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The intracellular pathogen Burkholderia pseudomallei, the etiological agent of melioidosis in humans and various animals, is capable of survival and movement within the cytoplasm of host cells by a process known as actin-based motility. The bacterial factor BimA is required for actin-based motility through its direct interaction with actin, and by mediating actin polymerization at a single pole of the bacterium to promote movement both within and between cells. However, little is known about the other bacterial proteins required for this process. Here, we have investigated the role of the bimC gene (bpss1491) which lies immediately upstream of the bimA gene (bpss1492) on the B. pseudomallei chromosome 2. Conserved amongst all B. pseudomallei, B. mallei and B. thailandensis strains sequenced to date, this gene encodes an iron-binding protein with homology to a group of proteins known as the bacterial autotransporter heptosyltransferase (BAHT) family. We have constructed a B. pseudomallei bimC deletion mutant and demonstrate that it is defective in intracellular survival in HeLa cells, but not in J774.1 macrophage-like cells. The bimC mutant is defective in cell to cell spread as demonstrated by ablation of plaque formation in HeLa cells, and by the inability to form multi-nucleated giant cells in J774.1 cells. These phenotypes in intracellular survival and cell to cell spread are not due to the loss of expression and polar localization of the BimA protein on the surface of intracellular bacteria, however they do correlate with an inability of the bacteria to recruit and polymerize actin. Furthermore, we also establish a role for bimC in virulence of B. pseudomallei using a Galleria mellonella larvae model of infection. Taken together, our findings indicate that B. pseudomallei BimC plays an important role in intracellular behavior and virulence of this emerging pathogen.

The intracellular pathogen Burkholderia pseudomallei , the etiological agent of melioidosis in humans and various animals, is capable of survival and movement within the cytoplasm of host cells by a process known as actin-based motility. The bacterial factor BimA is required for actin-based motility through its direct interaction with actin, and by mediating actin polymerization at a single pole of the bacterium to promote movement both within and between cells. However, little is known about the other bacterial proteins required for this process. Here, we have investigated the role of the bimC gene (bpss1491) which lies immediately upstream of the bimA gene (bpss1492) on the B. pseudomallei chromosome 2. Conserved amongst all B. pseudomallei, B. mallei and B. thailandensis strains sequenced to date, this gene encodes an iron-binding protein with homology to a group of proteins known as the bacterial autotransporter heptosyltransferase (BAHT) family. We have constructed a B. pseudomallei bimC deletion mutant and demonstrate that it is defective in intracellular survival in HeLa cells, but not in J774.1 macrophage-like cells. The bimC mutant is defective in cell to cell spread as demonstrated by ablation of plaque formation in HeLa cells, and by the inability to form multi-nucleated giant cells in J774.1 cells. These phenotypes in intracellular survival and cell to cell spread are not due to the loss of expression and polar localization of the BimA protein on the surface of intracellular bacteria, however they do correlate with an inability of the bacteria to recruit and polymerize actin. Furthermore, we also establish a role for bimC in virulence of B. pseudomallei using a Galleria mellonella larvae model of infection. Taken together, our findings indicate that B. pseudomallei BimC plays an important role in intracellular behavior and virulence of this emerging pathogen. [ABSTRACT FROM AUTHOR]

Granulomas are inflammatory reactions featuring macrophages, epithelioid, T and multi-nucleated giant cells (MGC). Giant cells are present in a number of granulomatous reactions, but little is known about their formation and function, especially in man. We studied MGC in the granulomatous disorder sarcoidosis. In situ labelling of lymph nodes by means of [3H]-thymidine showed that proliferation and non-division of epithelioid cells leading towards giant cells was not observed in these granulomas. However, [3H]-uridine incorporation showed MGC with labelled as well as unlabelled nuclei in the same cell, pointing to a process of fusion of epithelioid cells to form giant cells. Apoptotic bodies were incidentally found in granulomas. A novel finding was that such bodies were statistically more often found in the close vicinity of MGC, but not within these cells. These apoptotic cells appeared to be CD4+ lymphocytes or histiocytes. CD44 and CCR-5 involved in the process of fusion were expressed in MGC. In conclusion, MGC in sarcoidosis derive by cell fusion rather than by proliferation and non-division, and seem to play an active role in the induction of apoptosis in granulomas. [ABSTRACT FROM AUTHOR]

Taenia solium metacestodes cause cysticercosis in both humans and pigs. In the former host species, the central nervous system involvement (neurocysticercosis (NCC)) may range from asymptomatic to life-threatening, but little is known about the corresponding variation in tissue response due to the difficulty in obtaining parasite-infected brain biopsies. The use of pigs as animal models for cysticercosis is ideal because the histological description of the animal’s response around the parasites resembles the one recorded in human specimens. In this study the histological features of the immune response in swine were complemented by immunohistochemical analysis to determine the phenotype of the inflammatory cells. The presence of mononuclear cells and eosinophils, and the co-localization of MHC-II with B lymphocytes and monocytes/macrophages within the granulomas surrounding the parasites, were features that closely resembled the descriptions made in prior studies with human specimens. In addition, there were novel findings such as the upregulation of the adhesin CD44 in cells resembling monocytes/macrophages, eosinophils and in astrocytes from the central nervous system. The upregulation of CD44 may be important for the recruitment of inflammatory cells to the site of the lesion. Finally, the presence of null-γδ-T cells since stage I of the immune response was similar to the early detection of these cells in mouse models for cysticercosis. [Copyright &y& Elsevier]

A 46-year-old woman under 6-year haemodialysis was admitted for uncontrollable hip pain. An X-ray film revealed calcified mass around the ‘left femur head’, which was diagnosed as calcium deposition by percutaneous biopsy. Calcinotic tissues were removed surgically, and the resected specimen revealed tumoral calcinosis caused by low bone turnover. A complete resolution of calcinotic lesions around the ‘left knee’ occurred 6 months after treatment modification. Immunohistochemistry showed recruitment of multi-nucleated giant cells positive for CD68, tartrate resistant acidic phosphatase and calcitonin receptor, indicative of osteoclast-like features. We propose the involvement of osteoclast-like cells in active resorption of tumoral calcinosis. [ABSTRACT FROM PUBLISHER]