An antibody against an Anopheles albimanus midgut myosin reduces Plasmodium berghei oocyst development.

BACKGROUND: Malaria parasites are transmitted by Anopheles mosquitoes. Although several studies have identified mosquito midgut surface proteins that are putatively important for Plasmodium ookinete invasion, only a few have characterized these protein targets and demonstrated transmission-blocking activity. Molecular information about these proteins is essential for the development of transmission-blocking vaccines (TBV). The aim of the present study was to test three monoclonal antibodies (mAbs), A-140, A-78 and A-10, for their ability to recognize antigens and block oocyst infection of the midgut of Anopheles albimanus, a major malaria vector in Latin America. METHOD: Western-blot of mAbs on antigens from midgut brush border membrane vesicles was used to select antibodies. Three mAbs were tested by membrane feeding assays to evaluate their potential transmission-blocking activity against Plasmodium berghei. The cognate antigens recognized by mAbs with oocyst-reducing activity were determined by immunoprecipitation followed by liquid chromatography tandem mass spectrometry. RESULTS: Only one mAb, A-140, significantly reduced oocyst infection intensity. Hence, its probable protein target in the Anopheles albimanus midgut was identified and characterized. It recognized three high-molecular mass proteins from a midgut brush border microvilli vesicle preparation. Chemical deglycosylation assays confirmed the peptide nature of the epitope recognized by mAb A-140. Immunoprecipitation followed by proteomic identification with tandem mass spectrometry revealed five proteins, presumably extracted together as a complex. Of these, AALB007909 had the highest mascot score and corresponds to a protein with a myosin head motor domain, indicating that the target of mAb A-140 is probably myosin located on the microvilli of the mosquito midgut. CONCLUSION: These results provide support for the participation of myosin in mosquito midgut invasion by Plasmodium ookinetes. The potential inclusion of this protein in the design of new multivalent vaccine strategies for blocking Plasmodium transmission is discussed.

Immunoglobulin G profile in hyperacute rejection after multivisceral xenotransplantation.

INTRODUCTION: Xenotransplantation is a potential solution for the high mortality of patients on the waiting list for multivisceral transplantation; nevertheless, hyperacute rejection (HAR) hampers this practice and motivates innovative research. In this report, we describe a model of multivisceral xenotransplantation in which we observed immunoglobulin G (IgG) involvement in HAR. METHODS: We recovered en bloc multivisceral grafts (distal esophagus, stomach, small intestine, colon, liver, pancreas, and kidneys) from rabbits (n = 20) and implanted them in the swine (n = 15) or rabbits (n = 5, control). Three hours after graft reperfusion, we collected samples from all graft organs for histological study and to assess IgG fixation by immunofluorescence. Histopathologic findings were graded according to previously described methods. RESULTS: No histopathological features of rejection were seen in the rabbit allografts. In the swine-to-rabbit grafts, features of HAR were moderate in the liver and severe in esophagus, stomach, intestines, spleen, pancreas, and kidney. Xenograft vessels were the central target of HAR. The main lesions included edema, hemorrhage, thrombosis, myosites, fibrinoid degeneration, and necrosis. IgG deposition was intense on cell membranes, mainly in the vascular endothelium. CONCLUSIONS: Rabbit-to-swine multivisceral xenotransplants undergo moderate HAR in the liver and severe HAR in the other organs. Moderate HAR in the liver suggests a degree of resistance to the humoral immune response in this organ. Strong IgG fixation in cell membranes, including vascular endothelium, confirms HAR characterized by a primary humoral immune response. This model allows appraisal of HAR in multiple organs and investigation of the liver's relative resistance to this immune response.

Immune homeostasis to microorganisms in the guts of triatomines (Reduviidae)--a review.

Bacteria, fungi and parasites are in constant contact with the insect gut environment and can influence different aspects of the host gut physiology. Usually, some of these microorganisms develop and survive in the digestive tract. Therefore, the gut environment must be able to tolerate certain populations of these organisms for the establishment of interactions between non-pathogenic bacteria, parasites and the gut. This review provides a brief overview of the biological and molecular mechanisms that microorganisms use to interact with the gut epithelia in mosquitoes and speculates on their significances for the development of bacteria and Trypanosoma cruzi in the guts of triatomines.

Immune homeostasis to microorganisms in the guts of triatomines (Reduviidae): a review

Bacteria, fungi and parasites are in constant contact with the insect gut environment and can influence different aspects of the host gut physiology. Usually, some of these microorganisms develop and survive in the digestive tract. Therefore, the gut environment must be able to tolerate certain populations of these organisms for the establishment of interactions between non-pathogenic bacteria, parasites and the gut. This review provides a brief overview of the biological and molecular mechanisms that microorganisms use to interact with the gut epithelia in mosquitoes and speculates on their significances for the development of bacteria and Trypanosoma cruzi in the guts of triatomines.

In vivo assessment of possible probiotic properties of Zymomonas mobilis in a Wistar rat model

In recent years the incorporation of probiotic bacteria into foods has received increasing scientific interest for health promotion and disease prevention. The safety and probiotic properties of Zymomonas mobilis CP4 (UFPEDA-202) was studied in a Wistar rat model fed the 10(9) colony forming units (cfu)/mL-1 of the assayed strain for 30 days. No abnormal clinical signs were noted in the group receiving viable cells of Z. mobilis and water (control) during the period of the experiment. There were no significant difference (p > 0.05) in feed intake and weight gain among mice fed the Z. mobilis in comparison to the control group. No bacteria were found in blood, liver and spleen of any animals. Mice receiving Z. mobilis showed significantly differences (p < 0.05) in total and differential leucocytes count, excepting for neutrophils, after the experimental period. Otherwise, it was not found in control group. Histological examination showed that feeding mice with Z. mobilis caused no signs of adverse effects on gut, liver and spleen. From these results, Z. mobilis CP4 (UFEPEDA-202) is likely to be nonpathogenic and safe for consumption, and could have a slight modulating effect on immunological performance in mice.

Prevalencia del complejo entamoeba histolytica/entamoeba dispar en pacientes con síntomas gastrointestinales de diarrea procedentes de Cumaná estado Sucre / Prevalence of entamoeba histolytica/entamoeba dispar in patients with gastrointestinal symptoms of diarrhea and who come from Cumaná Sucre state

Entamoeba histolytica es considerada un problema de salud pública debido a su alta prevalencia y las consecuencias para los individuos, especialmente a niños quienes puede considerar incluso la muerte. Pocos estudios se han llevado a cabo sobre la prevalencia de estas especies en el nororiente de Venezuela, por lo que se planteó analizar 400 muestras de heces de pacientes con síntomas gastrointestinales de diarrea de ambos sexos y diferentes grupos etarios para determinar la prevalencia del complejo entamoeba histolytica/entamoeba dispar y su asociación con otros parásitos además de su asociación con algunos parámetros epidemiológicos. Las muestras fueron analizadas por métodos coproparasitológicos usando solución salina fisiológica al 0,85 por ciento, lugol coloración tricrómica, sangre oculta y concentración por Ritchie. A cada paciente se le aplicó una encuesta para obtener datos clínicos y epidemiológicos. Se encontró una prevalencia de 16,0 por ciento (n=64) para el complejo entamoeba histolytica/entamoeba dispar. Otros parásitos frecuentes fueron blastocystis hominis 19,3 por ciento (n=77), entamoeba coli 9,3 por ciento (n=37), endolimax nana 8,0 por ciento (n=32), giardia lamblia 5,8 por ciento (n=23), trichuris trichiuria 4,0 por ciento (n=16), ascaris lumbricoides 3,8 por ciento (n=15). Un 15,5 por ciento de los pacientes estaban poliparasitados, mientras que 37,0 por ciento mostraron un único parásito. Blastocystis hominis resultó ser el parásito mayormente asociado con complejo entamoeba histolytica/entamoeba dispar 10,9 por ciento (n=7). La sintomatología fue variable entre lo que podemos mencionar vómitos (26,6 por ciento), nauseas (39,1 por ciento), dolor abdominal (68,8 por ciento), fiebre (28,1 por ciento) y flatulencia (65,6 por ciento). No se encontró asociación significativa entre la presencia de las amibas y el sexo (X²=16,63, P<0,05), pero sí con edad (x²=16,63, p<0,05), siendo el grupo etario 10-19 años el más efectado. Las cifras de prevalencia de parásitos intestinales, especialmente para el complejo entamoeba histolytica/entamoeba dispar, demuestran que existe un problema importante de salud que debe ser abordado por las autoridades sanitarias del estado

Role of mast cells in gastrointestinal mucosal defense.

The purpose of this review, based on studies from our laboratory as well as from others, is to summarize salient features of mast cell immunobiology and to describe their associations with gastrointestinal mucosal defense. Gastrointestinal mast cells are involved in many pathologic effects, such as food hypersensitivity. On the other hand, they also play a protective role in defense against parasitic and microbial infections. Thus, they have both positive and negative effects, but presently the mechanisms that control the balance of these various effects are poorly known. It has been suggested that stabilization of mast cells may be a key mechanism to protect the gastrointestinal tract from injury. Few molecules are known to possess both mast cell stabilizing and gastrointestinal cytoprotective activity. These include zinc compounds, sodium cromoglycate, FPL 52694, ketotifen, aloe vera, certain flavonoids such as quercetin, some sulfated proteoglycans such as chondroitin sulfate and dehydroleucodine. Dehydroleucodine, a sesquiterpene lactone isolated from Artemisia douglasiana Besser, exhibits anti-inflammatory and gastrointestinal cytoprotective action. The lactone stimulates mucus production, and inhibits histamine and serotonin release from intestinal mast cells. The lactone could act as a selective mast cell stabilizer by releasing cytoprotective factors and inhibiting pro-inflammatory mast cell mediators.

Role of mast cells in gastrointestinal mucosal defense

The purpose of this review, based on studies from our laboratory as well as from others, is to summarize salient features of mast cell immunobiology and to describe their associations with gastrointestinal mucosal defense. Gastrointestinal mast cells are involved in many pathologic effects, such as food hypersensitivity. On the other hand, they also play a protective role in defense against parasitic and microbial infections. Thus, they have both positive and negative effects, but presently the mechanisms that control the balance of these various effects are poorly known. It has been suggested that stabilization of mast cells may be a key mechanism to protect the gastrointestinal tract from injury. Few molecules are known to possess both mast cell stabilizing and gastrointestinal cytoprotective activity. These include zinc compounds, sodium cromoglycate, FPL 52694, ketotifen, aloe vera, certain flavonoids such as quercetin, some sulfated proteoglycans such as chondroitin sulfate and dehydroleucodine. Dehydroleucodine, a sesquiterpene lactone isolated from Artemisia douglasiana Besser, exhibits anti-inflammatory and gastrointestinal cytoprotective action. The lactone stimulates mucus production, and inhibits histamine and serotonin release from intestinal mast cells. The lactone could act as a selective mast cell stabilizer by releasing cytoprotective factors and inhibiting pro-inflammatory mast cell mediators. (AU)

Cow's milk protein-sensitive enteropathy at school age.

OBJECTIVES: Cow's milk protein-sensitive enteropathy (CMSE) may persist in children to school age. We sought to define the morphologic and immunohistochemical features of persistent CMSE. STUDY DESIGN: We studied 15 children with a definite diagnosis of CMSE on the basis of a blind challenge, 12 children with suspected cases of CMSE, 11 children with celiac disease, and 12 control children. RESULTS: Typical findings in children with CMSE were endoscopically visible lymphonodular hyperplasia of the duodenal bulb and lymphoid follicles without villous atrophy in biopsy samples. The patients with definite CMSE showed significantly increased densities of intraepithelial T cells skewed clearly to gammadelta(+) cells, compared with the control patients but fewer than in the patients with celiac disease. The study children showed no aberrant upregulation of HLA-DR expression in the duodenal mucosa, and the prevalence of HLA DQ2 antigen among them was equal to that in the control children. CONCLUSIONS: Our observations corroborated the claim that CMSE at school age is an identifiable clinical entity. Immunohistochemical findings suggest the abrogation of antigen tolerance locally on the gastrointestinal mucosa. A careful clinical assessment that includes a long elimination-challenge test supported by typical endoscopic and histologic findings form the basis for diagnosis.

Immunological control of ticks through vaccination with Boophilus microplus gut antigens.

The control of tick infestations and the transmission of tick-borne diseases remain a challenge for the scientific community. Traditional control methods have been only partially successful. Recently, vaccination with recombinant Boophilus microplus gut antigens has been shown to control tick infestations. Our Bm86-containing vaccine formulation (Gavac) has been effective for the control of artificial infestations of B. annulatus, B. decoloratus, and chemically sensitive and resistant B. microplus strains from Australia, Africa, America, and Iran. Preliminary results with Hyalomma spp. and Rhipicephalus spp. suggest partial cross protection. In field trials, vaccination with Gavac controlled B. microplus and B. annulatus infestations and reduced the transmission of babesiosis, resulting in important savings for the cattle industry. Different degrees of susceptibility to the vaccination with Bm86 and sequence variations in the Bm86 locus have been reported. The Bm95 antigen was isolated from the Argentinean Bm86-resistant B. microplus strain A. A Bm95-based vaccine was used to protect cattle against tick infestations under production conditions with similar results to that obtained with Gavac. The Bm95 antigen from strain A was able to protect against infestations with Bm86-sensitive and Bm86-resistant tick strains, thus suggesting that Bm95 could be a more universal antigen in protecting cattle against infestations by B. microplus strains from different geographical areas. These results clearly demonstrate the advantage and possibilities for the immunological control of ticks.

A review on the use of microorganisms as probiotics.

A literature review on the use of live microorganisms as probiotics is presented. Topics discussed are the definition of probiotic; the normal microflora of the digestive system of mammals, including bacterial interactions in the gut, colonization, modification of metabolic processes, and immunostimulation. Probiotics studies in humans and in farmed animals, with special emphasis on the use of Lactobacillus spp. and Bifidobacterium spp. are also discussed.

Monoassociation with Lactobacillus acidophilus UFV-H2b20 stimulates the immune defense mechanisms of germfree mice.

Probiotics are formulations containing live microorganisms or microbial stimulants that have some beneficial influence on the maintenance of a balanced intestinal microbiota and on the resistance to infections. The search for probiotics to be used in prevention or treatment of enteric infections, as an alternative to antibiotic therapy, has gained significant impulse in the last few years. Several studies have demonstrated the beneficial effects of lactic acid bacteria in controlling infection by intestinal pathogens and in boosting the host's nonspecific immune response. Here, we studied the use of Lactobacillus acidophilus UFV-H2b20, a lactic acid bacterium isolated from a human newborn from Viçosa, Minas Gerais, Brazil, as a probiotic. A suspension containing 10(8) cells of Lactobacillus acidophilus UFV-H2b20 was inoculated into groups of at least five conventional and germfree Swiss mice to determine its capacity to stimulate the host mononuclear phagocytic activity. We demonstrate that this strain can survive the stressing conditions of the intestinal tract in vivo. Moreover, the monoassociation of germfree mice with this strain for seven days improved the host's macrophage phagocytic capacity, as demonstrated by the clearance of a Gram-negative bacterium inoculated intravenously. Monoassociated mice showed an undetectable number of circulating E. coli, while 0.1% of the original inoculum was still present in germfree animals. Mice treated with viable or heat-killed Lactobacillus acidophilus UFV-H2b20 presented similarly improved clearance capacity when compared with germfree controls. In addition, monoassociated mice had twice the amount of Kupffer cells, which are responsible for the clearance of circulating bacteria, compared to germfree controls. These results suggest that the L. acidophilus strain used here stimulates a nonspecific immune response and is a strong candidate to be used as a probiotic.

Immunisation of dogs and guinea pigs against Rhipicephalus sanguineus ticks using gut extract.

Tick-bite naive guinea pigs were inoculated three times with Rhipicephalus sanguineus gut or salivary gland extracts and saponin as adjuvant. Dogs were inoculated three times with gut extract only as this fraction induced a more efficient resistance in guinea pigs (lower tick recovery and lower engorged female weights). Freund's adjuvant and saponin were used as adjuvants for the immunisation of dogs. Freund's adjuvant was used to enhance cellular immunity. The highest level of resistance in dogs was induced by the immunisation with gut extract and Freund's adjuvant. Many female ticks from dogs immunised this way engorged fully but died prior to oviposition. Resistant guinea pigs and dogs seemed to trigger different immune mechanisms against R. sanguineus ticks as damage to parasites also differed. A major role for cellular immunity in the resistance of dogs against R. sanguineus ticks is suggested. Resistance mechanisms against R. sanguineus ticks is discussed.

Gastrointestinal immune responses in HIV infected subjects.

The gut associated lymphoid tissue is responsible for specific responses to intestinal antigens. During HIV infection, mucosal immune deficiency may account for the gastrointestinal infections. In this review we describe the humoral and cellular mucosal immune responses in normal and HIV-infected subjects.