Elucidating the role played by bone marrow in visceral leishmaniasis

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 the Leishmania genus, 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 for Leishmania 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 with Leishmania species 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.

A rare presentation of visceral leishmaniasis and epididymo-orchitis in a patient with chronic granulomatous disease

Visceral leishmaniasis (VL) has rarely been reported in patients with chronic granulomatous disease (CGD), despite the fact that they seem more susceptible to intracellular infection. We describe a rare presentation of VL and epididymo-orchitis in a patient with CGD, which has not been seen previously in the literature following inflammatory syndrome.

The Emergence of Co-Infection of Visceral Leishmaniasis in an Iranian Child with Chronic Granulomatous Disease: A Case Report

Chronic granulomatous disease (CGD) described as an essential immunodeficiency problem of phagocytic cells resulting in a phagocyte dysfunction and inability to kill a spectrum of bacteria and fungi. Despite the fact that CGD patients are more susceptible to intracellular infections, visceral leishmaniasis has been reported rarely in these cases. Here, we report an uncommon case of visceral leishmaniasis in a child with CGD. An 8-yr old boy with CGD presented to the infectious disease ward, Children’s Medical Center, Tehran University of Medical Sciences, Iran after the onset of 20 days fever with chronic crusted ulcer approximately 3 cm × 3cm on the left upper limb and a small ulcer measuring 0.5 cm × 0.5 cm on the right knee with moderate secretion. Bone Marrow Aspiration (BMA) and Bone Marrow Biopsies (BMB) of fragmented samples were performed and polymorphic population of hematopoietic cells, Megakaryocytes and Leishman bodies were seen. The patient was treated with meglumine antimoniate (Glucantime^®) 20 mg/kg for 28 days and after partial improvement patient discharged and continue the treatment at home. Amphotericin B lipid complex (Ambisome^®) (3–5 mg/kg per dose once) was administered every 3–4 weeks for 18 months as secondary prophylaxis that was well tolerated and effective.

Macrophages as host, effector and immunoregulatory cells in leishmaniasis: Impact of tissue micro-environment and metabolism

Leishmania are protozoan parasites that predominantly reside in myeloid cells within their mammalian hosts. Monocytes and macrophages play a central role in the pathogenesis of all forms of leishmaniasis, including cutaneous and visceral leishmaniasis. The present review will highlight the diverse roles of macrophages in leishmaniasis as initial replicative niche, antimicrobial effectors, immunoregulators and as safe hideaway for parasites persisting after clinical cure. These multiplex activities are either ascribed to defined subpopulations of macrophages (e.g., Ly6C^highCCR2⁺ inflammatory monocytes/monocyte-derived dendritic cells) or result from different activation statuses of tissue macrophages (e.g., macrophages carrying markers of of classical [M1] or alternative activation [M2]). The latter are shaped by immune- and stromal cell-derived cytokines (e.g., IFN-γ, IL-4, IL-10, TGF-β), micro milieu factors (e.g., hypoxia, tonicity, amino acid availability), host cell-derived enzymes, secretory products and metabolites (e.g., heme oxygenase-1, arginase 1, indoleamine 2,3-dioxygenase, NOS2/NO, NOX2/ROS, lipids) as well as by parasite products (e.g., leishmanolysin/gp63, lipophosphoglycan). Exciting avenues of current research address the transcriptional, epigenetic and translational reprogramming of macrophages in a Leishmania species- and tissue context-dependent manner.

Identification of deletion carriers in X-linked chronic granulomatous disease by real-time PCR

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency affecting the innate immune system. Even if functional tests address the diagnosis of CGD, the identification of a molecular defect is essential for counselling family members at risk for being CGD carriers and for prenatal diagnosis. The X-linked form occurs in 65% of CGD patients. It is due to mutations in the CYBB gene, up to 12% of which are caused by large deletions. CGD carriers are usually healthy, and molecular analysis is essential to reveal their carrier status. The aim of this study was to apply a gene dosage approach, using SYBR green quantitative real-time polymerase chain reaction (RT-PCR), to quantify the genomic copy number in carriers and noncarriers of gross deletions covering the region of the CYBB gene. We studied the expression of two different amplification products of the CYBB gene, and the results confirmed a highly reduced expression of the gene in the carrier samples. The results were confirmed by linkage analysis and fluorescence in situ hybridization. Quantitative real-time PCR is fast and simple to perform, and we propose it as a new routine diagnostic approach to detect CGD carriers of deletions covering the region spanning the CYBB gene.

Molecular characterization of a large cohort of patients with Chronic Granulomatous Disease and identification of novel CYBB mutations: an Italian multicenter study

Chronic Granulomatous Disease (CGD) is a rare inherited disorder in which phagocytes fail to produce antimicrobial superoxide because NADPH oxidase activity is absent. In about 65% of the cases, the disease is due to mutations affecting the X-linked CYBB gene, encoding the gp91(phox) subunit of NADPH oxidase. We investigated 34 CGD male patients by DHPLC and direct sequencing. A mutation was found in the CYBB gene of 33 patients and 9 of these were novel: one non-sense mutation (c.1123 G>T), three missense mutations (c.58G>A; c.1076 G>C; c.1357 T>A), two splice site mutations (c.141+5G>T; c.142-1G>A), one duplication (c.42_45dupCATT), one deletion (c.184delT), and one rare deletion of two non-contiguous nucleotides (c.1287delT+c.1290delC). One patient had the most frequent GT homozygous deletion in exon2 of the NCF-1 gene encoding the p47(phox) subunit of NADPH oxidase. The carrier analysis was performed in 23 patients' mothers and 16 female relatives through molecular and FISH studies. No clear correlation between the severity of clinical symptoms and the type of mutation could be demonstrated. This study further supports the great heterogeneity of the disease and the notion that genetic analysis is a critical step in obtaining a definitive diagnosis for CGD.