IgA levels, as well as the intentional microbiota transfer induces TGF-β expression in intestinal T follicular helper cells, thereby promoting IgA class switching in Peyer's patches, enhancing IgA+ plasma cell numbers in the small intestinal lamina propria and levels of mucosal IgA. We show that bacteria highly enriched for the genus Anaeroplasma are sufficient to induce these changes and enhance IgA levels when adoptively transferred. Thus, specific members of the intestinal microbiota and not the microbiota as such regulate gut homeostasis, by promoting the expression of immune-regulatory TGF-β and of mucosal IgA.

Elevated cerebrospinal fluid homocysteine is associated with blood-brain barrier disruption in amyotrophic lateral sclerosis patients.

Homocysteine (Hcy) has been shown to be relevant in the pathogenesis of amyotrophic lateral sclerosis (ALS). Although the CSF Hcy changes were explored in patients with ALS previously, the outcomes were inconsistent, and the permeability of the blood-brain barrier (BBB) may involve in the process. The aim of this study was to investigate the relationship between concentration of Hcy and BBB integrity indicated by CSF/serum albumin ratio (Qalb). CSF and plasma/serum levels of Hcy, folate, and vitamin B12 and other biochemical biomarkers such as albumin, β2-microglobulin, high sensitive-C reactive protein (hs-CRP), microalbumin, immunoglobulin G (IgG), IgM, IgA, and complement 3 and 4 were analyzed in all 31 ALS patients and 34 controls. Routine CSF analysis including cells/leukocytes count, total protein, glucose, and chlorides were also performed. CSF Hcy levels (0.50 ± 0.46 vs 0.25 ± 0.27μmol/L) and Qalb (8.09 ± 3.03 vs 6.39 ± 2.21) were significantly higher in the ALS group than that in controls (P < 0.05). The generalized linear mixed model analysis showed that the CSF Hcy was positively correlated with Qalb in ALS patients (P < 0.05). BBB permeability is increased in ALS patients. CSF Hcy level is associated with BBB integrity. Qalb is a significantly independent predisposing factor for CSF Hcy.