Heme oxygenase (HO)-1 is a stress-inducible enzyme protecting cells against oxidative stress, and mechanisms have been considered to depend exclusively on its enzyme activity. This study aimed to examine if the protein lacking catalytic activities could also display such resistance against oxidative stress. Stable transfectants of rat wild type HO-1 cDNA (HO-1-U937) and those of its H25A mutant gene (mHO-1-U937) were established using human monoblastic lymphoma cell U937. HO-1-U937 and mHO-1-U937 used in the study exhibited similar levels of the protein expression, while only the former increased enzyme activities. HO-1-and mHO-1 U937 cells became more and less sensitive to H 2 O 2 than mock transfectants, respectively; such distinct susceptibility between the cells was ascribable to differences in the capacity to scavenge H 2 O 2 through catalase and to execute iron-mediated oxidant propagation. On the other hand, both cell lines exhibited greater resistance to tertbutyl hydroperoxide than mock transfectants. The resistance of HO-1-U937 to hydroperoxides appeared to result from antioxidant properties of bilirubin, an HOderived product, while that of mHO-1-U937 was ascribable to increased contents of catalase and glutathione.
Polyarteritis nodosa (PN) is a classical collagen disease with poor prognosis that demonstrates systemic necrotizing vasculitis of small and medium-sized arteries. Cutaneous symptoms are observed in 25-60% of PN patients. On other hand, cutaneous polyarteritis nodosa (CPN) is designated for the cutaneous limited form of PN and demonstrates benign prognosis. However, there has been much debate on whether or not CPN can progress to PN. Although CPN lesions are fundamentally limited to skin, some CPN cases show extracutaneous symptoms such as peripheral neuropathy and myalgia. According to PN diagnostic criteria, which were established by the Ministry of Health, Labour and Welfare of Japan, a disease with both cutaneous and at least one extracutaneous symptom with appropriate histopathological findings can be diagnosed as PN. The same is true according to diagnostic criteria established by the American College of Rheumatology. In addition, there are no specific diagnostic criteria for CPN. In this study, CPN cases were retrospectively collected from multiple Japanese clinics, and analyzed for detailed clinical and histopathological manifestations, in order to redefine the clinical entity of CPN and to propose appropriate diagnostic criteria for CPN and PN. According to the CPN description in Rook's Textbook of Dermatology, we collected 22 cases with appropriate histopathological findings. Of the 22 cases, none progressed to PN or death during the follow-up period, 32% had peripheral neuropathy and 27% had myalgia. Regarding extracutaneous symptoms with CPN, 17 dermatological specialists in vasculitis sustained the opinion that CPN can be accompanied by peripheral neuropathy and myalgia but these symptoms are limited to the same area as skin lesions. Based on these results, we devised new drafts for CPN and PN diagnostic criteria. Our study shows the efficacy of these criteria and most dermatologists recognized that our new diagnostic criteria for CPN and PN are appropriate at the present time. In conclusion, this study suggests that CPN does not progress to PN, and introduces new drafts for CPN and PN diagnostic criteria.
Based on these findings, the loss of CD34 vascular endothelial markers occurs in the early phase of the disease because of the MPO, which is presumed to have burst out from the infiltrated, activated neutrophils. This MPO, which releases proteolytic enzymes and radical oxygen species, acts on tissue destruction, namely the lysis of endothelial cell membranes as well as vascular basement membranes in the peritubular capillary. This mechanism eventually proceeds to the destruction of the peritubular capillary walls (vasculitis). This pathogenesis is thought to play an important role in the pathogenesis of TI nephritis, which is associated with MPO-ANCA vasculitis.
We (JMAAV [Japanese patients with MPO-ANCA-associated vasculitis] Study Group) performed a prospective, open-label, multi-center trial to evaluate the usefulness of severity-based treatment in Japanese patients with myeloperoxidase-anti-neutrophil cytoplasmic antibodies (MPO-ANCA)-associated vasculitis. Patients with MPO-ANCA-associated vasculitis received a severity-based regimen according to the appropriate protocol: low-dose corticosteroid and, if necessary, cyclophosphamide or azathioprine in patients with mild form; high-dose corticosteroid and cyclophosphamide in those with severe form; and the severe-form regimen plus plasmapheresis in those with the most severe form. We followed up the patients for 18 months. The primary end points were the induction of remission, death, and end-stage renal disease (ESRD). Fifty-two patients were registered, and 48 patients were enrolled in this study (mild form, n = 23; severe form, n = 23; most severe form, n = 2). Among the 47 patients who received the predefined therapies, 42 achieved remission within 6 months, 5 died, and 1 developed ESRD. Disease flared up in 8 of the 42 patients with remission during the 18-month follow-up period. The JMAAV trial is the first prospective trial for MPO-ANCA-associated vasculitis to be performed in Japan. The remission and death rates were comparable to those in several previous clinical trials performed in western counties. The regimen employed in this trial was tailor-made based on patients’ disease severity and disease type, and it seems that standardization can be consistent with treatment choices made according to severity.
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