The regulation of the mucosal immune response by secretory IgA

L'immunoglobuline A sécrétoire (SlgA) est l'anticorps qui est dominant dans la réponse humorale des muqueuses. IgA est produit localement sous la forme de dimère ou polymère. Ces derniers sont ensuite relâchés dans les sécrétions muqueuses sous forme d'un complexe avec la pièce sécrétoire (SC). SlgA est capable d'identifier des antigènes microbiens dans l'environnement des muqueuses et de prévenir leur diffusion en bloquant l'adhésion ou la surface des cellules épithéliales. Au-delà de sa fonction classique d'exclusion immune, SlgA peut aussi adhérer aux cellules M présente au niveau des follicules associés à l'épithélium dans des structures organisées appelées plaques de Peyer (PPs) dans le système gastrointestinal. L'interaction sélective avec les SlgA amène cette dernière à être transportée à travers les cellules M Ce procès facilite l'association de l'anticorps avec les cellules dendritiques (DCs) CDllc+CDllb+, localisées dans la région sous-épithéliale des PPs. L'entrée de SlgA ou de microorganismes couverts par la SlgA via ce chemin est cruciale pour la modulation de la réponse immunitaire locale. Dans la première partie du travail, nous avons établi les conditions pour l'analyse de l'interaction entre SlgA et une lignes de DCs dérivée in vitro. Nous avons aussi montré que l'internalisation de la SlgA par les DCs est affecté après traitement avec des inhibiteurs de l'endocytose ou par l'utilisation de compétiteurs moléculaires. En utilisant le microscope confocal, on a observé qu'après internalisation la SlgA suit la voie endocytique, vers le compartiment lysozomal. Dans la deuxième partie du travail, une partie des résultats a été confirmée pour les DCs CDllc+CDllb+ des muqueuses. En outre, l'importance des sucres présents sur la SlgA a été mis en évidence par la réduction de l'interaction avec les DCs des muqueuses après déglycosylation. On a montré pour la première fois à notre connaissance que Dectin-1 et SIGNR3 sont des récepteurs potentiels pour la SlgA sur les DCs des muqueuses de la souris. De plus, les DCs de la souris prélevées des PPs, des ganglions lymphatiques mésentériques (MLNs) et de la rate ont été infectés avec Shigella flexneri (Sf) seule ou en complexe avec SlgA. Les DCs infectées ont montré une augmentation de l'expression des marqueurs co-stimulateurs, une forte production des cytokines pro¬inflammatoires et une induction de la prolifération des cellules T. Après l'association des Sf avec SlgA, les profils pro-inflammatoires des DCs ont diminués. En particulier, SlgA a un effet sur les cytokines sécrétées et sur la prolifération des cellules T. Ces données démontrent le rôle de la SlgA dans la réponse immunitaire par les DCs des muqueuses.

Severe Cutaneous Leishmaniasis in a Human Immunodeficiency Virus Patient Coinfected with Leishmania braziliensis and Its Endosymbiotic Virus.

Leishmaniaparasites cause a broad range of disease, with cutaneous afflictions being, by far, the most prevalent. Variations in disease severity and symptomatic spectrum are mostly associated to parasite species. One risk factor for the severity and emergence of leishmaniasis is immunosuppression, usually arising by coinfection of the patient with human immunodeficiency virus (HIV). Interestingly, several species ofLeishmaniahave been shown to bear an endogenous cytoplasmic dsRNA virus (LRV) of theTotiviridaefamily, and recently we correlated the presence of LRV1 withinLeishmaniaparasites to an exacerbation murine leishmaniasis and with an elevated frequency of drug treatment failures in humans. This raises the possibility of further exacerbation of leishmaniasis in the presence of both viruses, and here we report a case of cutaneous leishmaniasis caused byLeishmania braziliensisbearing LRV1 with aggressive pathogenesis in an HIV patient. LRV1 was isolated and partially sequenced from skin and nasal lesions. Genetic identity of both sequences reinforced the assumption that nasal parasites originate from primary skin lesions. Surprisingly, combined antiretroviral therapy did not impact the devolution ofLeishmaniainfection. TheLeishmaniainfection was successfully treated through administration of liposomal amphotericin B.

Leishmaniavirus : a possible target against metastatic leishmaniasis

Leishmaniasis is widely spread disease found in bath tropical and temperate regions but limited to the habitat of its sand fly vector. lt affects over 12 million people with 2 million new cases each year. As cutaneous leishmaniasis patients show varying levels of immunity to the disease after recovery, the development of a vaccine has much promise as a prevention strategy. Unfortunately however, existing anti-leishmanial vaccines are plagued by safety issues and have only ever shown limited efficacy .So, despite much effort, no effective vaccine is currently available. Recent studies suggest a correlation between the presence of Leishmania RNA virus (LRV) and the development of mucocutaneous leishmaniasis (MCL), which is characterised by the presence of secondary lesions in nasal and buccal mucosa, causing destructive and disfiguring facial lesions. Moreover, recent research has associated the viral presence to treatment fa ilure in patients. ln the first part of this work, we propose that these viral particles may serve as promising vaccine candidates due to their powerful TLR-3 antigenicity, launching an early cell-mediated attack on stimulated cells and thus eliminating their virulent complications. The second part of this work discusses a preliminary study on the lymphocyte immune response against Leishmania guyanensis infection. The lymphocyte response (and in particular, the raie of CDS+ T cells) is controversial and varies greatly between Leishmania species. Here, we illustrate the importance of a small CDS+ T cell subpopulation, expressing the CDSaa+ receptor. These intraepithelial lymphocytes are mainly present in the skin, vagina and intestinal tissue and are best known for their raie in the early immune response against pathogens. Similarly to traditional CDS+ cells, they secrete the tissue-destructive enzymes, perforin and granzyme, which can result in a hyper-inflammatory cutaneous lesion, raising a possibility for their raie in Leishmania infection. lndeed, our initial results in a murine mode( of Leishmania guyanensis infection suggest a pathogenic raie for CDSaa+ T cells. Further research into species-specific immune responses against the various Leishmania parasites is critical to realising the clinical potential of immunotherapy in the treatment and prevention of this disfiguring disease . -- La Leishmaniose est une maladie infectieuse causée par le parasite Leishmania. Elle est localisée dans les régions où son vecteur se reproduit, c'est-à-dire dans des régions tropicales ou tempérées. Cette pathologie affecte 12 millions des personnes dans le monde et 2 millions de nouveaux cas sont recensés chaque année. D'autres facteurs, tels la déforestation, les conditions d'hygiène ou encore l'accès limité aux médicaments, aggravent la pathologie et renforcent sa propagation. Les patients affectés par la leishmaniose et qui arrivent à en guérir, présentent une protection contre une réinfection. Pour cette raison, le développement d'un vaccin reste la meilleure solution pour combattre ce fléau. Mais, à ce jour, et malgré beaucoup d'efforts, aucun vaccin efficace n'a encore été développé. Un autre facteur responsable de l'aggravation de la pathologie et de la résistance de ces parasites aux drogues est un virus qui peut infecter certaines souches de Leishmania. Ce virus, appelé Leishmania RNA virus, peut induire une réponse inflammatoire exagérée, ce qui a comme résultat l'aggravation de la pathologie, la survie et la dissémination de ce parasite au sein de l'hôte infecté. Vu l'absence d'un vaccin contre ce parasite, Leishmania, nous proposons de développer un vaccin non pas contre le parasite lui- même mais contre l'agent qui provoque l'exacerbation de la pathologie, c'est-à-dire le virus. Dans cette étude, nous décrivons le développement d'un vaccin contre LRV, qui empêche le parasite d'induire des inflammations exagérées dans les souris. En d'autres mots, nous essayons de prévenir toutes les complications générées par cet hyperpathogène qu'est le LRV, en utilisant sa capside comme cible pour le développement d'un vaccin. Dans la deuxième partie de ce manuscrit, nous avons aussi étudié plus en détail la réponse immunitaire, et en particulier la réponse des lymphocytes T COB suite à l'infection du parasite Leishmania guyanensis porteur du LRV.

Review and new therapeutic alternatives for the treatment of cutaneous Leishmaniasis

Leishmaniasis comprises a group of diseases caused by protozoa of the genus Leishmania and has two basic clinical forms, visceral Leishmaniasis and cutaneous Leishmaniasis. The clinical features of Leishmaniasis depend on the species of Leishmania, the interaction between host and parasite and the immune response. This work focuses on cutaneous leishmaniosis because although it is not a deadly disease it results in significant scars and facial disfigurements, thus being clinically important. Furthermore, the first-line treatment consists of intravenous or intramuscular administration of intralesional pentavalent antimonials, which are highly toxic, making hospitalization of patients compulsory during treatment, with the associated financial costs. Herein, we review studies on drugs and treatments with fewer side effects and easier routes of administration such as topical administration. Recent research shows that the topical route of administration holds promise for the future treatment of cutaneous leishmaniosis.

Review and new therapeutic alternatives for the treatment of cutaneous Leishmaniasis

Leishmaniasis comprises a group of diseases caused by protozoa of the genus Leishmania and has two basic clinical forms, visceral Leishmaniasis and cutaneous Leishmaniasis. The clinical features of Leishmaniasis depend on the species of Leishmania, the interaction between host and parasite and the immune response. This work focuses on cutaneous leishmaniosis because although it is not a deadly disease it results in significant scars and facial disfigurements, thus being clinically important. Furthermore, the first-line treatment consists of intravenous or intramuscular administration of intralesional pentavalent antimonials, which are highly toxic, making hospitalization of patients compulsory during treatment, with the associated financial costs. Herein, we review studies on drugs and treatments with fewer side effects and easier routes of administration such as topical administration. Recent research shows that the topical route of administration holds promise for the future treatment of cutaneous leishmaniosis.

Spatial distribution of canine Visceral Leishmaniasis in Ilha Solteira, São Paulo, Brazil

Visceral Leishmaniasis (VL) is caused by protozoan of genus Leishmania and transmitted by sand flies of genus Lutzomyia, which has been adapted to the peridomicile environment where dogs are their mainly food source, increasing the risk for human cases. In this study, techniques of geoprocessing and spatial statistics were utilized as a contribution to understanding the epidemiological dynamics of VL in the urban area of Ilha Solteira, SP.

Effect of the celexoxib in microscopic changes of the esophageal mucosal of rats induced by esofagojejunostomy

OBJECTIVE: To evaluate the protective effect of celecoxib in the esophageal mucosa in rats undergoing esofagojejunostomy.METHODS: Sixty male Wistar rats from the vivarium of the University of Health Sciences of Alagoas were used for the experiment. The animals were divided into four groups: Group I, 15 rats undergoing esofagojejunostomy with the use of celecoxib postoperatively; Group II, 15 rats undergoing esofagojejunostomy without the use of celecoxib; Group III, 15 rats undergoing celiotomy with bowel manipulation; and Group IV, 15 rats without surgery and using celecoxib. The observation period was 90 days. After the death of the animals, the distal segment of the esophagus was resected and sent for microscopic analysis.RESULTS: esofagojejunostomy caused macroscopic and microscopic esophagitis. Esophagitis was equal in both groups I and II. In groups III and IV esophageal lesions were not developed.CONCLUSIONS: celecoxib had neither protective nor inducing effect on esophagitis, but had a protective effect on dysplasia of the animals of group I.

Serological diagnosis of visceral leishmaniasis by an enzyme immunoassay using protein A in naturally infected dogs

A rapid indirect enzyme-linked immunosorbent assay (ELISA) was developed for measuring antibodies against Leishmania chagasi using total antigen from lysed promastigotes. Fifty symptomatic mixed breed dogs from a region of high incidence of visceral leishmaniasis in Brazil were examined. The results showed that in the positive animals, diagnosed by cytological examination, the ELISA using protein A assay system (mean optical density ± SD / 2.078 ± 0.631) detected more antibodies than the anti-IgG assay (mean optical density ± SD / 1.008 ± 0.437), while in the negative animals, the results by both systems were similar. These results suggest that the ELISA assay using protein A peroxidase conjugated could be useful to detect early infected animals in endemic areas, and thus help to control the spread of the infection.

Occurrence of anti-Neospora caninum and anti-Toxoplasma gondii antibodies in dogs with visceral leishmaniasis

Uninfected dogs and those naturally infected with Leishmania chagasi exhibiting different clinical forms of disease were evaluated for the presence of anti-Neospora caninum and anti-Toxoplasma gondii antibodies. Blood samples were collected from 110 mongrel dogs. Sera were tested using the indirect fluorescent antibody test (IFAT), and the animals with visceral leishmaniasis (VL) (n=60) were classified clinically. Out of the 110 sera investigated, 5 (4.5%) were positive for N. caninum (IFAT>50) and 36 (32.7%) for T. gondii (IFAT>16). Anti-L. chagasi antibody titers in asymptomatic dogs (n=10) were found to be significantly lower (P<0.05) than those in oligosymptomatic ones (n=22), which were in turn significantly lower (P<0.05) than those in symptomatic ones (n=28). No association between Leishmania and N. caninum infections was observed. Among dogs infected with L. chagasi, a tendency (P=0.053) towards an association between the infection with T. gondii and the appearance of VL symptoms was observed, suggesting that the clinical manifestation of VL in dogs may enhance their susceptibility to T. gondii. The possible influence of the immunosuppressive status of canine leishmaniasis in the different clinical forms of the disease is discussed.

The influence of selected pathological states on the somatostatin-like immunoreactive (SOM-LI) endocrine cells in the mucosal layer of the porcine descending colon

This study reports on changes in the number of somatostatin-like immunoreactive (SOM-LI) endocrine cells in the porcine descending colon, caused by chemically driven inflammation, axotomy and proliferative enteropathy (PE). The distribution pattern of SOM-LI endocrine cells has been studied using the routine single-labelling immunofluorescence technique. Semi-quantitative evaluation of the number of the SOM-immunostained endocrine cells within the mucosal layer of the porcine descending colon has been based on counting of all endocrine cells immunoreactive to SOM per unit area (0,1 mm²). Under physiological conditions the number of SOM-LI endocrine cells has been shown to constitute 3,30±0,22. All applied pathological processes resulted in changes in the SOM-like immunoreactivity, which varied in particular processes studied. The number of SOM-LI endocrine cells increased to 6,28±0,31 and 4,43±0,35 during chemically driven inflammation and proliferative enteropathy, respectively, and decreased to 1,17%±0,16 after axotomy. The obtained results suggest that SOM-LI endocrine cells may participate in various pathological states within porcine descending colon and their functions probably depend on the type of pathological factor.

Outbreak of autochthonous canine visceral leishmaniasis in Santa Catarina, Brazil

The present study reports the first outbreak of autochthonous canine visceral leishmaniasis in Florianópolis, Santa Catarina, southern Brazil. Following the report of two cases of CVL, the Control Center of Zoonotic Diseases conducted a serological survey by ELISA and IFAT assays in seven districts of the Santa Catarina Island. Eleven seropositive dogs of autochthonous transmission were used in the present study. Infection by Leishmania sp. was confirmed by parasitological examination of bone marrow, liver, spleen and lymph nodes, culture in Schneider's medium and PCR. Leishmania sp. isolates were characterized by PCR-RFLP and hybridization with specific probes, allowing for the identification of Leishmania infantum. Autochthonous transmission of this disease in an area with high tourist traffic presents a major public health concern and signifies the emergence of an important zoonosis in southern Brazil. Therefore, the implementation of surveillance and control measures is imperative to prevent the spread of the disease among the canine population as well as transmission to the human population.

Assessment of the electrocardiogram in dogs with visceral leishmaniasis

As myocarditis and arrhythmias have been shown to occur in both human beings and dogs with leishmaniasis, electrocardiograms of 105 dogs serologically positive for this disease were assessed for rhythm disturbances and changes in ECG waves. A few expressive alterations were seen, including sinus arrest, right bundle branch block, and atrial premature beats in 14.3%, 4.8%, and 4.8% of the studied subjects, respectively. Also, the analysis of ECG waves showed changes suggestive of left atrium and ventricle enlargements, and myocardial hypoxia in some animals. Although cardiac compromise has been previously reported in dogs with leishmaniasis, only a small subset of dogs showed any alteration in the electrocardiogram, which cannot support the occurrence of myocarditis in this investigation.

Wheat bran- but not oat bran-enriched diets increase the mucosal height of the cecum and colon of newly weaned and aged rats

The effect of diets enriched with oat or wheat bran (prepared by the addition of 300 g of each fiber to 1000 g of the regular diet), given for 8 weeks, on the mucosal height of the colon and cecum was investigated. Newly weaned (21 days old) and aged (12 months old) male Wistar rats were used in this study. As compared to controls, diets enriched with wheat bran provoked a significant increase in the mucosal height, whereas oat bran did not cause any effect. In newly weaned rats (21 days old), wheat bran increased the mucosal height (µm) in the cecum by 20% (mean ± SEM for 8 rats; 169.1 ± 5.2 and 202.9 ± 8.0 for control and wheat bran, respectively) and in the colon (218.8 ± 7.2 and 264.5 ± 18.8 for control and wheat bran, respectively). A similar effect was observed in aged rats (12 months old), with an increase of 15% in the mucosal height (µm) of the cecum (mean ± SEM of 8 rats; 193.2 ± 8.6 and 223.7 ± 8.3 for control and wheat bran, respectively) and of 17% in the colon (300.4 ± 9.2 and 352.2 ± 15.9 for control and wheat bran, respectively)

Immunologic patterns associated with cure in human American cutaneous leishmaniasis

Patients with American cutaneous leishmaniasis were studied before therapy (active lesion) and at the end of therapy (cured patients). Assays of lymphocyte proliferative responses of peripheral blood mononuclear cells induced in vitro by Leishmania braziliensis promastigote antigens (Lb) were performed. Antigen-stimulated cells were harvested for CD4 and CD8 phenotype analysis and the levels of gamma interferon (IFN-g) and interleukin 4 (IL-4) produced were also determined in the culture supernatants. Two different patterns of Lb-induced T cell responses were observed: a) predominance of responding CD4+ cells and mixed type 1 and type 2 cytokine production (IFN-g and IL-4) during the active disease, and b) similar proportions of responding CD4+ and CD8+ cells, and type 1 cytokine production (presence of IFN-g and very low IL-4) at the end of therapy (healed lesions). This last pattern is probably associated with a beneficial T cell response

Electrocardiographic changes during low-dose, short-term therapy of cutaneous leishmaniasis with the pentavalent antimonial meglumine

The pentavalent antimonial (Sb5+) meglumine is the drug of choice for the treatment of cutaneous leishmaniasis (CL) in Brazil. Although the cardiotoxicity of high-dose, long-term Sb5+ therapy is well known, the use of low-dose, short-term meglumine has been considered to be safe and relatively free from significant cardiac effects. In order to investigate the cardiotoxicity of low-dose, short-term therapy with meglumine in cutaneous leishmaniasis, 62 CL patients treated with meglumine were studied. A standard ECG was obtained before and immediately after the first cycle of treatment (15 mg Sb5+ kg-1 day-1). The electrocardiographic interpretation was carried out blindly by two investigators using the Minnesota Code. There were no significant differences in qualitative ECG variables before and after meglumine treatment. However, the corrected QT interval was clearly prolonged after antimonial therapy (420.0 vs 429.3 ms, P<10-6). QTc augmentation exceeded 40 ms in 12 patients, 7 of whom developed marked QTc interval enlargement (500 ms) after meglumine therapy. This previously unrecognized cardiac toxicity induced by short-term, low-dose antimonial therapy has potentially important clinical implications. Since sudden death has been related to QTc prolongation over 500 ms induced by high-dose antimonial therapy, routine electrocardiographic monitoring is probably indicated even in CL patients treated with short-term, low-dose meglumine schedules. Until further studies are conducted to establish the interactions between pentavalent antimonials and other drugs, special care is recommended when using meglumine in combination with other medications, in particular with drugs that also increase the QTc interval.