Potential of Minocycline for Treatment of Resistant Hypertension

Antioxidative and cardioprotective effects of minocycline in ischemia/reperfusion injury in experimental model of hypertension

Cardiovascular diseases remains leading cause of death and disabilities. Coronary artery occlusion and consequent ischemia leads to acute myocardial infarction, but restoration of blood flow, paradoxically, provokes further myocardial damage known as reperfusion injury. Minocycline is possessing anti-inflammatory and anti-apoptotic activity, immune-modulating and antioxidative properties besides its primary antibacterial effect. Recently it gained significant interest in preventing cardiac damage especially due to myocardial ischemia/reperfusion injury (MI/RI). The aim of this study was to assess the protective ability of pre-treatment and post-treatment of isolated hearts from healthy and spontaneously hypertensive rats with minocycline, on functional recovery and redox status after MI/RI using Langendorff technique. Using sensor in the left ventricle, the cardiodynamic parameters were recorded and in the samples of the coronary venous effluent oxidative stress biomarkers were analyzed. Minocycline was injected directly into the coronary vessels, in pre-treatment 5 min before global ischemia, and in post-treatment during the first 5 min of reperfusion. Changes in redox balance induced by minocycline were more prominent in post-treatment fashion of application. Cardioprotective effects of minocycline due to MI/RI are even more significant in hypertensive hearts. Minocycline showed significant cardioprotective effects, which was more pronounced in hypertensive compared to healthy hearts. Reduction of pro-oxidative biomarkers was more prominent in hypertensive hearts compared to the normotensive, especially if it is applied in the form of post-treatment. Minocycline could be important tool in reduction of heart damage induced by MI/RI due to its antioxidative potential, if these results are confirmed by clinical study.

Reprograming of transcriptional profile of colonic organoids from patients with high blood pressure by minocycline

Minocycline, an anti-inflammatory antibiotic drug, rebalances impaired gut microbiota, attenuates neuroinflammation and lowers high blood pressure in animal models of hypertension and in hypertensive patients. Our objective in this study was to investigate if antihypertensive effects of minocycline involve the expression of gut epithelial genes relevant to blood pressure homeostasis using human colonic 3-dimensional organoid culture and high-throughput RNA sequencing. The data demonstrates that minocycline could restore impaired expression of functional genes linked to viral and bacterial immunity, inflammation, protein trafficking and autophagy in human hypertensive organoids.

Minocycline Reduces Hypothalamic Microglia Activation and Improves Metabolic Dysfunction in High Fat Diet-Induced Obese Mice

Obesity is associated with insulin resistance, glucose intolerance, inflammation, and altered neuronal activity in brain regions controlling metabolic functions including food intake, energy expenditure, and glucose homeostasis, such as the hypothalamus. In this study, we tested the hypothesis that inhibiting inflammation with minocycline could reduce adverse metabolic consequences associated with high-fat diet (HFD)-induced obesity in mice and sought to determine if metabolic improvements were associated with reduced hypothalamic microglia activity. Male C57Bl/6J mice were placed on 60% HFD for 12 weeks, with minocycline (40 mg/kg, p.o.) or normal tap water given during the last 6 weeks of diet. Age-matched mice maintained on control diet were used as an additional comparator group. Metabolic function was assessed during the last week of treatment. Ramified (resting) and non-ramified (active) microglia were quantified in the hypothalamus following immunohistochemical staining of ionized calcium-binding adaptor 1 (Iba-1) and further assessed by RNAseq. In HFD fed mice, minocycline attenuated body mass and adiposity without altering food intake suggesting enhanced energy expenditure. Minocycline also attenuated hyperinsulinemia and improved insulin sensitivity in HFD mice. Increased microglial activation and autophagy gene network changes were observed in the paraventricular nucleus (PVN) of the hypothalamus of HFD mice, which was prevented by minocycline treatment. Contrary to PVN findings, there were no significant effects of either HFD or minocycline on microglia activation in the hypothalamic arcuate nucleus or central amygdala. Together, these findings suggest that minocycline improves HFD-induced weight gain and insulin resistance in part by reducing inflammatory processes in the PVN, a key hypothalamic region regulating metabolic function.

Gut Microbiome and Neuroinflammation in Hypertension

Hypertension is a worldwide problem with major impacts on health including morbidity and mortality, as well as consumption of health care resources. Nearly 50% of American adults have high blood pressure, and this rate is rising. Even with multiple antihypertensive drugs and aggressive lifestyle modifications, blood pressure is inadequately controlled in about 1 of 5 hypertensive individuals. This review highlights a hypothesis for hypertension that suggests alternative mechanisms for blood pressure elevation and maintenance. A better understanding of these mechanisms could open avenues for more successful treatments. The hypothesis accounts for recent understandings of the involvement of gut physiology, gut microbiota, and neuroinflammation in hypertension. It includes bidirectional communication between gut microbiota and gut epithelium in the gut-brain axis that is involved in regulation of autonomic nervous system activity and blood pressure control. Dysfunction of this gut-brain axis, including dysbiosis of gut microbiota, gut epithelial dysfunction, and deranged input to the brain, contributes to hypertension via inflammatory mediators, metabolites, bacteria in the circulation, afferent information alterations, etc resulting in neuroinflammation and unbalanced autonomic nervous system activity that elevates blood pressure. This in turn negatively affects gut function and its microbiota exacerbating the problem. We focus this review on the gut-brain axis hypothesis for hypertension and possible contribution to racial disparities in hypertension. A novel idea, that immunoglobulin A-coated bacteria originating in the gut with access to the brain could be involved in hypertension, is raised. Finally, minocycline, with its anti-inflammatory and antimicrobial properties, is evaluated as a potential antihypertensive drug acting on this axis.