Alterations in macrophage-produced cytokines and nitrite associated with poult enteritis and mortality syndrome

Poult enteritis and mortality syndrome (PEMS) is an acute, transmissible, i nfectious intestinal disease associated with high mortality and morbidity i n turkey poults. Earlier studies demonstrated immune dysfunction, involving both humoral and cell-mediated immunity, associated with PEMS. The current study examined cytokines and metabolites produced by macrophages from poul ts exposed to PEMS agent(s). Six trials were conducted with six separate ha tches of poults. Poults in the PEMS group were exposed to PEMS agent(s) via contact exposure at 7 days of age whereas uninfected poults served as cont rol poults. Abdominal macrophages were harvested from control (uninfected) and PEMS poults at various times postexposure and cultured for 18-24 hr in the presence of Escherichia coli lipopolysaccharide. Interleukin-1 (IL-1), interleukin-6 (IL-G), and tumor necrosis factor-alpha (TNF-alpha) bioactivi ties and nitrite levels in macrophage culture supernatants were quantified. Macrophage supernatants from PEMS poults had greater IL-l-mediated stimula tion index compared with the macrophage supernatants from uninfected contro l poults in both trials. However, this increase was significant only in tri al 1. IL-6 activity tested in three separate trials was significantly highe r in PEMS macrophage supernatants over the controls. On the contrary, TNF-a lpha production by macrophages was decreased in PEMS macrophage culture sup ernatants. Nitrite levels in PEMS macrophage culture supernatants were sign ificantly higher in two out of three trials. These findings suggest that th e enhanced production of proinflammatory cytokine/metabolites by activated macrophages in PEMS poults may be responsible, at least in part, for the ph ysiological intestinal inflammation, gut motility, and anorexia that charac terize this disease.