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Different endothelins stimulate cytokine production by peritoneal macrophages and microglial cell line
L Speciale1, K Roda, M Saresella
1Laboratory of Biology, Don C. Gnocchi Foundation, IRCCS, Milan, Italy.
Abstract:
Endothelins (ETs), potent vasoconstricting peptides, are produced by macrophages upon stimulation and may participate in the amplification or regulation of the inflammatory response. However, it is not clear whether ETs can act in an autocrine manner on macrophages and which role they play in relationship with other cytokines. To address these issues, we studied the effects of ETs on the production of inflammatory cytokines by mouse peritoneal macrophages or by a retrovirus-transformed microglial cell line. Here, we report that ET-2, but not ET-1 or ET-3, is able to stimulate the production of interleukin-1 (IL-1) and interleukin-6 (IL-6) by peptone-elicited mouse macrophages (pMO). In contrast, ET-3 and ET-1, but not ET-2, are active on microglial cells. No tumour necrosis factor-alpha (TNF-alpha) or nitric oxide (NO) were detected in the supernatants of ET-stimulated cultures. The activity of ET-2 on pMO was time and dose dependent and was inhibited by the addition of ETA and ETB receptor antagonists, BQ123 and IRL1038, respectively. In addition, when pMO were stimulated by interferon-gamma (IFN-gamma) in the presence of ET-2, a significant inhibition of IL-6 and IL-1 production was observed compared with the effects of the same doses of IFN-gamma or ET-2 used separately. The inhibition was specifically due to the activity of ET-2, since it was reversed by the addition of BQ123 or IRL1038. Similar results were seen when the content of NO in the supernatants of pMO stimulated by IFN-gamma plus ET-2 was evaluated. These results suggest that ETs may possess both a pro-inflammatory action on macrophages from different tissues and a regulatory activity on IFN-gamma.
Insights
Endothelins (ETs) differentially affect inflammatory cytokine production in macrophages. ET-2 stimulates interleukin-1 and -6 in peritoneal macrophages, while ET-1 and ET-3 act on microglial cells, suggesting complex regulatory roles.
Area of Science:
- Immunology
- Molecular Biology
- Endocrinology
Background:
- Endothelins (ETs) are potent vasoconstrictors produced by macrophages.
- Their role in macrophage-mediated inflammation and autocrine signaling is not fully understood.
- Investigating ETs' interaction with cytokines is crucial for understanding inflammatory responses.
Purpose of the Study:
- To investigate the effects of different endothelins (ET-1, ET-2, ET-3) on inflammatory cytokine production by macrophages.
- To determine if ETs act in an autocrine manner on macrophages.
- To elucidate the regulatory role of ETs in conjunction with other inflammatory mediators like interferon-gamma (IFN-gamma).
Main Methods:
- Primary mouse peritoneal macrophages (pMO) and a microglial cell line were treated with ET-1, ET-2, and ET-3.
- Cytokine production (IL-1, IL-6, TNF-alpha) and nitric oxide (NO) levels were measured.
- Receptor antagonists (BQ123, IRL1038) were used to block ET receptor activity.
- Cells were stimulated with IFN-gamma in the presence or absence of ET-2 to assess synergistic or inhibitory effects.
Main Results:
- ET-2 stimulated interleukin-1 (IL-1) and interleukin-6 (IL-6) production in pMO, an effect blocked by ETA and ETB antagonists.
- ET-1 and ET-3, but not ET-2, stimulated cytokine production in microglial cells.
- Tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) were not detected in ET-stimulated cultures.
- ET-2 significantly inhibited IFN-gamma-induced IL-1 and IL-6 production in pMO, an effect reversible with antagonists.
Conclusions:
- Endothelins exhibit differential effects on cytokine production depending on the macrophage type.
- ET-2 plays a pro-inflammatory role in peritoneal macrophages by inducing IL-1 and IL-6.
- ETs can modulate the inflammatory response, as demonstrated by ET-2's regulatory activity on IFN-gamma-induced cytokine production and NO levels.