Analysis of Plasma Citrulline and Intestinal Morphometry in Mice with Hepatosplenic Schistosomiasis

Post-splenectomy infections in chronic schistosomiasis as a consequence of bacterial translocation

INTRODUCTION

Bacterial translocation is the invasion of indigenous intestinal bacteria through the gut mucosa to normally sterile tissues and internal organs. Schistosomiasis may cause alterations in the immune system and damage to the intestines, portal system and mesenteric lymph nodes. This study investigated bacterial translocation and alterations in the intestinal microbiota and mucosa in schistosomiasis and splenectomized mice.

METHODS

Forty female 35-day-old Swiss Webster mice were divided into the following four groups with 10 animals each: schistosomotic (ESF), splenectomized schistosomotic (ESEF), splenectomized (EF) and control (CF). Infection was achieved by introduction of 50 Schistosoma mansoni (SLM) cercariae through the skin. At 125 days after birth, half of the parasitized and unparasitized mice were subjected to splenectomy. Body weights were recorded for one week after splenectomy; then, the mice were euthanized to study bacterial translocation, microbiota composition and intestinal morphometry.

RESULTS

We observed significant reductions in the weight increases in the EF, ESF and ESEF groups. There were increases of at least 1,000 CFU of intestinal microbiota bacteria in these groups compared with the CF. The EF, ESF and ESEF mice showed decreases in the heights and areas of villi and the total villus areas (perimeter). We observed frequent co-infections with various bacterial genera.

CONCLUSIONS

The ESEF mice showed a higher degree of sepsis. This finding may be associated with a reduction in the immune response associated with the absence of the spleen and a reduction in nutritional absorption strengthened by both of these factors (Schistosoma infection and splenectomy).

Changes in the small intestine ofSchistosoma mansoni-infected mice fed a high-fat diet

The consumption of a high-fat diet modifies both the morphology of the small intestine and experimentally tested effects of schistosomiasis mansoni. However, whether a schistosomiasis infection associated with a high-fat diet causes injury to the small intestine has never been investigated. Mice were fed either a high-fat or a standard-fat diet for 6 months and were then infected withSchistosoma mansonicercariae. Physical characteristics of the intestinal tissue (mucosal thickness, small intestinal villi length and height, and abundance of goblet cells and enterocytes on the villous surface) and the distribution of granulomas along the intestinal segments and their developmental stage were measured at the time of sacrifice (9 or 17 weeks post-infection). The group fed a high-fat diet exhibited different granuloma stages, whereas the control group possessed only exudative granulomas. The chronically infected mice fed a high-fat diet exhibited higher granuloma and egg numbers than the acutely infected group. Exudative, exudative/exudative-productive and exudative-productive granulomas were present irrespective of diet. Computer-aided morphometric analysis confirmed that villus length, villus width, muscular height and submucosal height of the duodenal and jejunal segments were affected by diet and infection. In conclusion, a high-fat diet and infection had a significant impact on the small intestine morphology and morphometry among the animals tested.

Influence of the inversion of the portal/splenic vein diameter in the results of the surgical treatment of schistossomotic portal hypertension

OBJECTIVE

To evaluate the morbidity and mortality in surgical treatment of schistosomal portal hypertension in patients with inversion of the Portal/Splenic Vein diameter ratio.

METHODS

We conducted a retrospective cross-sectional study of patients undergoing surgical treatment of portal hypertension in the period between September 1993 and January 2004. The study population was divided into two groups: a) Inversion--splenic vein diameter greater than or equal to portal vein's--and b) control group (portal vein diameter greater than the splenic vein's). Statistical comparisons used the Student t test for averages difference, chi-square test for proportions difference and Fisher's exact test for small samples.

RESULTS

169 patients were analyzed, with follow-up averaging 23.6 months. Twenty-one patients (12.4%) had splenic vein caliber greater of equal than the portal vein's (Inversion--study group). The mean preoperative diameter of the portal and splenic veins were respectively 1.49 and 1.14 cm in the control group, and 0.98 versus 1.07 cm in the inversion group. The portal vein diameter was significantly higher in the control group when compared to the inversion group (p <0.05). Varices in the gastric fundus were found in 33.3% of the inversion group and in 38.5% of patients in the control group. Postoperative rebleeding occurred in 23.1% of patients in the inversion group and in 13.4% of the control group ones (p > 0.05). In the postoperative evaluation with Doppler ultrasonography of portal vessels, no cases of portal vein thrombosis were observed in the inversion group, whilst in the control group portal thrombosis was identified in 16.9% of the patients (p <0.05). Death occurred in one (4.8%) individual from the inversion group; mortality was 4.1% in the control group (p>0.05). The mean serum level of platelets was significantly lower (65,950/mm²) in the inversion group than in the controls (106,647/mm²) (p<0.05).

CONCLUSION

The results suggest that the reversal of portal/splenic vein caliber ratio does not represent a contraindication to surgical treatment of schistosomal portal hypertension.