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Interleukin 1-alpha and tumor necrosis factor-alpha induce oxygen radical production in mesangial cells
H H Radeke1, B Meier, N Topley
1Department of Molecular Pharmacology, Medical School, Hannover, Federal Republic of Germany.
Abstract:
Adherent human mesangial cells (HMC) were unable to phagocytose serum-treated zymosan (STZ), nevertheless this stimulus (1 mg/ml) induced a marked immediate increase of H2O2 and O2- release at a rate of 3.15 +/- 0.35 and 3.40 +/- 0.12 nmol/10(6) HMC/hr, respectively. Zymosan alone resulted in no release of either H2O2 or O2-. Phorbol myristate acetate (PMA, 2 X 10(-6) M) had only marginal effects on HMC leading to the generation of 0.273 +/- 0.014 nmol O2-/10(6) HMC/hr. After a lag period, human recombinant tumor necrosis factor-alpha (TNF-alpha) and human recombinant interleukin 1-alpha IL-1 alpha) both induced significant O2- production measured as SOD inhibitable reduction of cytochrome c, 5 X 10(-5) M, by adherent HMC for up to five hours, the maximum rates being 3.04 +/- 0.08 and 3.2 +/- 0.08 nmol/10(6) HMC/hr for IL-1 alpha and TNF-alpha, respectively. Significant O2- release was detectable at 0.625 ng/ml (37 pM) IL-1 alpha or 1 ng/ml (59 pM) TNF-alpha (P less than 0.05). Catalase inhibitable H2O2 production was also induced by IL-1 alpha and TNF-alpha in a dose dependent manner. Using scopoletin (40 nM) and 1 microM peroxidase we fluorimetrically measured 1.73 +/- 0.14 and 1.49 +/- 0.19 nmol H2O2/10(6) HMC/hr induced by IL-1 alpha (25 ng/ml) and TNF-alpha (20 ng/ml). Finally, we ascertained the type of radical species produced by HMC stimulated by cytokines employing ESR-spin-trapping with DMPO.2+ These results demonstrated that O2- was the primary radical species formed.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Human mesangial cells (HMC) release hydrogen peroxide (H2O2) and superoxide (O2-) when stimulated by cytokines like interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha). These reactive oxygen species play a key role in cellular responses.
Area of Science:
- Cellular and Molecular Biology
- Immunology
- Renal Physiology
Background:
- Human mesangial cells (HMC) are crucial components of the kidney glomerulus.
- The role of reactive oxygen species (ROS) production by HMC in response to inflammatory stimuli is not fully understood.
- Understanding HMC responses is vital for comprehending kidney disease pathogenesis.
Purpose of the Study:
- To investigate the production of hydrogen peroxide (H2O2) and superoxide (O2-) by human mesangial cells (HMC).
- To determine the effect of specific inflammatory stimuli, including serum-treated zymosan (STZ), phorbol myristate acetate (PMA), interleukin-1 alpha (IL-1 alpha), and tumor necrosis factor-alpha (TNF-alpha), on ROS generation in HMC.
- To identify the primary radical species produced by stimulated HMC.
Main Methods:
- Measurement of H2O2 and O2- release from adherent HMC using various assays.
- Stimulation of HMC with serum-treated zymosan (STZ), phorbol myristate acetate (PMA), and recombinant cytokines (IL-1 alpha, TNF-alpha).
- Electron spin resonance (ESR) spectroscopy with spin-trapping (DMPO) to identify radical species.
Main Results:
- HMC did not phagocytose STZ but released significant amounts of H2O2 and O2- upon stimulation.
- IL-1 alpha and TNF-alpha induced dose-dependent O2- and H2O2 production in HMC, with O2- being the primary radical species.
- PMA had only marginal effects on ROS production in HMC.
Conclusions:
- Human mesangial cells (HMC) are capable of generating significant amounts of superoxide (O2-) and hydrogen peroxide (H2O2) when stimulated by inflammatory cytokines.
- Interleukin-1 alpha (IL-1 alpha) and tumor necrosis factor-alpha (TNF-alpha) are potent inducers of ROS production in HMC.
- Superoxide (O2-) is identified as the primary reactive oxygen species generated by cytokine-stimulated HMC, suggesting its role in inflammatory kidney conditions.