Blockade of interleukin-6 signaling inhibits the classic pathway and promotes an alternative pathway of macrophage activation after spinal cord injury in mice

Background Recent in vivo and in vitro studies in non-neuronal and neuronal tissues have shown that different pathways of macrophage activation result in cells with different properties. Interleukin (IL)-6 triggers the classically activated inflammatory macrophages (M1 phenotype), whereas the alternatively activated macrophages (M2 phenotype) are anti-inflammatory. The objective of this study was to clarify the effects of a temporal blockade of IL-6/IL-6 receptor (IL-6R) engagement, using an anti-mouse IL-6R monoclonal antibody (MR16-1), on macrophage activation and the inflammatory response in the acute phase after spinal cord injury (SCI) in mice. Methods MR16-1 antibodies versus isotype control antibodies or saline alone were administered immediately after thoracic SCI in mice. SC tissue repair was compared between the two groups by Luxol fast blue (LFB) staining for myelination and immunoreactivity for the neuronal markers growth-associated protein (GAP)-43 and neurofilament heavy 200 kDa (NF-H) and for locomotor function. The expression of T helper (Th)1 cytokines (interferon (IFN)-? and tumor necrosis factor-a) and Th2 cytokines (IL-4, IL-13) was determined by immunoblot analysis. The presence of M1 (inducible nitric oxide synthase (iNOS)-positive, CD16/32-positive) and M2 (arginase 1-positive, CD206-positive) macrophages was determined by immunohistology. Using flow cytometry, we also quantified IFN-? and IL-4 levels in neutrophils, microglia, and macrophages, and Mac-2 (macrophage antigen-2) and Mac-3 in M2 macrophages and microglia. Results LFB-positive spared myelin was increased in the MR16-1-treated group compared with the controls, and this increase correlated with enhanced positivity for GAP-43 or NF-H, and improved locomotor Basso Mouse Scale scores. Immunoblot analysis of the MR16-1-treated samples identified downregulation of Th1 and upregulation of Th2 cytokines. Whereas iNOS-positive, CD16/32-positive M1 macrophages were the predominant phenotype in the injured SC of non-treated control mice, MR16-1 treatment promoted arginase 1-positive, CD206-positive M2 macrophages, with preferential localization of these cells at the injury site. MR16-1 treatment suppressed the number of IFN-?-positive neutrophils, and increased the number of microglia present and their positivity for IL-4. Among the arginase 1-positive M2 macrophages, MR16-1 treatment increased positivity for Mac-2 and Mac-3, suggestive of increased phagocytic behavior. Conclusion The results suggest that temporal blockade of IL-6 signaling after SCI abrogates damaging inflammatory activity and promotes functional recovery by promoting the formation of alternatively activated M2 macrophages

An overview of tissue engineering approaches for management of spinal cord injuries

Severe spinal cord injury (SCI) leads to devastating neurological deficits and disabilities, which necessitates spending a great deal of health budget for psychological and healthcare problems of these patients and their relatives. This justifies the cost of research into the new modalities for treatment of spinal cord injuries, even in developing countries. Apart from surgical management and nerve grafting, several other approaches have been adopted for management of this condition including pharmacologic and gene therapy, cell therapy, and use of different cell-free or cell-seeded bioscaffolds. In current paper, the recent developments for therapeutic delivery of stem and non-stem cells to the site of injury, and application of cell-free and cell-seeded natural and synthetic scaffolds have been reviewed

DNA–protein crosslinks and p53 protein expression in relation to occupational exposure to formaldehyde

Background: Formaldehyde (FA) is classified as a probable human carcinogen. Aims: To examine DNA protein crosslinks (DPC) and p53, which are generally known to be involved in carcinogenesis, in peripheral blood lymphocytes of workers exposed to FA. Methods: DPC and p53 ("wild type" and mutant) were examined in peripheral blood lymphocytes of 186 workers exposed to FA (mean years of exposure = 16) and 213 unexposed workers. Every worker completed a questionnaire on demographic data, occupational and medical history, smoking, and hygiene. Results: The adjusted mean level of DPC in the exposed and the unexposed workers differed significantly. Adjustment was made for age, sex, years of education, smoking, and origin. Exposure to FA increased the risk of having a higher level of pantropic p53 above 150 pg/ml (OR 1.6, 95% CI 0.8 to 3.1). A significant positive correlation was found between the increase of pantropic p53 protein and mutant p53 protein, as well as between pantropic p53 >150 pg/ml and mutant p53 protein. In the exposed group a significantly higher proportion of p53 >150 pg/ml was found among workers with DPC >0.187 (55.7%) (0.187 = median level of DPC) than among workers with DPC ⩽0.187 (33.3%). The risk of having pantropic p53 protein >150 pg/ml was determined mainly by levels of DPC. Workers with DPC above the median level had a significantly higher risk of having pantropic p53 >150 pg/ml (adjusted OR 2.5, 95% CI 1.2 to 5.4). Conclusions: Results suggest that DPC and mutation in p53 may represent steps in FA carcinogenesis and a possible causal relation between DPC and mutation in p53. These biomarkers can be applied in the assessment of the development of cancer due to FA exposure