Contributions of HLA haplotypes, IL8 level and Toxoplasma gondii infection in defining celiac disease's phenotypes

Background: It is not clear why some patients with coeliac disease (CD) present with severe symptoms and small intestinal mucosal damages while others present with milder symptoms and no frank enteropathy. There is no study to assess the associated factors with mild/severe symptoms and enteropathy. The terminologies like latent, silent and potential are difficult to use and are unrepresentative. In the present study we describe coeliac disease's phenotypes based on HLA haplotypes, IL8 production and past infection with Toxoplasma gondii (T. gondii) infection. Methods: In this case-control study, sera originating from 150 healthy subjects and 150 patients diagnosed with CD during the years 2013-14 were analyzed for the presence of antibodies specific T. gondii of the IgG and IgM subclasses. The level of IL8 were measured and HLA-DQ2 and HLA-DQ8 alleles were genotyped. The correlation between these parameters and the damages in intestinal mucosal were assessed using an accepted histopathological classification. Results: High levels of IgG antibodies against T. gondii were found in the sera of control group compared to the CD group (52.6% vs. 39.4%, P=0.02). Mean serum levels of IL8 was significantly higher in CD patients compared with control (P≤0.05). By comparing the level of anti- T. gondii IgG and mucosal damage in celiac disease, we found a significant relationship between the severity of mucosal damages and anti- T. gondii IgG level (P=0.02). No correlation was detected between Toxoplasma gondii infection and types of HLA (P>0.05). However, patients with severely abnormal histology carried HLA-DQ2 risk alleles (92 patients (61%)) more often than the controls and those with mild histological abnormalities. Conclusions: CD patients with severe histological changes had more often Toxoplasma gondii infection than those affected with mild histological features. This suggests that CD's phenotypes are correlated to additional factors like infections and to particular HLA DQ2 alleles that may need additional investigations and potentially will require additional treatment.