Pathophysiology of Hypertension

Identification and verification of immune-related genes for diagnosing the progression of atherosclerosis and metabolic syndrome

BACKGROUND

Atherosclerosis and metabolic syndrome are the main causes of cardiovascular events, but their underlying mechanisms are not clear. In this study, we focused on identifying genes associated with diagnostic biomarkers and effective therapeutic targets associated with these two diseases.

METHODS

Transcriptional data sets of atherosclerosis and metabolic syndrome were obtained from GEO database. The differentially expressed genes were analyzed by RStudio software, and the function-rich and protein-protein interactions of the common differentially expressed genes were analyzed.Furthermore, the hub gene was screened by Cytoscape software, and the immune infiltration of hub gens was analyzed. Finally, relevant clinical blood samples were collected for qRT-PCR verification of the three most important hub genes.

RESULTS

A total of 1242 differential genes (778 up-regulated genes and 464 down-regulated genes) were screened from GSE28829 data set. A total of 1021 differential genes (492 up-regulated genes and 529 down-regulated genes) were screened from the data set GSE98895. Then 23 up-regulated genes and 11 down-regulated genes were screened by venn diagram. Functional enrichment analysis showed that cytokines and immune activation were involved in the occurrence and development of these two diseases. Through the construction of the Protein-Protein Interaction(PPI) network and Cytoscape software analysis, we finally screened 10 hub genes. The immune infiltration analysis was further improved. The results showed that the infiltration scores of 7 kinds of immune cells in GSE28829 were significantly different among groups (Wilcoxon Test < 0.05), while in GSE98895, the infiltration scores of 4 kinds of immune cells were significantly different between groups (Wilcoxon Test < 0.05). Spearman method was used to analyze the correlation between the expression of 10 key genes and 22 kinds of immune cell infiltration scores in two data sets. The results showed that there were 42 pairs of significant correlations between 10 genes and 22 kinds of immune cells in GSE28829 (|Cor| > 0.3 & P < 0.05). There were 41 pairs of significant correlations between 10 genes and 22 kinds of immune cells in GSE98895 (|Cor| > 0.3 & P < 0.05). Finally, our results identified 10 small molecules with the highest absolute enrichment value, and the three most significant key genes (CX3CR1, TLR5, IL32) were further verified in the data expression matrix and clinical blood samples.

CONCLUSION

We have established a co-expression network between atherosclerotic progression and metabolic syndrome, and identified key genes between the two diseases. Through the method of bioinformatics, we finally obtained 10 hub genes in As and MS, and selected 3 of the most significant genes (CX3CR1, IL32, TLR5) for blood PCR verification. This may be helpful to provide new research ideas for the diagnosis and treatment of AS complicated with MS.

Blood pressure is linked to salt intake and modulated by the angiotensinogen gene in normotensive and hypertensive elderly subjects

OBJECTIVES

To evaluate salt sensitivity in elderly subjects with different forms of hypertension and controls and to investigate any modulation by genotype

DESIGN

Randomized, double-blinded, placebo-controlled latin-square

SETTING

Tertiary referral hospital

PARTICIPANTS

Community subjects (n = 46) aged > or = 60 years classified as isolated systolic hypertension [ISH; systolic blood pressure (SBP) > or = 160, diastolic blood pressure (DBP) < 90 mmHg, n = 19], diastolic +/- systolic hypertension (SDH; DBP > or = 90 mmHg, n = 10) and normotension (SBP < 160, DBP < 90 mmHg, n = 17).

INTERVENTION

Four 14 day treatments, 50, 100, 200 and 300 mmol/day of sodium chloride supplementation interspersed with 14 day washout periods on a salt-restricted diet.

MAIN OUTCOME MEASURES

The 24 h blood pressure, heart rate, weight, urinary sodium and creatinine clearance measured during baseline, treatment and washout periods and angiotensinogen (AGT) and angiotensin converting enzyme (ACE) genotypes.

RESULTS

For the entire cohort, the mean +/- standard error (SE) of change from baseline in SBP for 50, 100, 200 and 300 mmol/day salt was 7.7+/-2.4, 12.1+/-2.4, 16.6+/-3.0, 18.5+/-2.6 mmHg, respectively. For DBP, the respective changes were: -0.1+/-1.5, 2.4+/-1.6, 3.0+/-1.5, 5.8+/-1.7 mmHg. The increase in SBP among ISH subjects was significantly higher than among subjects in the SDH and normotensive groups (P < 0.05). AGT genotype influenced the effect of salt dose on the change in DBP (P = 0.006) but not SBP (P = 0.7).

CONCLUSIONS

In healthy, older subjects, a linear increase in BP occurred with increasing salt dose, it appeared most pronounced in ISH subjects and could be modulated by AGT genotype.

Systolic and diastolic blood pressure, pulse pressure, and mean arterial pressure as predictors of cardiovascular disease risk in Men

We compared systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP) in predicting the risk of cardiovascular disease (CVD), stratifying results at age 60 years, when DBP decreases while SBP continues to increase. We prospectively followed 11 150 male physicians with no history of CVD or antihypertensive treatment through the 2-year questionnaire, after which follow-up began. Reported blood pressure was averaged from both the baseline and 2-year questionnaires. During a median follow-up of 10.8 years, there were 905 cases of incident CVD. For men aged <60 years (n=8743), those in the highest versus lowest quartiles of average SBP (>/=130 versus <116 mm Hg), DBP (>/=81 versus <73 mm Hg), and MAP (>/=97 versus <88 mm Hg) had relative risks (RRs) of CVD of 2.16, 2.23, and 2.52, respectively. Models with average MAP and PP did not add information compared with models with MAP alone (P>0.05). For men aged >/=60 years (n=2407), those in the highest versus lowest quartiles of average SBP (>/=135 versus <120 mm Hg), PP (>/=55 versus <44 mm Hg), and MAP (>/=99 versus <91 mm Hg) had RRs of CVD of 1.69, 1.83, and 1.43, respectively. The addition of other blood pressure measures did not add information compared with average SBP or PP alone (all P>0.05). These data suggest that average SBP, DBP, and MAP strongly predict CVD among younger men, whereas either average SBP or PP predicts CVD among older men. More research should distinguish whether MAP, highly correlated with SBP and DBP, better predicts CVD.

Two-year changes in blood pressure and subsequent risk of cardiovascular disease in men

BACKGROUND-It is unclear whether, given a current blood pressure level, the previous 2-year change in blood pressure adds important predictive information for cardiovascular disease (CVD). METHODS AND RESULTS-We conducted a prospective cohort study of 11 150 middle-aged and older men reporting blood pressure in the Physicians' Health Study. These men had no history of CVD or antihypertensive medication use through the time of the 2-year follow-up questionnaire; after this time, follow-up for the current study began. A total of 905 incident cases of CVD (705 cases of coronary heart disease and 200 cases of stroke) occurred during a median follow-up of 10.8 years. After controlling for current blood pressure and other coronary risk factors, we found that previous 2-year changes in systolic blood pressure were not associated with the risk of CVD. A similar lack of association was found for individual end points of coronary heart disease and stroke. However, previous 2-year changes in diastolic blood pressure (DBP) may be inversely associated with the risk of CVD (linear trend, P=0.049) independent of coronary risk factors and current DBP. In subgroup analyses, previous 2-year blood pressure changes only added information in leaner men (body mass index <24.39 kg/m(2)). CONCLUSIONS-In this normotensive population of men, the prior 2-year change in DBP, but not systolic blood pressure, may add information to current levels in relation to the risk of CVD. Clinicians may need to consider the previous pattern of DBP change when considering the risk associated with the current DBP level. These data require confirmation in other studies in which blood pressure is measured.

Epidemiology, pathophysiology, and management of isolated systolic hypertension in the elderly

Isolated systolic hypertension (ISH) is a common disorder in the elderly, carrying with it a high risk of cardiovascular morbidity and mortality. Environmental and age-related factors believed to contribute to ISH include obesity, declining physical activity, stress, and such dietary changes as increased salt intake and decreased intake of calcium and potassium. Increased rigidity of the aorta resulting in reduced compliance is an important hemodynamic feature, but factors that increase peripheral resistance also appear to play a role. Antihypertensive drugs have been shown to effectively and safely lower the systolic blood pressure elevations characteristic of ISH. To date, use of low drug doses and careful titration of dosage have avoided significant orthostatic hypotension and undue lowering of the diastolic pressure. Studies of relatively small groups of patients suggest that antihypertensive drugs can lower the risk of cardiovascular morbidity/mortality associated with ISH but the definitive answer awaits results of the ongoing large-scale Systolic Hypertension in the Elderly Program trial. In the interim, management should begin with conservative measures such as weight loss, salt restriction and, possibly, calcium supplementation. If this fails, drug therapy should be considered in patients with systolic blood pressures above 180 mm Hg and in those with systolic readings between 160 and 180 mm Hg who have concomitant cardiovascular risk factors. To date, no controlled trials of sufficient size have demonstrated that one drug class is more effective than another in treating ISH. Drug therapy should be tailored to the individual patient, starting with a low dose of a single drug and, if necessary, slowly increasing dosage until a systolic blood pressure under 160 mm Hg is attained.