Susceptibility of dendritic cells from individuals with schistosomiasis to infection by Leishmania braziliensis

Co-endemicity of schistosomiasis and tegumentary leishmaniasis: Spatial co-clustering in endemic areas

OBJECTIVES

Schistosomiasis and tegumentary leishmaniasis simultaneously affect areas in tropical and subtropical regions. Co-infected individuals show a less-than-optimal response to treatment and increased regulatory immune responses. However, no study has determined where Schistosoma-Leishmania co-infections are more likely to occur.

METHODS

Data from The Global Health Observatory were collected to determine the worldwide endemicity status of schistosomiasis and tegumentary leishmaniasis in 2023. To determine co-endemic areas at a local level, an ecological study was conducted on confirmed cases of American tegumentary leishmaniasis and schistosomiasis in the State of Minas Gerais, Brazil, between 2013 and 2017. Local Indicators of Spatial Association analyses were used to search for co-endemic hotspots.

RESULTS

Thirty-one countries were considered co-endemic, 23 of which presented active transmission of both diseases. Univariate Local Indicators of Spatial Association indicated 13 municipalities as high-high clusters for both American tegumentary leishmaniasis and schistosomiasis in Minas Gerais. Furthermore, bivariate Local Indicators of Spatial Association analyses identified 61 municipalities as high-high clusters, grouped in seven co-endemic hotspots.

CONCLUSION

Local Indicators of Spatial Association analyses are a useful tool for identifying areas where co-infection cases are more likely to occur. Similar analyses will assist authorities and healthcare providers when formulating policies and treating Schistosoma-Leishmania co-infected patients and will provide valuable data to enable researchers to explore the impact of this and other co-infections.

Schistosoma and Leishmania: An Untold Story of Coinfection

A remarkable characteristic of infectious diseases classified as Neglected Tropical Diseases (NTDs) is the fact that they are mostly transmitted in tropical and subtropical regions with poor conditions of sanitation and low access to healthcare, which makes transmission areas more likely to overlap. Two of the most important NTDs, schistosomiasis and leishmaniasis, despite being caused by very different etiological agents, have their pathogenesis heavily associated with immune-mediated mechanisms, and Schistosoma spp. and Leishmania spp. have been shown to simultaneously infect humans. Still, the consequences of Schistosoma-Leishmania coinfections remain underexplored. As the inflammatory processes elicited by each one of these parasites can influence the other, several changes have been observed due to this coinfection in naturally infected humans, experimental models, and in vitro cell assays, including modifications in susceptibility to infection, pathogenesis, prognostic, and response to treatment. Herein, we review the current knowledge in Schistosoma-Leishmania coinfections in both human populations and experimental models, with special regard to how schistosomiasis affects tegumentary leishmaniasis, discuss future perspectives, and suggest a few steps to further improve our understanding in this model of parasite-host-parasite interaction.

Pulmonary inflammation promoted by type-2 dendritic cells is a feature of human and murine schistosomiasis

Schistosomiasis is a parasitic disease affecting over 200 million people in multiple organs, including the lungs. Despite this, there is little understanding of pulmonary immune responses during schistosomiasis. Here, we show type-2 dominated lung immune responses in both patent (egg producing) and pre-patent (larval lung migration) murine Schistosoma mansoni (S. mansoni) infection. Human pre-patent S. mansoni infection pulmonary (sputum) samples revealed a mixed type-1/type-2 inflammatory cytokine profile, whilst a case-control study showed no significant pulmonary cytokine changes in endemic patent infection. However, schistosomiasis induced expansion of pulmonary type-2 conventional dendritic cells (cDC2s) in human and murine hosts, at both infection stages. Further, cDC2s were required for type-2 pulmonary inflammation in murine pre-patent or patent infection. These data elevate our fundamental understanding of pulmonary immune responses during schistosomiasis, which may be important for future vaccine design, as well as for understanding links between schistosomiasis and other lung diseases.

Combined chemotherapy manifest less severe immunopathology effects in helminth-protozoa comorbidity

BACKGROUND

Co-infection with Leishmania major and Schistosoma mansoni may have significant consequences for disease progression, severity and subsequent transmission dynamics. Pentavalent antimonials and Praziquantel (PZQ) are used as first line of treatment for Leishmania and Schistosoma infections respectively. However, there is limited insight on how combined therapy with the standard drugs impacts the host in comorbidity. The study aimed to determine the efficacy of combined chemotherapy using Pentostam (P) and PZQ in murine model co-infected with L. major and S. mansoni.

METHODS

A 3 × 4 factorial design with three parasite infection groups (Lm, Sm, Lm + Sm to represent L. major, S. mansoni and L. major + S. mansoni respectively) and four treatment regimens [P, PZQ, P + PZQ, and PBS designating Pentostam (GlaxoSmithKline UK), Praziquantel (Biltricide^®, Bayer Ag. Leverkusen, Germany), Pentostam + Praziquantel and Phosphate buffered saline] as factors was applied.

RESULTS

Significant changes were observed in the serum Interferon gamma (IFN-γ), and Macrophage inflammatory protein-one alpha (MIP-1α) levels among various treatment groups between week 8 and week 10 (p < 0.05). There was increased IFN-γ in the L. major infected mice subjected to PZQ and PBS, and in L. major + S. mansoni infected BALB/c mice treated with P + PZQ. Subsequently, MIP-1α levels increased significantly in both the L. major infected mice under PZQ and PBS and in L. major + S. mansoni infected BALB/c mice undergoing concurrent chemotherapy with P + PZQ between 8 and 10 weeks (p < 0.05). In the comorbidity, simultaneous chemotherapy resulted in less severe histopathological effects in the liver.

CONCLUSION

It was evident, combined first line of treatment is a more effective strategy in managing co-infection of L. major and S. mansoni. The findings denote simultaneous chemotherapy compliments immunomodulation in the helminth-protozoa comorbidity hence, less severe pathological effects following the parasites infection. Recent cases of increased incidences of polyparasitism in vertebrates call for better ways to manage co-infections. The findings presented necessitate intrinsic biological interest on examining optimal combined chemotherapeutic agents strategies in helminth-protozoa concomitance and the related infections abatement trends vis-a-vis host-parasite relationships.

Cutaneous schistosomiasis and leishmaniasis coinfection: a case report

BACKGROUND

The polymorphic clinical presentations of schistosomiasis and leishmaniasis allow their inclusion in the differential diagnoses of several conditions. Although an overlap in distribution of these diseases has been reported in endemic areas, coinfection with cutaneous schistosomiasis and cutaneous leishmaniasis in the same patient is rare.

OBJECTIVES

We report an unusual case of concomitant cutaneous schistosomiasis and cutaneous leishmaniasis. Actions for the management and diagnosis were proposed.

METHODS

A patient presented with cutaneous lesions on the abdomen and left elbow. The presence of degenerated ova of Schistosoma mansoni in the skin biopsy led to perform a complementary investigation with immunohistochemical techniques, rectal biopsy and abdominal ultrasonography. After the left elbow lesions had failed to improve after several weeks of standard treatment, a new biopsy was performed and led to diagnosis of another infection.

RESULTS

The patient lived in an endemic area for two infectious diseases (schistosomiasis and leishmaniasis). Biopsies revealed chronic granulomatous dermatitis. Degenerated S. mansoni eggs were found in the abdominal lesion and in a rectal biopsy specimen. Ultrasonography revealed hepatic involvement. Despite combination treatment with oxamniquine and praziquantel, a cutaneous lesion persisted on the left elbow; a new biopsy revealed amastigote forms of Leishmania. The patient was successfully treated with intramuscular and intralesional meglumine antimoniate.

CONCLUSIONS

The presence of a similar granulomatous infiltrate in lesions caused by the two different infectious agents led to a delay in the diagnosis of cutaneous leishmaniasis. This report serves as a warning of the unusual possibility of cutaneous schistosomiasis and leishmaniasis coinfection in an endemic area.

The role of heparan sulfate in host macrophage infection by Leishmania species

The leishmaniases are a group of neglected tropical diseases caused by parasites from the Leishmania genus. More than 20 Leishmania species are responsible for human disease, causing a broad spectrum of symptoms ranging from cutaneous lesions to a fatal visceral infection. There is no single safe and effective approach to treat these diseases and resistance to current anti-leishmanial drugs is emerging. New drug targets need to be identified and validated to generate novel treatments. Host heparan sulfates (HSs) are abundant, heterogeneous polysaccharides displayed on proteoglycans that bind various ligands, including cell surface proteins expressed on Leishmania promastigote and amastigote parasites. The fine chemical structure of HS is formed by a plethora of specific enzymes during biosynthesis, with various positions (N-, 2-O-, 6-O- and 3-O-) on the carbon sugar backbone modified with sulfate groups. Post-biosynthesis mechanisms can further modify the sulfation pattern or size of the polysaccharide, altering ligand affinity to moderate biological functions. Chemically modified heparins used to mimic the heterogeneous nature of HS influence the affinity of different Leishmania species, demonstrating the importance of specific HS chemical sequences in parasite interaction. However, the endogenous structures of host HSs that might interact with Leishmania parasites during host invasion have not been elucidated, nor has the role of HSs in host-parasite biology. Decoding the structure of HSs on target host cells will increase understanding of HS/parasite interactions in leishmaniasis, potentiating identification of new opportunities for the development of novel treatments.