Unravelling CD4+ T cell diversity and tissue adaptation of Tregs in abdominal aortic aneurysms through single-cell sequencing.

Immune cell infiltration is a significant pathological process in abdominal aortic aneurysms (AAA). T cells, particularly CD4+ T cells, are essential immune cells responsible for substantial infiltration of the aorta. Regulatory T cells (Tregs) in AAA have been identified as tissue-specific; however, the time, location, and mechanism of acquiring the tissue-specific phenotype are still unknown. Using single-cell RNA sequencing (scRNA-seq) on CD4+ T cells from the AAA aorta and spleen, we discovered heterogeneity among CD4+ T cells and identified activated, proliferating and developed aorta Tregs. These Tregs originate in the peripheral tissues and acquire the tissue-specific phenotype in the aorta. The identification of precursors for Tregs in AAA provides new insight into the pathogenesis of AAA.

Increased expression of protein tyrosine phosphatase nonreceptor type 22 alters early T-cell receptor signaling and differentiation of CD4+ T cells in chronic heart failure.

CD4+ T-cell counts are increased and activated in patients with chronic heart failure (CHF), whereas regulatory T-cell (Treg) expansion is inhibited, probably due to aberrant T-cell receptor (TCR) signaling. TCR signaling is affected by protein tyrosine phosphatase nonreceptor type 22 (PTPN22) in autoimmune disorders, but whether PTPN22 influences TCR signaling in CHF remains unclear. This observational case-control study included 45 patients with CHF [18 patients with ischemic heart failure versus 27 patients with nonischemic heart failure (NIHF)] and 16 non-CHF controls. We used flow cytometry to detect PTPN22 expression, tyrosine phosphorylation levels, zeta-chain-associated protein kinase, 70 kDa (ZAP-70) inhibitory residue tyrosine 292 and 319 phosphorylation levels, and CD4+ T cell and Treg proportions. We conducted lentivirus-mediated PTPN22 RNA silencing in isolated CD4+ T cells. PTPN22 expression increased in the CD4+ T cells of patients with CHF compared with that in controls. PTPN22 expression was positively correlated with left ventricular end-diastolic diameter and type B natriuretic peptide but negatively correlated with left ventricular ejection fraction in the NIHF group. ZAP-70 tyrosine 292 phosphorylation was decreased, which correlated positively with PTPN22 overexpression in patients with NIHF and promoted early TCR signaling. PTPN22 silencing induced Treg differentiation in CD4+ T cells from patients with CHF, which might account for the reduced frequency of peripheral Tregs in these patients. PTPN22 is a potent immunomodulator in CHF and might play an essential role in the development of CHF by promoting early TCR signaling and impairing Treg differentiation from CD4+ T cells.

T lymphocyte characteristics and immune repertoires in the epicardial adipose tissue of heart failure patients.

Background: Epicardial adipose tissue (EAT) acts as an active immune organ and plays a critical role in the pathogenesis of heart failure (HF). However, the characteristics of immune cells in EAT of HF patients have rarely been elucidated. Methods: To identify key immune cells in EAT, an integrated bioinformatics analysis was performed on public datasets. EAT samples with paired subcutaneous adipose tissue (SAT), heart, and peripheral blood samples from HF patients were collected in validation experiments. T cell receptor (TCR) repertoire was assessed by high-throughput sequencing. The phenotypic characteristics and key effector molecules of T lymphocytes in EAT were assessed by flow cytometry and histological staining. Results: Compared with SAT, EAT was enriched for immune activation-related genes and T lymphocytes. Compared with EAT from the controls, activation of T lymphocytes was more pronounced in EAT from HF patients. T lymphocytes in EAT of HF patients were enriched by highly expanded clonotypes and had greater TCR clonotype sharing with cardiac tissue relative to SAT. Experiments confirmed the abundance of IFN-γ+ effector memory T lymphocytes (TEM) in EAT of HF patients. CCL5 and GZMK were confirmed to be associated with T lymphocytes in EAT of HF patients. Conclusion: EAT of HF patients was characterized by pronounced immune activation of clonally expanded IFN-γ+ TEM and a generally higher degree of TCR clonotypes sharing with paired cardiac tissue.

Cholesterol suppresses human iTreg differentiation and nTreg function through mitochondria-related mechanisms.

BACKGROUND: Both the crystalline and soluble forms of cholesterol increase macrophage secretion of interleukin 1ß (IL-1ß), aggravating the inflammatory response in atherosclerosis (AS). However, the link between cholesterol and regulatory T cells (Tregs) remains unclear. This study aimed to investigate the effect of cholesterol treatment on Tregs. METHODS: Differentiation of induced Tregs (iTregs) was analyzed using flow cytometry. The expression of hypoxia-inducible factor-1a (HIF-1a) and its target genes was measured by western blotting and/or RT-qPCR. Two reporter jurkat cell lines were constructed by lentiviral transfection. Mitochondrial function and the structure of natural Tregs (nTregs) were determined by tetramethylrhodamine (TMRM) and mitoSOX staining, Seahorse assay, and electron microscopy. The immunoregulatory function of nTregs was determined by nTreg-macrophage co-culture assay and ELISA. RESULTS: Cholesterol treatment suppressed iTreg differentiation and impaired nTreg function. Mechanistically, cholesterol induced the production of mitochondrial reactive oxygen species (mtROS) in naïve T cells, inhibiting the degradation of HIF-1α and unleashing its inhibitory effects on iTreg differentiation. Furthermore, cholesterol-induced mitochondrial oxidative damage impaired the immunosuppressive function of nTregs. Mixed lymphocyte reaction and nTreg-macrophage co-culture assays revealed that cholesterol treatment compromised the ability of nTregs to inhibit pro-inflammatory conventional T cell proliferation and promote the anti-inflammatory functions of macrophages. Finally, mitoTEMPO (MT), a specific mtROS scavenger, restored iTreg differentiation and protected nTreg from further deterioration. CONCLUSION: Our findings suggest that cholesterol may aggravate inflammation within AS plaques by acting on both iTregs and nTregs, and that MT may be a promising anti-atherogenic drug.

Gene polymorphism in IL17A and gene-gene interaction in the IL23R/IL17A axis are associated with susceptibility to coronary artery disease.

AIMS: Studies have confirmed that the IL-23R/IL-17A axis plays an important role in the development of autoimmune and inflammatory diseases. However, its role in coronary artery disease (CAD) remains unclear. Here, we conducted a large sample case-control study to investigate the association between the IL23R/IL17A axis and CAD in the Chinese Han population. METHODS: Two SNPs, rs2275913: G>A (IL17A) and rs6682925: T>C (IL23R), were genotyped in 3042 CAD cases and 3216 controls using the high-resolution melt technology (HRM). Logistic regression analyses were used to adjust the traditional risk factors for CAD and perform the gene interaction analyses. Multiple linear regression analyses were used to study the relationships between the selected SNPs and the levels of serum lipids. In addition, meta-analysis also was performed for the association between rs6682925 and rs2275913 with CAD in different popolations. RESULTS: Our case-control and meta-analysis for single SNPs demonstrated that the frequencies of the alleles and the distribution of the genotypes had no significant differences in CAD cases compared with controls. In the stratified analysis, we observed that the frequency of the IL17A rs2275913-A allele was more epidemic in early-onset CAD than in the controls (Padj = 0.005, OR = 1.209, 95% CI: 1.059-1.382), and the minor allele C of rs6682925 was associated with a decreased level of serum total cholesterol under a recessive model (Padj = 0.011). We demonstrated a significant interaction between rs6682925 and rs2275913 and CAD in the Chinese Han population. Four genotypes (CTGG, CCAA, CCAG, CCGG) were significantly associated with CAD (Padj = 2.94 × 10-4, OR = 0.619, 95% CI: 0.478-0.803; Padj = 0.01, OR = 1.808, 95% CI: 1.152-1.869; Padj = 6 × 10-6, OR = 2.179, 95% CI: 1.558-3.049; Padj = 0.001, OR = 1.883, 95% CI: 1.282-2.762, respectively). CONCLUSION: Our study found no single SNP of rs2275913 in IL17A and rs6682925 in IL23R was associated with CAD in the Chinese population, but the interaction of them were significantly associated with CAD susceptibility, highlighting the key role of the IL-23R/IL-17A axis in the development of CAD. In addition, we also found rs2275913 was associated with early-onset CAD and rs6682925 was associated with total cholesterol levels, which will contribute to the clinical stratified management of this common disease.

Propionate Alleviates Abdominal Aortic Aneurysm by Modulating Colonic Regulatory T-Cell Expansion and Recirculation.

Emerging evidence supports that intestinal microbial metabolite short-chain fatty acids (SCFAs) increase the pool of regulatory T cells (Tregs) in the colonic lamina propria (cLP) and protect against nonintestinal inflammatory diseases, such as atherosclerosis and post-infarction myocardial inflammation. However, whether and how SCFAs protect the inflamed aortas of subjects with abdominal aortic aneurysm (AAA) remains unclear. Here, the authors revealed the protective effect of SCFAs on AAA in mice and the expansion of Tregs in the cLP, and propionate exerted Treg-dependent protection against AAA by promoting the recirculation of cLP-Tregs through colonic draining lymph nodes (dLNs) to the inflamed aorta.

Aorta Regulatory T Cells with a Tissue-Specific Phenotype and Function Promote Tissue Repair through Tff1 in Abdominal Aortic Aneurysms.

In addition to maintaining immune tolerance, Foxp3+ regulatory T cells (Tregs) perform specialized functions in tissue homeostasis and remodeling. However, whether Tregs in aortic aneurysms have a tissue-specific phenotype and function is unclear. Here, a special group of Tregs that potentially inhibit abdominal aortic aneurysm (AAA) progression are identified and functionally characterized. Aortic Tregs gradually increase during the process of AAA and are mainly recruited from peripheral circulation. Single-cell TCR sequencing and bulk RNA sequencing demonstrate their unique phenotype and highly expressed trefoil factor 1 (Tff1). Foxp3cre/cre Tff1flox/flox mice are used to clarify the role of Tff1 in AAA, suggesting that aortic Tregs secrete Tff1 to regulate smooth muscle cell (SMC) survival. In vitro experiments confirm that Tff1 inhibits SMC apoptosis through the extracellular signal-regulated kinase (ERK) 1/2 pathway. The findings reveal a tissue-specific phenotype and function of aortic Tregs and may provide a promising and novel approach for the prevention of AAA.

Pathogenic Tconvs promote inflammatory macrophage polarization through GM-CSF and exacerbate abdominal aortic aneurysm formation.

Abdominal aortic aneurysms (AAAs) elicit massive inflammatory leukocyte recruitment to the aorta. CD4+ T cells, which include regulatory T cells (Tregs) and conventional T cells (Tconvs), are involved in the progression of AAA. Tregs have been reported to limit AAA formation. However, the function and phenotype of the Tconvs found in AAAs remain poorly understood. We characterized aortic Tconvs by bulk RNA sequencing and discovered that Tconvs in aortic aneurysm highly expressed Cxcr6 and Csf2. Herein, we determined that the CXCR6/CXCL16 signaling axis controlled the recruitment of Tconvs to aortic aneurysms. Deficiency of granulocyte-macrophage colony-stimulating factor (GM-CSF), encoded by Csf2, markedly inhibited AAA formation and led to a decrease of inflammatory monocytes, due to a reduction of CCL2 expression. Conversely, the exogenous administration of GM-CSF exacerbated inflammatory monocyte infiltration by upregulating CCL2 expression, resulting in worsened AAA formation. Mechanistically, GM-CSF upregulated the expression of interferon regulatory factor 5 to promote M1-like macrophage differentiation in aortic aneurysms. Importantly, we also demonstrated that the GM-CSF produced by Tconvs enhanced the polarization of M1-like macrophages and exacerbated AAA formation. Our findings revealed that GM-CSF, which was predominantly derived from Tconvs in aortic aneurysms, played a pathogenic role in the progression of AAAs and may represent a potential target for AAA treatment.

Genetic association analysis between IL9 and coronary artery disease in a Chinese Han population.

Interleukin-9 (IL-9) plays important role in coronary artery disease (CAD). However, the exact relationship between them is not explored yet. Here, four tag SNPs covering IL9 (rs31563, rs2069868, rs2069870 and rs31564) were selected to conduct case-control association analyses in a total of 3704 individuals from Chinese Han population (1863 CAD vs 1841 control). Results showed that: first, rs2069868 was associated with CAD combined with hypertension (Padj = 0.027); second, IL9 haplotype (CGAT) was associated with CAD (Padj = 0.035), and the combination genotype of "rs31563_CC/rs31564_TT" would remarkably decrease the risk of CAD (Padj = 0.001); third, significant associations were found between rs2069870 and decreased LDL-c levels and decreased total cholesterol levels, and between rs31563 and increased HDL-c levels (Padj < 0.05). Therefore, we conclude that IL9 might play a causal role in CAD by interacted with CAD traditional risk factors, which might confer a new way to improve the prevention and treatment of CAD.

Effects of Insomnia on Peptic Ulcer Disease Using Mendelian Randomization.

OBJECTIVES: Observational studies indicate that insomnia may increase risk of peptic ulcer disease (PUD). Our purpose is to clarify the possible causal relationship between insomnia and PUD by Mendelian randomization analyses. METHODS: We carried out analyses using summary statistics data for genetic variants reported from a GWAS of insomnia (N = up to 1,331,010 individuals) and from a GWAS of PUD (N = up to 456,327 individuals). Three Mendelian randomization approaches were used to explore whether insomnia might play a causal role in PUD, and pathway and functional enrichment analyses were conducted to anticipate the underlying mechanisms. RESULTS: Conventional Mendelian randomization analysis showed clear causality between insomnia and PUD; 1 SD increased insomnia incident was related to a 19% higher risk of PUD (P = 6.69 × 10-16; OR, 1.19 (95% CI, 1.14-1.24)). The associations between insomnia and PUD were consistent in the other two analyses performed using the weighted median method (P = 7.75 × 10-7; OR, 1.16 (95% CI, 1.09-1.23)) and MR-Egger regression (P = 5.00 × 10-3; OR, 1.27 (95% CI, 1.07-1.50)). Moreover, no evidence indicated a reverse causality between PUD events and insomnia symptoms. Pathway and functional enrichment analyses indicated that the mechanisms of insomnia effect on PUD may be through various ways, such as the immune system and oxidative stress. CONCLUSIONS: This Mendelian randomization study suggests insomnia as a causal risk factor for PUD. The potential mechanisms included may be immune and oxidative stress. These findings indicate that improving sleep quality could have substantial health benefits.

Regulatory B cells improve ventricular remodeling after myocardial infarction by modulating monocyte migration.

Overactivated inflammatory responses contribute to adverse ventricular remodeling after myocardial infarction (MI). Regulatory B cells (Bregs) are a newly discovered subset of B cells with immunomodulatory roles in many immune and inflammation-related diseases. Our study aims to determine whether the expansion of Bregs exerts a beneficial effect on ventricular remodeling and explore the mechanisms involved. Here, we showed that adoptive transfer of Bregs ameliorated ventricular remodeling in a murine MI model, as demonstrated by improved cardiac function, decreased scar size and attenuated interstitial fibrosis without changing the survival rate. Reduced Ly6Chi monocyte infiltration was found in the hearts of the Breg-transferred mice, while the infiltration of Ly6Clo monocytes was not affected. In addition, the replenishment of Bregs had no effect on the myocardial accumulation of T cells or neutrophils. Mechanistically, Bregs reduced the expression of C-C motif chemokine receptor 2 (CCR2) in monocytes, which inhibited proinflammatory monocyte recruitment to the heart from the peripheral blood and mobilization from the bone marrow. Breg-mediated protection against MI was abrogated by treatment with an interleukin 10 (IL-10) antibody. Finally, IL-10 neutralization reversed the effect of Bregs on monocyte migration and CCR2 expression. The present study suggests a therapeutic value of Bregs in limiting ventricular remodeling after MI through decreasing CCR2-mediated monocyte recruitment and mobilization.

Inhibition of fibroblast IL-6 production by ACKR4 deletion alleviates cardiac remodeling after myocardial infarction.

Fibrotic scarring is tightly linked to the development of heart failure in patients with post-myocardial infarction (MI). Atypical chemokine receptor 4 (ACKR4) can eliminate chemokines, such as C-C chemokine ligand 21 (CCL21), which is independently associated with heart failure mortality. However, the role of ACKR4 in the heart during MI is unrevealed. This study aimed to determine whether ACKR4 modulates cardiac remodeling following MI and to illuminate the potential molecular mechanisms. The expression of ACKR4 was upregulated in the border/infarct area, and ACKR4 was predominantly expressed in cardiac fibroblasts (CFs). Knockout of ACKR4 protected against adverse ventricular remodeling in mice post-MI. These protective effects of ACKR4 deficiency were independent of dendritic cell immune response but could be attributed to downregulated CF-derived IL-6, affecting CF proliferation and endothelial cell (EC) functions, which consequently inhibited cardiac fibrosis. ACKR4 promoted IL-6 generation and proliferation of CFs. Besides, ACKR4 induced endothelial-to-mesenchymal transition (EndMT) in ECs through IL-6 paracrine effect. The p38 MAPK/NF-κB signaling pathway was involved in ACKR4 facilitated IL-6 generation. Moreover, ACKR4 overexpression in vivo via AAV9 carrying a periostin promoter aggravated heart functional impairment post-MI, which was abolished by IL-6 neutralizing antibody. Therefore, our study established a novel link between ACKR4 and IL-6 post-MI, indicating that ACKR4 may be a novel therapeutic target to ameliorate cardiac remodeling.

A Unique Population of Regulatory T Cells in Heart Potentiates Cardiac Protection From Myocardial Infarction.

BACKGROUND: Regulatory T cells (Tregs), traditionally recognized as potent suppressors of immune response, are increasingly attracting attention because of a second major function: residing in parenchymal tissues and maintaining local homeostasis. However, the existence, unique phenotype, and function of so-called tissue Tregs in the heart remain unclear. METHODS: In mouse models of myocardial infarction (MI), myocardial ischemia/reperfusion injury, or cardiac cryoinjury, the dynamic accumulation of Tregs in the injured myocardium was monitored. The bulk RNA sequencing was performed to analyze the transcriptomic characteristics of Tregs from the injured myocardium after MI or ischemia/reperfusion injury. Photoconversion, parabiosis, single-cell T-cell receptor sequencing, and adoptive transfer were applied to determine the source of heart Tregs. The involvement of the interleukin-33/suppression of tumorigenicity 2 axis and Sparc (secreted acidic cysteine-rich glycoprotein), a molecule upregulated in heart Tregs, was further evaluated in functional assays. RESULTS: We showed that Tregs were highly enriched in the myocardium of MI, ischemia/reperfusion injury, and cryoinjury mice. Transcriptomic data revealed that Tregs isolated from the injured hearts had plenty of differentially expressed transcripts in comparison with their lymphoid counterparts, including heart-draining lymphoid nodes, with a phenotype of promoting infarct repair, indicating a unique characteristic. The heart Tregs were accumulated mainly because of recruitment from the circulating Treg pool, whereas local proliferation also contributed to their expansion. Moreover, a remarkable case of repeatedly detected T-cell receptor of heart Tregs, more than that of spleen Tregs, suggests a model of clonal expansion. Besides, HelioshighNrp-1high phenotype proved the mainly thymic origin of heart Tregs, with a small contribution of phenotypic conversion of conventional CD4+ T cells, proved by the analysis of T-cell receptor repertoires and conventional CD4+ T cells adoptive transfer experiments. The interleukin-33/suppression of tumorigenicity 2 axis was essential for sustaining heart Treg populations. Last, we demonstrated that Sparc, which was highly expressed by heart Tregs, acted as a critical factor to protect the heart against MI by increasing collagen content and boosting maturation in the infarct zone. CONCLUSIONS: We identified and characterized a phenotypically and functionally unique population of heart Tregs that may lay the foundation to harness Tregs for cardioprotection in MI and other cardiac diseases.

Interleukin 35 ameliorates myocardial ischemia-reperfusion injury by activating the gp130-STAT3 axis.

Myocardial ischemia-reperfusion injury (MIRI) is common clinical complication, which represents significant challenge in the treatment of acute myocardial infarction (AMI) diseases. Interleukin 35 (IL-35) exhibits anti-inflammatory properties via the engagement of the gp130, IL-12Rß2 and IL-27Rα receptors. However, whether IL-35 plays a beneficial role in the treatment of MIRI and potential underling mechanism are unclear. We showed that IL-35 conferred protection from MIRI as demonstrated by reduced infarct size and cardiac troponin T, improved cardiac function and decreased cardiomyocyte apoptosis in a mouse model. Despite activation of both STAT3 and STAT5 phosphorylation in the heart by IL-35, signal transducers and activators of transcription 3 (STAT3) was essential for mediating the IL-35-mediated protective effect on MIRI using cardiomyocyte-specific STAT3 deficient mice. Furthermore, gp130 was required for the STAT3 activation and cardio-protection induced by IL-35. Interestingly, IL-35 induced gp130 homodimer and gp130/IL-12Rß2 heterodimers in cardiomyocyte. Our results indicate that IL-35 can execute a protective role against MIRI through a novel signaling pathway, IL-35-gp130-STAT3 pathway, in cardiomyocytes, which may be beneficial for the development of novel and effective therapeutic approaches to treat the MIRI.

Pathologic T-cell response in ischaemic failing hearts elucidated by T-cell receptor sequencing and phenotypic characterization.

AIMS: A persistent cardiac T-cell response initiated by myocardial infarction is linked to subsequent adverse ventricular remodelling and progression of heart failure. No data exist on T-cell receptor (TCR) repertoire changes in combination with phenotypic characterization of T cells in ischaemic failing human hearts. METHODS AND RESULTS: Analysis of TCR repertoire with high-throughput sequencing revealed that compared with T cells in control hearts, those in ischaemic failing hearts showed a clonally expanded TCR repertoire but similar usage patterns of TRBV-J rearrangements and V gene segments; compared with T cells in peripheral blood, those in ischaemic failing hearts exhibited a restricted and clonally expanded TCR repertoire and different usage patterns of TRBV-J rearrangements and V gene segments, suggesting the occurrence of tissue-specific T-cell expansion in ischaemic failing hearts. Consistently, TCR clonotype sharing was prominent in ischaemic failing hearts, especially in hearts of patients who shared human leucocyte antigen (HLA) alleles. Furthermore, ischaemia heart failure (IHF) heart-associated clonotypes were more frequent in peripheral blood of IHF patients than in that of controls. Heart-infiltrating T cells displayed memory- and effector-like characteristics. Th1 cells were the predominant phenotype among CD4+ T cells; CD8+ T cells were equally as abundant as CD4+ T cells and produced high levels of interferon-γ, granzyme B, and perforin. CONCLUSION: We provide novel evidence for a tissue-specific T-cell response predominated by Th1 cells and cytotoxic CD8+ T cells in ischaemic failing human hearts that may contribute to the progression of heart failure.

IL (Interleukin)-33 Suppresses Abdominal Aortic Aneurysm by Enhancing Regulatory T-Cell Expansion and Activity.

Objective- Inflammation occurs during the progression of abdominal aortic aneurysm (AAA). IL (interleukin)-33 is a pleiotropic cytokine with multiple immunomodulatory effects, yet its role in AAA remains unknown. Approach and Results- Immunoblot, immunohistochemistry, and immunofluorescent staining revealed increased IL-33 expression in adventitia fibroblasts from mouse AAA lesions. Daily intraperitoneal administration of recombinant IL-33 or transgenic IL-33 expression ameliorated periaorta CaPO4 injury- and aortic elastase exposure-induced AAA in mice, as demonstrated by blunted aortic expansion, reduced aortic wall elastica fragmentation, enhanced AAA lesion collagen deposition, attenuated T-cell and macrophage infiltration, reduced inflammatory cytokine production, skewed M2 macrophage polarization, and reduced lesion MMP (matrix metalloproteinase) expression and cell apoptosis. Flow cytometry analysis, immunostaining, and immunoblot analysis showed that exogenous IL-33 increased CD4+Foxp3+ regulatory T cells in spleens, blood, and aortas in periaorta CaPO4-treated mice. Yet, ST2 deficiency muted these IL-33 activities. Regulatory T cells from IL-33-treated mice also showed significantly stronger activities in suppressing smooth muscle cell inflammatory cytokine and chemokine expression, macrophage MMP expression, and in increasing M2 macrophage polarization than those from vehicle-treated mice. In contrast, IL-33 failed to prevent AAA and lost its beneficial activities in CaPO4-treated mice after selective depletion of regulatory T cells. Conclusions- Together, this study established a role of IL-33 in protecting mice from AAA formation by enhancing ST2-dependent aortic and systemic regulatory T-cell expansion and their immunosuppressive activities.

Liver-heart crosstalk controls IL-22 activity in cardiac protection after myocardial infarction.

Interleukin (IL)-22 regulates tissue inflammation and repair. Here we report participation of the liver in IL-22-mediated cardiac repair after acute myocardial infarction (MI). Methods: We induced experimental MI in mice by ligation of the left ascending artery and evaluated the effect of IL-22 on post-MI cardiac function and ventricular remodeling. Results: Daily subcutaneous injection of 100 µg/kg mouse recombinant IL-22 for seven days attenuated adverse ventricular remodeling and improved cardiac function in mice at 28 days after left anterior descending coronary artery ligation-induced MI. Pharmacological inhibition of signal transducer and activator of transcription (STAT3) muted these IL-22 activities. While cardiomyocyte-selective depletion of STAT3 did not affect IL-22 activities in protecting post-MI cardiac injury, hepatocyte-specific depletion of STAT3 fully muted these IL-22 cardioprotective activities. Hepatocyte-derived fibroblast growth factor (FGF21) was markedly increased in a STAT3-dependent manner following IL-22 administration and accounted for the cardioprotective benefit of IL-22. Microarray analyses revealed that FGF21 controlled the expression of cardiomyocyte genes that are involved in cholesterol homeostasis, DNA repair, peroxisome, oxidative phosphorylation, glycolysis, apoptosis, and steroid responses, all of which are responsible for cardiomyocyte survival. Conclusions: Supplementation of IL-22 in the first week after acute MI effectively prevented left ventricular dysfunction and heart failure. This activity of IL-22 involved crosstalk between the liver and heart after demonstrating a role of the hepatic STAT3-FGF21 axis in IL-22-induced post-MI cardiac protection.

Genetic Regulation of the Thymic Stromal Lymphopoietin (TSLP)/TSLP Receptor (TSLPR) Gene Expression and Influence of Epistatic Interactions Between IL-33 and the TSLP/TSLPR Axis on Risk of Coronary Artery Disease.

The thymic stromal lymphopoietin (TSLP)/TSLP receptor (TSLPR) axis is involved in multiple inflammatory immune diseases, including coronary artery disease (CAD). To explore the causal relationship between this axis and CAD, we performed a three-stage case-control association analysis with 3,628 CAD cases and 3,776 controls using common variants in the genes TSLP, interleukin 7 receptor (IL7R), and TSLPR. Three common variants in the TSLP/TSLPR axis were significantly associated with CAD in a Chinese Han population [rs3806933T in TSLP, Padj = 4.35 × 10-5, odds ratio (OR) = 1.18; rs6897932T in IL7R, Padj = 1.13 × 10-7, OR = 1.31; g.19646A>GA in TSLPR, Padj = 2.04 × 10-6, OR = 1.20]. Reporter gene analysis demonstrated that rs3806933 and rs6897932 could influence TSLP and IL7R expression, respectively. Furthermore, the "T" allele of rs3806933 might increase plasma TSLP levels (R2 = 0.175, P < 0.01). In a stepwise procedure, the risk for CAD increased by nearly fivefold compared with the maximum effect of any single variant (Padj = 6.99 × 10-4, OR = 4.85). In addition, the epistatic interaction between TSLP and IL33 produced a nearly threefold increase in the risk of CAD in the combined model of rs3806933TT-rs7025417TT (Padj = 3.67 × 10-4, OR = 2.98). Our study illustrates that the TSLP/TSLPR axis might be involved in the pathogenesis of CAD through upregulation of mRNA or protein expression of the referenced genes and might have additive effects on the CAD risk when combined with IL-33 signaling.