Two IL-10 single nucleotide polymorphisms (rs1800871 and rs1800896) were detected in 120 patients with IBS-D and 144 healthy controls (HC) using SNaPshot.
When comparing IBS subtypes, TNFα and IL-17 were significantly (P<0.05) higher, and IL-10 was significantly (P<0.05) lower in diarrhea predominant IBS (IBS-D) compared to HCs, whereas the inflammatory cytokine profile of other subtypes more closely resembled that of HCs.
IBS-SSS was associated with high tumor necrosis factor and low IL-10 in the CSF; pc = 0.341 and <i>p</i> = 0.009 and pc = -0.299 and <i>p</i> = 0.023, respectively.
Stimulation with Eubacterium limosum resulted in a significantly decreased IL-10 release in HC compared to PI-IBS patients (p < 0.05) and a tendency to decreased IL-13 release in HC compared to PI-IBS patients (p = 0.07).
An association of certain polymorphisms of IL-8 and IL-10 in IBS patients compared to controls was demonstrated, suggesting a role of these cytokine SNPs in the pathophysiology of IBS.
Our results suggest that some IL-8 and IL-10 SNPs could change individual susceptibility increasing the relative risk in the development of IBS in Blastocystis carriers.
Multifactor dimensionality reduction analysis revealed that there were no significant interactions of GNB3, IL-10, and TNF-alpha gene variants with susceptibility to IBS (P > 0.05).
While production of cytokines could be affected by genetic polymorphisms within coding and promoter regions of cytokine genes, IL-4 and IL-10 gene polymorphisms could affect individual susceptibility to IBS.
Genetic association studies with IBS symptom phenotype have generally provided inconsistent results for many candidate genes investigated, such as SLC6A4, GNB3, and IL-10.
Possession of a high producer TNF-alpha and a low producer IL-10 genotype were significantly more prevalent in IBS (9%) versus controls (3%, p= 0.035; OR 3.11, 95% CI 1.03-9.36) and in diarrhea (20%) compared to other IBS subtypes (<4%, p= 0.026).
Patients with irritable bowel syndrome had significantly reduced frequencies of the high producer genotype for interleukin 10 than controls (21% v 32%; p=0.003).