Associations between interleukin-1 (IL-1) gene variations or IL-1 receptor antagonist levels and the development of type 2 diabetes.

OBJECTIVES: To examine whether interleukin-1 receptor antagonist (IL-1Ra) is a predictor for clinically incident diabetes in subjects with metabolic syndrome (MetS) and whether its predictive power is independent of C-reactive protein (CRP), an established marker of inflammation. We further examined whether genetic variants at the interleukin-1 (IL-1) locus would predict clinically incident diabetes. DESIGN: Two observational prospective cohort studies. SETTING: Two separate cohorts, Health 2000 and FINRISK 1997, followed up for an average of 7.1 and 10.8 years, respectively. SUBJECTS: Random population samples consisting of 5511 subjects aged 30-74 years in Health 2000 and 7374 subjects aged 25-74 years in FINRISK 1997. RESULTS: During follow-up, 141 cases of clinically incident diabetes were observed amongst subjects with MetS at baseline in Health 2000 and 248 cases in FINRISK 97. After adjustment for multiple traditional risk factors of diabetes, including age and body mass index, IL-1Ra was a significant (P < 0.01) predictor of incident diabetes amongst men in both cohorts and amongst women in FINRISK 1997. Further adjustment for CRP reduced the hazard ratios only slightly. Genetic analyses produced nominally significant associations for three single-nucleotide polymorphisms: rs3213448 in IL-1 receptor antagonist (IL1RN), rs1143634 in IL-1 beta (IL1B) and rs1800587 in IL-1 alpha (IL1A). The two latter variants had an interaction with gender (P = 0.023 and 0.002, respectively) suggesting the presence of gender-specific associations with the risk of clinically incident diabetes. CONCLUSIONS: IL-1Ra predicted the progression of MetS to clinically incident diabetes independently of CRP and other risk factors. Genetic variation in the IL-1 locus may have gender-specific associations with the risk of type 2 diabetes.

Allele 2 of interleukin-1 receptor antagonist gene increases the risk of thyroid peroxidase antibodies in subacute thyroiditis.

Subacute granulomatous thyroiditis (SAT) is a self-limiting systemic inflammatory disorder with possible transient expression of thyroid antibodies. Persistent hypothyroidism is uncommon. The interleukin-1 receptor antagonist IL-1ra is an inhibitor of IL-1 activity and allele 2 of the IL-1ra gene is associated with inflammatory diseases and IL-1ra production. Forty-eight subjects with SAT were investigated. Polymorphisms of IL-1ra, IL-1beta-511 and TNFalpha genes were studied with respect to thyroid peroxidase antibodies (TPOab), thyroglobulin antibodies, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Serum IL-1ra levels were measured. An increased allelic frequency (43% vs 22%, p=0.039) and carriage rate (79% vs 41%, p=0.018) for IL-1ra allele 2 were observed with expression of TPOab in 14 (29.2%) subjects compared with those with negative findings. The carriage rate for both IL-1ra allele 2 and IL-1beta-511 allele 2 was also increased with TPOab expression (71% vs 27%, p=0.004, respectively). No difference in allele frequency or carriage rate was found compared with healthy controls. Serum IL-1ra levels correlated with S-CRP (r=0.41, p=0.004) and ESR (r=0.34, p=0.016), but the association with genes or thyroid antibodies was statistically insignificant. S-CRP levels and ESR were lower and negatively correlated with expression of TPOab (r=-0.27, p=0.046 and r=-0.32, p=0.017). This study describes the multiplicity of the mechanisms responsible for the severity of the acute-phase response during the course of SAT. IL-1ra may have a significant anti-inflammatory role in SAT. Presence of IL-1ra allele 2 increases the risk of developing TPOab.

Evaluation of infectious etiology in subacute thyroiditis--lack of association with coxsackievirus infection.

The etiology of subacute granulomatous thyroiditis (SAT) is obscure, although it is postulated to be associated with viral infections and genetic factors. In the present study, the possibility of an infectious etiology was prospectively studied in 27 consecutive patients with SAT. Special emphasis was put on the role of enteroviruses. Coupled sera (interval one month) were taken from all patients and single sera from 29 control subjects for virus antibody determinations. Stool samples were collected for virus isolation and fine-needle aspiration samples from thyroid gland for the detection of enterovirus RNA using RT-PCR were taken from SAT patients. Enteroviral antibodies were tested using three different methods: indirect EIA, heavy chain capture RIA, and standard complement fixation (CF) test. Antibodies against other common viral pathogens, including enteroviruses, were screened using the CF test and those against Mycoplasma pneumoniae and Chlamydia pneumoniae using EIA and microimmunofluorescence techniques, respectively. Common respiratory viruses were also screened from nasopharyngeal suction samples by antigen detection EIA. Based on serological findings, one patient had acute Cytomegalovirus infection. All other patients were negative in antibody tests, virus isolation, RT-PCR, and antigen detection. Enterovirus RNA was not detected by PCR in the thyroid tissue in any of the fine-needle aspiration samples. There was no evidence of recent enteroviral infections in SAT patients. The results suggest that SAT is not usually associated with acute infections. No evidence was obtained to support the proposed role of enteroviruses as an important etiologic agent of SAT.

Clinical and subclinical autoimmune thyroid disease in adult celiac disease.

Our aim was to investigate the occurrence of clinical and subclinical autoimmune thyroid disease in 79 patients with celiac disease as reflected in thyroid function, antibodies, and ultrasound. Since subclinical thyroid diseases are common in the population, 184 nonceliac controls were also studied. Normal thyroid function combined with positive antibodies and marked hypoechogenicity was considered subclinical disease. Autoimmune thyroid disease was observed in 13.9% of celiac patients and in 2.1% of controls (P = 0.0005); and subclinical disease in 10.1% and 3.3%, respectively (P = 0.048). The mean thyroid gland volume was 8.3 ml in celiac patients and 10.4 ml in controls (P = 0.007). Hypoechogenicity was found in 73% of celiac patients and in 42% of controls (P < 0.0001). Positive thyroid antibodies were associated with hypoechogenicity in celiac patients but not in controls. In conclusion, the occurrence of both clinical and subclinical autoimmune thyroid disease was increased in celiac disease; subclinical thyroid disease indicates regular surveillance.