Antihypertensive Mechanisms of Minocycline in Resistant Hypertension

The goal of this clinical trial is to learn about the mechanisms by which minocycline effect blood pressure in individuals with treatment-resistant hypertension. The main questions it aims to answer are: * To what extent does minocycline lower blood pressure and are these effects different across races? * Are such blood pressure effects mediated through changes in gut microbiota, gut leakiness, systemic inflammation, neuroinflammation, or some combination of these? Participants will be randomly assigned to treatment with minocycline or placebo, treated daily for 3 months, to evaluate these questions.