Background:
Immune responses play a significant role in hypertension, though the importance of key inflammatory mediators remains to be defined. We used a systematic literature review and meta-analysis to study the associations between key cytokines and incident hypertension.

Methods:
We performed a systematic search of Pubmed/Medline, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL), for peer-reviewed studies published up to August 2022. Incident hypertension was defined as systolic blood pressure ≥140 mmHg or diastolic blood pressure ≥90 mmHg and/or the use of antihypertensive medications. Random effects meta-analyses were used to calculate pooled hazard ratios (HRs)/risk ratios (RRs) and 95% confidence intervals by cytokine levels (highest vs. lowest quartile).

Results:
Only IL-6 and IL-1β levels have evidence allowing for quantitative evaluation concerning the onset of hypertension. Six studies (10,406 participants, 2,932 incident cases) examined the association of IL-6 with incident hypertension. The highest versus lowest quartile of circulating IL-6 was associated with a significant HR/RR of hypertension (1.61, 95% CI: 1.00 to 2.60; I2=87%). After adjusting for potential confounders, including body mass index (BMI), HR/RR was no longer significant (HR/RR: 1.24; 95% CI, 0.96 to 1.61; I2= 56%). About IL-1β, neither the crude (HR/RR: 1.03; 95% CI, 0.60 to 1.76; n=2) nor multivariate analysis (HR/RR: 0.97, 95% CI, 0.60 to 1.56; n=2) suggested a significant association with the risk of developing hypertension.

Conclusions:
A limited number of studies suggest that higher IL-6, but not IL-1β, might be associated with the development of hypertension.