Transforming growth factor-beta in leishmanial infection: a parasite escape mechanism.

The course of infection with the protozoan parasite Leishmania is determined in part by their early replication in macrophages, the exclusive host cells for these organisms. Although factors contributing to the survival of Leishmania are not well understood, cytokines influence the course of infection. Transforming growth factor-beta (TGF-beta) is a multipotential cytokine with diverse effects on cells of the immune system, including down-regulation of certain macrophage functions. Leishmanial infection induced the production of active TGF-beta, both in vitro and in vivo. TGF-beta was important for determining in vivo susceptibility to experimental leishmanial infection.

Presence of parasite DNA in clinically unaffected nasal mucosa during cutaneous leishmaniasis caused by Leishmania (Viannia) braziliensis.

OBJECTIVES: We aimed to detect Leishmania DNA carriage in nasal mucosa of individuals with cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis. METHODS: A cross-sectional study was performed in all individuals with CL without nasal lesions (n = 153) attended within 2 years in an endemic area of L. (Viannia) braziliensis in Bahia (Brazil). An otorhinolaryngologist assessed the clinical status of the nasal mucosa by anterior rhinoscopy and endoscopic examinations. Swab samples were collected for parasite DNA detection by PCR from all individuals before standard treatment for leishmaniasis. A second evaluation 3 months after treatment was performed to assess clinical outcomes. RESULTS: Parasite DNA was detected in 7.8% (12/153) of clinically healthy nasal mucosa of individuals with CL. Interestingly, DNA was more frequently identified in individuals with more skin lesions (median 1.5, interquartile range (IQR) 1-3.5 versus 1.0, IQR 1-1.5; p 0.044), or larger injuries (median 2.7, IQR 2-3.8 versus 1.6, IQR 1-2.5; p 0.013). Additionally, the disease of those individuals with positive PCR evolved more frequently to unusual forms of leishmaniasis (recidiva cutis and disseminated) (45.5% (5/11) versus 11.5% (14/122); p 0.009), and required more cycles of treatment to reach clinical cure (median 2, IQR 1-4 versus 1, IQR 1-2; p 0.05). CONCLUSION: These findings suggest an early parasite tropism to nasal mucosa in L. (Viannia) braziliensis infection and a clinical phenotype of CL cases associated with parasite DNA in nasal mucosa. Future studies should evaluate whether PCR of nasal swab samples could serve as a prognostic tool for individuals at risk of mucocutaneous leishmaniasis.

The Centre for Data and Knowledge Integration for Health (CIDACS): Linking Health and Social Data in Brazil.

The Centre for Data and Knowledge Integration for Health (CIDACS) was created in 2016 in Salvador, Bahia-Brazil with the objective of integrating data and knowledge aiming to answer scientific questions related to the health of the Brazilian population. This article details our experiences in the establishment and operations of CIDACS, as well as efforts made to obtain high-quality linked data while adhering to security, ethical use and privacy issues. Every effort has been made to conduct operations while implementing appropriate structures, procedures, processes and controls over the original and integrated databases in order to provide adequate datasets to answer relevant research questions. Looking forward, CIDACS is expected to be an important resource for researchers and policymakers interested in enhancing the evidence base pertaining to different aspects of health, in particular when investigating, from a nation-wide perspective, the role of social determinants of health and the effects of social and environmental policies on different health outcomes.

Changes in amounts of total salivary gland proteins of Lutzomyia longipallpis (Diptera: Psychodidae) according to age and diet.

Saliva plays important roles in facilitation of a bloodmeal, lubrication of mouthparts, and parasite transmission for some vector insects. Salivary composition changes during the lifetime of an insect, and differences in the salivary profile may influence its functions. In this report, the amount and profile of salivary gland protein of the American visceral leishmaniasis vector Lutzomyia longipalpis (Lutz & Neiva, 1912) were analyzed at different times of insect development and diet. Protein content from unfed female sand flies increased significantly with age, and a significant difference was observed in sugar-fed females during the first 10 d of adult life. Salivary protein content sharply decreased 1 d after blood feeding, with gradual increase in concentration the following days. SDS-polyacrylamide gel electrophoresis analysis revealed that most polypeptides present in the saliva of sugar-fed also were present in the saliva of blood-fed females. Understanding changes in sand fly's saliva contents at distinct days after emergence and the influence of a bloodmeal in this aspect may reveal the role played by saliva during leishmaniasis transmission.

Treatment of multiple sclerosis patients with interferon-beta primes monocyte-derived macrophages for apoptotic cell death.

Although interferon (IFN)-beta has shown a significant clinical benefit in multiple sclerosis (MS), its mechanism of action remains unclear. We found that IFN-beta treatment of patients with MS resulted in a significant increase in apoptotic cell death (measured by annexin V staining and nuclear fragmentation) of monocyte-derived macrophages, as compared with cells derived from patients before treatment. Stimulation of the cells with IFN-beta in vitro resulted in an even further increase of annexin V binding, as well as increased Fas (CD 95, APO-1) expression. However, no increased Fas expression, apoptotic monocytes, or monocytopenia were observed upon in vivo treatment. This indicates that IFN-beta does not deliver a death signal to monocytes but rather primes for subsequent macrophage apoptosis upon activation or differentiation.

Revisiting proteus: do minor changes in lectin structure matter in biological activity? Lessons from and potential biotechnological uses of the Diocleinae subtribe lectins.

Significant differences in function have been observed among lectins structurally similar to concanavalin A, but their high homology with this widely used lectin has kept them in obscurity. The observation of large differences in the potency of many of these Diocleinae lectins as stimulators of Interferon-g production by human peripheral blood mononuclear cells has lead to a major effort to unravel their chemical structure and biological activity. Modeling studies of some of these lectins reveal conformational changes in side chains of some residues involved in the carbohydrate-binding site, with possible effects on the ability of these proteins to recognize specific carbohydrate structures. Additionally, all them constitute in fact a mixture of isolectins, which in different proportions could lead to diverse effects. The present review of the biological actions of Diocleinae lectins includes several in vitro and in vivo immunological findings, as well as their effects on insect growth and reproduction. In these systems Diocleinae lectins proved to be quite diverse in their potency. Such diversity in the biological activity of highly related proteins recalls the origin of the name protein: like Proteus, the capability of assuming various forms is the essential feature of this class of molecules.

IFN-beta and TGF-beta differentially regulate IL-12 activity in human peripheral blood mononuclear cells.

Both IFN-beta and TGF-beta have demonstrated their ability to antagonize several of the stimulatory activities of IFN-gamma on human macrophages, thereby classifying them as Th2-like. Aiming at a further characterization of their role in Th1/Th2 development, we studied their possible interaction with IL-12, the key Th1 cytokine. We found that IFN-beta by itself induced modest amounts of IFN-gamma, but was able to synergize with IL-12 for IFN-gamma induction. TGF-beta, on the other hand, had no effect by itself and inhibited significantly the IL-12-induced IFN-gamma secretion. The differential effect of IFN-beta and TGF-b on IL-12 bioactivity was most pronounced upon IFN-gamma synthesis, since IFN-beta induced only marginal amounts of IL-10 and IL-12 and TGF-beta diminished constitutive IL-10 production, while neither had a significant effect on TNF-alpha production. Although monocytes did not produce detectable IFN-gamma with any of the stimuli, adherent cells were found to cooperate with non-adherent lymphocytes for maximal IFN-gamma production. However, IL-18, a monocyte-derived IFN-gamma-inducing cytokine able to synergize with IL-12, was undetectable in IFN-beta or IFN-beta+IL-12-stimulated cells. In conclusion, the ability of IFN-beta to synergize with IL-12 for IFN-gamma synthesis, without significant concomitant IL-10 production, suggest a strong boost to Th1 development, which seems to be IL-18-independent.

Leishmania (Leishmania) chagasi infection alters the expression of cell adhesion and costimulatory molecules on human monocyte and macrophage.

The initial steps of Leishmania infection in humans are largely unknown. There is limited information on the Leishmania infected human monocytes, the first cells that the parasite lives in, particularly related to costimulatory molecules. We show here that Leishmania (L.) chagasi infection avoids inducing proinflammatory molecules and has striking down modulating effects on human monocytes or macrophages. It does not induce CD54, interleukin (IL)-12 or tumour necrosis factor-alpha, potent proinflammatory cytokines and down modulates CD11b expression in monocytes. Lipopolysaccharide stimulated IL-12 (p40) levels, CD54 and HLA-DR expression are diminished in infected monocytes as well as interferon-gamma stimulated HLA-DR and HLA-ABC expression in infected macrophages. There is a negative correlation between CD54 and CD86 expression in both monocytes and macrophages. The depressed expression of class I and II molecules, absence of key proinflammatory cytokines and impaired expression of costimulatory molecules induced by L. chagasi could leave the immune system, at least in its initial phases in anergy or ignorance.

Destruction of Leishmania mexicana amazonensis promastigotes by normal human serum.

Fresh normal human serum was observed to have a lethal effect on Leishmania mexicana amazonensis promastigotes obtained from laboratory-bred Lutzomyia longipalpis or on promastigotes grown in liquid culture medium, inoculated with the same isolates. Heat inactivation abolished the Leishmania lytic activity from the sera. Resistance of culture promastigotes to lysis by normal human serum was investigated in three isolates of L. m. amazonensis. Development of resistance (up to 7%) was found in only one isolate, obtained from the bone marrow in a human case of visceral leishmaniasis.

Parasitological and pathological findings in capuchin monkeys infected with Schistosoma japonicum or Schistosoma mansoni.

Capuchin monkeys were studied for 7 months after exposure to Schistosoma mansoni or to either a Japanese or a Philippine strain of Schistosoma japonicum. The number of eggs present in the tissues and passed in the feces of S. mansoni-infected monkeys correlated well with the number of worm pairs recovered. Monkeys infected with the Philippine strain of S. japonicum passed large numbers of eggs in the feces and the number of these eggs correlated well with the number of worm pairs present. In monkeys infected with the Japanese strain of S. japonicum, fewer eggs were passed in the feces and there was little correlation with the number of worm pairs. Schistosome eggs were found predominantly in the small intestine in monkeys infected with the Philippine strain and predominantly in the colon in monkeys infected with the Japanese strain. The patterns of egg excretion in the feces and egg distribution in the tissues contrast with the patterns we recently described in rabbits, in which animals infected with the Philippine strain passed few eggs in the feces and showed a high proportion of tissue eggs in the colon. A single host species is thus shown to be inadequate to characterize the behavior of a schistosome strain.

Specificity of antibody and cellular immune responses in human schistosomiasis.

Thirty patients infected with Schistosoma mekongi, S. mansoni or S. japonicum had cell-mediated immune responses assessed by lymphocyte transformation in vitro (LT), immediate hypersensitivity responses determined by basophil histamine release in vitro (HR) and IgG antibody responses evaluated in an enzyme-linked immunosorbent assay (ELISA). Species specificity was evaluated with antigens obtained from adult worms or eggs of the three schistosome species. Though cross-reactivity was present in all tests, homologous antigens elicited responses significantly greater than those to heterologous antigens in all comparisons of parasite specific IgG and IgE antibody in these groups of patients. A similar generalization could be made for the lymphocyte responses to the same antigen preparations, but statistically significant differences were achieved only in certain comparisons.

Suppression of lymphocyte proliferative responses by sera from patients with American visceral leishmaniasis.

We examined the effect of sera from 11 patients with American visceral leishmaniasis on mitogen-driven lymphocyte proliferative capacity. All sera inhibited lymphocyte proliferation of patients' peripheral blood mononuclear cells (PBMC) when stimulated by either phytohemagglutinin, Concanavalin A or pokeweed mitogen. Serum was also strongly inhibitory for Concanavalin A-pulsed normal volunteers' PMBC. The effect of the serum was not due to cytotoxicity, inadequate nutritional support or altered kinetics of DNA synthesis. High levels of IgM or IgG (both total and antiparasite) and high levels of triglycerides were found in patients' sera.

Aggravation of both Trypanosoma cruzi and murine leukemia virus by concomitant infections.

Given the dissemination of acquired immunodeficiency syndrome (AIDS) in Latin America, where Chagas' disease is endemic, there is a present and increasing risk of concurrent infections with human immunodeficiency virus (HIV) and Trypanosoma cruzi. We used the model of murine acquired immunodeficiency syndrome (MAIDS) caused by a murine leukemia virus (MuLV) that induces immunologic alterations with similarities to those accompanying human HIV infection to study aspects of concomitant infections. The MuLV infection was found to reactivate T. cruzi infection in C57Bl/10 mice, as indicated by elevated parasitemia and lymphocytic infiltration in the myocardium. The T cells from these animals did not respond to T. cruzi antigens (lymphocyte proliferation, interferon-gamma, or interleukin-2 [IL-2] production) but had increased levels of IL-10. Trypanosoma cruzi-specific antibody was decreased but not absent in dually infected animals. In a second set of experiments, we infected MAIDS-resistant B6D2 mice with MuLV, followed by infection with T. cruzi. These animals had higher parasitemia than those infected with T. cruzi alone. More interestingly, only dually infected animals developed MAIDS. The present report describes the activation of T. cruzi infection by MuLV as well as the aggravation of MuLV infection by T. cruzi. These results may be relevant to coinfections with retrovirus and protozoan parasites in humans.

Cell-mediated and humoral immune responses in capuchin monkeys infected with Schistosoma japonicum or Schistosoma mansoni.

Cell-mediated immune responses, assessed by lymphocyte clonal expansion in vitro, as well as humoral responses, assessed by an enzyme-linked immunosorbent assay (ELISA), were evaluated in capuchin monkeys during a 7-month infection with Schistosoma mansoni or with a Japanese or Philippine strain of Schistosoma japonicum. Although mounting a vigorous antibody response against parasite antigens, the S. mansoni-infected monkeys failed to show lymphocyte proliferation in response to stimulation with soluble adult worm antigen or soluble egg antigen derived from S. mansoni. Monkeys infected with S. japonicum responded to parasite antigens obtained from S. japonicum both by antibody production and lymphocyte blastogenesis. Monkeys infected with S. japonicum (Japanese strain) never developed detectable levels of circulating immune complexes (CIC). On the other hand high levels of CIC appeared at 7 months of infection in the monkeys infected with S. mansoni. The CIC levels exhibited negative correlations with intensity of infection. In studies of antigen species specificity, sera from S. mansoni-infected monkeys showed much higher IgG antibody titers to antigens derived from S. mansoni than to S. japonicum-derived antigens. On the other hand, monkeys infected with S. japonicum had comparable IgG antibody titers to antigens of both schistosome species.

Serum levels of bothropic venom in patients without antivenom intervention.

Serum kinetics of bothropic venom were evaluated in eight snakebite patients, who due to a national shortage, received no specific antivenom therapy. The cases were clinically classified as mild, moderate, and severe. Patients were bled sequentially and serum levels of venom were assayed by ELISA. Venom level ranges differed among the groups, with peak levels of less than 13 ng/ml, 32 ng/ml, and 120 ng/ml for the mild, moderate, and severe groups, respectively. There was no clear pattern of kinetics in the groups. Regression analysis involving the variables severity and peak venom levels yielded a statistically significant correlation (rs = 0.80, P less than 0.05). These data indicate that different amounts of circulating venom correlate with clinical severity, even in highly complex venoms, and stress the importance of careful clinical classification in the proper management of bothropic incidents.

Enhancement of the autologous mixed lymphocyte reaction in patients with Chagas' heart disease.

Autologous mixed lymphocyte reactions (AMLR) were studied in 18 individuals chronically infected with Trypanosoma cruzi. These individuals were further classified into three clinical groups: the asymptomatic indeterminate form (n = 5); the mega disease form (n = 5); and the cardiomyopathy form (n = 8). While patients with mega disease showed a normal proliferative response when compared with normal controls, the indeterminate group showed a lowered response in sharp contrast with the heart disease group, which presented a very high proliferative response to autologous non-T cells. These abnormal AMLR represent direct evidence for an immunoregulatory malfunction which may be involved in the inflammatory cardiac damage in chronic Chagas' disease.

Isolation of Leishmania mexicana amazonensis from the bone marrow in a case of American visceral leishmaniasis.

The first documented human case of visceral leishmaniasis caused by L. mexicana amazonensis is reported. Leishmania were isolated from bone marrow aspirate material from a typical visceral leishmaniasis patient. Further characterization by isoenzyme electrophoresis and by a panel of species- and subspecies-specific monoclonal antibodies established its classification as L. m. amazonensis.

Lymphadenopathy as the first sign of human cutaneous infection by Leishmania braziliensis.

This paper describes the presence of transitory lymphadenopathy as an initial sign of cutaneous leishmaniasis, and sometimes the only manifestation of Leishmania braziliensis infection. Ten patients with lymphadenopathy living in an area of L. braziliensis transmission had Leishmania cultivated from their lymph nodes previous to any other manifestation of cutaneous leishmaniasis. Seven of the 10 developed leishmanial ulcers later in the course of infection, whereas lymphadenopathy regressed in three cases and no other sign of infection developed. Results of tests for anti-Leishmania antibodies and an intradermal skin test were positive in four and five patients, respectively, at the time of the diagnosis. The documentation of Leishmania amastigotes in the lymph nodes before any clinical evidence of cutaneous disease indicates that early spread of L. braziliensis from the skin to lymph nodes occurs before a local lesion develops. All medical doctors examining patients coming from endemic areas of leishmaniasis should be aware that lymph node enlargement, even in the absence of a typical ulceration, may be indicative of leishmanial infection and warrants further investigation.

Human immune response to sand fly salivary gland antigens: a useful epidemiological marker?

Antibody (IgG) responses to salivary gland homogenate and to a recombinant salivary protein from the sand fly Lutzomyia longipalpis were investigated using sera from children living in an endemic area of visceral leishmaniasis in Brazil. We classified children into four groups according to their responses to Leishmania antigen: (Group I) positive serology and positive delayed type hypersensitivity (DTH), (Group II) positive serology and negative DTH, (Group III) negative serology and positive DTH, and (Group IV) negative serology and negative DTH. A highly significant correlation was found between anti-salivary gland IgG levels and DTH responses. An L. longipalpis salivary recombinant protein used as an antigen in an enzyme-linked immuno sorbent assay (ELISA) gave a significant but different result. A positive correlation was found between anti-Leishmania IgG and anti-recombinant protein IgG titers. The results indicate that sand fly salivary proteins may be of relevance to the study the epidemiology of leishmaniasis.

Lymphadenopathy associated with Leishmania braziliensis cutaneous infection.

Lymph node involvement by Leishmania during human cutaneous leishmaniasis was reported more than 90 years ago, but the importance of certain Leishmania strains in such dissemination remains largely speculative. We have examined 36 consecutively untreated cutaneous leishmaniasis patients early in their disease; 66.7% had enlarged lymph nodes. Patients with enlarged lymph nodes had higher anti-Leishmania immune responses than patients without such involvement, both at the IgG antibody level (mean +/- SD optical density at 492 nm = 0.163 +/- 0.089 versus 0.098 +/- 0.086; P = 0.009) and in skin test responses (12.4 +/- 10.2 mm versus 5.7 +/- 7.3; P = 0.03). Thirteen (62%) of 21 lymph node cultures and 16 (53%) of 30 cultures from cutaneous sites were positive for Leishmania. Eleven of 13 isolates from lymph nodes were characterized by a panel of monoclonal antibodies, and all were typed as L. braziliensis. Our findings stress the importance of L. braziliensis as an agent involved in the early invasion of the lymphatic system.