Overexpression of toll-like receptors and co-stimulatory molecules on immature dendritic cells of Crohn's disease

Abstract

IntroductionCrohn's disease (CD) is a chronic, relapsing inflammatory disorder of the gastrointestinal tract resulting from a loss of homeostasis between the intestinal immune system and the gut microbiome. Also, evidence shows dendritic cells (DC) are the main antigen-presenting cells (APC) in the intestinal mucosa; they can regulate innate and adaptive immunity that is pivotal for maintaining immunological tolerance in the gut. The maturation of immature DC (iDCs) regulate by their surface molecules such as Toll-Like Receptors (TLRs) and co-stimulatory molecules (CD80 and CD86). The level of TLRs on iDCs plays a critical role in developing adaptive responses to antigens. Crohn's disease has a dysfunctional immune system and low tolerance of dendritic cells. This study aimed to investigate the expression of TLR2, TLR4, TLR5, and TLR9 and co-stimulatory molecules (CD80 and CD86). MethodologyHuman peripheral blood mononuclear cells (PBMCs) were collected from 15 CD patients and 12 healthy controls. PBMCs were isolated by density gradient centrifugation, and then iDCs were derived for 6 days. Flow cytometry was performed on iDCs to characterize and distinguish the phenotype of iDC populations. iDCs were harvested for RNA extraction, and the mRNA expression level of TLRs was examined by quantitative RT-PCR using SYBR Green chemistry. ResultThe results showed that TLR2, TLR4, TLR5, and TLR9 mRNA expression significantly increased in the iDCs isolated from patients with CD compared with healthy control P ≤ 0.0001. Although, TLR2 had the lowest expression among other TLRs on iDCs in CD patients. Also, the expression level of CD80 and CD86 were significantly higher in iDCs isolated from CD patients compared to healthy controls P < 0.001 OR = 0.75 CI (−8.76 to −3.17). ConclusionTLR2, TLR4, TLR5, and TLR9 expression on iDCs may be critical in the biological pathogenesis of CD. TLR alterations in the iDCs may contribute to determining dendritic cell maturation pathway lead to increases inflammatory response.