Anti-cytokine autoantibodies suggest pathogenetic links with autoimmune regulator deficiency in humans and mice

Autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) is a recessive disorder resulting from mutations in the autoimmune regulator (AIRE). The patients' autoantibodies recognize not only multiple organ-specific targets, but also many type I interferons (IFNs) and most T helper type 17 (Th17) cell-associated cytokines, whose biological actions they neutralize in vitro. These anti-cytokine autoantibodies are highly disease-specific: otherwise, they have been found only in patients with thymomas, tumours of thymic epithelial cells that fail to express AIRE. Moreover, autoantibodies against Th17 cell-associated cytokines correlate with chronic mucocutaneous candidiasis in both syndromes. Here, we demonstrate that the immunoglobulin (Ig)Gs but not the IgAs in APECED sera are responsible for neutralizing IFN-ω, IFN-α2a, interleukin (IL)-17A and IL-22. Their dominant subclasses proved to be IgG1 and, surprisingly, IgG4 without IgE, possibly implicating regulatory T cell responses and/or epithelia in their initiation in these AIRE-deficiency states. The epitopes on IL-22 and IFN-α2a appeared mainly conformational. We also found mainly IgG1 neutralizing autoantibodies to IL-17A in aged AIRE-deficient BALB/c mice - the first report of any target shared by these human and murine AIRE-deficiency states. We conclude that autoimmunization against cytokines in AIRE deficiency is not simply a mere side effect of chronic mucosal Candida infection, but appears to be related more closely to disease initiation.

An influence of HLA-A, B, DR, DQ, and MICA on the occurrence of Celiac disease in patients with type 1 diabetes

Celiac disease (CD) is more common in individuals with insulin dependent diabetes mellitus (T1D) than in the general population. HLA class II molecules DQ8 (DQB1*0302-DQA1*0301) and DQ2 (DQB1*0201-DQA1*0501) have been identified as key genetic risk factors in both diseases. While DQ8 conveys a higher risk for T1D, DQ2 is more frequent in CD. Less is known about the contribution of HLA class I. The gut immune system has been implicated in the pathogenesis of both diseases. The MICA, which is mainly expressed in the gastrointestinal epithelium and recognized by gammadeltaT lymphocytes and natural killer (NK) cells via the NKG2D, might play a role. The aim of our study was to identify possible HLA class I and MICA alleles and conserved extended haplotypes as risk factors for the development of CD in T1D. Three groups consisting of 37 individuals with T1D and CD, 67 individuals with only T1D and 70 controls were analyzed. HLA class I and MICA alleles were determined using Luminex technology. An occurrence of CD in individuals with T1D was most significantly associated with B*08 (P = 7.3 x 10(-13)), contributing more than any of the HLA class II alleles (DRB1*0301, P = 5.00 x 10(-10); DQB1*0201, P = 7.65 x 10(-8)). Moreover, the association with CD became stronger when B*08(B*08-DQA*0501-DQB1*0201-DRB1*0301, P = 5.07 x 10(-12)) was present in the DRB1*0301-DQB1*0201-DQA1*0501 (P = 5.00 x 10(-10)) extended haplotype. We suggest a combined influence of alleles present in the MICA*008-B*08-A1-DR3-DQ2 extended haplotype on the development of CD in Slovenian individuals with T1D, where B*08 or/and a gene located close to it may play an important role, independently of HLA class II.

Thyroid autoimmunity in children with coexisting type 1 diabetes mellitus and celiac disease: a multicenter study

BACKGROUND

Children with type 1 diabetes mellitus (DM1) are more prone to developing thyroid autoimmunity (TAI); TAI also occurs more frequently in patients with celiac disease (CD).

AIM

To determine whether TAI occurs more frequently in children with coexisting DM1 and CD compared to children with DM1 only, and whether the clinical course of DM1 is influenced by concomitant TAI.

PATIENTS AND METHODS

We performed a multicenter retrospective case-control study comparing data from 84 diabetic children with CD (group 1) to 167 diabetic children without CD (group 2), matched by age at DM1 onset, duration of DM1 and center. Markers of TAI, thyroid function and HbA1c were recorded. The TAI follow-up lasted 4.9 +/- 2.8 years.

RESULTS

TAI was diagnosed in 13% of children in group 1 and 19% of children in group 2 (ns). Diabetes control was not influenced by TAI in either group.

CONCLUSIONS

Occurrence of TAI in diabetic children is not related to coexisting CD. TAI does not lead to worsening of metabolic control in children with DM1.