L-arginine metabolites contribute to parasite elimination

Nitric oxide (NO) is an important effector molecule of the immune system in eliminating numerous pathogens. Peritoneal macrophages fromTrypanosoma brucei brucei-infected mice express type II NO synthase (NOS-II), produce NO, and kill parasites in the presence ofl-arginine in vitro. Nevertheless, parasites proliferate in the vicinity of these macrophages in vivo. The present study shows thatl-arginine availability modulates NO production.

Trypanosomes use l-arginine for polyamine synthesis, required for DNA and trypanothione synthesis. Moreover, arginase activity is up-regulated in macrophages from infected mice from the first days of infection. Arginase competes with NOS-II for their common substrate, l-arginine. In vitro, arginase inhibitors decreased urea production, increased macrophage nitrite production, and restored trypanosome killing. In vivo, a dramatic decrease inl-arginine concentration was observed in plasma from infected mice.

In situ restoration of NO production and trypanosome killing were observed when excess l-arginine, but notd-arginine or l-arginine plusN ω-nitro-l-arginine (a NOS inhibitor), was injected into the peritoneum of infected mice. These data indicate the role of l-arginine depletion, induced by arginase and parasites, in modulating the l-arginine–NO pathway under pathophysiological conditions.

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connie dello buono

Health educator, author and enterpreneur motherhealth@gmail.com or conniedbuono@gmail.com ; cell 408-854-1883 Helping families in the bay area by providing compassionate and live-in caregivers for homebound bay area seniors. Blogs at www.clubalthea.com Currently writing a self help and self cure ebook to help transform others in their journey to wellness, Healing within, transform inside and out. This is a compilation of topics Connie answered at quora.com and posts in this site.

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