ALTERATION OF INTESTINAL BLOOD PERFUSION AND PERMEABILITY IN SICKLE CELL DISEASE MICE

Abstract

Recent evidence has demonstrated that the gut microbiota plays an important role in the pathophysiology of sickle cell disease (SCD). Enterocyte damage, increased permeability and intestinal dysbiosis may be directly involved in modulating inflammatory processes, increasing cell adhesion properties and the aging of neutrophils, which contribute to vaso-occlusion. The objective of this study was to investigate intestinal perfusion and permeability in mice with SCD. Townes AS (hemizygous) and SS (homozygous) mice aged 8 weeks were subjected, or not, to a model of overnight dehydration. The mice were subjected to nocturnal dehydration for 7 days consecutive and the water was returned after the 14-hour period of water restriction, always in the morning. In vivo intestinal permeability assays were carried out using the oral administration of FITC-dextran and blood perfusion was measured in the mesenteric region using the PeriCam PSI System (Perimed) and laser speckle contrast analysis. Plasma FITC-dextran levels were found to be higher in SS mice, compared to AS mice (0.6 ± 0.04 and 1.5 ± 0.1 μg/mL for AS and SS, respectively, p < 0.0001; n = 4-8), indicating that intestinal permeability is altered in 8-week-old sickle cell mice. Blood perfusion in the areas of the intestinal folds and mesenteric regions was also significantly lower in SS mice compared to AS mice (204.3 ± 4.2 and 116.4 ± 19.7 P.U for AS and SS, respectively, p = 0.012; n = 3), suggesting altered intestinal vascular function. Submitting mice to a model of chronic dehydration did not alter circulating FITC-dextran concentrations in SS mice, compared to SS mice that were not dehydrated, suggesting that existing intestinal permeability is not exacerbated by dehydration. However, mesenteric blood perfusion was lower in the dehydrated Townes SS mice, compared to the SS controls that were not dehydrated (154.7 ± 9.9 and 114.3 ± 14.3 for basal SS and dehydrated SS, respectively, p = 0.04; n = 5), indicating that dehydration negatively affects intestinal blood flow in SS mice. Thus, these findings suggest that the integrity of the intestinal barrier and mesenteric microcirculation are compromised in mice with SCD, highlighting the importance of the intestine in the pathophysiology of the disease and the need for new therapeutic approaches focusing on the modulation of gut microbiota and the preservation of vascular integrity.