Colchicine therapy for hepatic murine schistosomal fibrosis: image analysis and serological study

Human schistosomiasis: clinical perspective: review

The clinical manifestations of schistosomiasis pass by acute, sub acute and chronic stages that mirror the immune response to infection. The later includes in succession innate, TH1 and TH2 adaptive stages, with an ultimate establishment of concomitant immunity. Some patients may also develop late complications, or suffer the sequelae of co-infection with other parasites, bacteria or viruses. Acute manifestations are species-independent; occur during the early stages of invasion and migration, where infection-naivety and the host's racial and genetic setting play a major role. Sub acute manifestations occur after maturity of the parasite and settlement in target organs. They are related to the formation of granulomata around eggs or dead worms, primarily in the lower urinary tract with Schistosoma haematobium, and the colon and rectum with Schistosoma mansoni, Schistosoma japonicum, Schistosoma intercalatum and Schistosoma mekongi infection. Secondary manifestations during this stage may occur in the kidneys, liver, lungs or other ectopic sites. Chronic morbidity is attributed to the healing of granulomata by fibrosis and calcification at the sites of oval entrapment, deposition of schistosomal antigen-antibody complexes in the renal glomeruli or the development of secondary amyloidosis. Malignancy may complicate the chronic lesions in the urinary bladder or colon. Co-infection with salmonella or hepatitis viruses B or C may confound the clinical picture of schistosomiasis, while the latter may have a negative impact on the course of other co-infections as malaria, leishmaniasis and HIV. Prevention of schistosomiasis is basically geared around education and periodic mass treatment, an effective vaccine being still experimental. Praziquantel is the drug of choice in the treatment of active infection by any species, with a cure rate of 80%. Other antischistosomal drugs include metrifonate for S. haematobium, oxamniquine for S. mansoni and Artemether and, possibly, Mirazid for both. Surgical treatment may be needed for fibrotic lesions.

Prophylactic effect of the anti-inflammatory drug diclofenac in experimental schistosomiasis mansoni

OBJECTIVES

This study was a trial to demonstrate the prophylactic effect of diclofenac, a widely used anti-inflammatory drug (diclofenac potassium, CAS-15307-81-0, Ciba Geigy, 334.2) in experimental schistosomiasis mansoni. Two different dose regimens were used to explore the effects upon worm load, tissue egg load, and hepatic granuloma size.

METHODS

In this study, a group of 50 Swiss albino mice was used. This group was divided into five subgroups: subgroup I constituted infected untreated control mice; subgroup II, infected mice given 0.5 mg diclofenac orally 24 h post infection, then sacrificed three weeks later; subgroup III, infected mice given 0.5 mg diclofenac orally six weeks post infection and sacrificed one week later; subgroup IV, infected mice administered 1mg diclofenac orally 24 h post infection and sacrificed three weeks later; and subgroup V, infected mice given 1mg of the drug orally six weeks post infection and sacrificed one week later.

RESULTS

Mice given the high dose regimen (1mg orally/mouse) 24 h post infection, then sacrificed three weeks later, demonstrated a significant reduction in the immature worms recovered, compared to the untreated controls. Animals receiving the high dose of the drug six weeks post infection, then sacrificed one week later, revealed a drop in the number of mature worms and in the tissue egg load (hepatic and intestinal), and the smallest hepatic granuloma measurement compared to the untreated controls. These findings were less conspicuous in animals given the low dose regimen.

CONCLUSION

Diclofenac could be used successfully as a preventive agent against schistosomiasis mansoni infection in endemic areas.

Experimental models of Schistosoma mansoni infection

Experimental models of Schistosoma mansoni infections in mammals have contributed greatly to our understanding of the pathology and pathogenesis of infection. We consider here hepatic and extrahepatic disease in models of acute and chronic infection. Experimental schistosome infections have also contributed more broadly to our understanding of granulomatous inflammation and our understanding of Th1 versus Th2 related inflammation and particularly to Th2-mediated fibrosis of the liver.

The cell and molecular biology of hepatic fibrogenesis. Clinical and therapeutic implications

Much has been learned in the past 2 decades about the cellular and molecular mechanisms underlying hepatic fibrogenesis and about potential therapeutic approaches in patients with liver disease. The central event in fibrogenesis seems to be the activation of hepatic stellate cells. Stellate cell activation is characterized by several important features, including enhanced matrix synthesis and a prominent contractile phenotype, processes that probably contribute to the physical distortion and dysfunction of the liver in advanced disease. It is important to emphasize that the factors controlling activation are multifactorial and complex. The extracellular matrix is a dynamic, active constituent of the fibrogenic response and undergoes active remodeling, including synthesis and degradation. Effective therapy for hepatic fibrogenesis will probably also be multifactorial, based on the basic mechanisms underlying the fibrogenic process. The most effective therapies will probably be directed at the stellate cell. Approaches that address matrix remodeling (i.e., by enhancing matrix degradation or by inhibiting factors that prevent matrix breakdown) may be effective.