Exposure to mixed asymptomatic infections with Trypanosoma cruzi, Leishmania braziliensis and Leishmania chagasi in the human population of the greater Amazon

Lack of conservation of the Amazon tropical rainforest has imposed severe threats to its human population living in newly settled villages, resulting in outbreaks of some infectious diseases. We conducted a seroepidemiological survey of 1100 inhabitants of 15 villages of Paço do Lumiar County, Brazil. Thirty‐five (3%) individuals had been exposed to Trypanosoma cruzi (Tc), 41 (4%) to Leishmania braziliensis (Lb) and 50 (4.5%) to Leishmania chagasi (Lc) infections. Also, 35 cases had antibodies that were cross‐reactive against the heterologous kinetoplastid antigens. Amongst these, the Western blot assays revealed that 11 (1%) had Tc and Lb, that seven (0.6%) had Lc and Tc, and that 17 (1.6%) had Lb and Lc infections. All of these cases of exposures to mixed infections with Leishmania sp, and eight of 11 cases of Tc and Lb were confirmed by specific PCR assays and Southern hybridizations. Two cases had triple infections. We consider these asymptomatic cases showing phenotype and genotype markers consistent with mixed infections by two or more kinetoplastid flagellates a high risk factor for association with Psychodidae and Triatominae vectors blood feeding and transmitting these protozoa infections. This is the first publication showing human exposure to mixed asymptomatic kinetoplastid infections in the Amazon.     

GENOTYPE CHARACTERIZATION OF Leishmania (Viannia) braziliensis ISOLATED FROM HUMAN AND CANINE BIOPSIES WITH AMERICAN CUTANEOUS LEISHMANIASIS

Introduction:

American tegumentary leishmaniasis (ATL) can be caused by Leishmania (Viannia) braziliensis complex. The evolution of ATL initially results in lesions and can develop into disseminated or diffuse forms. The genetic diversity of L. (V.) braziliensis in some endemic areas of Brazil has been poorly studied, such as in the state of São Paulo. This study analyzed the genetic diversity of L. (V.) braziliensis isolates collected from patients and dogs with LTA from the state of São Paulo.

Methods:

Leishmaniasis diagnosis was determined by PCR. The 132 biopsies were collected in different regions of Sao Paulo State, Brazil (36 municipalities). The genetic characterization of L. (V.) braziliensis isolates was tested by RFLP-PCR using DNA extracted from biopsies. The primer set amplified a specific region of Leishmania internal transcribed spacers of the ribosomal DNA locus.

Results:

Of the 132 samples, 52 (40%) were completely genotyped by RFLP-PCR (44 from human patients and eight from dogs). The results showed nine distinct patterns. The majority of the genotyped samples were from Sorocaba (30), and the others were distributed among 14 other municipalities. The first pattern was more frequent (29 samples), followed by pattern 2 (nine samples) and pattern 3 (three samples). Patterns 4, 6, 7, 8 and 9 were composed of two samples each and pattern 5 of one sample.

Conclusion:

These results suggest that polymorphic strains of L. (V.) braziliensis circulate in the state of São Paulo. These data agree with studies from other regions of Brazil, showing great variability among the natural populations of endemic foci.     

Clinical value of anti-live Leishmania (Viannia) braziliensis immunoglobulin G subclasses, detected by flow cytometry, for diagnosing active localized cutaneous leishmaniasis

OBJECTIVE: To evaluate the clinical value of flow cytometry anti-live promastigate antibody (FC-ALPA), for diagnosing active cutaneous leishmaniasis. METHOD: Serum samples from 145 individuals living in endemic areas for localized cutaneous leishmaniasis (population 1) were classified as having the disease or not and then tested for their IgG reactivity by indirect immunofluorescence assay and FC-ALPA-IgG. The results of FC-ALPA-IgG were expressed as percentage of positive fluorescent parasite. Both tests were also evaluated in serum samples of people with visceral leishmaniasis and Chagas disease (population 1A). RESULTS: In population 1, FC-ALPA-IgG performed better than the immunofluorescence assay regarding sensitivity, specificity and predictive values. Analysis of the results according to the likelihood ratios indicated that a percentage of positive fluorescent parasite 60% it reinforces diagnosis of the disease (likelihood ratio = 7.0). Immunofluorescent assay is of little value (likelihood ratio=2.04). In population 1A, both tests performed worse, but FC-ALPA-IgG achieved better statistical indexes than immunofluorescent assay. CONCLUSION: The FC-ALPA-IgG is a valuable method for serological diagnosis of localized cutaneous leishmaniasis. FC-ALPA-IgG1/ALPA-IgG2 combined analysis is an additional serological tool for discriminating localized visceral leishmaniasis, Chagas disease and visceral leishmaniasis in areas where these infections co-exist.     

Endemically exposed asymptomatic individuals show no increase in the specific Leishmania (Viannia) panamensis-Th1 immune response in comparison to patients with localized cutaneous leishmaniasis

In Colombia, most cases of human cutaneous leishmaniasis are caused by Leishmania (Viannia) panamensis. Interestingly, up to 30% of the exposed population do not suffer from clinical leishmaniasis although it is likely that they are continuously infected with Leishmania parasites. Since it is believed that the induction of efficient Th1 immune responses protects against Leishmania infections both in humans and in animal models, we determined if endemically exposed asymptomatics showed stronger Leishmania-specific Th1 immune responses than patients with active localized cutaneous leishmaniasis (LCL). We found that Montenegro skin test responses were slightly higher among asymptomatic individuals compared to patients suffering from LCL. However, PBMC from patients with LCL showed similar Leishmania-specific proliferative responses compared to PBMC from asymptomatic individuals. Furthermore, PBMC from both groups also secreted similar amounts of IFN-gamma, IL-12p40 and IL-10 after in vitro exposure to L. panamensis. No IL-4 was detected in the supernatants. Taken together our results suggest that lack of LCL development in endemically exposed asymptomatics cannot be explained by stronger systemic anti-Leishmania Th1 immune responses or decreased Th2 responses in these individuals in comparison to individuals who develop LCL. It may be possible that other mechanisms are responsible for resistance to cutaneous leishmaniasis in Colombia in endemically exposed asymptomatics.     

Immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis in American cutaneous leishmaniasis

The immunopathogenic competences of Leishmania (V.) braziliensis and L. (L.) amazonensis were reviewed in the light of more recent features found in the clinical and immunopathological spectrum of American cutaneous leishmaniasis. It was shown a dichotomy in the interaction between these Leishmania species and human T-cell immune response; while L. (V.) braziliensis shows a clear tendency to lead infection from the localized cutaneous leishmaniasis (LCL), a moderate T-cell hypersensitivity form at the centre of the spectrum, toward to the mucocutaneous leishmaniasis (MCL) at the T-cell hypersensitivity pole and with a prominent Th1-type immune response, L. (L.) amazonensis shows an opposite tendency, leading infection to the anergic diffuse cutaneous leishmaniasis (ADCL) at the T-cell hyposensitivity pole and with a marked Th2-type immune response. Between the central LCL and the two polar MCL and ADCL, the infection can present an intermediary form known as borderline disseminated cutaneous leishmaniasis, characterized by an incomplete inhibition of T-cell hypersensitivity but with a evident supremacy of Th1 over Th2 immune response (Th1 ≥ Th2). These are probably the main immunopathogenic competences of L. (V.) braziliensis and L. (L.) amazonensis regarding the immune response dichotomy that modulates human infection outcome by these Leishmania parasites.     

AIM2 inflammasome is associated with disease severity in tegumentary leishmaniasis caused by Leishmania (V.) braziliensis

The inflammasome is a multiprotein signalling platform involved in the pathogenesis of various inflammatory skin diseases. Herein, we investigated gene and protein expression of the inflammasome molecules AIM2 and NLRP3 in active lesions from patients with L. (V.) braziliensis‐associated tegumentary leishmaniasis (TL) and correlated these findings with the clinical presentations and responses to therapy. Real‐time PCR assays showed a significantly higher AIM2 gene expression in mucosal leishmaniasis (ML) compared with that in cutaneous leishmaniasis (CL). Additionally, AIM2 mRNA expression was significantly higher in lesions from poor responders than in lesions from good responders. In situ protein quantification analyses revealed greater AIM2 expression in ML lesions than in CL lesions. The percentage of AIM2‐producing cells was higher in poor responders than in good responders. Although not quite significant, IL‐1β+ cells were slightly more prominent in poor responders than in good responders. Similar results were observed when patients were evaluated according to clinical form. GP63 immunostaining was identified in all samples, but no significant variation between mucosal and cutaneous lesions was observed. GP63 could be associated with reduced NLRP3 inflammasome expression in CL and ML patients. Taken together, these data demonstrate that AIM2 is an important component of the inflammasome in TL patients and is directly associated with the severity of lesions.     

Species diversity of Leishmania (Viannia) parasites circulating in an endemic area for cutaneous leishmaniasis located in the Atlantic rainforest region of northeastern Brazil

Objectives  To identify the aetiological agents of cutaneous leishmaniasis and to investigate the genetic polymorphism of Leishmania (Viannia) parasites circulating in an area with endemic cutaneous leishmaniasis (CL) in the Atlantic rainforest region of northeastern Brazil.
Methods  Leishmania spp. isolates came from three sources: (i) patients diagnosed clinically and parasitologically with CL based on primary lesions, secondary lesions, clinical recidiva, mucocutaneous leishmaniasis and scars; (ii) sentinel hamsters, sylvatic or synanthropic small rodents; and (iii) the sand fly species Lutzomyia whitmani . Isolates were characterised using monoclonal antibodies, multilocus enzyme electrophoresis (MLEE) and polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer region rDNA locus.
Results  Seventy-seven isolates were obtained and characterised. All isolates were identified as Leishmania (Viannia) braziliensis serodeme 1 based on reactivity to monoclonal antibodies. MLEE identified 10 zymodemes circulating in the study region. Most isolates were classified as zymodemes closely related to L. (V.) braziliensis, but five isolates were classified as Leishmania (Viannia) shawi . All but three of the identified zymodemes have so far been observed only in the study region. Enzootic transmission and multiclonal infection were observed.
Conclusions  Our results confirm that transmission cycle complexity and the co-existence of two or more species in the same area can affect the level of genetic polymorphism in a natural Leishmania population. Although it is not possible to make inferences as to the modes of genetic exchange, one can speculate that some of the zymodemes specific to the region are hybrids of L. (V.) braziliensis and L. (V.) shawi .     

Cellular localization and expression of gp63 homologous metalloproteases in Leishmania (Viannia) braziliensis strains

Leishmania (Viannia) braziliensis is the major causative agent of American tegumentary leishmaniasis, a disease that encompasses a broad spectrum of clinical manifestations. In a previous study, we showed that Brazilian and Colombian L. braziliensis strains, isolated from patients with distinct clinical manifestations, display different pattern of metalloprotease activities. Following these results, we investigated the cellular localization of these molecules and their relation to the major surface protease (gp63) of Leishmania. Comparative analyses of metalloprotease expression among different clinical isolates as well as an evaluation of the effect of long-term in vitro passage on the expression pattern of these metalloproteases were also performed. Western blot analysis, using an anti-gp63 antibody, revealed polypeptide patterns with a similar profile to that observed in zymographic analysis. Flow cytometry and fluorescence microscopy analyses corroborated the presence of metalloproteases with homologous domains to gp63 in the parasites and revealed differences in the expression level of such molecules among the isolates. The cellular distribution of metalloproteases, assessed by confocal analysis, showed the existence of intracellular metalloproteases with homologous domains to gp63, predominantly located near the flagellar pocket. Finally, it was observed that differential zymographic profiles of metalloproteases exhibited by L. (V.) braziliensis isolates remain unaltered during prolonged in vitro culture, suggesting that the proteolytic activity pattern is a stable phenotypic characteristic of these parasites.     

Leishmania braziliensis amastigotes stimulate production of IL‐1β, IL‐6, IL‐10 and TGF‐β by peripheral blood mononuclear cells from nonendemic area healthy residents

Leishmania (Viannia) braziliensis causes cutaneous and mucosal leishmaniasis in several countries in Latin America. In mammals, the parasites live as amastigotes, interacting with host immune cells and stimulating cytokine production that will drive the type of the specific immune responses. Generation of Th17 lymphocytes is associated with tissue destruction and depends on IL‐1β, IL‐6, TGF‐β and IL‐23 production, whereas IL‐10 and TGF‐β are associated with tissue protection. Here, we evaluate whether amastigotes stimulate peripheral blood mononuclear cells (PBMCs) from healthy donors to produce the major cytokines responsible for the generation of Th17. Seven L. (V.) braziliensis isolates from patients with different clinical forms of leishmaniasis were expanded in interferon‐γ knockout mice to obtain amastigotes and in culture to get promastigotes. The parasites were used to stimulate PBMCs from healthy donors, and cytokine production was evaluated by ELISA or qPCR. Amastigotes and promastigotes induced IL‐10 production in PBMCs; however, only amastigotes induced IL‐1β, IL‐6 and TGF‐β. These data demonstrate for the first time that L. (V.) braziliensis amastigotes directly stimulate production of a unique pattern of cytokines that could contribute to the generation of Th17.     

Case Report: Simultaneous Infection with Leishmania (Viannia) braziliensis and L. (V.) lainsoni in a Peruvian Patient with Cutaneous Leishmaniasis

Conventional understanding suggests that simultaneous infection with more than one species of Leishmania is unlikely. In Peru, co-infections are clinically relevant because causative species dictates prognosis, treatment response, and follow-up. We describe a case of Leishmania (Viannia) braziliensis and L. (V.) lainsoni co-infection in a Peruvian patient with cutaneous leishmaniasis.     

In vivo and in vitro phagocytosis of Leishmania (Leishmania) amazonensis promastigotes by B‐1 cells

Leishmaniasis is caused by Leishmania parasites that infect several cell types. The promastigote stage of Leishmania is internalized by phagocytic cells and transformed into the obligate intracellular amastigote form. B‐1 cells are a subpopulation of B cells that are able to differentiate in vitro and in vivo into mononuclear phagocyte‐like cells with phagocytic properties. B‐1 cells use several receptors for phagocytosis, such as the mannose receptor and third complement receptor. Leishmania binds to the same receptors on macrophages. In this study, we demonstrated that phagocytes derived from B‐1 cells (B‐1 CDP) were able to internalize promastigotes of L. (L.) amazonensis in vitro. The internalized promastigotes differentiated into amastigotes. Our results showed that the phagocytic index was higher in B‐1 CDP compared to peritoneal macrophages and bone marrow‐derived macrophages. The in vivo phagocytic ability of B‐1 cells was also demonstrated. Parasites were detected inside purified B‐1 cells after intraperitoneal infection with L. (L.) amazonensis promastigotes. Intraperitoneal stimulation with the parasites led to an increase in both IL‐10 and TNF‐α. These results highlight the importance of studying B‐1 CDP cells as phagocytic cells that can participate and contribute to immunity to parasites.     

Decrease in anti-Leishmania IgG3 and IgG1 after cutaneous leishmaniasis lesion healing is correlated with the time of clinical cure

For better efficiency in the establishment of American tegumentary leishmaniasis clinical cure, the World Health Organization suggests that the clinical criteria are supported by serologic data. The present study aims to investigate the dynamics of IgG subclass production in clinical evolution post‐treatment of cutaneous leishmaniasis (CL). Paired sera from 23 subjects with CL resulting from Leishmania braziliensis infection were studied during the active lesion phase (aCL) and after clinical cure post‐therapy (hCL), which included an alternative protocol with a low dose of antimony. Anti‐Leishmania IgG and its subclasses were measured using ELISA, and the immunoglobulin levels were correlated with patients’ clinical data. All of the subjects were clinically healed and did not present relapse during follow‐up. Serum levels of anti‐Leishmania IgG (r = ?0·79; P < 0·0001), IgG1 (r = ?0·64, P < 0·001) and IgG3 (r = ?0·42, P < 0·045) in hCL were negatively correlated with the duration of clinical cure. After 24 months of clinical cure, 73% of samples were negative for IgG1 and 78% were negative for IgG3. In conclusion, the detection of serum anti‐Leishmania IgG1 and IgG3 is an improved laboratory strategy to aid in the decision of interruption of the ambulatory follow‐up of CL patients.     

Comparison of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis and L. (V.) guyanensis in Brazil: clinical findings and diagnostic approach.

We compared the clinical findings and diagnostic methods for 66 patients with cutaneous leishmaniasis in the state of Bahia, Brazil, who were infected by Leishmania (Viannia) braziliensis (group A), with those for 68 patients in the state of Amazonas, Brazil, who were mainly infected by Leishmania (Viannia) guyanensis (group B). Differences were observed with regard to number, size, and location of skin lesions and to the pattern of lymphatic involvement. Patients in group B had smaller and more numerous lesions, which were frequently located above the waist, versus the larger but less numerous lesions among patients in group A, which were usually located on the lower limbs. Lymphatic involvement was present in 55 (83.3%) of the 66 patients in group A and in 42 (61.8%) of the 68 patients in group B (P=0.005). The positivity rates of imprints and skin culture procedures were higher in group B. Sensitivity of in vitro culture of skin aspirates was 47.0% and 91.2% for groups A and B, respectively (P<.001). Although hamster inoculation showed similar results in both groups, the interval before development of disease was shorter in group B. Our data provide substantial evidence that indicate that the disease caused by these species differs with regard to clinical presentation and diagnostic approach.     

Comparison of cutaneous leishmaniasis due to Leishmania (Viannia) braziliensis and L. (V.) guyanensis in Brazil: therapeutic response to meglumine antimoniate.

We conducted a quasi-experimental study to compare the response to meglumine antimoniate in patients with localized cutaneous leishmaniasis from two endemic areas of Brazil that were infected by two Leishmania species. Sixty-one were infected by Leishmania (Viannia) braziliensis (group B) and 57 by L. (V.) guyanensis (group G). All had a parasitologically proven diagnosis and were treated with 20 mg of pentavalent antimonial (SbV)/kg/day given intravenously or intramuscularly for 20 days. Main outcomes were diagnosed using clinical criteria three months after treatment and patients were followed for six months. Intention-to-treat analysis showed a higher failure rate in group G (relative risk [RR] = 1.5, 95% confidence interval [CI] = 1.1-2.0, chi2 = 7.44, P = 0.006). The analysis using an explanatory approach including 52 patients from group B and 49 from group G, who were regularly treated and followed for six months, showed a low cure rate (50.8% in group B and 26.3% in group G) with a greater risk of failure in the latter group (RR = 1.7, 95% CI = 1.2-2.5, chi2 = 8.56, P = 0.003). The effect of the etiologic agent remained significant after adjusting for age, disease duration, and site and number of lesions that were identified as predictors of failure in a logistic regression model. We concluded that Leishmania species constitute an important factor in predicting the outcome of cutaneous leishmaniasis treated with a pentavalent antimonial.     

Changes in the haemolytic activity of bovine serum complement by Hypoderma lineatum (insect oestridae) larval proteinases in naive and immune cattle

Summary Three serine proteinases (hypodermin A, B and C) of the first instar larvae of Hypoderma lineatum have been assayed for their ability to deplete seric complement of naive or immune cattle. In naive cattle complement consumption is initiated by hypodermin B through the sequence C1-C3 at a concentration of 5 pg/ml of serum, and by hypodermin A through the sequence of C3-C9 at a higher concentration of 150 μg. The third enzyme presenting a collagenolytic activity has no anti-complementary activity even on C1 q. In immune cattle a 70% complement depletion through the classical pathway is observed with 15 μg of hypodermin B per ml of serum. The two enzymes A and C appear to play a minor role in the complement depletion via the classical pathway. The biological role of each of these enzymes in the parasite-host interrelationships is discussed. The participation of these enzymes in the immediate hypersensitive reactions following systemic treatment of cattle infested by this endoparasite is considered.     

Experimental cutaneous leishmaniasis. III. Histopathological aspects of the developmental behavior of the cutaneous lesion induced in Cebus apella (Primates: Cebidae) by Leishmania (Viannia) lainsoni, L. (V.) braziliensis and L. (Leishmania) amazonensis

We have studied the histopathological aspects related to the evolution of cutaneous lesions experimentally produced in the monkey Cebus apella (Primates: Cebidae) by Leishmania (V.) lainsoni, L. (V.) braziliensis and L. (L.) amazonensis. Microscopical examination of a series of biopsies obtained from these animals showed the kinetics of the cutaneous lesions regarding three species of Leishmania inoculated, as follows: 1) an initial non-specific chronic inflammatory infiltrate; 2) macrophagic nodules; 3) necrosis of parasitized phagocytic cells; 4) epitheliode granuloma; 5) absorption of the necrotic area (sometimes forming "foreign-body granuloma"); 6) a non-specific residual inflammatory infiltration; and 7) cicatrization. These pathological processes are, of course, responsible for both development and resolution of the leishmaniotic lesion. We also discuss some immunopathological mechanisms probably related with the sequential events, and that could be also responsible for the different clinical aspects found in man.     

Leishmania (Viannia) braziliensis: comparative pathology of golden hamsters infected with isolates from cutaneous and mucosal lesions of patients residing in Tres Bracos, Bahia, Brazil.

The histopathology of primary forepaw and metastatic lymph node, spleen, and liver lesions produced in golden hamsters infected with cutaneous leishmaniasis (CL) strains (LTB 111 and LTB558) and mucocutaneous leishmaniasis (MCL) strains (LTB12 and LTB201) of Leishmania (Viannia) braziliensis isolated from patients residing in Tres Bracos, Bahia, Brazil is described. No pathological features providing clear differentiation of the CL and MCL strains were found. Although amastigotes were plentiful early in the development of primary forepaw lesions, they were either absent or could not be identified with certainty in sections of late stage lesions. Similarly, amastigotes were not found in histologic lesions at metastatic sites; however, leishmanial DNA was detected in both early and late stage forepaw lesions and metastatic lesions using Leishmania kinetoplast DNA and the gene coding for gp63 as hybridization probes. The DNA recovered from metastatic lesions was extracted from formalin-fixed paraffin-embedded tissues that had been stored at room temperature for prolonged periods.     

The interactions and essential effects of intrinsic insulin‐like growth factor‐I on Leishmania (Leishmania) major growth within macrophages

Previously, we showed in Leishmania infections that extrinsic insulin‐like growth factor (IGF)‐I favored Leishmania proliferation and leishmaniasis development. In this study, the interaction of intrinsically expressed IGF‐I and Leishmania (Leishmania) major in macrophages was addressed, and a key finding was the observation, using confocal microscopy, of the co‐localization of IGF‐I and parasites within macrophages. Following stimulation with interferon‐γ (IFN‐γ), which is known to inhibit IGF‐I production in macrophages, we observed a reduction in the expression of both IGF‐I mRNA and protein. This reduced expression was accompanied by a reduction in the cellular parasite load that was completely recovered with the addition of extrinsic IGF‐I, which suggests an essential role for IGF‐I in Leishmania growth.     

American cutaneous leishmaniasis: In situ immune response of patients with recent and late lesions

TNF‐α, IFN‐γ, IL‐10, IL‐17, CD68 and CD57 were evaluated in biopsies of patients with American cutaneous leishmaniasis living in Sorocaba, Brazil. The analyses were performed considering the time of lesions from 23 patients with recent lesions (Group I) and 19 patients with late lesions (Group II). All patients were infected with Leishmania (Viannia) braziliensis. Immunostaining cells for CD68, CD57, TNF‐ α, IFN‐γ, IL‐10 and IL‐17 were performed by immunohistochemistry. Except for CD68 and IL‐17, the distribution of in situ for CD57, IL‐10, TNF‐α and IFN‐γ showed that patients with recent lesions expressed higher levels than those with late lesions. The comparison of cytokine expression/group showed that IL‐10 was significantly higher than IL‐17 and IFN‐γ (similar data were shown in IL‐17 compared with TNF‐α), suggesting an immunological balance between inflammatory‐anti‐inflammatory agents. This balance was similar for two groups of patients. In conclusion, these data suggested that (i) patients from Group I had recent lesions (in the beginning of chronic phase) compared to those from Group II and (ii) the modulation of inflammatory response in patients with recent American cutaneous leishmaniasis was correlated with IL‐10 expression in skin lesions preventing the development of mucosal forms. The parasite treatment also prevented the evolution of severe forms.