ovalbumin and Spinal-Cord-Injuries

Autonomic dysreflexia (AD), a potentially dangerous complication of high-level spinal cord injury (SCI) characterized by exaggerated activation of spinal autonomic (sympathetic) reflexes, can cause pulmonary embolism, stroke, and, in severe cases, death. People with high-level SCI also are immune compromised, rendering them more susceptible to infectious morbidity and mortality. The mechanisms underlying postinjury immune suppression are not known. Data presented herein indicate that AD causes immune suppression. Using in vivo telemetry, we show that AD develops spontaneously in SCI mice with the frequency of dysreflexic episodes increasing as a function of time postinjury. As the frequency of AD increases, there is a corresponding increase in splenic leucopenia and immune suppression. Experimental activation of spinal sympathetic reflexes in SCI mice (e.g., via colorectal distension) elicits AD and exacerbates immune suppression via a mechanism that involves aberrant accumulation of norepinephrine and glucocorticoids. Reversal of postinjury immune suppression in SCI mice can be achieved by pharmacological inhibition of receptors for norepinephrine and glucocorticoids during the onset and progression of AD. In a human subject with C5 SCI, stimulating the micturition reflex caused AD with exaggerated catecholamine release and impaired immune function, thus confirming the relevance of the mouse data. These data implicate AD as a cause of secondary immune deficiency after SCI and reveal novel therapeutic targets for overcoming infectious complications that arise due to deficits in immune function.

Topics: Adrenergic beta-2 Receptor Antagonists; Animals; Antigens, CD; Autonomic Dysreflexia; Blood Pressure; Butoxamine; Colon; Corticosterone; Disease Models, Animal; Epinephrine; Female; Hormone Antagonists; Humans; Immune System Diseases; Immunosuppression Therapy; Mice; Mifepristone; Norepinephrine; Ovalbumin; Physical Stimulation; Spinal Cord Injuries; T-Lymphocytes; Telemetry

Lipid peroxidation (LP) is one of the most harmful mechanisms developed after spinal cord (SC) injury. Several strategies have been explored in order to control this phenomenon. Protective autoimmunity is a physiological process based on the modulation of inflammatory cells that can be boosted by immunizing with neural-derived peptides, such as A91. Since inflammatory cells are among the main contributors to lipid peroxidation, we hypothesized that protective autoimmunity could reduce LP after SC injury. In order to test this hypothesis, we designed two experiments in SC contused rats. First, animals were immunized with a neural-derived peptide seven days before injury. With the aim of inducing the functional elimination of CNS-specific T cells, for the second experiment, animals were tolerized against SC-protein extract and thereafter subjected to a SC injury. The lipid-soluble fluorescent products were used as an index of lipid peroxidation and were assessed after injury. Immunization with neural-derived peptides reduced lipid peroxidation after SC injury. Functional elimination of CNS-specific T cells avoided the beneficial effect induced by protective autoimmunity. The present study demonstrates the beneficial effect of immunizing with neural-derived peptides on lipid peroxidation inhibition; besides this, it also provides evidence on the neuroprotective mechanisms exerted by protective autoimmunity.

Topics: Animals; Autoimmunity; Immunization; Lipid Peroxidation; Myelin Basic Protein; Neuropeptides; Ovalbumin; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; T-Lymphocytes

Although macrophages (MPhi) are known as essential players in wound healing, their contribution to recovery from spinal cord injury (SCI) is a subject of debate. The difficulties in distinguishing between different MPhi subpopulations at the lesion site have further contributed to the controversy and led to the common view of MPhi as functionally homogenous. Given the massive accumulation in the injured spinal cord of activated resident microglia, which are the native immune occupants of the central nervous system (CNS), the recruitment of additional infiltrating monocytes from the peripheral blood seems puzzling. A key question that remains is whether the infiltrating monocyte-derived MPhi contribute to repair, or represent an unavoidable detrimental response. The hypothesis of the current study is that a specific population of infiltrating monocyte-derived MPhi is functionally distinct from the inflammatory resident microglia and is essential for recovery from SCI.. We inflicted SCI in adult mice, and tested the effect of infiltrating monocyte-derived MPhi on the recovery process. Adoptive transfer experiments and bone marrow chimeras were used to functionally distinguish between the resident microglia and the infiltrating monocyte-derived MPhi. We followed the infiltration of the monocyte-derived MPhi to the injured site and characterized their spatial distribution and phenotype. Increasing the naïve monocyte pool by either adoptive transfer or CNS-specific vaccination resulted in a higher number of spontaneously recruited cells and improved recovery. Selective ablation of infiltrating monocyte-derived MPhi following SCI while sparing the resident microglia, using either antibody-mediated depletion or conditional ablation by diphtheria toxin, impaired recovery. Reconstitution of the peripheral blood with monocytes resistant to ablation restored the lost motor functions. Importantly, the infiltrating monocyte-derived MPhi displayed a local anti-inflammatory beneficial role, which was critically dependent upon their expression of interleukin 10.. The results of this study attribute a novel anti-inflammatory role to a unique subset of infiltrating monocyte-derived MPhi in SCI recovery, which cannot be provided by the activated resident microglia. According to our results, limited recovery following SCI can be attributed in part to the inadequate, untimely, spontaneous recruitment of monocytes. This process is amenable to boosting either by active vaccination with a myelin-derived altered peptide ligand, which indicates involvement of adaptive immunity in monocyte recruitment, or by augmenting the naïve monocyte pool in the peripheral blood. Thus, our study sheds new light on the long-held debate regarding the contribution of MPhi to recovery from CNS injuries, and has potentially far-reaching therapeutic implications.

Topics: Adoptive Transfer; Animals; Glycoproteins; Inflammation; Interleukin-10; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Monocytes; Myelin-Oligodendrocyte Glycoprotein; Ovalbumin; Peptide Fragments; Spinal Cord; Spinal Cord Injuries

We investigated whether antibody production to antigens arising in the subarachnoid space is depressed acutely after spinal cord injury (SCI), and whether such depression is due to abnormal catecholamine levels. To assess antibody responses, ovalbumin (OVA) was injected into the spinal subarachnoid space (i.t.) of rats via an indwelling catheter after SCI at T4 or laminectomy (LAM). Antibody responses tested at days 0, 7, and 14 (d0, d7, d14) postinjury revealed that SCI animals exhibited an antibody response significantly lower than LAM animals on d7, but one that reached control levels by d14. ELISPOT assays indicated that the cervical lymph nodes, known to be innervated by superior cervical ganglia (SCG), processed i.t. OVA. The reduction in antibody production after SCI could not be mimicked with surgical deafferentation of the SCG. However, blockade of beta-adrenergic receptors prior to SCI did reverse the decrease, suggesting an adverse effect of the surge of catecholamines that accompanies the injury. Surgical removal of sympathetic inputs to the cervical lymph nodes prior to SCI failed to reverse the effect on antibody production, suggesting a systemic source of catecholamines. We conclude that antibody responses against i.t. antigens are attenuated acutely after SCI due to the massive release of systemic catecholamines that accompanies SCI.

Topics: Adrenergic beta-Antagonists; Analysis of Variance; Animals; Antibodies, Anti-Idiotypic; Antibody Formation; Catecholamines; Down-Regulation; Enzyme-Linked Immunosorbent Assay; Laminectomy; Nadolol; Ovalbumin; Rats; Rats, Sprague-Dawley; Spinal Cord Injuries; Subarachnoid Space; Superior Cervical Ganglion; Sympathectomy; Time Factors

Primary damage caused by injury to the CNS is often followed by delayed degeneration of initially spared neurons. Studies in our laboratory have shown that active or passive immunization with CNS myelin-associated self-antigens can reduce this secondary loss. Here we show, using four experimental paradigms in rodents, that CNS trauma spontaneously evokes a beneficial T cell-dependent immune response, which reduces neuronal loss. (1) Survival of retinal ganglion cells in rats was significantly higher when optic nerve injury was preceded by an unrelated CNS (spinal cord) injury. (2) Locomotor activity of rat hindlimbs (measured in an open field using a locomotor rating scale) after contusive injury of the spinal cord (T8) was significantly better (by three to four score grades) after passive transfer of myelin basic protein (MBP)-activated splenocytes derived from spinally injured rats than in untreated injured control rats or rats similarly treated with splenocytes from naive animals or with splenocytes from spinally injured rats activated ex vivo with ovalbumin or without any ex vivo activation. (3) Neuronal survival after optic nerve injury was 40% lower in adult rats devoid of mature T cells (caused by thymectomy at birth) than in normal rats. (4) Retinal ganglion cell survival after optic nerve injury was higher (119 +/- 3.7%) in transgenic mice overexpressing a T cell receptor (TcR) for MBP and lower (85 +/- 1.3%) in mice overexpressing a T cell receptor for the non-self antigen ovalbumin than in matched wild types. Taken together, the results imply that CNS injury evokes a T cell-dependent neuroprotective response.

Topics: Animals; Autoimmunity; Cell Survival; Cells, Cultured; Disease Models, Animal; Female; Guinea Pigs; Hindlimb; Immunity, Cellular; Immunization, Passive; Interleukin-10; Male; Mice; Mice, Inbred Strains; Mice, Transgenic; Myelin Basic Protein; Nerve Crush; Optic Nerve Injuries; Ovalbumin; Rats; Rats, Inbred Lew; Rats, Sprague-Dawley; Receptors, Antigen, T-Cell; Retinal Ganglion Cells; Spinal Cord Injuries; Spleen; Thymectomy; Wounds, Nonpenetrating

Partial injury to the spinal cord can propagate itself, sometimes leading to paralysis attributable to degeneration of initially undamaged neurons. We demonstrated recently that autoimmune T cells directed against the CNS antigen myelin basic protein (MBP) reduce degeneration after optic nerve crush injury in rats. Here we show that not only transfer of T cells but also active immunization with MBP promotes recovery from spinal cord injury. Anesthetized adult Lewis rats subjected to spinal cord contusion at T7 or T9, using the New York University impactor, were injected systemically with anti-MBP T cells at the time of contusion or 1 week later. Another group of rats was immunized, 1 week before contusion, with MBP emulsified in incomplete Freund's adjuvant (IFA). Functional recovery was assessed in a randomized, double-blinded manner, using the open-field behavioral test of Basso, Beattie, and Bresnahan. The functional outcome of contusion at T7 differed from that at T9 (2.9+/-0.4, n = 25, compared with 8.3+/-0.4, n = 12; p<0.003). In both cases, a single T cell treatment resulted in significantly better recovery than that observed in control rats treated with T cells directed against the nonself antigen ovalbumin. Delayed treatment with T cells (1 week after contusion) resulted in significantly better recovery (7.0+/-1; n = 6) than that observed in control rats treated with PBS (2.0+/-0.8; n = 6; p<0.01; nonparametric ANOVA). Rats immunized with MBP obtained a recovery score of 6.1+/-0.8 (n = 6) compared with a score of 3.0+/-0.8 (n = 5; p<0.05) in control rats injected with PBS in IFA. Morphometric analysis, immunohistochemical staining, and diffusion anisotropy magnetic resonance imaging showed that the behavioral outcome was correlated with tissue preservation. The results suggest that T cell-mediated immune activity, achieved by either adoptive transfer or active immunization, enhances recovery from spinal cord injury by conferring effective neuroprotection. The autoimmune T cells, once reactivated at the lesion site through recognition of their specific antigen, are a potential source of various protective factors whose production is locally regulated.

Topics: Animals; Female; Guinea Pigs; Immunization, Passive; Lymphocyte Transfusion; Myelin Basic Protein; Ovalbumin; Rats; Rats, Inbred Lew; Red Nucleus; Spinal Cord Injuries; T-Lymphocytes; Time Factors