Inflammation Alters Angiotensin Converting Enzymes (ACE and ACE-2) Balance in Rat Heart Sherif Hanafy, 1 Mahtab Tavasoli, 1 and Fakhreddin Jamali 1,2 Abstract—Angiotensin converting enzymes (ACE) and more recently discovered ACE-2 are important proteins involved in the renin–angiotensin system. The balance between ACE and ACE-2 is important for the regulation of blood pressure and electrolyte homeostasis. Inflammatory diseases like rheumatoid arthritis are associated with increased risk for cardiovascular complications. We studied the effect of inflammation on the expression levels of ACE and ACE-2 in two groups (n =4/ group) of adjuvant arthritis (AA) and healthy (control) rats. The AA group received 0.2 ml of 50 mg ml -1 of Mycobacterium butyricum suspended in squalene into the tail base. On day 12, rats were euthanized and their organs (hearts, liver, kidney, and intestine) were excised. The mRNA of ACE and ACE-2 were determined by real-time polymerase chain reaction. ACE and ACE-2 protein expression in rat heart was determined by Western blot. Inflammation resulted in 80% reduction of ACE-2 gene expression in rat heart. ACE-2/ACE expression ratio was significantly reduced from 0.7±0.4 in control rats to 0.07±0.09 in AA. Similarly, ACE-2/ACE protein expression ratio was also disrupted with a significant reduction in AA animals (6.7±4.8 vs. 0.9±05 in control and AA, respectively). ACE-2 has been found to provide negative feedback of renin–angiotensin system and protection of the heart and kidneys. Disruption of the balance between ACE and ACE-2 observed in inflammation may be, at least in part, involved in the cardiovascular complications seen in patients with inflammatory diseases. KEY WORDS: inflammation; cardiac function; experimental arthritis; ACE; ACE-2; angiotensin converting enzymes. Rheumatoid arthritis (RA) patients have demon- strated higher mortality rates as compared to the general population [1, 2], at least in part, due to increased cardiovascular complications [3]. The degree of sys- temic inflammation is considered as one of the main factors contributing to adverse cardiovascular events and increased mortality in RA [2]. Elevated levels of tumor necrosis factor alpha, interleukins (IL-1 and IL-6), and C-reactive protein in RA patients accelerate the development of atherosclerosis and vascular dysfunc- tion [3]. Recently, renin–angiotensin system (RAS) activation has been implicated in the pathogenesis of endothelial vascular dysfunction in inflammatory conditions [4]. Sakuta et al. have found that the expression of angiotensin converting enzyme (ACE) and angiotensin II receptor 1 are increased in the aorta of adjuvant arthritis (AA) rats contributing to endo- thelial dysfunction [4]; however, the discovery of the new enzyme ACE-2 added to the complexity of the RAS system [5]. Crackower et al. who examined ACE-2 knockout mice have reported severe cardiac impairment suggestive of a cardioprotective function for ACE-2 [6]. Interestingly, ACE and ACE-2 knock- out mice do not exhibit cardiac impairment which can be interpreted as a need for an ACE-2/ACE balance [6, 7]. Therefore, we were interested in determining the effect of inflammation on ACE and ACE-2 expression balance in the rat model of AA that is commonly used as a model for RA. 1 Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada T6G 2N8 2 To whom correspondence should be addressed at Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada T6G 2N8. E-mail: fjamali@pharmacy. ualberta.ca 0360-3997/11/0600-0609/0 # 2010 Springer Science+Business Media, LLC Inflammation, Vol. 34, No. 6, December 2011 ( # 2010) DOI: 10.1007/s10753-010-9269-1 609