| Objective:Guillian-Barre Syndrome, GBS, is an acute inflammatory demyelinating polyneuropathy, characterized by inflammatory cell infiltrates and demyelination of the peripheral nerves. Experimental autoimmune neuritis (EAN) is a CD4+T-helper 1 (Thl) cell-mediated inflammatory demyelinating disease of the peripheral nervous system (PNS) that mirrors many clinical and immunological features of human acute inflammatory demyelinating polyradiculoneuropathies (AIDP). EAN serves as an animal model of Guillain Barre Syndrome (GBS). However the exact mechanism of GBS/EAN is elusive, hence development of effective therapy for GBS is still a challenge.Recently, there has been an increased focus on the therapeutic usage of drugs that target the nuclear receptor peroxisome proliferatbr activated receptor y, PPARy. PPARy, originally identified on adipocytes playing a role in adipocyte differentiation and regulation of insulin responses, has now been identified in other tissues as well as exerting an important role in macrophages and dendritic cells. Pioglitazone, a synthetic PPARy ligand has proven to be an attractive target for the treatment of autoimmune diseases whereby amelioration of disease related symptomatology and pathology in a number of animal models were observed. A rationale of pioglitazone in these disease models is that it activates PPARy receptors with a subsequent repression of inflammatory response. It has been demonstrated that PPARy agonists act by repressing the transcription of a broad range of inflammatory genes of macrophages causing suppression of inflammatory cytokines such as TNFa, IFNy, IL1βwhich are all involved in the pathogenesis of EAN.In this study, the animal model of EAN was administered with pioglitazone as from the first day postimmunization in the first interventional group and as from the appearance of the first symptom in the second interventional group and variation in clinical symptoms were compared between the interventional and EAN groups. Our aim was to investigate the suppressive and the therapeutic role of pioglitazone, PPARy agonist, as anti-inflammatory drug, thus providing a new target for treatment of EAN. Methods:80 Lewis rats, specified pathogen free, male, age 6-8 weeks,160-180g were randomly divided into 5 groups:CFA group(4,4,4,4); EAN group(4,4,4,4); EAN+PIO(Ⅰ) (4,4,4,4); EAN+PIO(Ⅱ)(4,4,4,4); EAN+PBS(4,4,4,4).The EAN model was established by injecting 200μl of antigen (a mixture of P253-78 with NS dissolved in Freund's adjuvant). CFA group was injected only with Freund's adjuvant (200μl/rat). Rats were immunized by injection into both hind foot pads subcutaneously.The EAN+PIO(Ⅰ), EAN+PIO(Ⅱ) and EAN+PBS groups were given 1ml pioglitazone solution (10mg/kg) from day 1 to day 24, lml pioglitazone solution (10mg/kg) from day 11 to day 24 and 1 ml of PBS from day 1 to day 24 by oral gavage respectively.Body weight.and clinical scoring were done for all rats from day 1 to day 33. Four rats from each group were sacrificed on day 7,16,24 and 33 postimmunisation respectively. Pathological examination of inflammatory infiltrates and demyelination in sciatic nerve was done by H/E and Weil's staining. The expression of TNFαmRNA, PPARγmRNA and IL4 mRNA in lymph nodes were determined by Real-Time PCR while expression of nuclear NFκB p65 protein in lymph nodes was assessed by western blot. Expression level of IFNγwas measured in the supernatant of lymph node cell culture by ELISA.Results: The clinical score of the EAN group peaked on day 16 post immunization with obvious amelioration by day 32. Compared to EAN, the pioglitazone interventional groups [EAN+PIO(Ⅰ) and EAN+PIO(Ⅱ)] had lower clinical scores and reduced duration of disease. EAN+PIO(Ⅰ) had reduced disease severity and duration compared to EAN+PIO(Ⅱ). The TNFαand IFNγexpression were lower while IL4 expression was higher in the interventional groups [EAN+PIO(Ⅰ) and EAN+PIO(Ⅱ)] compared to the EAN group, p<0.05. In the EAN+PIO(Ⅰ) group, the level of TNFαwas lower than that of EAN+PIO(Ⅱ) with significant differences in the early and peak phases, p<0.05. In the EAN+PIO(Ⅰ) group, the level of IL 4 was higher in all phases compared to EAN+PIO(Ⅱ), with significant differences in the early and peak phases, p<0.01. The PPARγexpression was higher while NFκB p65 expression was lower in the interventional groups compared to the EAN group, p<0.05. In the EAN+PIO(Ⅰ) group, the level of PPARy was higher than EAN+PIO(II), with significant difference in all phases, p<0.05. In the EAN+PIO(I) group, NFκB p65 levels was significantly lower than the EAN+PIO(II) group with significant differences in early and peak phases, p<0.05. CFA group did not show any neurological sign of disease. No significant differences were observed between EAN and EAN+PBS groups.Conclusion:Pioglitazone exerts significant suppressive and therapeutic anti-inflammatory effects which ameliorate clinical symptoms of EAN. Pioglitazone acts by PPARy receptor dependent inhibition of NFκB signaling pathway. |
PDF Full Text Request