Non-invasive left ventricular myocardial work identifies subclinical myocardial involvement in patients with systemic lupus erythematosus

OBJECTIVE

Global myocardial work (MW) is a novel indicator that accounts for deformation and afterload, which may provide additional value for assessment of myocardial function. Non-invasive echocardiographic estimated left ventricular (LV) MW incorporates longitudinal strain curves and blood pressure data. This study sought to assess MW in systemic lupus erythematosus (SLE) patients with normal LV ejection fraction (LVEF) by two-dimensional speckle-tracking imaging (2D-STI) to reflect subclinical myocardial damage.

METHODS

98 SLE patients and 98 gender and age-matched healthy subjects were included. The patients with SLE were divided into mild activity (SLE disease activity index (SLEDAI) ≤ 4; n = 45), moderate activity (5 ≤ SLEDAI≤9; n = 23), and high activity (SLEDAI≥10; n = 30) subgroups. Standard transthoracic echocardiography was applied to evaluate the systolic myocardial function of the global LV. The parameters of non-invasive MW including global wasted work (GWW) and global work efficiency (GWE) were calculated from echocardiographic LV pressure-strain loops (PSL) and blood pressure at rest.

RESULTS

The SLE group had a significantly higher GWW (75.7 ± 39.1 mmHg% vs 37.9 ± 18.0 mmHg%, P < 0.001) and decreased GWE ratio (95.5 ± 2.0% vs 97.4 ± 1.0%, P < 0.001) compared with the controls. Among the subgroups with elevating level of disease activity, SLE patients with preserved LVEF had a significantly higher GWW (61.6 ± 29.9 mmHg% to 96.2 ± 42.2 mmHg%, P for trend = 0.001) and markedly decreased GWE (96.4 ± 1.5% to 94.4 ± 2.0%, P for trend = 0.001). In two separate multiple linear regression analyses, SLEDAI were independently associated with GWW (β = 0.271, P = 0.005) and GWE (β = -0.354, P<0.001).

CONCLUSION

GWW and GWE are promising novel tools for the early detection of subclinical LV dysfunction. GWW and GWE could distinguish distinct patterns in different grades of SLEDAI.

Adiponectin attenuates Ang Ⅱ-induced TGFβ1 production in human mesangial cells via an AMPK-dependent pathway

Glomerulosclerosis is a key element in end-stage renal failure. Angiotensin II (Ang II) plays an important role in modulating cell growth and extracellular matrix (ECM) synthesis and degradation. Adiponectin, a protein derived from adipocytes, is primarily involved in regulating glucose levels and fatty acid break down. It has recently been shown to have antiatherosclerotic and anti-inflammatory properties. However, the role of adiponectin as a renoprotective agent has not been fully explored. We herein examine the effect of adiponectin on Ang II-induced TGFβ1 and ECM production in human renal mesangial cells (HRMCs) and explore the signaling pathway involved. In this study, we found that both adiponectin receptor 1 and adiponectin receptor 2 are expressed in HRMCs. Adiponectin (10 μg/mL) attenuated the stimulatory effect of Ang II on TGF-β1 and fibronectin. Furthermore, adiponectin activated the AMP-activated protein kinase (AMPK), and the AMPK-specific inhibitor (compound C) blocked AMPK activation. We also determined that compound C blocked the inhibitory effect of adiponectin on Ang II-stimulated TGFβ1 and fibronectin production. In summary, these results demonstrate that adiponectin suppresses Ang II-induced synthesis of ECM in mesangial cells via activation of the AMPK pathway. Based on our data, we suggest that this mechanism could delay the progression of kidney disease.

Microtubule associated tumor suppressor 1 deficient mice develop spontaneous heart hypertrophy and SLE-like lymphoproliferative disease

The microtubule associated tumor suppressor gene 1 (MTUS1) is a recently published tumor suppressor gene, which has also been shown to act as an early component in the growth inhibitory signaling cascade of the angiotensin II type 2 receptor (AT2R). In this study we report the generation of MTUS1 knock-out (KO) mice, which develop normally but reveal higher body weights and slightly decreased blood pressure levels. Twenty-eight percent of the studied MTUS1 KO mice also developed heart hypertrophy and 12% developed nephritis, independent of blood pressure levels. Forty-three percent of the MTUS1 KO mice revealed lymphoid hyperplasia affecting spleen (20%), kidney (37%), lung (23%), lymph nodes (17%), and liver (17%) accompanied with leukocytosis, lymphocytosis, and mild anemia. One animal (3%) developed a marginal zone B-cell lymphoma affecting submandibular salivary gland and regional lymph nodes. The symptoms of all mentioned animals are consistent with a B-cell lymphoproliferative disease with features of systemic lupus erythematosus. In addition, body weight of the MTUS1 KO mice was significantly increased and isolated skin fibroblasts showed increased cell proliferation and decreased cell size, compared to wild-type (WT) fibroblasts in response to depleted FCS concentration and lack of growth factors. In conclusion we herein report the first generation of a MTUS1 KO mouse, developing spontaneous heart hypertrophy and increased cell proliferation, confirming once more the anti-proliferative effect of MTUS1, and a SLE-like lymphoproliferative disease suggesting crucial role in regulation of inflammation. These MTUS1 KO mice can therefore serve as a model for further investigations in cardiovascular disease, autoimmune disease and carcinogenesis.