New insights into the life cycle, host cell tropism, and infection amplification of Leishmania spp. Anna Luiza Silva-Moreira, Artur Metzker Serravite, Laura Valéria Rios-Barros, Juliana Perrone Bezerra de Menezes, Maria Fátima Horta, et al. Infection and Immunity, 2025 The genus Leishmania comprises several species of digenetic protozoan parasites that cause a spectrum of diseases known as leishmaniases, which are transmitted to humans and other mammals through the bite of hematophagous female sand flies. Leishmania spp. and their invertebrate vectors are widely distributed across the globe, putting more than a billion people at risk. Once inside mammalian hosts, these intracellular parasites reside within parasitophorous vacuoles of host cells. Although macrophages are the primary infected cells in lesions, Leishmania can also infect other cell types, whose roles in maintaining the parasite’s life cycle and contributing to pathogenesis remain unclear. Similarly, the processes governing parasite dissemination from the initial infection site in the skin to internal organs, as well as the mechanisms driving the infection of new cells, are still under investigation. In this review, we underscore some existing gaps in Leishmania ’s life cycle, discussing i) the various cell types that serve as host cells for the parasite and their potential roles in the disease, ii) the mechanisms that might contribute to infection amplification, iii) the strategies possibly involved in dissemination and visceralization, iv) the mechanisms driving the generation of super-infective vectors, and v) the occurrence of a mating stage in the cycle. Altogether, these aspects may reshape our perspective on the basic biology of Leishmania , deepening our understanding of the host-parasite relationship and hopefully opening avenues toward a better understanding of the disease.
Simultaneous Durvalumab and Platinum-Based Chemoradiotherapy in Unresectable Stage III Non–Small Cell Lung Cancer: The Phase III PACIFIC-2 Study Jeffrey D. Bradley, Shunichi Sugawara, Ki Hyeong Lee, Gyula Ostoros, Ahmet Demirkazik, et al. Journal of Clinical Oncology, 2025 PURPOSE Immunotherapy targeting PD-L1 improves outcomes in patients with unresectable stage III non–small cell lung cancer (NSCLC) and no progression after definitive, concurrent chemoradiotherapy (cCRT). Earlier administration of immunotherapy, simultaneously with cCRT, may improve outcomes further. METHODS Eligible patients were randomly assigned (2:1) to receive either durvalumab or placebo administered from the start of cCRT. Patients without progression after completing cCRT received consolidation durvalumab or placebo (per initial random assignment) until progression. The primary end point was progression-free survival (PFS) by blinded independent central review. Key secondary end points included objective response rate (ORR), overall survival (OS), the proportion of patients alive at 24 months (OS24), and safety. RESULTS In total, 328 patients were randomly assigned to receive durvalumab (n = 219) or placebo (n = 109). There was no statistically significant difference with durvalumab versus placebo in PFS (hazard ratio [HR], 0.85 [95% CI, 0.65 to 1.12]; P = .247) or OS (HR, 1.03 [95% CI, 0.78 to 1.39]; P = .823); OS24 was 58.4% versus 59.5%, respectively. Confirmed ORR was 60.7% with durvalumab versus 60.6% with placebo (difference, 0.2% [95% CI, −15.2 to 16.3%]; P = .976). With durvalumab versus placebo, respectively, maximum grade 3 or 4 adverse events (AEs) occurred in 53.4% versus 59.3% of patients, pneumonitis or radiation pneumonitis (group term) in 28.8% (grade ≥3: 4.6%) versus 28.7% (grade ≥3: 5.6%), AEs leading to discontinuation of durvalumab or placebo in 25.6% versus 12.0%, and fatal AEs in 13.7% versus 10.2%. CONCLUSION Among patients with unresectable stage III NSCLC, durvalumab administered from the start of cCRT failed to demonstrate additional benefit compared with cCRT plus placebo. Consolidation durvalumab following definitive cCRT remains the standard of care in this setting.
Pharmacokinetics, Dose-Proportionality, and Tolerability of Intravenous Tanespimycin (17-AAG) in Single and Multiple Doses in Dogs: A Potential Novel Treatment for Canine Visceral Leishmaniasis Marcos Ferrante, Bruna Martins Macedo Leite, Lívia Brito Coelho Fontes, Alice Santos Moreira, Élder Muller Nascimento de Almeida, et al. Pharmaceuticals, 2024 In the New World, dogs are considered the main reservoir of visceral leishmaniasis (VL). Due to inefficacies in existing treatments and the lack of an efficient vaccine, dog culling is one of the main strategies used to control disease, making the development of new therapeutic interventions mandatory. We previously showed that Tanespimycin (17-AAG), a Hsp90 inhibitor, demonstrated potential for use in leishmaniasis treatment. The present study aimed to test the safety of 17-AAG in dogs by evaluating plasma pharmacokinetics, dose-proportionality, and the tolerability of 17-AAG in response to a dose-escalation protocol and multiple administrations at a single dose in healthy dogs. Two protocols were used: Study A: four dogs received variable intravenous (IV) doses (50, 100, 150, 200, or 250 mg/m2) of 17-AAG or a placebo (n = 4/dose level), using a cross-over design with a 7-day “wash-out” period; Study B: nine dogs received three IV doses of 150 mg/m2 of 17-AAG administered at 48 h intervals. 17-AAG concentrations were determined by a validated high-performance liquid chromatographic (HPLC) method: linearity (R2 = 0.9964), intra-day precision with a coefficient of variation (CV) ≤ 8%, inter-day precision (CV ≤ 20%), and detection and quantification limits of 12.5 and 25 ng/mL, respectively. In Study A, 17-AAG was generally well tolerated. However, increased levels of liver enzymes–alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT)–and bloody diarrhea were observed in all four dogs receiving the highest dosage of 250 mg/m2. After single doses of 17-AAG (50–250 mg/m2), maximum plasma concentrations (Cmax) ranged between 1405 ± 686 and 9439 ± 991 ng/mL, and the area under the curve (AUC) plotting plasma concentration against time ranged between 1483 ± 694 and 11,902 ± 1962 AUC 0–8 h μg/mL × h, respectively. Cmax and AUC parameters were dose-proportionate between the 50 and 200 mg/m2 doses. Regarding Study B, 17-AAG was found to be well tolerated at multiple doses of 150 mg/m2. Increased levels of liver enzymes–ALT (28.57 ± 4.29 to 173.33 ± 49.56 U/L), AST (27.85 ± 3.80 to 248.20 ± 85.80 U/L), and GGT (1.60 ± 0.06 to 12.70 ± 0.50 U/L)–and bloody diarrhea were observed in only 3/9 of these dogs. After the administration of multiple doses, Cmax and AUC 0–48 h were 5254 ± 2784 μg/mL and 6850 ± 469 μg/mL × h in plasma and 736 ± 294 μg/mL and 7382 ± 1357 μg/mL × h in tissue transudate, respectively. In conclusion, our results demonstrate the potential of 17-AAG in the treatment of CVL, using a regimen of three doses at 150 mg/m2, since it presents the maintenance of high concentrations in subcutaneous interstitial fluid, low toxicity, and reversible hepatotoxicity.
Leishmania amazonensis infection impairs VLA-4 clustering and adhesion complex assembly at the adhesion site of J774 cells Reginaldo Brito, Erina Masayo Hassegawa, Patrick Camardelli, Kalene Elpídio, Juliana de Menezes, et al. Pathogens and Disease, 2023 Cutaneous leishmaniasis is an infectious disease that may lead to a single or multiple disseminated cutaneous lesions. The mechanisms involved in Leishmania dissemination to different areas of the skin and the internal organs remain poorly understood. Evidence shows that Very Late Antigen-4 (VLA-4)-dependent phagocyte adhesion is impaired by Leishmania infection, which may be related to the mechanisms of parasite dissemination. We investigated factors potentially associated with decreased VLA-4-mediated adhesion in Leishmania-infected macrophages, including lipid raft-mediated VLA-4 mobilization along the cellular membrane, integrin cluster formation at the cell base (adhesion site), and focal adhesion complex assembly. Phagocytes treated with Methyl-β-Cyclodextrin (MβCD) demonstrated reduced adhesion, similarly to Leishmania amazonensis-infected J774 cells. Infected and MβCD-treated macrophages presented decreased VLA-4 mobilization to the adhesion plane, as well as reduced integrin clustering. Leishmania amazonensis-infected cells exhibited talin depletion, as well as a decreased mobilization of adhesion complex proteins, such as talin and viculin, which were associated with lower VLA-4 concentrations at the adhesion site and limited cell-spreading. Our results suggest that Leishmania infection may modulate the firm adhesion phase of the cell-spreading process, which could contribute to the bloodstream dissemination of infected cells.
Elucidating the role played by bone marrow in visceral leishmaniasis Patricia Sampaio Tavares Veras, Maria Borges Rabêlo de Santana, Claudia Ida Brodskyn, Deborah Bittencourt Mothé Fraga, Manuela Silva Solcà, et al. Frontiers in Cellular and Infection Microbiology, 2023 Leishmaniasis is a widespread group of infectious diseases that significantly impact global health. Despite high prevalence, leishmaniasis often receives inadequate attention in the prioritization of measures targeting tropical diseases. The causative agents of leishmaniasis are protozoan parasites of theLeishmaniagenus, which give rise to a diverse range of clinical manifestations, including cutaneous and visceral forms. Visceral leishmaniasis (VL), the most severe form, can be life-threatening if left untreated. Parasites can spread systemically within the body, infecting a range of organs, such as the liver, spleen, bone marrow and lymph nodes. Natural reservoirs for these protozoa include rodents, dogs, foxes, jackals, and wolves, with dogs serving as the primary urban reservoir forLeishmania infantum. Dogs exhibit clinical and pathological similarities to human VL and are valuable models for studying disease progression. Both human and canine VL provoke clinical symptoms, such as organ enlargement, fever, weight loss and abnormal gamma globulin levels. Hematologic abnormalities have also been observed, including anemia, leukopenia with lymphocytosis, neutropenia, and thrombocytopenia. Studies in dogs have linked these hematologic changes in peripheral blood to alterations in the bone marrow. Mouse models of VL have also contributed significantly to our understanding of the mechanisms underlying these hematologic and bone marrow abnormalities. This review consolidates information on hematological and immunological changes in the bone marrow of humans, dogs, and mice infected withLeishmaniaspecies causing VL. It includes findings on the role of bone marrow as a source of parasite persistence in internal organs and VL development. Highlighting gaps in current knowledge, the review emphasizes the need for future research to enhance our understanding of VL and identify potential targets for novel diagnostic and therapeutic approaches.
Leishmania infection alters macrophage and dendritic cell migration in a three-dimensional environment Yasmin Luz, Amanda Rebouças, Carla Polyana O. S. Bernardes, Erik A. Rossi, Taíse S. Machado, et al. Frontiers in Cell and Developmental Biology, 2023 Background: Leishmaniasis results in a wide spectrum of clinical manifestations, ranging from skin lesions at the site of infection to disseminated lesions in internal organs, such as the spleen and liver. While the ability of Leishmania-infected host cells to migrate may be important to lesion distribution and parasite dissemination, the underlying mechanisms and the accompanying role of host cells remain poorly understood. Previously published work has shown that Leishmania infection inhibits macrophage migration in a 2-dimensional (2D) environment by altering actin dynamics and impairing the expression of proteins involved in plasma membrane-extracellular matrix interactions. Although it was shown that L. infantum induces the 2D migration of dendritic cells, in vivo cell migration primarily occurs in 3-dimensional (3D) environments. The present study aimed to investigate the migration of macrophages and dendritic cells infected by Leishmania using a 3-dimensional environment, as well as shed light on the mechanisms involved in this process.Methods: Following the infection of murine bone marrow-derived macrophages (BMDM), human macrophages and human dendritic cells by L. amazonensis, L. braziliensis, or L. infantum, cellular migration, the formation of adhesion complexes and actin polymerization were evaluated.Results: Our results indicate that Leishmania infection inhibited 3D migration in both BMDM and human macrophages. Reduced expression of proteins involved in adhesion complex formation and alterations in actin dynamics were also observed in Leishmania-infected macrophages. By contrast, increased human dendritic cell migration in a 3D environment was found to be associated with enhanced adhesion complex formation and increased actin dynamics.Conclusion: Taken together, our results show that Leishmania infection inhibits macrophage 3D migration, while enhancing dendritic 3D migration by altering actin dynamics and the expression of proteins involved in plasma membrane extracellular matrix interactions, suggesting a potential association between dendritic cells and disease visceralization.
Advances in development of new treatment for leishmaniasis Juliana Perrone Bezerra de Menezes, Carlos Eduardo Sampaio Guedes, Antônio Luis de Oliveira Almeida Petersen, Deborah Bittencourt Mothé Fraga, Patrícia Sampaio Tavares Veras Biomed Research International, 2015
