OBJECTIVETo investigate the expression of the integrin alpha6beta4 in experimental allergic neuritis (EAN) and the relationship of the integrin alpha6beta4 with functional states of Schwann cells (Sc) as well as the injury and repair of the myelin during EAN.

METHODSEAN was induced in Lewis rats and sciatic nerves were resected in 18 EAN and 3 normal rats. The expression of tissue integrin alpha6beta4 was analyzed during the course of EAN induction and in controls by in situ hybridization and semi-quantitative RT-PCR.

RESULTSThe detection of integrin alpha6 and beta4 subunit by hybridization in situ demonstrated that expression of alpha6 subunit present no significant changes during the course of EAN, while expression of beta4 declined in the early phase, showing less positive signals than those of the control, and restored its expression in the later or recovery phase. The changes of expression of integrin alpha6 and beta4 in EAN were confirmed by semi-quantitative PT-PCR, using GAPDH as the internal standard.

CONCLUSIONSThe degeneration and injury of Sc caused by inflammation affect the expression of integrin, which shows similar changes in Sc during embryogenesis, indicating alpha6beta4 may be a marker of Sc differentiation and at least an important molecule to mark the course of EAN. The expression of alpha6beta4 correlate with the injury and repair of myelin during EAN.

Animals ; Disease Models, Animal ; In Situ Hybridization ; Integrin alpha6beta4 ; genetics ; physiology ; Neuritis, Autoimmune, Experimental ; metabolism ; pathology ; RNA, Messenger ; analysis ; Rats ; Rats, Inbred Lew ; Reverse Transcriptase Polymerase Chain Reaction

To investigate the pattern of expression of osteopontin (OPN) in tissues of the central nervous system (CNS) responding to peripheral immunological stimulation, the expression of OPN was studied in the spinal cord of rats with experimental autoimmune neuritis (EAN). In this model system, the sciatic nerves and spinal nerve roots are the target organs of EAN and the spinal cord is a remote organ that may be indirectly affected. OPN was constitutively expressed in some astrocytes adjacent to the pia mater and neurons in normal rats. In rats with EAN, OPN was increased in the same cells and in some inflammatory cells, including macrophages in the subarachnoid space. Expression of CD44, a receptor of OPN, was weak in normal spinal cord tissue and increased in the entire spinal cord parenchyma in rats with EAN, as well as in inflammatory cells. These findings suggest that inflammatory cells as well as reactive astrocytes are major sources of OPN and CD44 in the spinal cord of rats with EAN. Further study is needed to elucidate the functional role of OPN in the spinal cord affected by EAN.
Animals ; Antigens, CD44/metabolism ; Astrocytes/metabolism ; Ectodysplasins ; Female ; Immunohistochemistry ; Macrophages/metabolism ; Membrane Proteins ; Neuritis, Autoimmune, Experimental/*metabolism ; Neuroglia/metabolism ; Neurons/metabolism ; Osteopontin ; Rats ; Rats, Inbred Lew ; Sciatic Nerve/metabolism ; Sialoglycoproteins/*metabolism ; Spinal Cord/*metabolism ; Spinal Nerve Roots/metabolism

OBJECTIVE: To examine the expression of mRNA of Oxford 40(OX40) and Oxford 40 ligand(OX40L) in the sciatic nerve, spleen, peripheral blood mononuclear cells and lymph nodes of experimental allegic neuritis (EAN). METHODS: Thirty-six Lewis rats were randomly assigned into an EAN group and a CFA group. The rats were sacrificed on 9th, 17th, and 26th day after immunization. OX40 and OX40L mRNA was detected by reverse transcription polymerase chain reaction in the spleen, sciatic nerves, peripheral blood mononuclear cells and lymphonodes. RESULTS: The peak of clinical course came on 17th day after the immunization in EAN. The mRNA expression of OX40/OX40L was higher on 8th day and 17th day than that on 26th day after the immunization (P<0.05). There was significant difference between the EAN group and the CFA group at the 3 time points (P<0.05); rats in the CFA group didn't have any clinical manifestations. The mRNA expression of OX40 and OX40L in the EAN group raised in the sciatic nerves and lymph nodes at the above 3 time points (P<0.05). Weak expression was seen in the peripheral blood mononuclear cells. CONCLUSION OX40 and OX40L may play a role in the pathogenesis of experimental allegic neuritis.
Animals ; Female ; Membrane Glycoproteins ; genetics ; metabolism ; Neuritis, Autoimmune, Experimental ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Random Allocation ; Rats ; Rats, Inbred Lew ; Receptors, OX40 ; genetics ; metabolism ; Sciatic Nerve ; metabolism ; Tumor Necrosis Factors ; genetics ; metabolism

The phosphorylation of c-Jun NH (2)-terminal protein kinase (JNK), one of the mitogen-activated protein kinases, was analyzed in the sciatic nerves of Lewis rats with experimental autoimmune neuritis (EAN). Western blot analysis showed that the expression levels of both phosphorylated JNK1 (p-JNK1, approximately 46 kDa) and phosphorylated JNK2 (p-JNK2, approximately 54 kDa) in the sciatic nerves of rats with EAN increased significantly (p < 0.05) at day 14 post-immunization (PI) and remained at this level at days 24 and 30 PI, with a slight decrease. In EANaffected sciatic nerves, there was intense immunostaining for p-JNK in the infiltrating inflammatory cells (especially ED1- positive macrophages) and Schwann cells on days 14-24 PI, compared with those of controls. Some macrophages with increased p-JNK immunoreactivity was shown to be apoptotic, while some Schwann cells remained survived in this rat EAN model, suggesting that JNK is differentially involved in the EAN-affected sciatic nerves. These findings suggest that JNK phosphorylation is closely associated with the clearance of inflammatory cells as well as the activation of Schwann cells in the EAN affected sciatic nerves.
Animals ; Apoptosis/physiology ; Blotting, Western ; Ectodysplasins ; Female ; Immunohistochemistry ; In Situ Nick-End Labeling ; JNK Mitogen-Activated Protein Kinases/*metabolism ; Membrane Proteins/metabolism ; Neuritis, Autoimmune, Experimental/*enzymology/metabolism/pathology ; Phosphorylation ; Rats ; Rats, Inbred Lew ; S100 Proteins/metabolism ; Schwann Cells/metabolism ; Sciatic Nerve/*enzymology/metabolism/pathology ; Tumor Necrosis Factors/metabolism