The effect of protein deficiency on systemic release of rat mucosal mast cell protease II during Nippostrongylus brasiliensis infection and following systemic anaphylaxis.

Serum rat mucosal mast cell protease II (RMCPII) was measured in protein-deficient rats to assess mucosal mast cell (MMC) activation during primary infection with the nematode, Nippostrongylus brasiliensis, and during systemic anaphylaxis produced by Nippostrongylus antigen in immune animals. In the first study, serum RMCPII increased 4-fold by day 15 after infection. By day 20, serum RMCPII continued to rise in protein-deficient animals, but decreased in nutritionally normal animals. This was associated with impaired worm rejection in protein-deficient rats. During systemic anaphylaxis, serum RMCPII was elevated in three groups of protein-deficient rats on 6%, 8% and 10% low protein diets and in nutritionally normal rats. All protein-deficient rats exhibited 3 to 7-fold less mucosal permeability of the small intestine to Evan's blue dye injected intravenously compared to nutritionally normal animals following anaphylactic stimulation. These results demonstrated that MMC are activated during infection in protein deficiency, and suggest that reduced MMC function does not explain delay in worm expulsion. Impaired mucosal anaphylaxis in protein deficiency could not be attributed to a failure of MMC response.

Blood loss during Nippostrongylus brasiliensis infection in the rat.

Faecal blood loss was measured during Nippostrongylus brasiliensis infection in the DA rat using 51Cr-labelled red blood cells (r.b.c.s). In an initial study, faecal blood loss was measured on day 7 of primary infection with 3000 larvae administered subcutaneously (s.c.), and found to be 0.03 ml/24 h in uninfected animals and 0.14 ml/24 h in infected animals. In a further experiment, blood loss was measured on the day before infection and for 13 days after primary s.c. infection with 5000 larvae. Faecal blood loss was 0.05 ml/24 h or less until day 3, began to rise from day 5, reached a peak of 0.51 ml/24 h on day 8, and fell until day 13. This was closely associated with the rise and fall of the pooled faecal egg count. Direct worm count confirmed a high worm burden on day 7 and expulsion by day 14. The effect of the worm burden on the haemoglobin concentration (Hb) was measured in a further experiment and showed a fall in Hb with a mean worm burden of 726 compared to that of 47 or 284 worms. The study concluded that there is minimal background blood loss in uninfected rats but that infection with N. brasiliensis is a cause of intestinal blood loss and this is associated with a fall in Hb concentration that is dependent on the worm burden.

The effect of methionine and protein deficiency in delaying expulsion of Nippostrongylus brasiliensis in the rat.

Three protein-deficient diets containing 5%, 6%, or 7% casein, with and without 0.3% methionine supplementation, were fed to Wistar rats from weaning for 6 wk. Animals were infected subcutaneously with 1500 larvae of Nippostrongylus brasiliensis and killed after 14 days when nutritionally normal animals have expelled more than 97% of the worm burden. There was a delay in worm expulsion that was related to both the protein content (p = 0.0006) and to methionine content (p less than 0.0001). Methionine supplementation significantly reduced the worm burden in animals fed the 7% protein diet from a geometric mean of 32.4 to 5.2 (p = 0.0408) and in rats fed the 6% protein diet from a mean of 162 to 8.1 (p = 0.0002) but had no effect in rats on the 5% casein diet. Thus, addition of methionine overcame the adverse effect of protein deficiency in these less severely affected groups.

The effect of iron and protein deficiency on plasma levels and parasite uptake of [14C] fenbendazole in rats infected with Nippostrongylus brasiliensis.

The Nippostrongylus brasiliensis-rat model was used to determine whether iron and protein deficiency, which are commonly associated with parasitic infections, affected the pharmacokinetic behaviour of fenbendazole as measured by plasma concentrations and uptake by worms. Plasma 14C concentrations after [14C] fenbendazole administration were higher in iron and protein-deficient rats than in sufficient rats. However, the uptake of 14C by N. brasiliensis in iron and protein-deficient rats was significantly less than in worms from diet-sufficient rats. The reduced anthelmintic uptake by worms in protein and iron-deficient hosts may account, in part, for reduced anthelmintic efficacy under these circumstances. These findings are relevant to understanding variations in response to chemotherapy in populations of parasitised hosts containing malnourished individuals.

Delayed expulsion of the nematode Nippostrongylus brasiliensis from rats on a low protein diet: the role of a bone marrow derived component.

Rats on a low protein diet, containing 10% casein as the only source of protein, have an impaired capacity to expel primary infections with the nematode Nippostrongylus brasiliensis and remain susceptible to reinfection. In the present study, the transfer of syngeneic bone marrow cells to rats on a low protein diet reconstituted the expulsion mechanism allowing parasite rejection to occur at the same rate as rats on a sufficient diet. Serum transfer, on the other hand, did not significantly alter the rate of worm expulsion. These results demonstrate that a bone marrow derived component plays an important role in the impaired immunity of rats fed a low protein diet.

Nippostrongylus brasiliensis infection in the rat: effect of iron and protein deficiency on the anthelmintic efficacy of mebendazole, pyrantel, piperazine, and levamisole.

The benzimidazole anthelmintics mebendazole and fenbendazole have been shown to be much less effective against Nippostrongylus brasiliensis infections in the rat on a combined iron and protein deficient diet. In the present experiments it was shown that the anthelmintic efficacy of mebendazole was significantly impaired in the rat on either an iron deficient or a protein deficient diet. Furthermore, iron and protein deficiency reduced the efficacy of the anthelmintics pyrantel and piperazine but not levamisole. The finding that nutritional deficiencies reduce anthelmintic efficacy may well be relevant to worm eradication programmes in iron deficient and protein calorie malnourished populations.

The effect of iron and protein deficiency on the development of acquired resistance to reinfection with Nippostrongylus brasiliensis in rats.

Iron and protein deficiency delays the immunological rejection of Nippostrongylus brasiliensis from the small intestine of rats undergoing a primary infection with the parasite. In the present study, iron and protein deficiency significantly reduced acquired resistance to reinfection with N. brasiliensis. Repletion of deficient animals with iron and protein restored their capacity to mount an effective immune response to a secondary infection with the parasite. These results suggest that chemotherapy of helminthiasis should be integrated with nutritional supplementation.

Suppression of rejection of Nippostrongylus brasiliensis in iron and protein deficient rats: effect of syngeneic lymphocyte transfer.

Rejection of Nippostrongylus brasiliensis is impaired in iron and protein deficient rats and this suggests that iron and protein deficiency directly or indirectly suppresses the immune response. The site of the immunological defect in deficient rats was investigated using the technique of cellular transfer of resistance. The functional activity of immune mesenteric lymph node cells obtained from iron and protein deficient donors was not depressed as measured by their capacity to cause parasite rejection in nutritionally sufficient recipients. In contrast, immune lymph node cells obtained from either sufficient or deficient donors did not result in parasite rejection in iron and protein deficient recipients. These results indicate that there is no permanent defect of lymphocyte function in iron and protein deficient rats and suggest that either some other component of the rejection mechanism is defective, or that lymphocyte function is blocked in an iron and protein deficient environment.

Nippostronglylus brasiliensis infection in the rat: effect of iron and protein deficiency and dexamethasone on the efficacy of benzimidazole anthelmintics.

Malnutrition, anaemia, and gut parasites are commonly interrelated. Using the Nippostrongylus brasiliensis-rat model, the effect of iron and protein deficiency on the efficacy of benzimidazole anthelmintics was studied. It was demonstrated that the anthelmintics mebendazole and fenbendazole were significantly less effective in eradicating parasites when animals were deficient in iron and protein. This decreased efficacy of anthelmintics in iron and protein deficiency could not be overcome by intraperitoneal administration of the drug. Since nutritional deficiencies may act via impairment of the immune response, anthelmintic efficacy was determined in adequately nourished rats treated with the immunosuppressive drug dexamethasone. A similar decrease in efficacy of mebendazole was shown when these animals were treated with dexamethasone. Thus it is possible that lowered anthelmintic efficacy in iron and protein deficient animals is mediated by immune deficiency. These findings may be relevant to anthelmintic programmes in malnourished communities.

Effect of iron and protein deficiency on the expulsion of Nippostrongylus brasiliensis from the small intestine of the rat.

The relationship between iron deficiency and protein deficiency and infestation of the rat with the nematode Nippostrongylus brasiliensis was investigated. There was a significant delay in the expulsion of N. brasiliensis from the small intestine of both iron deficient and protein deficient animals and those with a combined deficiency of iron and protein. Iron repletion returned the time of worm expulsion to normal and this would appear to be related to iron deficiency per se rather than to anaemia. Antibody initiated damage to worms was normal in the control animals and in animals with nutritional deficiencies. This suggests that the defect in worm expulsion occurs either in the cell-mediated immune system or in one of the other mediators of expulsion. Extrapolation to the human situation has important therapeutic implications in that iron and protein deficiency may play an important role in the perpetuation of helminth infestations. Thus, to be successful antihelminth therapy should be accompanied by iron and protein supplementation.