Blastocystis infection is associated with irritable bowel syndrome in a Mexican patient population
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In recent times, some common “non-pathogenic” parasites, such as Blastocystis and Dientamoeba fragilis, have been associated to the aetiology of irritable bowel syndrome (IBS), while host pro-inflammatory cytokine gene polymorphisms might have a role in the pathophysiology of the disease. Therefore, Blastocystis subtypes (ST), D. fragilis and gene promoter single nucleotide polymorphisms of interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α) in IBS patients and controls were studied. After giving written consent, 45 patients with symptoms of IBS according to the Rome III criteria and 45 controls were enrolled. DNA was extracted from peripheral blood for SNP analysis at position -174 for IL-6 as well as -238 and -308 for TNF-α. Blastocystis was more common in the IBS group (p = 0.043). Interestingly, D. fragilis was found more frequently in the control group (p = 0.002); Blastocystis ST1 and 3 were most frequent in both groups. Haploview analysis revealed linkage disequilibrium in TNF-α (p < 0.0001); however, none of the SNPs for IL-6 and TNF-α were found to be significantly related with IBS. The clinical and molecular approaches undertaken for the first time in Latin American IBS patients demonstrated an association with Blastocystis that supports a pathogenic role of this parasite in IBS Furthermore, co-infections with ST1 and ST3 were frequent; thus, the genetic diversity proposed within ST polymorphisms does not rule out that particular strains might be associated with disease. In addition, our results do not support a major contribution of IL-6 and TNF-α gene polymorphisms in the susceptibility to IBS.
KeywordsIrritable Bowel Syndrome Irritable Bowel Syndrome Patient Schistosoma Haematobium Mexican Patient Blastocystis Infection
The authors would like to thank Rune Stensvold for his critical comments; Maria Elena Rodriguez-Campa, Alberto Gonzalez-Angulo, Jesus Lopez-Olivera, Joel Martinez-Ocaña, Simon Kawa-Karasik, David Moncada-Barron, Humberto Torres-Pinzon, Maria de Lourdes Puga, Leonor Escobedo-Ramos, Eduardo Lopez-Escamilla, Lucia Guerra-Sanchez, Rocio Jimenez-Lucio and David Sierra performed colonoscopies, obtained biopsies and undertook routine pathogen identification. This study is part of DEJG Master's studies in the Facultad de Ciencias, Universidad Nacional Autonoma de Mexico. This work was supported by CONACYT grant 69,589.
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