Leishmania (L.) infantum chagasi isolated from skin lesions of patients affected by non-ulcerated cutaneous leishmaniasis lead to visceral lesion in hamsters

In Central America, Leishmania (L.) infantum chagasi infection causes visceral leishmaniasis (VL) and non-ulcerated cutaneous leishmaniasis (NUCL). The aim of the present study was to evaluate the course of an experimental infection in hamsters caused by L. (L.) infantum chagasi isolated from patients affected by NUCL compared with a strain isolated from a patient with VL. Stationary phase parasites in culture were inoculated through subcutaneous and intraperitoneal routes in hamsters. Following the post-infection times, a histopathological study, parasite load and cytokine determination in skin from the cutaneous inoculation site and viscera were performed. Animals subcutaneously infected with the different strains did not develop macroscopic lesions at the inoculation site, and the histopathological changes in the dermis were very slight. Regarding the histopathological study of the viscera, we observed the portal mononuclear inflammatory infiltrate, the presence of nodules in the hepatic parenchyma and the proliferation of macrophages in the spleen, which increased over the infection course. Overall, the parasite load in the liver and spleen and in the total IgG titres in the sera of infected hamster showed an increase with the time of infection, regardless of the route of inoculation. Regarding cellular immunity, we did not observe an increase or decrease in pro- and anti-inflammatory cytokines compared to the healthy control, except for IL-10, which was evident in the infected animals. The data showed that strains isolated from NUCL cause visceral lesions in the hamsters regardless of the route of inoculation, and they were similar to parasites isolated from VL humans.

Role of antigen-presenting cells in non-ulcerated skin lesions caused by Leishmania (Leishmania) infantum chagasi

In Central America, infection by Leishmania (Leishmania) infantum chagasi causes visceral leishmaniasis and non-ulcerated cutaneous leishmaniasis (NUCL). This work aimed to evaluate the participation of subpopulations of antigen-presenting cells in skin lesions of patients affected by NUCL through double-staining immunohistochemistry using cellular and intracellular markers. Twenty-three skin biopsies from patients affected by NUCL were used. Histological sections stained by HE were used for histopathological study. Immunohistochemical studies were performed using primary antibodies against Langerhans cells, dermal dendritic cells, T lymphocytes, and the cytokines IL-12, IFN-γ, TNF-α, iNOS, and IL-10. The histopathological lesions were characterized by an inflammatory infiltrate, predominantly lymphohistiocytic, of variable intensity, with a diffuse arrangement associated with epithelioid granulomas and discreet parasitism. Double-staining immunohistochemistry showed higher participation of dendritic cells producing the proinflammatory cytokine IL-12 in relation to the other evaluated cytokines. Activation of the cellular immune response was marked by a higher density of CD8 Tc1-lymphocytes followed by CD4 Th1-lymphocytes producing mainly IFN-γ. The data obtained in the present study suggest that antigen-presenting cells play an important role in the in situ immune response through the production of proinflammatory cytokines, directing the cellular immune response preferentially to the Th1 and Tc1 types in NUCL caused by L. (L.) infantum chagasi.

Lipophosphoglycans from dermotropic Leishmania infantum are more pro-inflammatory than those from viscerotropic strains

Although Leishmania infantum is well-known as the aethiological agent of visceral leishmaniasis (VL), in some Central American countries it may cause atypical non-ulcerated cutaneous leishmaniasis (NUCL). However, the mechanisms favoring its establishment in the skin are still unknown. Lipophosphoglycan (LPG) is the major Leishmania multivirulence factor involved in parasite-host interaction. In the case of viscerotropic L. infantum, it causes an immunosuppression during the interaction with macrophages. Here, we investigated the biochemical and functional roles of LPGs from four dermotropic L. infantum strains from Honduras during in vitro interaction with murine macrophages. LPGs were extracted, purified and their repeat units analysed. They did not have side chains consisting of Gal(β1,4)Man(α1)-PO₄ common to all LPGs. Peritoneal macrophages from BALB/c and C57BL/6 were exposed to LPG for nitric oxide (NO) and cytokine (TNF-α and, IL-6) production. LPGs from dermotropic strains from Honduras triggered higher NO and cytokine levels compared to those from viscerotropic strains. In conclusion, LPGs from dermotropic strains are devoid of side-chains and exhibit high pro-inflammatory activity.

Glucose-6-phosphate dehydrogenase deficiency among malaria patients of Honduras: a descriptive study of archival blood samples

BACKGROUND

The frequency of deficient variants of glucose-6-phosphate dehydrogenase (G6PDd) is particularly high in areas where malaria is endemic. The administration of antirelapse drugs, such as primaquine, has the potential to trigger an oxidative event in G6PD-deficient individuals. According to Honduras´ national scheme, malaria treatment requires the administration of chloroquine and primaquine for both Plasmodium vivax and Plasmodium falciparum infections. The present study aimed at investigating for the first time in Honduras the frequency of the two most common G6PDd variants.

METHODS

This was a descriptive study utilizing 398 archival DNA samples of patients that had been diagnosed with malaria due to P. vivax, P. falciparum, or both. The most common allelic variants of G6PD: G6PD A+(376G) and G6PD A-(376G/202A) were assessed by two molecular methods (PCR-RFLP and a commercial kit).

RESULTS

The overall frequency of G6PD deficient genotypes was 16.08%. The frequency of the "African" genotype A- (Class III) was 11.9% (4.1% A- hemizygous males; 1.5% homozygous A- females; and 6.3% heterozygous A- females). A high frequency of G6PDd alleles was observed in samples from malaria patients residing in endemic regions of Northern Honduras. One case of Santamaria mutation (376G/542T) was detected.

CONCLUSIONS

Compared to other studies in the Americas, as well as to data from predictive models, the present study identified a higher-than expected frequency of genotype A- in Honduras. Considering that the national standard of malaria treatment in the country includes primaquine, further research is necessary to ascertain the risk of PQ-triggered haemolytic reactions in sectors of the population more likely to carry G6PD mutations. Additionally, consideration should be given to utilizing point of care technologies to detect this genetic disorder prior administration of 8-aminoquinoline drugs, either primaquine or any new drug available in the near future.