Metformin Improves Metabolic Memory in High Fat Diet (HFD)-induced Renal Dysfunction.

Recently, we have shown that high fat diet (HFD) in vivo and in vitro generates metabolic memory by altering H3K36me2 and H3K27me3 on the promoter of FOXO1 (transcription factor of gluconeogenic genes) (Kumar, S., Pamulapati, H., and Tikoo, K. (2016) Mol. Cell. Endocrinol. 422, 233-242). Here we checked the hypothesis whether concomitant diet reversal and metformin could overcome HFD-induced metabolic memory and renal damage. Male adult Sprague-Dawley rats were rendered insulin-resistant by feeding high fat diet for 16 weeks. Then the rats were subjected to diet reversal alone and along with metformin for 8 weeks. Biochemical and histological markers of insulin resistance and kidney function were measured. Blood pressure and in vivo vascular reactivity to angiotensin II (200 ng kg-1) were also checked. Diet reversal could improve lipid profile but could not prevent renal complications induced by HFD. Interestingly, metformin along with diet reversal restored the levels of blood glucose, triglycerides, cholesterol, blood urea nitrogen, and creatinine. In kidney, metformin increased the activation of AMP-activated protein kinase (AMPK) and decreased inflammatory markers (COX-2 and IL-1ß) and apoptotic markers (poly(ADP-ribose) polymerase (PARP) and caspase 3). Metformin was effective in lowering elevated basal blood pressure and acute change in mean arterial pressure in response to angiotensin II (Ang II). It also attenuated tubulointerstitial fibrosis and glomerulosclerosis induced by HFD feeding in kidney. Here we report, for the first time, that metformin treatment overcomes metabolic memory and prevents HFD-induced renal damage.

Activation of angiotensin-converting enzyme 2 (ACE2) attenuates allergic airway inflammation in rat asthma model.

Angiotensin-I converting enzyme (ACE) is positively correlated to asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS) and is highly expressed in lungs. ACE2, the counteracting enzyme of ACE, was proven to be protective in pulmonary, cardiovascular diseases. In the present study we checked the effect of ACE2 activation in animal model of asthma. Asthma was induced in male wistar rats by sensitization and challenge with ovalbumin and then treated with ACE2 activator, diminazene aceturate (DIZE) for 2weeks. 48h after last allergen challenge, animals were anesthetized, blood, BALF, femoral bone marrow lavage were collected for leucocyte count; trachea for measuring airway responsiveness to carbachol; lungs and heart were isolated for histological studies and western blotting. In our animal model, the characteristic features of asthma such as altered airway responsiveness to carbachol, eosinophilia and neutrophilia were observed. Western blotting revealed the increased pulmonary expression of ACE1, IL-1ß, IL-4, NF-κB, BCL2, p-AKT, p-p38 and decreased expression of ACE2 and IκB. DIZE treatment prevented these alterations. Intraalveolar interstitial thickening, inflammatory cell infiltration, interstitial fibrosis, oxidative stress and right ventricular hypertrophy in asthma control animals were also reversed by DIZE treatment. Activation of ACE2 by DIZE conferred protection against asthma as evident from biochemical, functional, histological and molecular parameters. To the best of our knowledge, we report for the first time that activation of ACE2 by DIZE prevents asthma progression by altering AKT, p38, NF-κB and other inflammatory markers.