Recently, Prof. Zhou Shenghua's research team from Second Xiangya Hospital of Central South University published an original research article online on the international top-notch journal Circulation Research (IF=20.1; 5-year IF=22.4). The article aims to explore the pathophysiological mechanisms as well as effective intervention targets of hypertension’s damage on target organs and its increased residual risk. It has confirmed that the specific knockout of legumain (LGMN) in T-cells can promote the differentiation and function of Treg cells, improving target organ damage caused by hypertension. Prof. Zhou Shenghua from the Department of Cardiology of Second Xiangya Hospital of Central South University is the corresponding author of this article, while Associate Researcher He Yuhu from the same department is the first author and co-corresponding author.

Background

Hypertension is a major cause of the increasing incidence and mortality of cardiovascular diseases globally, as well as a primary risk factor for chronic kidney disease, stroke, coronary heart disease, and heart failure. However, little is known about the exact mechanism of essential hypertension. Long-term epidemiological follow-up studies have found that even though hypertensive patients respond well to antihypertensive treatment with their blood pressure being maintained at a stable level, they still have significantly higher cardiovascular risks than healthy individuals with similar blood pressure levels. This suggests that existing antihypertensive drugs may not fully realize both blood pressure reduction and effective protection of target organs, indicating that hypertension-related target organ damage continues to persist despite good blood pressure control. Exploration of the pathophysiological mechanisms behind hypertension-related target organ damage will provide experimental evidence and directions for the treatment of hypertension-induced organ injury. In recent years, a growing emphasis has been placed on T cell-related immunity and inflammation in hypertension and its target organ damage, which have become the forefront topics in this field.

Methods

Isolating peripheral CD4+ T cells from healthy subjects and hypertensive patients for analysis on gene expression and protein electrophoresis; constructing T cell-specific LGMN-knockout (TLGMNKO) mice and establishing mouse models of hypertension induced by Ang II or DOCA/Salt; elucidating the specific mechanisms by which T cell LGMN is involved in hypertension-induced target organ damage through proteomics, flow cytometry, inhibition of Tregs’ in vitro functions, and in vivo adoptive transfer.

Results

To address the challenge of target organ damage and the corresponding increased cardiovascular residual risk, Prof. Zhou Shenghua's team first isolated peripheral CD4+ T cells from healthy individuals and patients with uncontrolled or well-controlled hypertension. Through detection, a significant elevation of LGMN in CD4+ T cells was spotted in hypertensive patients, and its expression level was significantly correlated with the residual cardiovascular risk in the hypertensive patient population (Figure 1).

Figure 1. CD4+ T cells’ LGMN expression increases significantly and showed correlation with residual cardiovascular risk indicators in hypertensive patients

Following this, the team constructed TLGMNKO mice and developed hypertension models induced by angiotensin II, characterized by the activated renin-angiotensin-aldosterone system (RAAS), and a salt-sensitive model induced by deoxycorticosterone acetate/salt (DOCA/Salt). They found that CD4+ T cell-specific LGMN knockout significantly reduced blood pressure in both animal models and correspondingly attenuated target organ damage in the blood vessels and kidneys (Figures 2-3).

Figure 2. TLGMNKO Improves Ang II-Induced Hypertension and Target Organ Damage

Figure 3. TLGMNKO improves DOCA/ SALT-induced hypertension and target organ damage

In terms of mechanism, through proteomic and bioinformatic analysis, it was found that LGMN deficiency facilitates the activation of the TRAF6-NF-kappa B signaling pathway by upregulating TRAF6 protein expression. This, in turn, enhances the immunoregulatory function of Treg cells and thereby improves hypertension and the associated target organ damage (Figure 4).

Figure 4. LGMN knockout promotes the activation of TRAF6-NF-Kappa B signaling pathway through up-regulation of TRAF6 protein levels, thus promoting the immunomodulatory function of Treg cells

Furthermore, this study first identified TRAF6 as a chaperone-mediated autophagy substrate. LGMN knockout was able to block TRAF6 degradation via chaperone-mediated autophagy (Figure 5).

Figure 5. LGMN knockout blocks TRAF6 degradation via chaperone-mediated autophagy

Importantly, the exclusive use of losartan, a classical antihypertensive drug, only slightly alleviated hypertension and related target organ damage in the salt-sensitive mouse model. However, the combination of losartan with the adoptive transfer of Tregs after LGMN knockout significantly reversed DOCA/Salt-induced hypertension and corresponding target organ damage (Figure 6). This suggests that under conventional clinical drug treatment, targeting T cell LGMN can provide additional benefits for hypertension-induced target organ damage.

Figure 6. Adoptive transfer of LGMN-knockout Tregs combined with losartan therapy reverses DOCA/ Salt-induced hypertension and target organ damage

Conclusions

In summary, starting from clinical issues, this study revealed a significant correlation between the elevated expression of LGMN in CD4+ T cells and target organ damage, as well as the increased residual cardiovascular risk in hypertensive patients. Building upon these findings, through the construction of TLGMNKO mice and various hypertension models, the study elaborated through various molecular biology techniques the molecular mechanisms and potential intervention targets for hypertension-induced target organ damage and increased residual cardiovascular risk in hypertensive patients (Figure 7). These findings hold significant clinical and translational implications and value, providing new perspectives and insights for targeted immunotherapy and inflammation treatment in the field of hypertension in the future.

Figure 7. Molecular mechanism of endogenous LGMN in CD4+T cells that promotes hypertension and target organ damage

Expert Profile

Prof. Zhou Shenghua

Known as a “famous doctor of Xiangya” at Central South University, Prof. Zhou Shenghua is a renowned interventional cardiologist in China, and the honorary recipient of the third Outstanding Model Physician of China Award. Currently, Prof. Zhou Shenghua serves as the Director of the Cardiovascular Department, Chief Physician, Ph.D. Supervisor at Second Xiangya Hospital of Central South University, Director of Hunan Provincial Cardiovascular Disease Hospital (Center), Director of Hunan Provincial Cardiovascular Disease Intervention Treatment Center, Director of Hunan Provincial Quality Control Center for Clinical Intervention Treatment of Cardiovascular Diseases, and Director of Hunan Provincial Modern Medical Technology Research Center for Cardiovascular Diseases.

Additionally, Prof. Zhou is a Member of the 11th Standing Committee and Deputy Secretary-General of the Chinese Society of Cardiology, Deputy Director of the Heart Failure Branch of the Chinese Medical Doctor Association, Director of the Cardiovascular Disease Committee of Hunan Province, Member of the Standing Committee of the Chinese Society of Pacing and Electrophysiology, the Cardiovascular Internal Medicine Physicians Branch of the Chinese Medical Doctor Association, the Heart Rhythm Branch of the Chinese Society of Biomedical Engineering, and Executive Director of the Chinese Heart Rhythm Society.

Prof. Zhou has been recognized as a ‘young and middle-aged expert with outstanding contributions by the Ministry of Health’, an Outstanding Young Science and Technology Talent of the Ministry of Health, a quality control expert in cardiovascular intervention diagnosis and treatment, a panelist appointed by China’s National Center for Cardiovascular Diseases, a recipient of special government allowances from the State Council, and a leading talent in relevant medical disciplines in Hunan Province.

In recent years, Prof. Zhou has undertaken one project in the Original Exploration Program and four projects in the General Program of the National Natural Science Foundation of China, one project from the Chinese Medical Board, and one key clinical discipline project of the Ministry of Health's key affiliated hospitals. As the corresponding author, he has published over 70 SCI papers in top-notch journals such as NEJM and Lancet. Also, he has received eight provincial science and technology progress awards and co-authored two English monographs on interventional cardiology.