Nociceptin/orphanin and substance P concentrations in critically III patients with sepsis

ABSTRACT

Sepsis is estimated to affect eighteen million people worldwide each year and kill 1, 400 people each day. Sepsis affects about 700, 000 people annually in the United States alone. The neuropeptide nociceptin/orphanin [N/OFQ] and substance P [SP] are two neuropathies involved in control of pain pathways. They have been implicated in neural, immune, inflammatory process and cardiovascular system function. In this study we evaluated the N/OFQ plasma levels and SP serum levels in critically ill patients with severe sepsis. Blood samples were collected from twenty patients with the diagnosis of severe sepsis. They were admitted in the intensive care unit. Plasma N/OFQ concentrations were determined by radio immunoassay. SP in the serum was evaluated by enzyme-linked immunoassay. Samples were collected within twenty four hours of diagnosis of sepsis in all cases. Another set of samples were collected in nine patients before death [non-survivors] and eleven patient upon recovery from severe sepsis [survivors]. The results revealed significant high levels of N/OFQ in patients with severe sepsis [non-survivors] compared with the other group of survivors [p<0.031]. The levels were significantly high in cases near death [non-survivors] compared to the survivors [p<0.012] near recovery. SP levels were significantly high in sepsis non-survivors compared to survivors [p<0.001] and significantly elevated in non-survivors before death compared to survivors near recovery [p<0.001]. Plasma N/OFQ and Serum SP, concentrations were increased in critically ill patients with sepsis and more elevated in patients who subsequently died. These two neuropeptides represent an important item for further studies to confirm their prognostic value as predictive indicators of lethal outcome or recovery. Also this study invites more work to determine the neuroendocrine system critical role in the pathogenesis of sepsis