Different cell death mechanisms are involved in leprosy pathogenesis.

Leprosy is a chronic granulomatous disease that remains a serious public health problem in developing countries. According to the Madrid classification, leprosy presents in four clinical forms: two immunologically unstable forms (indeterminate and borderline) and two stable polar forms (tuberculoid and lepromatous). In leprosy, the relationship of cell death to clinical disease outcome remains unclear. Therefore, we investigated the extent of autophagy and different cell death mechanisms-such as apoptosis, necroptosis, and pyroptosis-in cutaneous lesions of patients with leprosy, as well as the role of these mechanisms in clinical disease progression. This cross-sectional analytical study included 30 patients with a confirmed diagnosis of leprosy, with 10 patients in each of the following groups: lepromatous (LL), tuberculoid (TT), and indeterminate (II) leprosy groups. For histopathological analysis, skin samples were subjected to haematoxylin-eosin staining and immunostaining for apoptotic and necroptotic markers. The results indicated that FasL expression was much higher in the LL form than in the TT and II forms. Similar results (higher expression in the LL form than in the TT and II forms) were observed for caspase 8, RIP1, and RIP3 expressions. MLKL, BAX, and caspase 3 expression levels were highest in the LL form, especially in globular foamy macrophages. Beclin-1 expression was highest in the TT form but was low in LL and II forms. Caspase 1 expression was highest in the LL form, followed by that in the TT and II forms. In conclusion, our study elucidates the role of different cell death mechanisms in the pathophysiology of various forms of leprosy and suggests measures that may be used to control the host response to infection and disease progression.

The innate immune response in Zika virus infection.

Zika virus (ZIKV; Flaviviridae, Flavivirus) was discovered in 1947 in Uganda, Africa, from the serum of a sentinel Rhesus monkey (Macaca mulatta). It is an enveloped, positive-sense, single-stranded RNA virus, which encodes a single polyprotein that is cleaved into 10 individual proteins. In 2015, the Zika-epidemic in Brazil was marked mainly by the exponential growth of microcephaly cases and other congenital defects. With regard to host-pathogen relationships, understanding the role of the immune response in the pathogenesis ZIKV infection is challenging. The innate immune response is the first-line immunological defence, in which pathogen-associated molecular patterns are recognized by pattern-recognition receptors that trigger macrophages, dendritic cells, natural killer cells and endothelial cells to produce several mediators, which modulate viral replication and immune evasion. In this review, we have summarized current knowledge on the innate immune response against ZIKV.

Endothelium adhesion molecules ICAM-1, ICAM-2, VCAM-1 and VLA-4 expression in leprosy.

Leprosy triggers a complex relationship between the pathogen and host immune response. Endothelium plays an important role in this immune response by directly influencing cell migration to infected tissues. The objective of this work is to investigate the possible role of endothelium in M. leprae infection, correlating the characteristics of endothelial markers with the expression pattern of cytokines. Thirty-six skin biopsy samples were cut into 5-µm thick sections and stained with hematoxylin-eosin and Ziehl-Neelsen for morphological analysis and then submitted to immunohistochemical analysis using monoclonal antibodies against ICAM-1, ICAM-2, VCAM-1, and VLA-4. Immunostaining for ICAM-1 showed a significantly larger number of stained endothelial cells in the tuberculoid leprosy (9.92 ± 1.11 cells/mm2) when compared to lepromatous samples (5.87 ± 1.01 cells/mm2) and ICAM-2 revealed no significant difference in the number of endothelial cells expressing this marker between the tuberculoid (13.21 ± 1.27 cells/mm2) and lepromatous leprosy (14.3 ± 1.02 cells/mm2). VCAM-1-immunostained showed 18.28 ± 1.46/mm2 cells in tuberculoid leprosy and 10.67 ± 1.25 cells/mm2 in the lepromatous leprosy. VLA-4 exhibited 22.46 ± 1.38 cells/mm2 in the tuberculoid leprosy 16.04 ± 1.56 cells/mm2 in the lepromatous leprosy. Samples with characteristics of the tuberculoid leprosy exhibited a larger number of cells stained with ICAM-1, VCAM-1 and VLA-4, demonstrating the importance of these molecules in the migration and selection of cells that reach the inflamed tissue.