Epidemiological findings support the hypothesis that type 2 diabetes mellitus (T2DM) is a risk factor for osteoarthritis (OA). Moreover, OA cartilage from patients with T2DM exhibits a greater response to inflammatory stress, but the molecular mechanism is unclear. To investigate whether the antioxidant defense system participates in this response, we examined here the expression of nuclear factor-erythroid 2-related factor (Nrf-2), a master antioxidant transcription factor, and of heme oxygenase-1 (HO-1), one of its main target genes, in OA cartilage from T2DM and non-T2DM patients as well as in murine chondrocytes exposed to high glucose (HG). Ex vivo experiments indicated that Nrf-2 and HO-1 expression is reduced in T2DM versus non-T2DM OA cartilage (0.57-fold Nrf-2 and 0.34-fold HO-1), and prostaglandin E 2 (PGE 2 ) release was increased in samples with low HO-1 expression. HG-exposed, IL-1β-stimulated chondrocytes had lower Nrf-2 levels in vitro, particularly in the nuclear fraction, than chondrocytes exposed to normal glucose (NG). Accordingly, HO-1 levels were also decreased (0.49-fold) in these cells. The HO-1 inducer cobalt protoporphyrin IX more efficiently attenuated PGE 2 and IL-6 release in HG+IL-1β-treated cells than in NG+IL-1β-treated cells. Greater reductions in HO-1 expression and increase in PGE 2 /IL-6 production were observed in HG+IL-1β-stimulated chondrocytes from Nrf-2 −/− mice than in chondrocytes from wild-type mice. We conclude that the Nrf-2/HO-1 axis is a critical pathway in the hyperglucidic-mediated dysregulation of chondrocytes. Impairments in this antioxidant system may explain the greater inflammatory responsiveness of OA cartilage from T2DM patients and may inform treatments of such patients.
The species composition of cyanobacteria assemblages was studied in six thermo-mineral springs of spas in Atlantic environments of Galicia (NW Spain). Two are considered hot (T a ≥ 40 °C), two intermediate (T a 20-40 °C) and two cold (T a ≤ 20 °C), and four contain hydrogen sulphide. A total of 21 taxa (14 genera) have been recorded. Two diversity indices, Shannon index and Evenness were determined. The Shannon-Wiener index ranged between 0.31 and 0.73 and the Evenness index between 0.44 and 0.88. nMDS ordination showed that cyanobacteria assemblage composition was influenced mostly by temperature. Of the species identified, the most diverse genus is Leptolyngbya with four species, followed by Chroococcus with three species and Aphanocapsa, Phormidium and Lyngbya with two species. The most abundant species was Jaaginema angustissimum, followed by Leptolyngbya laminosa and Symploca thermalis. In the two cold springs, seven different species were found, and only Aphanocapsa conferta was common to both springs. Cyanobacterial species were more numerous in the four hot springs, with 15 different species and only Calothrix thermalis common to these hot springs. It is difficult to establish characteristic cyanobacterial flora for the thermo-mineral waters of the Galician springs since there are significant differences in the communities from the six sites studied.
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