Complement: a novel factor in basal and ischemia-induced neurogenesis.
ABSTRACT Through its involvement in inflammation, opsonization, and cytolysis, the complement protects against infectious agents. Although most of the complement proteins are synthesized in the central nervous system (CNS), the role of the complement system in the normal or ischemic CNS remains unclear. Here we demonstrate for the first time that neural progenitor cells and immature neurons express receptors for complement fragments C3a and C5a (C3a receptor (C3aR) and C5a receptor). Mice that are deficient in complement factor C3 (C3(-/-)) lack C3a and are unable to generate C5a through proteolytic cleavage of C5 by C5-convertase. Intriguingly, basal neurogenesis is decreased both in C3(-/-) mice and in mice lacking C3aR or mice treated with a C3aR antagonist. The C3(-/-) mice had impaired ischemia-induced neurogenesis both in the subventricular zone, the main source of neural progenitor cells in adult brain, and in the ischemic region, despite normal proliferative response and larger infarct volumes. Thus, in the adult mammalian CNS, complement activation products promote both basal and ischemia-induced neurogenesis.
Full-textDOI: · Available from: Marcela Pekna, Jun 22, 2015
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ABSTRACT: Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly, especially in Western countries. Although the prevalence, risk factors, and clinical course of the disease are well described, its pathogenesis is not entirely elucidated. AMD is associated with a variety of biochemical abnormalities, including complement components deposition in the retinal pigment epithelium-Bruch's membrane-choriocapillaris complex. Although the complement system (CS) is increasingly recognized as mediating important roles in retinal biology, its particular role in AMD pathogenesis has not been precisely defined. Unrestricted activation of the CS following injury may directly damage retinal tissue and recruit immune cells to the vicinity of active complement cascades, therefore detrimentally causing bystander damage to surrounding cells and tissues. On the other hand, recent evidence supports the notion that an active complement pathway is a necessity for the normal maintenance of the neurosensory retina. In this scenario, complement activation appears to have beneficial effect as it promotes cell survival and tissue remodeling by facilitating the rapid removal of dying cells and resulting cellular debris, thus demonstrating anti-inflammatory and neuroprotective activities. In this review, we discuss both the beneficial and detrimental roles of CS in degenerative retina, focusing on the diverse aspects of CS functions that may promote or inhibit macular disease.Research Journal of Immunology 09/2014; 2014:483960. DOI:10.1155/2014/483960
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ABSTRACT: Acute brain injuries cause rapid cell death that activates bidirectional crosstalks between the injured brain and the immune system. In the acute phase, the damaged central nervous system (CNS) activates resident and circulating immune cells via the local and systemic release of soluble mediators. This early immune activation is necessary to confine the injured tissue and foster the clearance of cellular debris, which would ultimately bring the inflammatory reaction to a close. In the chronic phase, a sustained immune activation is described in many CNS disorders, and the degree of this prolonged response has variable effects on the spontaneous brain regenerative processes. The challenge for treating acute CNS damages is to understand how to optimally engage and modify these immune responses, thus providing new strategies that will compensate for tissue lost to injury. Here we have reviewed the available information about the role and function of the innate and adaptive immune responses in influencing CNS plasticity during the acute and chronic phases of recovery after injury. We have examined how CNS damage evolves along the activation of main cellular and molecular pathways that ultimately are associated to intrinsic repair, neuronal functional plasticity and facilitation of tissue reorganization.Neuroscience 04/2014; 283. DOI:10.1016/j.neuroscience.2014.04.036 · 3.33 Impact Factor
- Journal of biomedical science and engineering 01/2013; 6(08):1-13. DOI:10.4236/jbise.2013.68A1001 · 0.27 Impact Factor