A double-bind and randomized trial to evaluate Miltefosine and topical GM-CSF in the treatment of cutaneous leishmaniasis caused by Leishmania braziliensis in Brazil

Use of topical rSm29 in combination with intravenous meglumine antimoniate in the treatment of cutaneous leishmaniasis: A randomized controlled trial

BACKGROUND

Cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) braziliensis is associated with an inflammatory response. Granzyme (GzmB) and IL-1β play a key role in the pathology. Meglumine antimoniate (MA) is the first-choice drug for the treatment of CL, but therapy failure is observed in up to 50% of the cases. The protein, rSm29 of Schistosoma mansoni, down-modulates pro-inflammatory cytokine production. We evaluate if the combination of topical rSm29 plus MA increases the cure rate of CL.

METHODS

In this randomized clinical trial, 91 CL patients were allocated in 3 groups. All cases received MA (20 mg/kg/weight) for 20 days. Group 1 used topical rSm29 (10 µg), group 2 a placebo topically applied, and group 3 received only MA.

RESULTS

The cure rate on day 90 was 71% in subjects treated with rSm29 plus MA, and 43% in patients who received MA plus placebo or MA alone (P < 0.05). There was a decrease in GzmB and an increase in IFN-γ (P < 0.05) in supernatants of skin biopsies of the lesions obtained on D7 of therapy (P < 0.05) in patients who received rSm29.

CONCLUSION

rSm29 associated with MA reduces GzmB levels, is more effective than MA alone, and decreases CL healing time.

CLINICAL TRIALS REGISTRATION

ClinicalTrial.gov under NCT06000514.

Disseminated Leishmaniasis, a Severe Form of Leishmania braziliensis Infection

Disseminated leishmaniasis (DL) is an emergent severe disease manifesting with multiple lesions. To determine the relationship between immune response and clinical and therapeutic outcomes, we studied 101 DL and 101 cutaneous leishmaniasis (CL) cases and determined cytokines and chemokines in supernatants of mononuclear cells stimulated with leishmania antigen. Patients were treated with meglumine antimoniate (20 mg/kg) for 20 days (CL) or 30 days (DL); 19 DL patients were instead treated with amphotericin B, miltefosine, or miltefosine and meglumine antimoniate. High levels of chemokine ligand 9 were associated with more severe DL. The cure rate for meglumine antimoniate was low for both DL (44%) and CL (60%), but healing time was longer in DL (p = 0.003). The lowest cure rate (22%) was found in DL patients with >100 lesions. However, meglumine antimoniate/miltefosine treatment cured all DL patients who received it; therefore, that combination should be considered as first choice therapy.

Short communication: The miR-155a-5p is correlated with increased ROS and impaired apoptosis in macrophages infected by Leishmania braziliensis

Cutaneous leishmaniasis (CL) caused by Leishmania braziliensis, is a disease characterized by well-limited ulcerated lesions with raised borders in exposed parts of the body. miRNAs are recognized for their role in the complex and plastic interaction between host and pathogens, either as part of the host's strategy to neutralize infection or as a molecular mechanism employed by the pathogen to modulate host inflammatory pathways to remain undetected. The mir155 targets a broad range of inflammatory mediators, following toll-like receptors (TLRs) signaling. In this work, we evaluated the effects of the expression of miR155a-5p in human macrophages infected with L. braziliensis. Our results show that miR155a-5p is inversely correlated with early apoptosis and conversely, seems to influence an increment in the oxidative burst in these cells. Altogether, we spotted a functional role of the miR155a-5p in CL pathogenesis, raising the hypothesis that an increased miR-155 expression by TLR ligands influences cellular mechanisms settled to promote both killing and control of parasite density after infection.

Treatment of cutaneous leishmaniasis with a sequential scheme of pentamidine and tamoxifen in an area with a predominance of Leishmania (Viannia) guyanensis: A randomised, non-inferiority clinical trial

OBJECTIVE

To determine whether a combination of a single intramuscular (IM) dose of pentamidine (7 mg/kg) followed by oral tamoxifen 40 mg/day for 20 days is non-inferior to three IM doses of pentamidine 7 mg/kg in the treatment of cutaneous leishmaniasis with a margin of 15%.

METHODS

Phase II, randomised, controlled, open-label, non-inferiority clinical trial. Primary outcome was the complete healing of the lesions 6 months after starting treatment. Secondary outcomes were healing 3 months after starting treatment and determining the presence and severity of adverse effects (AE).

RESULTS

The research was concluded with 49 patients; Leishmania (Viannia) guyanensis was the most frequent species isolated. In the primary outcome, 18 (72%) (95% CI: 52.4%-85.7%) of the 25 patients allocated to the intervention group and 24 (100%) (95% CI: 86.2%-100%) of the control group (p = 0.015) met the established criteria of cure. There was no AE with tamoxifen.

CONCLUSION

Although a 72% cure rate presented by the combination of tamoxifen and pentamidine was lower than in the control group that achieved a 100% cure, it is still a safe and is a clinically relevant result. It indicates that the therapeutic scheme evaluated may be a promising option for populations in remote areas, however it should be further studied, in order to include a larger number of patients.

Efficacy of intralesional meglumine antimoniate in the treatment of canine tegumentary leishmaniasis: A Randomized controlled trial

Dogs living in areas of Leishmania (Viannia) braziliensis transmission may present canine tegumentary leishmaniasis (CTL) characterized by cutaneous or muzzle ulcers as well as asymptomatic L. braziliensis infection. It is not clear if dogs participate in the transmission chain of L. braziliensis to humans. However, dogs may remain with chronic ulcers for a long time, and as there are no public policies about CTL, these animals die or are sacrificed. Here we compare the efficacy of intralesional meglumine antimoniate with intralesional 0.9% NaCl solution in CTL treatment. This randomized control study included 32 dogs with cutaneous or muzzle lesions who had L. braziliensis DNA detected by PCR in tissue biopsied. Group one received 5ml of intralesional Glucantime, and group two received 5ml 0.9% NaCl solution, both applied in the four cardinal points on days 0, 15, and 30. Cure was defined as complete healing of the ulcers in the absence of raised borders on day 90. There was no difference in animals' demographic and clinical features in the two groups (p >.05). While at the endpoint, the cure rate was 87.5% in the group test, and in those who received 0.9 NaCl the cure rate was only 12.5%. As important as the high cure rate, the healing time was faster in dogs treated with antimony than in those treated with saline (p < .001). Intralesional meglumine antimoniate is effective in the treatment of dogs with L. braziliensis infection and accelerates the healing time of CTL.

Cutaneous Leishmaniasis: A 2022 Updated Narrative Review into Diagnosis and Management Developments

This review is an update of an earlier narrative review published in 2015 on developments in the clinical management of cutaneous leishmaniasis (CL) including diagnosis, treatment, prevention and control measurements. CL is a vector-borne infection caused by the protozoan parasite Leishmania. The vector is the female sandfly. Globally, CL affects 12 million cases and annually 2 million new cases occur. CL is endemic in almost 100 countries and the total risk population is approximately 350 million people. WHO lists CL an emerging and uncontrolled disease and a neglected tropical disease. Local experience-based evidence remains the mainstay for the management of CL. Whereas intralesional therapeutic options are the first treatment option for most CL patients, those with mucocutaneous and disseminated involvement require a systemic therapeutic approach. Moreover, different Leishmania species can vary in their treatment outcomes. Therefore, species determination is critical for optimal CL clinical management. New DNA techniques allow for relatively easy Leishmania species determination, yet they are not easily implemented in resource-limited settings. There is a desperate need for novel, less toxic, and less painful treatment options, especially for children with CL. Yet, the large and well conducted studies required to provide the necessary evidence are lacking. To further control and potentially eliminate CL, we urgently need to improve vector control, and diagnostics, and we require efficient and safe vaccines. Alas, since CL primarily affects poor people, biotechnical companies dedicate little investment into the research programs that could lead to diagnostic, pharmaceutical, and vaccine innovations.

A Mouse Model of Ulcerative Cutaneous Leishmaniasis by Leishmania (Viannia) panamensis to Investigate Infection, Pathogenesis, Immunity, and Therapeutics

A mouse model of cutaneous leishmaniasis (CL) by Leishmania (Viannia) panamensis (L(V)p) that reproduces the characteristics of the human disease remains elusive. Here we report the development of a CL model that uses a mouse-adapted L(V)p isolate to reproducibly induce a dermal disease with a remarkable similarity to human CL. BALB/c mice infected intradermally in the ear with 105 stationary UA-946 L(V)p promastigotes develop a progressive cutaneous disease that exhibits the typical ulcerated lesions with indurated borders observed in CL patients. Although most of parasites in the inoculum die within the first week of infection, the survivors vigorously multiply at the infection site during the following weeks, paralleling disease appearance and aggravation. Regional lymphadenopathy as well as lymphatic dissemination of parasites to draining lymph nodes (dLN) was evidenced early after infection. Viable parasites were also isolated from spleen at later timepoints indicating systemic parasitic dissemination, but, strikingly, no signs of systemic disease were observed. Increasing numbers of myeloid cells and T lymphocytes producing IFNγ and IL-4 were observed in the dLN as disease progressed. A mixed adaptive L(V)p-specific T cell-mediated response was induced, since ex vivo recall experiments using dLN cells and splenocytes revealed the production of type 1 (IFNγ, IL-2), type 2 (IL-4, IL-13), regulatory (IL-10), and inflammatory (GM-CSF, IL-3) cytokines. Humoral adaptive response was characterized by early production of IgG1- followed by IgG2a-type of L(V)p-specific antibodies. IFNγ/IL-4 and IgG2a/IgG1 ratios indicated that the initial non-protective Th2 response was redirected toward a protective Th1 response. In situ studies revealed a profuse recruitment of myeloid cells and of IFNγ- and IL-4-producing T lymphocytes to the site of infection, and the typical histopathological changes induced by dermotropic Leishmania species. Evidence that this model is suitable to investigate pharmacological and immunomodulatory interventions, as well as for antigen discovery and vaccine development, is also presented. Altogether, these results support the validity and utility of this novel mouse model to study the pathogenesis, immunity, and therapeutics of L(V)p infections.

Protection and Pathology in Leishmania braziliensis Infection

Leishmania killing is mediated by IFN-γ-activated macrophages, but IFN-γ production and macrophage activation are insufficient to control L. braziliensis infection. In American tegumentary leishmaniasis (ATL), pathology results from an exaggerated inflammatory response. This report presents an overview of our contributions regarding ATL pathogenesis, highlighting future directions to improve the management of L. braziliensis infection. Monocytes and lymphocytes from individuals exposed to L. braziliensis but who do not develop CL, i.e., subclinical infection (SC), exhibit lower respiratory burst and IFN-γ production, yet more efficiently kill L. braziliensis. As vaccines aimed at inducing IL-12 and IFN-γ do not sufficiently prevent CL, the elucidation of how subjects with SC infection kill Leishmania may lead to new approaches to controlling ATL. While inflammation arising from the recruitment of inflammatory cells via chemokines induced by IFN-γ and TNF or IL-17 is observed and contributes to pathology, cytotoxic CD8⁺ T cells and NK cells play a key role in the pathogenesis of L. braziliensis infection. The increased transcription of genes related to inflammation and cytotoxicity, e.g., granzyme A, granzyme B, NLRP3 and IL-1β, has been documented in CL tissue samples. The release of products by killed cells leads to NLRP3 inflammasome activation, IL-1β production and additional damage to skin and mucosal tissues. The use of drugs that downmodulate the inflammatory response in combination with chemotherapy improves the ATL cure rate and decreases healing time.

Pleiotropic Effect of Hormone Insulin-Like Growth Factor-I in Immune Response and Pathogenesis in Leishmaniases

Leishmaniases are diseases caused by several Leishmania species, and many factors contribute to the development of the infection. Because the adaptive immune response does not fully explain the outcome of Leishmania infection and considering that the initial events are crucial in the establishment of the infection, we investigated one of the growth factors, the insulin-like growth factor-I (IGF-I), found in circulation and produced by different cells including macrophages and present in the skin where the parasite is inoculated. Here, we review the role of IGF-I in leishmaniasis experimental models and human patients. IGF-I induces the growth of different Leishmania species in vitro and alters the disease outcome increasing the parasite load and lesion size, especially in L. major- and L. amazonensis-infected mouse leishmaniasis. IGF-I affects the parasite interacting with the IGF-I receptor present on Leishmania. During Leishmania-macrophage interaction, IGF-I acts on the arginine metabolic pathway, resulting in polyamine production both in macrophages and Leishmania. IGF-I and cytokines interact with reciprocal influences on their expression. IL-4 is a hallmark of susceptibility to L. major in murine leishmaniasis, but we observed that IGF-I operates astoundingly as an effector element of the IL-4. Approaching human leishmaniasis, patients with mucosal, disseminated, and visceral diseases presented surprisingly low IGF-I serum levels, suggesting diverse effects than parasite growth. We observed that low IGF-I levels might contribute to the inflammatory response persistence and delayed lesion healing in human cutaneous leishmaniasis and the anemia development in visceral leishmaniasis. We must highlight the complexity of infection revealed depending on the Leishmania species and the parasite's developmental stages. Because IGF-I exerts pleiotropic effects on the biology of interaction and disease pathogenesis, IGF-I turns up as an attractive tool to explore biological and pathogenic processes underlying infection development. IGF-I pleiotropic effects open further the possibility of approaching IGF-I as a therapeutical target.

Ros3 (Lem3p/CDC50) Gene Dosage Is Implicated in Miltefosine Susceptibility in Leishmania (Viannia) braziliensis Clinical Isolates and in Leishmania (Leishmania) major

The Ros3 protein is a component of the MT-Ros3 transporter complex, considered as the main route of miltefosine entry in Leishmania. L. braziliensis clinical isolates presenting differences in miltefosine susceptibility and uptake were previously shown to differentially express ros3. In this work, we showed that the ros3 gene copy number was increased in the isolate presenting the highest rates of miltefosine uptake and, thus, the highest susceptibility to this drug. The role of the ros3 gene dosage in miltefosine susceptibility was then investigated through a modulation of the gene copy number using two distinct approaches: through an overexpression of ros3 in a tolerant L. braziliensis clinical isolate and in L. major and by generating mono- and diallelic knockouts of this gene in L. major using clustered regularly interspaced short palindromic repeats (CRISPR) Cas9 (Cas = CRISPR-associated). Although the levels of ros3 mRNA were increased at least 40-fold in overexpressing clones, no significant reduction in the half-maximal effective concentration (EC₅₀) for miltefosine was observed in these parasites. The partial or complete deletion of ros3 in L. major, in turn, resulted in a significant increase of 3 and 20 times, respectively, in the EC₅₀ to miltefosine. We unequivocally showed that the ros3 copy number is one of the factors involved in the differential susceptibility and uptake of miltefosine.