Pathophysiology of NSAID-Associated Intestinal Lesions in the Rat: Luminal Bacteria and Mucosal Inflammation as Targets for Prevention

Abstract

Non-steroidal anti-inflammatory drugs (NSAIDs) can damage the small intestine, mainly through an involvement of enteric bacteria. This study examined the pathophysiology of NSAID-associated intestinal lesions in a rat model of diclofenac-enteropathy and evaluated the effect of rifaximin on small bowel damage. Enteropathy was induced in 40-week old male rats by intragastric diclofenac (4 mg/kg BID, 14 days). Rifaximin (delayed release formulation) was administered (50 mg/kg BID) 1 h before the NSAID. At the end of treatments, parameters dealing with ileal damage, inflammation, barrier integrity, microbiota composition, and TLR-NF-κB-inflammasome pathway were evaluated. In addition, the modulating effect of rifaximin on NLRP3 inflammasome was tested in an in vitro cell system. Diclofenac induced intestinal damage and inflammation, triggering an increase in tissue concentrations of tumor necrosis factor and interleukin-1β, higher expression of TLR-2 and TLR-4, MyD88, NF-κB and activation of caspase-1. In addition, the NSAID decreased ileal occludin expression and provoked a shift of bacterial phyla toward an increase in Proteobacteria and Bacteroidetes abundance. All these changes were counterbalanced by rifaximin co-administration. This drug was also capable of increasing the proportion of Lactobacilli, a genus depleted by the NSAID. In LPS-primed THP-1 cells stimulated by nigericin (a model to study the NLRP3 inflammasome), rifaximin reduced IL-1β production in a concentration-dependent fashion, this effect being associated with inhibition of the up-stream caspase-1 activation. In conclusion, diclofenac induced ileal mucosal lesions, driving inflammatory pathways and microbiota changes. In conclusion, rifaximin prevents diclofenac-induced enteropathy through both anti-bacterial and anti-inflammatory activities.

Protective effects of the combination Bifidobacterium longum plus lactoferrin against NSAID-induced enteropathy

“…The use of NSAIDs is associated with the development of enteric damage and occult bleeding, the so-called enteropathy [2], which occur even more frequently than upper digestive injury [3]. In the present study, consistently with current evidence [17,18,19] However, trends in changes in plasma hemoglobin levels and MPO, as well as in reduction of the expression of TLR-4 and p65, were observed for the combined treatment. Therefore, it is likely that the overall sum of such trends concurred to produce a significantly better efficacy against the histologic damage upon administration of lactoferrin plus Bifidobacterium, which represents the most significant and clinically relevant outcome.…”

“…MPO concentration in intestinal tissues represents a reliable marker reflecting the inflammatory infiltration of polymorphonuclear cells [24]. In line with previous observations [17,18], repeated administrations of diclofenac resulted in a significant increment of ileal MPO concentrations. Under these conditions, treatment with lactoferrin or Bifidobacterium counteracted significantly such an increment, while ileal MPO levels were normalized when these agents were administered in combination.…”

“…Western blot assays were performed as previously described by Colucci et al [17]. Specimens of mucosa were excised from ileum, weighed and homogenized in lysis buffer using a polytron homogenizer.…”

“…Calprotectin, a calcium binding protein of neutrophil granulocytes that correlates well with neutrophil infiltration of the intestinal mucosa was measured in fecal pellets, as previously described by Colucci et al [17] (see Supplementary material).…”

Influence of Microbiota on NSAID Enteropathy: A Systematic Review of Current Knowledge and the Role of Probiotics

“…Recently, the effect of rifaximin on diclofenac small bowel enteropathy was studied on a rat model [9]. The animals had received diclofenac 4 mg/kg for 2 weeks.…”