Abstract
Background: Empagliflozin (EMPA) demonstrates cardioprotective effects on the patients with heart failure, but its effects in cardiorenal syndrome (CRS) remain unspecified. The purpose of the exploratory study was to investigate the effect of EMPA on patients with type 2 CRS and type 2 diabetes mellitus (DM).
Methods: This study was a randomized trial of patients with type 2 CRS and DM done between December 2020 and January 2022. Patients were randomly allocated to the control group and the EMPA group using EMPA as an add-on treatment. Serum interleukin 6 (IL-6), janus kinase 2 (JAK-2), and signal transducer and activator of transcription 3 (STAT-3) concentrations were measured in 102 patients with CRS and healthy individuals without any disease using enzyme-linked immunosorbent assay before and after treatment. The evaluation of renal function was measured by immunoturbidimetry, and cardiac function was estimated by doppler echocardiography. Rates of adverse events and major adverse cardiac events (MACE) were documented.
Results: The results showed that EMPA decreased the level of IL-6 but increased the level of JAK-2 and STAT-3 in patients. Additionally, the results suggest EMPA significantly reduced the incidence of MACE compared to the control group, while the rate of adverse events did not significantly differed.
Conclusions: Our study suggested that the cardiorenal benefits conferred by EMPA might be driven by anti-inflammatory effects, cooperated with the activation of JAK2/STAT3 signaling pathways, leading to modest short-term improvements in patients with type 2 CRS. The overall safety and low complication make EMPA a significant choice for clinical application.
Highlights
- Effects of empagliflozin (EMPA) on cardiorenal syndrome (CRS) remain unclear. The purpose of the exploratory study was to investigate its effect on patients with type 2 CRS and type 2 diabetes mellitus.
- Empagliflozin decreased the level of interleukin 6 (IL-6) while increasing the level of janus kinase 2 (JAK-2) and signal transducer and activator of transcription 3 (STAT-3) in patients.
- The cardiorenal benefits conferred by EMPA might be driven by anti-inflammatory effects, cooperated with the activation of JAK2/STAT3 signaling pathways.
Introduction
Cardiorenal syndrome (CRS) has been known as a spectrum of disorders of the heart and kidneys, whereby acute or chronic dysfunction of one organ may induce acute or chronic dysfunction in the other. Different syndromes have been categorized into 5 subtypes and type 2 occured when chronic abnormalities in cardiac function result in progressive chronic kidney injury or dysfunction, leading to high mortality.1 Heart failure is a major public health problem affecting more than 23 million patients worldwide, and nearly 25% of the patients have type 2 CRS which is associated with reduced survival.2,
Consequently, there is a profound and urgent need for new drug therapies that prevent, treat, or slow the progression of CRS type 2. In recent years, there is evidence that empagliflozin (EMPA), a sodium-dependent glucose transporter 2 inhibitor, significantly reduced the incidence of cardiovascular and renal events in patients with or without type 2 diabetes mellitus (T2DM).4-
Methods
Participants
The research was conducted ethically in accordance with the World Medical Association Declaration of Helsinki. All subjects have given their written informed consent and this study protocol was reviewed and approved by the Ethical and Experimental Committee of the Loudi Central Hospital, approval number [2021-ethics (research)-032].
The trial was designed as a randomized trial of EMPA 10 mg or not for at least 12 weeks and ran between December 2020 and January 2022. The blood samples (4 mL) were collected from CRS patients and healthy subjects who were diagnosed or received routine examinations at the Loudi Central Hospital. Patients with CRS were eligible if they were aged between 40 and 80, had type 2 DM, prevalent cardiovascular disease typically of atherosclerotic origin (coronary artery disease, hypertension), and an estimated glomerular filtration rate of 45-60 mL/min/1.73 m2. A total of 102 eligible participants were randomly assigned to the control group (n = 52) and experimental group (n = 50) treated with EMPA (10 mg once daily) added to their standard care, including HFrEF (n = 20), heart failure with mid-range ejection fraction (HfmrEF) (n = 36), and heart failure with preserved ejection fraction (HFpEF) (n = 36). All patients met the 2019 American Heart Association (AHA) diagnostic criteria for CRS type 211 and were treated with conventional heart failure and antihyperglycemic therapy. Another group of normal person (n = 20) was selected as the healthy group. Fasting blood samples and echocardiographic measurements were performed before and 12 weeks after treatment. Enzyme-Linked Immunosorbent Assay (ELISA) was performed using the supernatants to measure the levels of IL-6, JAK-2, and STAT-3. The evaluation of renal function was measured by immunoturbidimetry, and cardiac function was estimated by Doppler echocardiography. The rates of adverse reactions and major adverse cardiac events (MACE) during the treatment were recorded.
Blood Testing
Blood samples were obtained via peripheral vein after 12 weeks of treatment and at admission. Plasma after receiving treatment of EMPA was separated by centrifugation and stored at −80°C. IL-6, JAK-2, and STAT-3 were measured by an ELISA kit (RENJIEBIO, RJ11850, RJ13240, RJ14355, Shanghai, China) according to the manufacturer’s instructions. Serum creatinine (Ser), blood urea nitrogen (BUN), and uric acid (UA) were measured by the same biochemical detector.
Echocardiography
After 12 weeks of treatment and at admission, Doppler echocardiography was performed in all patients using an echo machine (EPIQ7, PHILIPS, Netherlands) equipped with a 10 MHz phased array linear transducer for serial assessment of cardiac structure and function, as previously described.
According to standard procedures, to survey left atrium diameter (LAD), left ventricular end diastolic (LVED), and left ventricular ejection fraction (LVEF), all measurements performed with an off-line analysis system by 2 practiced sonographers who were blinded to prior results, were based on the average of 3 to 6 consecutive cardiac cycles.
Adverse and Major Adverse Cardiac Events
Although well tolerated, there are known adverse effects with EMPA that require clinical monitoring, such as incidence of urinary and genital tract infections, diabetic ketoacidosis, volume depletion particularly in the setting of concomitant diuretic use, hypoglycemia, kidney failure, and anaphylactic response. Major adverse cardiac events events include nonfatal myocardial infarction, serious cardiac arrhythmias, stroke, heart failure hospitalization, and cardiovascular mortality.
Statistical Analysis
Before data was collected, a statistical power analysis was performed for estimating the required sample size. The analysis revealed that at least 114 participants and 20 healthy controls would be required to detect significant differences in serum IL-6 levels between patients with EMPA or not, with a power of 90% and an alpha error of 10%. The power was 86% in our experiment. Data was analyzed with SPSS version 25.0 (IBM Corp, Armonk, NY, USA). Continuous data were presented as means ± standard deviations, while categorical variables or median and interquartile range for non-normally distributed variables. We compared the experimental parameters and the rate of adverse events and MACE between groups were performed using Mann–Whitney
Results
Baseline Clinical Characteristics and Medications of Patients with Empagliflozin and Controls
The health group had a low level of NT-proBNP, D-dimer, FBG, and HbA1c compared with patients with CRS. While basic information (e.g., age, sex, etc.), baseline biomarkers (e.g., BMI, NT-proBNP, cTnI, blood lipids), and past medical history (e.g., hypertensive disease, hyperlipidemia, chronic bronchitis) between these groups were not significantly different (
Effect of Empagliflozin on IL-6, JAK-2 and STAT-3 of Cardiorenal Syndrome Patients Compared with Healthy people
Patients with CRS have a higher level of IL-6, and low expression of JAK-2 and STAT-3 was statistically significant compared to the control group (
Effect of Empagliflozin on Renal Function of Cardiorenal Syndrome Patients Compared to Healthy People
To determine whether EMPA was associated with changes in renal function, we performed a detailed analysis of 3 critical parameters (Ser, BUN, and UA). Patients with CRS have a higher level of Ser and BUN compared to healthy people, but UA has no significant difference between these groups. The detailed analysis revealed that renal injury was alleviated in the EMPA and control group. The level of BUN was decreased, but Ser revealed no significant decrease in the control group after treatment. Interestingly, the level of BUN and Ser were both decreased in the EMPA group, indicating EMPA exerts a nephroprotective effect to some extent (
Effect of Empagliflozin on Echocardiography of Cardiorenal Syndrome Patients Compared to Healthy People
Next, we examined the echocardiography. Patients with CRS have a higher level of LAD, LVED, and low level of LVEF compared to healthy people. However, the difference in LAD, LVED, and LVEF was not statistically significant when comparing the EMPA and control group, showing improved cardiac function. Therefore, this experiment did not show the cardioprotective effect of empagliflozin on patients with CRS, which may be related to the short duration of experimental research (
Effects of Empagliflozin on the Rate of Adverse Events and Major Adverse Cardiovascular Events
Finally, we examined the rate of adverse reactions and found that the incidence of adverse reactions in the 2 groups was 13.46% and 24.00% respectively, which were not significantly different among the experimental groups (
Discussion
The pathogenesis of CRS is complex, including chronic activation of the renin-angiotensin-aldosterone system and the sympathetic nervous system, contributing to cellular hypertrophy, inflammation, apoptosis, fibrosis, and oxidative stress in both the heart and the kidney. Augmented levels of reactive oxygen species can also stimulate the production of pro-inflammatory mediators such as IL-6 and TGF-β.12 Recent studies revealed an increased risk of developing macrovascular and microvascular complications in diabetic injury, which are associated with insulin resistance, further oxidative damage, advanced glycation end products (AGE), leading to high morbidity and mortality in CRS.13 Despite this, the role of renal mitochondrial oxidative stress in CRS type 2 pathology remains to be investigated.
While the data on the role of renal mitochondria in the setting of CRS type 2 is limited, there is considerable evidence that augmented levels of tumor necrosis factor alpha (TNF-α) and soluble tumor necrosis factor receptor type-1 within heart failure were significantly associated with congestion and renal impairment, and were independent predictors of a composite outcome of death and heart failure hospitalisation.14 In this study, in patients hospitalized for CRS the high level of IL-6 was associated with inflammation and the anti-inflammatory actions of EMPA were confirmed. Moreover, EMPA reduced inflammatory cytokines (IL-1β, IL-18), and substances related to oxidative stress (H2O2, 3-nitrotyrosine, lipid peroxide, etc.).15,
The JAK/STAT pathway, an important high-profile pathway of cytokine signaling, plays pivotal roles in proliferation, differentiation, apoptosis, and various inflammatory responses, participating in the occurrence and development of various diseases. In IL-6 signaling, the ligand binds IL-6R and generates hetero-dimeric IL-6/IL-6R complexes that associate with glycoprotein130 (gp130), resulting in the activation of gp130 and inducing the phosphorylation of JAKs, which in turn triggers STAT-3 homodimerization, nuclear translocation, DNA binding, and the activation of STAT-3 transcription targets genes.17,
A bunch of studies confirmed the expression of JAK2/STAT3 signaling was decreased in patients with heart failure. And our study is in agreement with those reported in an elegant study by Li et al22 showed that troxerutin, also known as vitamin P4, could inhibit the expression of oxidative stress, inflammation, and apoptosis of cardiomyocytes induced by H2O2 via activating the JAK2/STAT3 signaling. Similarly, researchers found that ligustrazine23 and astragaloside IV24 exert cardioprotective function by activating JAK2/STAT3 pathway. Additionally, it is demonstrated that remote ischemic preconditioning (RIPC) induced the cardioprotective effect by activating JAK/STAT pathway.25 Our data shows that the anti-inflammatory actions of EMPA were mediated by JAK2/STAT3 activation. Why do different drugs play a therapeutic role through different ways? We found that this may be related to a variety of factors by consulting many papers. First, the expression of STAT-3 is related to the stage of the disease. Signal transducer and activator of transcription 3 increased during the process of cardiac hypertrophy, while the tyrosine-phosphorylation of JAK-2 and STAT-3 is reduced in patients with end-stage dilated cardiomyopathy, indicating impaired downstream activation of this critical pathway.26,
Study Limitations
The limitations of the present study include its small sample size, which was determined by budgetary constraints. Furthermore, to verify whether the effects of EMPA were associated with JAK2/STAT3 signaling, we are determined to detect gp130, SOCS-1, and SOCS-3 in further study as the effects of drugs on patients are long-lasting. Nevertheless, our study provides unique insights into the renal effects of EMPA with JAK2/STAT3 signaling and supports the application of EMPA as a therapeutic option in CRS patients with diabetes. Our experiment may be complementary to Zannad et al,33 they confirmed the differential expression of a small select group of circulating proteins following SGLT2 inhibition after 52 weeks. Sodium-dependent glucose transporters-2 (SGLT2) inhibition is a new type of drug used to treat patients with CRS, and its exact physiological functions are not yet fully understood; therefore, its significance in JAK2/STAT3 signaling and prognosis in patients with CRS is limited. The relationship between EMPA and JAK2/STAT3 signaling warrants further investigation.
Conclusions
Empagliflozin therapy exerts anti-inflammatory effects and favorably affects to cardiac and renal function, associated with substantial improvements in short-term outcomes. Consequently, it’s demonstrated that EMPA might be of benefit in patients with CRS type 2 via activating JAK2/STAT3 signaling, worth application in medical treatment.
Footnotes
References
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