Hypertension is the single most prevalent risk factor for heart diseases, heart failure, kidney failure and stroke. About 1 in 3 adults in the United States have hypertension. Approximately 28-30% of hypertensive patients suffer from resistant hypertension (RH). Inflammation has been implicated in the pathogenesis of the hypertension. Additional data suggests the involvement of gut microbiota in host normal cardiovascular functions and pathophysiology. Accumulating evidence demonstrates that antibiotic treatment benefits patients with acute coronary syndromes and reduces the incidence of ischemic cardiovascular events. Even though these studies did not address effects of antibiotic treatment on the gut microbiota, it is possible that gut microbiota could affect neurologic inflammation. Finally, intestinal microbiota has recently been proposed to modulate blood pressure (BP) through production of short-chain fatty acids. In order to investigate this, the investigators hypothesize that gut microbiota is involved in the neuroinflammation-mediated initiation and establishment of RH, and targeting gut microbiota by minocycline would produce beneficial outcomes in RH.

This is a prospective cohort design. This study will enroll 388 subjects: 81 patients without HTN as a reference group, 81 patients with controlled HTN, 55 patients with uncontrolled HTN, 55 with remodeled RH, and 81 patients with RH to characterize gut microbiota composition. Subjects will provide stool samples for analysis. Subjects will also provide a blood sample for inflammatory marker and stem cell analysis.

Inclusion Criteria:

• age >18 and <80
• is competent and willing to provide consent

Inclusion criteria for each subject group:

• Control subjects will have a systolic BP <140mmHg with no cardiovascular disease
• Patients with controlled hypertension
• Patients with uncontrolled hypertension
• Resistant hypertension subjects will have systolic blood pressure (BP) ≥140 mmHg despite ≥3 anti-hypertensive medications of different classes one of which should be a diuretic
• Patients who are no longer RH subjects and have normal blood pressure
• Subjects participating in NCT 02133872 will be eligible to participate

Exclusion Criteria:

• currently pregnant or have been pregnant in the last 6 months;
• antibiotic treatment within 2 months of study enrollment;
• currently taking a medication (e.g., antibiotic, anti-inflammatory agents, glucocorticoids or other immune modulating medications);
• unwilling to discontinue vitamin or supplements, including probiotics, potentially affecting gut microbiota (vitamins/supplements and medications that possibly affect the gut microbiota should be discontinued for at least 2wks prior to stool collection);
• history of intestinal surgery, inflammatory bowel disease, celiac disease, lactose intolerance, chronic pancreatitis or other malabsorption disorder.

This study will initially enroll 10 patients without hypertension as normal controls, and 10 patients with controlled hypertension and 10 patients with resistant hypertension to characterize gut microbiota. In addition, all patients enrolled in IRB# 102-2013 will be approached for possible participation.