The present research summarizes the protective and immunomodulatory activity of hypothalamic
proline-rich
polypeptide galarmin against methicillin-resistant Staphylococcus aureus (MRSA). The protective effect of
galarmin was shown on MRSA-infected animals' survival and
weight loss recovery. The immunological impact of
galarmin was evaluated in terms of immunocompetent cell recruitment, serum
immunoglobulins,
complement components C3 and C4, and pro- and anti-inflammatory
cytokines (IL-6, IL-8, IL-10, IL-1b, TNFa, and KC) secretion.
Galarmin efficiently protects mice against lethal MRSA
infection (100% of survival vs. 0% in the untreated group) when intramuscularly injected 24 h before
infection and during the 1-h post-
infection period at a concentration of 1 μg per mouse, while its higher concentrations (5 and 10 μg) were protective when injected in parallel to the
infection process. The protective effect of
galarmin was not due to a direct effect on MRSA, but should be attributed to an action on the host response to
infection.
Galarmin significantly increased and modulated the levels of
IL-6,
IL-8, IL-1b,
IL-10, and KC in both peritoneal lavages and blood, leukocyte and platelet counts, lymphocytes percentage, serum
IgM and
IgG, and
complement C3 and C4 components secretion. The experimental results allow concluding that
galarmin is a powerful immunomodulatory and
protective agent for the in vivo prophylaxis and treatment of MRSA-induced
infection.