Journal of Applied Sciences Research, 4(4): 353-359, 2008 © 2008, INSInet Publication Corresponding Author: Maysa T. Saleh, National Research Centre, Cairo, Egypt. 353 Leptin: Does It Have a Role in Neonatal Sepsis? Maysa T. Saleh, Lobna S. Sherif, Amany S. Elwakkad and Wael A.M. Assal 1 1 1 2 National Research Centre, Cairo, Egypt. 1 Pediatric Department, Zagazig University, Egypt. 2 Abstract: The principal aim of this study is to evaluate serum leptin role in neonatal sepsis and whether circulating leptin was related to and interleukin-6 (IL-6) and interleukin-1 (IL-1â) release in septic newborn infants, as well as to analyze the interaction between their levels, before and after antimicrobial therapy in neonates with bacterial septicemia. Serum leptin was measured in 14 neonates with sepsis as soon as sepsis was diagnosed and before treatment (group I) and after recovery (Group II) and in 14 healthy control infants. There was a highly significant increase in serum leptin levels between septic and control neonates (p<0.001); Furthermore, there was a very highly significantly decrease of the levels of serum leptin, IL-6 and IL-1â in neonates after recovery than before treatment (p<0.001). A very good relationship between leptin and IL-6; as well as IL-1â before and after therapy was identified. These findings suggest that a role of leptin in acute neonatal sepsis appears to be likely. Key words: neonatal sepsis, serum leptin, interleukins, IL-6, IL-1â INTRODUCTION Bacterial sepsis is one of the major causes of neonatal morbidity and mortality. The incidence ranges from 1–10 per 1000 live births . [1] Diagnosis of neonatal sepsis may be difficult because clinical presentations are often nonspecific, bacterial cultures are time-consuming and other laboratory tests lack sensitivity and specificity . [2] It is vital to identify infected neonates as early as possible, but unreliable clinical signs and the absence of good diagnostic tests hinder an accurate early diagnosis . Thus, sick neonates are frequently treated [1] with broad-spectrum antibiotics, but true infection is only verified in a minority of cases . Previously, [3,1] various white blood cell counts and the acute phase reactant C-reactive protein (CRP) have been used to diagnose neonatal sepsis. The ratio between immature and total neutrophil cell count (I/T-ratio) is a sensitive, but not very specific, diagnostic method with substantial inter-observer variability . CRP is [4] specific, but less sensitive in the early stages of neonatal sepsis . [5] The inflammatory response is mediated by cytokines that are used as neonatal infection markers, especially interleukin-6 (IL-6). IL-6 is an inducer of hepatic protein synthesis, promotes production and liberation of C-reactive protein, and can be detected early when there is bacterial blood stream invasion. It acts as a signal for T-cell activation, promotes antibody secretion by B cells and differentiation of cytotoxic T cells, and stimulates liberation of other cytokines, particularly TNF- and IL-1 . [4,6,7,8] Leptin, the 16-kDa protein product of the ob gene, is a pleotropic hormone that is produced primarily by adipocytes. In general, circulating leptin levels are linearly correlated with total body fat mass . [9,10] However, leptin levels drop rapidly during fasting and increase in response to infection and inflammatory stimuli . In addition to regulating appetite and [11,12] energy expenditure, leptin is an important immunoregulatory hormone since it enhances a number of immune responses, including macrophage effector functions cytokine synthesis, and T helper (Th) cell [13,14] polarization to a Th1 phenotype . [15] The principal aim of this study is to evaluate serum leptin role in neonatal sepsis and whether circulating leptin was related to and interleukin-6 (IL-6) and interleukin-1 (IL-1â) release in septic newborn infants, as well as to analyze the interaction between their levels, before and after antimicrobial therapy in neonates with bacterial septicemia. MATERIALS AND METHODS Methods: This case-control follow up study was conducted on fourteen full-term neonates with blood- culture positivity and clinical sepsis (Group I). They were hospitalized for clinical suspicion of neonatal sepsis in neonatal intensive care unit, Pediatric department, Zagazig University, Egypt. Those cases were followed up after recovery and enrolled in the