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Growth hormone inhibits apoptosis and up-regulates reactive oxygen intermediates production by human
Background:
Growth hormone (GH) regulates the immune and metabolic systems; however, the effects of GH on the functions and cell death of polymorphonuclear neutrophils (PMNs) are not well understood. Therefore, this study was designed to investigate the effects of GH on PMN apoptosis, reactive oxygen intermediates (ROI) production, CD16, and Fas expression. We also investigated the effects of GH on the functions of other circulating leukocytes (ie, monocytes and lymphocytes).
Methods:
Venous blood was collected from healthy volunteers. Whole blood was washed and pretreated with GH (0 or 100 ng/mL) for 3 hours and then cultured for 0, 4, or 12 hours. PMNs in washed whole blood were analyzed by flow cytometry for cell death, phorbol myristate acetate-stimulated ROI production, CD16, and Fas expression at each time point. Morphologic features also were assessed. PMN apoptosis was confirmed by chromatin staining and DNA gel electrophoresis.
Results:
GH inhibited PMN apoptosis at 12 hours of culture. GH enhanced ROI production by PMNs and monocytes throughout the 12-hour culture but had no effects on CD16 expression on PMNs. Furthermore, GH decreased Fas expression on PMNs at 4 hours of culture. However, there were no effects of GH on apoptosis of monocytes or lymphocytes for the duration of this experiment.
Conclusions:
GH pretreatment down-regulates Fas expression on PMNs, inhibits apoptosis, and up-regulates ROI production. GH pretreatment also increases monocyte ROI production. Although activated PMNs have potentially harmful aspects, our results suggest that GH may improve host defense, mainly through enhancement of the PMN functional life span.
Insights
Growth hormone (GH) enhances immune defense by prolonging the lifespan of polymorphonuclear neutrophils (PMNs). GH boosts reactive oxygen intermediate (ROI) production and inhibits PMN apoptosis, improving host defense mechanisms.
Area of Science:
- Immunology
- Endocrinology
- Cell Biology
Background:
- Growth hormone (GH) plays a role in immune and metabolic regulation.
- The specific effects of GH on polymorphonuclear neutrophils (PMNs) function and apoptosis are not fully understood.
Purpose of the Study:
- To investigate the impact of GH on PMN apoptosis, reactive oxygen intermediate (ROI) production, CD16, and Fas expression.
- To examine GH's effects on monocyte and lymphocyte functions.
Main Methods:
- Human venous blood was collected and pretreated with GH.
- PMNs, monocytes, and lymphocytes were analyzed via flow cytometry for cell death, ROI production, CD16, and Fas expression.
- Apoptosis was confirmed using chromatin staining and DNA gel electrophoresis.
Main Results:
- GH inhibited PMN apoptosis at 12 hours.
- GH enhanced ROI production in PMNs and monocytes.
- GH decreased Fas expression on PMNs at 4 hours but did not affect CD16 expression.
- GH had no significant effect on monocyte or lymphocyte apoptosis.
Conclusions:
- GH down-regulates Fas expression, inhibits apoptosis, and up-regulates ROI production in PMNs.
- GH enhances monocyte ROI production.
- GH may improve host defense by extending the functional lifespan of PMNs.