Complement factor B allotypes in the susceptibility and severity of coeliac disease in patients and relatives

BF*F allotype of the alternative pathway of complement: A marker of protection against the development of antiphospholipid antibodies in patients with systemic lupus erythematosus

Background

B factor (BF) from the alternative complement pathway seems to participate in the pathophysiology of systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS).

Objective

To study the allotypic variability of BF in SLE and their associations with clinical and autoantibodies profile.

Methods

BF allotypes were determined by high-voltage agarose gel electrophoresis, under constant cooling, followed by immunofixation with anti-human BF antibody, in 188 SLE patients and 103 controls. Clinical and serological data were obtained from medical examination and records.

Results

No significant differences of BF variants between patients and controls were found, neither in relation to epidemiologic or clinical manifestations. Associations of phenotype BF SS07 and allotype BF*S07 were found with anticardiolipin IgM (aCl-IgM) antibodies ( p = 0.014 and p = 0.009 respectively), but not with aCl-IgG, lupus anticoagulant (LA), anti β2GPI or clinical APS. A significant decrease in BF*F allotype ( p = 0.043) and BF SF phenotype ( p = 0.018) was detected in patients with anti-phospholipid antibodies as a whole (aCl-IgG, aCl-IgM, LA and anti β2GPI).

Conclusions

There is a link between phenotype BF SS07 and allotype BF*S07 with aCl-IgM in SLE patients; BF*F allotype could be considered a marker of protection against the development of antiphospholipid antibodies in these patients.

Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA.

[Serological screening of relatives of celiac disease patients: antiendomysium antibodies, anti-tissue transglutaminase or both?]

BACKGROUND

Celiac disease is the most common intestinal disorder of caucasian populations and presents a prevalence of 8% to 18% between the relatives of patients. The anti-endomysial (IgA-EmA) and anti-tissue transglutaminase antibodies (IgA-tTG) have represented an important non invasive and sensitivity method of screening and diagnosis of celiac disease in risk groups and populations.

AIM

To investigate the prevalence of IgA-EmA and IgA-tTG antibodies in relatives of celiac patients and verify the degree of concordance between them.

METHODS

One hundred and seventy seven relatives of celiac patients (76(feminino); 101(masculino); 2-79 years) and 93 healthy individuals were evaluated (34(feminino); 59(masculino); 2-71 years). IgA-EmA were detected by indirect immunofluorescence, with human umbilical cord as substrate, while anti-IgA-tTG titers were measured by enzyme-linked immunosorbent assay (ELISA), using commercial kit.

RESULTS

Total positivity to antibodies in relatives of celiac patients was of 21% (37/177), and showed significant difference compared to control group (0%; 0/93). Twelve percent (21/177) of celiac disease relatives were positive to IgA-EmA, 13.56% (24/177) to IgA-tTG, and 4.52% (8/177) to both assays simultaneously. The concordance between both methods was 83.6% (148/177) and the discordance was 16.4% (29/177), with a positive and significant correlation (r = 0.435). Among the concordant results, 79.1% (140/177) were negative and 4.52% (8/177) were positive to both antibodies. Among the discordant results, 7.34% (13/177) were positive to IgA-EmA and negative to IgA-tTG, while 9.04% (16/177) were negative to IgA- EmA and positive to IgA-tTG.

CONCLUSION

Although the high positivity to IgA-EmA and IgA-tTG emphasizes the importance of the serological screening in relatives of celiac patients, the discordances detected in this study showed that the use of only one method can lead to false negative results. Consequently these relatives will not be submitted to intestinal biopsy to confirm the diagnosis of celiac disease, and to the correct and earlier treatment.

Serum mannan-binding lectin levels in patients with celiac disease: an analysis of clinical and autoimmune features

Mannan-binding lectin (MBL) is the central protein in the activation of complement through the lectin pathway. MBL plasma concentration is genetically determined and varies significantly among individuals. Recent findings suggest that MBL is associated with the pathogenesis of celiac disease (CD). In this study, MBL and C-reactive protein (CRP) levels were determined in 101 celiac patients and 120 controls, with the aim to associate with the presence of gluten in the diet, disease severity, and the presence of concomitant autoimmune diseases. MBL concentration was determined by ELISA and CRP by nephelometry, using a high-sensitivity method. EmA-IgA and other autoantibodies were tested by indirect immunofluorescence. Although a significant increase in MBL levels was observed in male patients compared to female (P = 0.024), the absence of any other association suggests that circulating MBL and CRP concentrations are not associated with clinical and autoimmune CD features in Brazilian patients.