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Inhibition of murine peritoneal macrophage functions by sulfated cholecystokinin octapeptide
M De la Fuente1, M Campos, M Del Rio
1Departamento de Biología Animal II (Fisiología Animal), Facultad de Ciencias Biológicas, Universidad Complutense de Madrid, Spain.
Abstract:
The effect in vitro of the sulfated octapeptide form of cholecystokinin, CCK-8, at concentrations from 10(-12) M to 10(-6) M on several functions of resting peritoneal macrophages from BALB/c mice: adherence to substrate, mobility (spontaneous and directed by chemical gradient or chemotaxis), ingestion of inert particles (latex beads) or cells (Candida albicans), and production of superoxide anion measured by nitroblue tetrazolium reduction was studied. CCK-8, at concentrations from 10(-10) M to 10(-8) M, inhibited significantly all functions studied with the exception of adherence to substrate, which was increased. A dose-response relationship was observed, with a maximum inhibition of macrophage functions found at 10(-8) M. This neuropeptide induced in murine macrophages a significant, but transient, increase of cAMP levels at 60 sec. On the contrary, CCK-8 produced a slight but significant decrease of protein kinase C (PKC) activity at 5 min of incubation. These results suggest that CCK-8 is a negative modulator of several macrophage functions, and that the inhibition of these activities is carried out through an increase of intracellular cAMP levels and a decrease in PKC activity.
Insights
The sulfated octapeptide cholecystokinin-8 (CCK-8) negatively impacts macrophage functions like mobility and particle ingestion. CCK-8 increases cAMP and decreases protein kinase C activity, modulating immune responses.
Area of Science:
- Immunology
- Neuroendocrinology
- Cellular Biology
Background:
- Macrophages are critical immune cells involved in phagocytosis and inflammatory responses.
- Cholecystokinin (CCK) is a neuropeptide hormone with diverse physiological roles, including potential immunomodulatory effects.
- Understanding the interaction between neuropeptides and immune cells is crucial for developing novel therapeutic strategies.
Purpose of the Study:
- To investigate the in vitro effects of cholecystokinin-8 (CCK-8) on various functions of resting murine peritoneal macrophages.
- To elucidate the intracellular signaling pathways, specifically cyclic adenosine monophosphate (cAMP) and protein kinase C (PKC) activity, involved in CCK-8's immunomodulatory actions.
Main Methods:
- Peritoneal macrophages from BALB/c mice were isolated and exposed to varying concentrations of CCK-8 (10^-12 M to 10^-6 M).
- Macrophage functions including adherence, spontaneous and directed mobility, particle and cellular ingestion, and superoxide anion production were assessed.
- Intracellular cAMP levels and PKC activity were measured at specific time points post-incubation with CCK-8.
Main Results:
- CCK-8 significantly inhibited macrophage adherence, mobility, ingestion of particles and Candida albicans, and superoxide anion production at concentrations between 10^-10 M and 10^-8 M.
- A dose-dependent inhibitory effect was observed, with maximal inhibition occurring at 10^-8 M CCK-8.
- CCK-8 induced a transient increase in intracellular cAMP levels and a decrease in PKC activity in macrophages.
Conclusions:
- CCK-8 acts as a negative modulator of key macrophage functions.
- The observed inhibition of macrophage functions by CCK-8 is mediated by an increase in intracellular cAMP and a decrease in PKC activity.
- These findings suggest a role for CCK-8 in regulating immune cell activity through neuro-immune interactions.