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Modulation of beta-galactosidase activity in peritoneal macrophages from C57B1 mice after exposure to
J M Rhodes1, S E Rasmussen, S Burchardt
1International Escherichia and Klebsiella Centre, Statens Seruminstitut, Copenhagen, Denmark.
Abstract:
Peritoneal macrophages (PM luminal diameter) from untreated C57B1 mice contain high levels of beta-galactosidase (beta-gal) and these PM luminal diameter are heterogeneous in their expression of this enzyme. Intraperitoneal (i.p.) injection of saline caused a transient depression in the level of enzyme activity in the PM luminal diameter whereas i.p. injection of Proprionibacterium acnes (P. acnes) gave rise to a marked decrease of beta-gal activity in these cells. This reduction in enzymatic activity persisted for as long as the PM luminal diameter were activated for cytotoxicity towards the L929 tumor cell line, up to 35 days after injection. beta-gal activity was present in the lavage fluid from day 2-21 after injection of P. acnes but none was detected in the lavage fluid after injection of saline. It is proposed that the enzymatic activity in the lavage fluid is derived from monocytes which migrate from the blood into the peritoneal cavity. There was an influx of granulocytes in the P. acnes group which persisted up to 35 days after injection. In contrast none were observed in the saline group after 2 days. PM luminal diameter harvested after 1-35 days were large, highly vacuolized and many contained bacteria; these PM luminal diameter had the typical morphology of activated cells. It is suggested that the processing of P. acnes by granulocytes may play a role in the activation of macrophages in the early inflammatory response, with concurrent loss in beta-gal activity. However, in the later stages, interferon-gamma and other induced lymphokines may be instrumental in causing a decrease in beta-gal activity.
Insights
Proprionibacterium acnes (P. acnes) significantly reduces beta-galactosidase (beta-gal) activity in mouse peritoneal macrophages. This reduction correlates with macrophage activation and cytotoxicity, suggesting a role in inflammatory responses.
Area of Science:
- Immunology
- Cell Biology
- Microbiology
Background:
- Peritoneal macrophages (PMs) in untreated mice exhibit heterogeneous beta-galactosidase (beta-gal) levels.
- Beta-gal is an enzyme found in macrophages, and its activity can be modulated by various stimuli.
Purpose of the Study:
- To investigate the effect of Proprionibacterium acnes (P. acnes) on beta-gal activity in peritoneal macrophages.
- To explore the relationship between P. acnes-induced changes in beta-gal activity and macrophage activation/cytotoxicity.
Main Methods:
- Intraperitoneal injection of saline or P. acnes into C57B1 mice.
- Measurement of beta-gal activity in peritoneal macrophages and lavage fluid.
- Assessment of macrophage morphology, bacterial presence, and cytotoxicity against L929 tumor cells.
- Monitoring of granulocyte influx into the peritoneal cavity.
Main Results:
- P. acnes injection markedly decreased beta-gal activity in peritoneal macrophages, persisting up to 35 days.
- This decrease correlated with macrophage activation, increased cytotoxicity, and granulocyte influx.
- Beta-gal activity was detected in lavage fluid after P. acnes but not saline injection, suggesting monocyte origin.
Conclusions:
- P. acnes induces a significant and sustained reduction in macrophage beta-gal activity, linked to inflammatory activation.
- Granulocyte processing of P. acnes may initiate early macrophage activation and beta-gal loss.
- Later stages of inflammation may involve lymphokines like interferon-gamma in further reducing beta-gal activity.