Photoperiodic conditions as a factor modulating leptin influenceon pro-inflammatory cytokinesand their receptors gene expression in ewe’s aorta

Abstract

Cardiovascular diseases (CVD) such as hypertension, ischemic heart or heart failure, are currently the leading cause of death worldwide. According to World Health Organization (WHO) statistics, in 2008 the number of deaths due to CVD was 17.3 mln, which accounted for nearly 30% of all deaths (WHO, 2011). The underlying cause of CVD is atherosclerosis which is a chronic inflammation state of the aorta and arteries of medium size (epicardial, coronary, carotid, renal, pelvic, mesenteric). Atherosclerosis can be however treated as ‘inflammation disease’ in two aspects. ABSTRACT. Atherosclerosis, a chronic inflammation state of the aorta, is characterised by increased levels of pro-inflammatory cytokines (tumour necrosis factor alpha (TNFα), interleukin (IL)-1β, IL-6). Sheep is used in both cardiovascular and immunological studies; besides, ‘long-day’ ewe can be a model of leptin resistance state. The aim of the study was to examine whether photoperiodic conditions (long-day (LD) and short-day (SD) seasons) are a key factor modulating exogenous leptin influence on pro-inflammatory cytokines and their receptors gene expression in aorta of ewe’s with or without prior induction of acute inflammation. The experiment was conducted on 48 ewes during SD and LD seasons which were randomly divided into 4 groups: control; with LPS injection (400 ng/kg of body weight (BW)); with leptin injection (20 μg/kg BW); and with LPS and 30-min later leptin injection. Three hours after LPS/control treatment animals were euthanized to collect the thoracic aorta samples. In both seasons leptin injection intensified LPS-induced increase in IL1B gene expression but only in SD season leptin injection increased IL1R1 and IL1R2 gene expressions. The leptin injection increased IL6 gene expression but only in SD season. In the LD season leptin enhanced the LPS effect on IL6 gene expression. Neither TNFA nor its receptors gene expression was influenced by leptin regardless of season. In the thoracic aorta tissue an exogenous leptin exerts effect on pro-inflammatory cytokines and their receptors gene expression; however in ewe this influence depends on photoperiodic conditions. Moreover, leptin can moderate progression of the inflammation reaction in this tissue. Received: 4 March 2019 Revised: 22 May 2019 Accepted: 17 June 2019