Increased Serum Interleukin-34 Levels Are Related to the Presence and Severity of Cardiac Dysfunction in Patients With Ischemic Cardiomyopathy

Cut-off value for interleukin-34 as an additional potential inflammatory biomarker for estimation of slow coronary flow risk

BACKGROUND

Inflammatory markers may provide insights into the underlying mechanisms of slow coronary flow (SCF), including subclinical atherosclerosis and endothelial dysfunction. Interleukin-34 (IL-34), known for its role in immuno-inflammatory diseases, might hold significance in SCF. We aimed to explore the potential association between IL-34 and SCF in patients undergoing diagnostic elective coronary angiography.

METHODS

This observational, cross-sectional study enrolled 256 participants: 124 with SCF and 132 with normal coronary flow (NCF). All participants had undergone outpatient coronary angiography for suspected coronary artery disease. SCF assessment employed the TIMI frame count (TFC) for quantifying coronary flow rate.

RESULTS

SCF patients exhibited significantly elevated TFC in all three major coronary arteries compared to controls (p < 0.05). IL-34 displayed a noteworthy positive correlation with average TFC [for all participants: r = 0.514, p < 0.001; for SCF patients: r = 0.526, p < 0.001; for normal controls: r = -0.288, p > 0.05]. Similarly, high-sensitivity C-reactive protein (hsCRP) showed a significant and positive relationship with average TFC [for all participants: r = 0.504, p < 0.001; for SCF patients: r = 0.558, p < 0.001; for normal controls: r = -0.148, p > 0.05]. SCF patients presented coronary arteries of larger size compared to controls.

CONCLUSION

Mean coronary diameter and IL-34 emerged as independent predictors of SCF. Additionally, hsCRP, mean coronary diameter, and IL-34 exhibited a positive correlation with mean TFC values. IL-34 appears to be a more effective indicator than hsCRP in SCF patients.

Ischemic cardiomyopathy: epidemiology, pathophysiology, outcomes, and therapeutic options

Ischemic cardiomyopathy (ICM) is the most prevalent cause of heart failure (HF) in developed countries, with significant morbidity and mortality, despite constant improvements in the management of coronary artery disease. Current literature on this topic remains fragmented. Therefore, this review aimed to summarize the most recent data on ICM, focusing on its definition, epidemiology, outcomes, and therapeutic options. The most widely accepted definition is represented by a left ventricular dysfunction in the presence of significant coronary artery disease. The prevalence of ICM is largely influenced by age and sex, with older individuals and males being more affected. Its pathophysiology is characterized by plaque buildup, thrombus formation, hypoperfusion, ischemic cell death, and left ventricular remodeling. Despite improvements in therapy, ICM still represents a public health burden, with a 1-year mortality rate of 16% and a 5-year mortality rate of approximately 40% in the USA and Europe. Therefore, optimization of cardiovascular function, prevention of progressive remodeling, reduction of HF symptoms, and improved survival are the main goals of treatment. Therapeutic options for ICM include lifestyle changes, optimal medical therapy, revascularization, device therapy, mechanical circulatory support, and cardiac transplantation. Personalized management strategies and tailored patient care are needed to improve the outcomes of patients with ICM.

Interleukin-34-NF-κB signaling aggravates myocardial ischemic/reperfusion injury by facilitating macrophage recruitment and polarization

BACKGROUND

Macrophage infiltration and polarization are integral to the progression of heart failure and cardiac fibrosis after ischemia/reperfusion (IR). Interleukin 34 (IL-34) is an inflammatory regulator related to a series of autoimmune diseases. Whether IL-34 mediates inflammatory responses and contributes to cardiac remodeling and heart failure post-IR remains unclear.

METHODS

IL-34 knock-out mice were used to determine the role of IL-34 on cardiac remodeling after IR surgery. Then, immunofluorescence, flow cytometry assays, and RNA-seq analysis were performed to explore the underlying mechanisms of IL-34-induced macrophage recruitment and polarization, and further heart failure after IR.

FINDINGS

By re-analyzing single-cell RNA-seq and single-nucleus RNA-seq data of murine and human ischemic hearts, we showed that IL-34 expression was upregulated after IR. IL-34 knockout mitigated cardiac remodeling, cardiac dysfunction, and fibrosis after IR and vice versa. RNA-seq analysis revealed that IL-34 deletion correlated negatively with immune responses and chemotaxis after IR injury. Consistently, immunofluorescence and flow cytometry assays demonstrated that IL-34 deletion attenuated macrophage recruitment and CCR2+ macrophage polarization. Mechanistically, IL-34 deficiency repressed both the canonical and noncanonical NF-κB signaling pathway, leading to marked reduction of P-IKKβ and P-IκBα kinase levels; downregulation of NF-κB p65, RelB, and p52 expression, which drove the decline in chemokine CCL2 expression. Finally, IL-34 and CCL2 levels were increased in the serum of acute coronary syndrome patients, with a positive correlation between circulating IL-34 and CCL2 levels in clinical patients.

INTERPRETATION

In conclusion, IL-34 sustains NF-κB pathway activation to elicit increased CCL2 expression, which contributes to macrophage recruitment and polarization, and subsequently exacerbates cardiac remodeling and heart failure post-IR. Strategies targeting IL-34-centered immunomodulation may provide new therapeutic approaches to prevent and reverse cardiac remodeling and heart failure in clinical MI patients after percutaneous coronary intervention.

FUNDING

This study was supported by the National Nature Science Foundation of China (81670352 and 81970327 to R T, 82000368 to Q F).

Association of Interleukin-32 and Interleukin-34 with Cardiovascular Disease and Short-Term Mortality in COVID-19

BACKGROUND

Excess cardiovascular (CV) morbidity and mortality has been observed in patients with COVID-19. Both interleukin-32 (IL-32) and interleukin-34 (IL-34) have been hypothesized to contribute to CV involvement in COVID-19.

METHODS

This prospective, observational study of patients with laboratory-confirmed COVID-19 infection was conducted from 6 June to 22 December 2020 in a tertiary care hospital in Vienna, Austria. IL-32 and IL-34 levels on admission were collected and tested for their association with CV disease and short-term mortality in patients with COVID-19. CV disease was defined by the presence of coronary artery disease, heart failure, stroke or atrial fibrillation and patients were stratified by CV disease burden.

RESULTS

A total of 245 eligible patients with COVID-19 were included, of whom 37 (15.1%) reached the primary endpoint of 28-day mortality. Of the total sample, 161 had no CV disease (65.7%), 69 had one or two CV diseases (28.2%) and 15 patients had ≥three CV diseases (6.1%). Median levels of IL-32 and IL-34 at admission were comparable across the three groups of CV disease burden. IL-32 and IL-34 failed to predict mortality upon both univariable and multivariable Cox regression analysis. The two CV disease groups, however, had a significantly higher risk of mortality within 28 days (one or two CV diseases: crude HR 4.085 (95% CI, 1.913-8.725), p < 0.001 and ≥three CV diseases: crude HR 13.173 (95% CI, 5.425-31.985), p < 0.001). This association persisted for those with ≥three CV diseases after adjustment for age, gender and CV risk factors (adjusted HR 3.942 (95% CI, 1.288-12.068), p = 0.016).

CONCLUSION

In our study population of hospitalized patients with COVID-19, IL-32 and IL-34 did not show any associations with CV disease or 28-day mortality in the context of COVID-19. Patients with multiple CV diseases, however, had a significantly increased risk of short-term mortality.

Prognostic value of interleukin-34 and interleukin-38 in patients with newly diagnosed atrial fibrillation

Background

Interleukin (IL)-34 and IL-38 are associated with cardiovascular disease (CVD). However, their involvement in atrial fibrillation (AF) and AF-associated adverse events remains uncertain. Therefore, we aimed to investigate their association with various AF prognostic factors in a cohort study and assessed their predictive value for the prognosis of patients with AF.

Methods

Patients with new-onset non-valvular AF were consecutively enrolled between 2013 and 2015 at the Department of Cardiovascular Medicine of the Southwest Hospital of the Army Medical University (Third Military Medical University) in Chongqing, China. The endpoints included stroke and all-cause mortality. The baseline levels of plasma IL-34, IL-38, NT-proBNP, high-sensitivity cardiac troponin T (hs-cTnT), and GDF-15 were measured and their correlation with AF-related adverse events were analyzed in a Cox proportional-hazards regression model. The C-statistic, net reclassification improvement (NRI), and integrated discrimination improvement (IDI) were used to evaluate the performance of the AF prognostic models. Decision curve analysis (DCA) was used to evaluate the clinical net benefit of the original and modified models.

Results

A total of 299 patients with new-onset AF were enrolled. During the median follow-up time of 28 (IQR: 27, 29) months, the higher levels of IL-34 were associated with a lower risk of stroke, and the higher levels of IL-38 were associated with an increased risk of all-cause death (all adjusted P < 0.05). In addition, elevated hs-cTnT and NT-proBNP concentrations were associated with a higher risk of stroke and all-cause mortality (all adjusted P < 0.05). Furthermore, the CHA₂DS₂-VASc score combined with IL-38 and NT-proBNP significantly improved the C-statistic, IDI, and NRI (all P < 0.01). There was no statistically significant difference (all P > 0.05) in the discrimination power between the preference models and the ABC (age, biomarkers, and clinical history) score for the two prognostic outcomes.

Conclusion

Our results suggested that IL-34 and IL-38 were independently associated with stroke and all-cause mortality in patients with AF. Moreover, adding IL-38 and NT-proBNP to the CHA₂DS₂-VASc score significantly improved its predictive ability of AF-related all-cause death. Finally, the preference model performed equally well as the ABC score in predicting AF prognosis.

Bioinformatics and Experimental Analyses Reveal Immune-Related LncRNA-mRNA Pair AC011483.1-CCR7 as a Biomarker and Therapeutic Target for Ischemic Cardiomyopathy

Ischemic cardiomyopathy (ICM), which increases along with aging, is the leading cause of heart failure. Currently, immune response is believed to be critical in ICM whereas the roles of immune-related lncRNAs remain vague. In this study, we aimed to systematically analyze immune-related lncRNAs in the aging-related disease ICM. Here, we downloaded publicly available RNA-seq data from ischemic cardiomyopathy patients and non-failing controls (GSE116250). Weighted gene co-expression network analysis (WGCNA) was performed to identify key ICM-related modules. The immune-related lncRNAs of key modules were screened by co-expression analysis of immune-related mRNAs. Then, a competing endogenous RNA (ceRNA) network, including 5 lncRNAs and 13 mRNAs, was constructed using lncRNA-mRNA pairs which share regulatory miRNAs and have significant correlation. Among the lncRNA-mRNA pairs, one pair (AC011483.1-CCR7) was verified in another publicly available ICM dataset (GSE46224) and ischemic cell model. Further, the immune cell infiltration analysis of the GSE116250 dataset revealed that the proportions of monocytes and CD8⁺ T cells were negatively correlated with the expression of AC011483.1-CCR7, while plasma cells were positively correlated, indicating that AC011483.1-CCR7 may participate in the occurrence and development of ICM through immune cell infiltration. Together, our findings revealed that lncRNA-mRNA pair AC011483.1-CCR7 may be a novel biomarker and therapeutic target for ICM.

Increased serum interleukin-34 levels as a novel diagnostic and prognostic biomarker in patients with acute ischemic stroke

BACKGROUND

Recent data reveal that interleukin-34 (IL-34) can drive inflammatory response, thereby participating in the pathogenesis of inflammatory diseases. However, the potential effect of IL-34 in acute ischemic stroke (AIS) remains unknown. The purpose of this study was to explore whether the levels of serum IL-34 were correlated with clinical severity or prognosis in AIS patients.

METHODS

In this prospective cohort study, serum IL-34 levels were detected in 150 healthy controls and 155 AIS patients. Univariate and multivariate logistic regression analysis were conducted to investigate the effect of IL-34 on the diagnosis and prognosis of AIS. ROC curve was utilized to evaluate predictive values for IL-34.

RESULTS

Serum IL-34 levels at admission were significantly higher in AIS patients than those in the healthy controls. Univariate and multivariate logistics regression analysis showed that IL-34 was an independent predictor of occurrence and functional outcome of AIS. The ROC curve demonstrated that IL-34 had a good predictive effect on the diagnosis and prognosis of AIS.

CONCLUSIONS

IL-34 can be used as a novel and independent diagnostic and predicting prognostic biomarker in AIS.

IL-34 and CSF-1, deciphering similarities and differences at steady state and in diseases

Although IL-34 and CSF-1 share actions as key mediators of monocytes/macrophages survival and differentiation, they also display differences that should be identified to better define their respective roles in health and diseases. IL-34 displays low sequence homology with CSF-1 but has a similar general structure and they both bind to a common receptor CSF-1R, although binding and subsequent intracellular signaling shows differences. CSF-1R expression has been until now mainly described at a steady state in monocytes/macrophages and myeloid dendritic cells, as well as in some cancers. IL-34 has also 2 other receptors, protein-tyrosine phosphatase zeta (PTPζ) and CD138 (Syndecan-1), expressed in some epithelium, cells of the central nervous system (CNS), as well as in numerous cancers. While most, if not all, of CSF-1 actions are mediated through monocyte/macrophages, IL-34 has also other potential actions through PTPζ and CD138. Additionally, IL-34 and CSF-1 are produced by different cells in different tissues. This review describes and discusses similarities and differences between IL-34 and CSF-1 at steady state and in pathological situations and identifies possible ways to target IL-34, CSF-1, and its receptors.

Functional and molecular effects of TNF-α on human iPSC-derived cardiomyocytes

Proinflammatory molecule tumor necrosis factor alpha (TNF-α) is predominantly elevated in cytokine storm as well as worsening cardiac function. Here we model the molecular and functional effects of TNF-α in cardiomyocytes (CMs) derived from human induced pluripotent stem cells (hiPSC). We found that treatment of hiPSC-CMs with TNF-α increased reactive oxygen species (ROS) and caspase 3/7 activity and caused cell death and apoptosis. TNF-α treatment also resulted in dysregulation of cardiomyocyte function with respect to the increased abnormal calcium handling, calcium wave propagation between cells and excitation–contraction coupling. We also uncovered significant changes in gene expression and protein localization caused by TNF-α treatment. Notably, TNF-α treatment altered the expression of ion channels, dysregulated cadherins, and affected the localization of gap-junction protein connexin-43. In addition, TNF-α treatment up-regulated IL-32 (a human specific cytokine, not present in rodents and an inducer of TNF-α) and IL-34 and down-regulated glutamate receptors and cardiomyocyte contractile proteins. These findings provide insights into the molecular and functional consequences from the exposure of human cardiomyocytes to TNF-α. Our study provides a model to incorporate inflammatory factors into hiPSC-CM-based studies to evaluate mechanistic aspects of heart disease.

Emerging roles of IL-34 in health and disease

Macrophages are part of the innate immune system and are present in every organ of the body. They fulfill critical roles in tissue homeostasis and development and are involved in various pathologies. An essential factor for the development, homeostasis, and function of mononuclear phagocytes is the colony stimulating factor-1 receptor (CSF-1R), which has two known ligands: CSF-1 and interleukin-34 (IL-34). While CSF-1 has been extensively studied, the biology and functions of IL-34 are only now beginning to be uncovered. In this review, we discuss recent advances of IL-34 biology in health and disease with a specific focus on mononuclear phagocytes.

Interleukin-34 Levels Were Associated with Prognosis in Patients with Acute Myocardial Infarction

Inflammatory factors have specific value in acute myocardial infarction (AMI). Our previous studies have identified the prognostic value of interleukin (IL)-34 during chronic heart failure. However, the potential impact of IL-34 on AMI remains unknown.Serum IL-34 was measured in 287 AMI patients, and they were followed up for the composite endpoint, including cardiovascular death, heart failure hospitalization, recurrent nonfatal myocardial infarction (MI), and nonfatal stroke.IL-34 levels were significantly associated with the presence of heart failure at baseline and its aggravation after a year. During the five-year follow-up, there was a significant increase in the risk of the composite endpoint (hazard ratio [HR] 1.38 [95% confidence intervals (CI) 1.12-1.70], P < 0.01) and cardiovascular death (HR 1.48 [95%CI 1.03-2.27], P = 0.03) after full adjustment as IL-34 levels increased.Higher IL-34 levels in the acute phase were associated with an increased risk of heart failure after MI and poor prognosis.