Clinical Implications of IL-32, IL-34 and IL-37 in Atherosclerosis: Speculative Role in Cardiovascular Manifestations of COVID-19

Role of IL-34 and its receptors in inflammatory diseases

In recent years, IL-34 has been widely discussed as a novel cytokine. IL-34 is a pro-inflammatory cytokine binding four distinct receptors, namely CSF-1R, syndecan-1, PTP-ζ and TREM2. Previous studies have shown that IL-34 and its receptors play important roles in the development and progression of various inflammatory diseases. Therefore, IL-34 has the potential to be a biomarker and therapeutic target for inflammatory diseases. However, further study is still needed to identify the specific mechanism through which IL-34 contributes to illness. In this article, we review the recent advances in the biological roles of IL-34 and its receptors as well as their roles in the development and therapeutic application of inflammatory diseases.

Novel insights into IL-37: an anti-inflammatory cytokine with emerging roles in anti-cancer process

Interleukin-37 (IL-37) is a newly discovered member of IL-1 family. The cytokine was proved to have extensive protective effects in infectious diseases, allergic diseases, metabolic diseases, autoimmune diseases and tumors since its discovery. IL-37 was mainly produced by immune and some non-immune cells in response to inflammatory stimulus. The IL-37 precursors can convert into the mature forms after caspase-1 cleavage and activation intracellularly, and then bind to Smad-3 and transfer to the nucleus to inhibit the production and functions of proinflammatory cytokines; extracellularly, IL-37 binds to cell surface receptors to form IL-37/IL-18Rα/IL-1R8 complex to exert immunosuppressive function via inhibiting/activating multiple signal pathways. In addition, IL-37 can attenuate the pro-inflammatory effect of IL-18 through directly or forming an IL-37/IL-18BP/IL-18Rβ complex. Therefore, IL-37 has the ability to suppress innate and acquired immunity of the host, and effectively control inflammatory stimulation, which was considered as a new hallmark of cancer. Specifically, it is concluded that IL-37 can inhibit the growth and migration of tumor cells, prohibit angiogenesis and mediate the immunoregulation in tumor microenvironment, so as to exert effective anti-tumor effects. Importantly, latest studies also showed that IL-37 may be a novel therapeutic target for cancer monitoring. In this review, we summarize the immunoregulation roles and mechanisms of IL-37 in anti-tumor process, and discuss its progress so far and potential as tumor immunotherapy.

Serum IL-38 Level Was Associated with Incidence of MACE in the STEMI Patients

Background

The relationship between serum IL-38 and major adverse cardiovascular events (MACE) in patients with ST elevation myocardial infarction (STEMI) remains unclear.

Methods

In the present study, 589 STEMI patients were included, the serum level of IL-38 was measured. The median follow-up time was 720 days, the STEMI patients were divided into high IL-38 (IL-38>6.49ng/mL) and low IL-38 groups (IL-38≤6.49ng/mL) to compare the probability of MACE.

Results

Plasma IL-38 levels were significantly lower in STEMI patients than in SAP patients (4.0±2.2 vs 6.9±3.2 ng/mL, P < 0.001). Ninety-three STEMI patients met the defined MACE study endpoint. The incidence of MACE was significantly lower in patients with high IL-38 group than in patients with low IL-38 group (7.8% vs 23.7%, P < 0.001). Low plasma IL-38 levels were independently associated with the occurrence of MACE (OR = 0.90, P < 0.001).

Conclusion

We get a conclusion that low plasma levels of IL-38 are independently associated with the occurrence of MACE.

IL‑37 suppresses macrophage ferroptosis to attenuate diabetic atherosclerosis via the NRF2 pathway

IL-37 is a newly discovered inflammatory factor. However, the protective effect and underlying mechanisms of IL-37 on atherosclerosis remain unclear. In the present study, IL-37 was used for intraperitoneal injection in diabetic ApoE^-/- mice caused by streptozotocin. High glucose (HG)/ox-LDL was used to stimulate THP-1 original macrophage followed by IL-37 pretreatment in vitro. The atheromatous plaque area, oxidative stress and inflammation levels in ApoE^-/- mice were evaluated, and the level of macrophage ferroptosis was detected in vivo and in vitro. It was identified that IL-37 treatment significantly decreased plaque area in diabetic ApoE^-/- mice. IL-37 not only improved blood lipid levels in mice, but also reduced serum levels of inflammatory factors including IL-1β and IL-18. Furthermore, IL-37 increased GPX4 and nuclear factor erythroid 2-related factor 2 (NRF2) in the aorta of diabetic mice. In vitro experiment revealed that IL-37 inhibited HG/ox-LDL-induced ferroptosis in macrophages, as evidenced by improved cell membrane oxidation, reduced malondialdehyde production and increased GPX4 expression. Moreover, it was also found that IL-37 enhanced the nuclear translocation of NRF2 in macrophages, while ML385, a specific NRF2 inhibitor, significantly attenuated the protective effect of IL-37 on macrophage ferroptosis caused by HG/ox-LDL. In conclusion, IL-37 suppressed macrophage ferroptosis to attenuate atherosclerosis progression via activating the NRF2 pathway.

Circulating Interlukin-32 and Altered Blood Pressure Control in Individuals with Metabolic Dysfunction

Fatty liver disease is most frequently related to metabolic dysfunction (MAFLD) and associated comorbidities, heightening the risk of cardiovascular disease, and is associated with higher hepatic production of IL32, a cytokine linked with lipotoxicity and endothelial activation. The aim of this study was to examine the relationship between circulating IL32 concentration and blood pressure control in individuals with metabolic dysfunction at high risk of MAFLD. IL32 plasma levels were measured by ELISA in 948 individuals with metabolic dysfunction enrolled in the Liver-Bible-2021 cohort. Higher circulating IL32 levels were independently associated with systolic blood pressure (estimate +0.008 log₁₀ per 1 mmHg increase, 95% c.i. 0.002-0.015; p = 0.016), and inversely correlated with antihypertensive medications (estimate -0.189, 95% c.i. -0.291--0.088, p = 0.0002). Through multivariable analysis, IL32 levels predicted both systolic blood pressure (estimate 0.746, 95% c.i 0.173-1.318; p = 0.010) and impaired blood pressure control (OR 1.22, 95% c.i. 1.09-1.38; p = 0.0009) independently of demographic and metabolic confounders and of treatment. This study reveals that circulating IL32 levels are associated with impaired blood pressure control in individuals at risk of cardiovascular disease.

Wellens' syndrome following severe COVID-19 infection, an innocent coincidence or a deadly association: two case reports

BACKGROUND

Coronavirus disease 2019 (COVID-19) has been associated with late-onset cardiovascular complications primarily due to a hypercoagulable state. Its association with Wellens' syndrome, which reflects a stenosis in the proximal left anterior descending coronary artery, is not well established. We present two cases diagnosed with this syndrome following their COVID-19 acute phase despite taking adequate anticoagulation.

CASE PRESENTATION

We present two patients with incidental electrocardiography (ECG) showing the typical Wellens'-related changes, with an underlying severe triple-vessel coronary artery disease a few weeks following a severe COVID-19 infection associated with high inflammatory markers. The stenotic lesions were diagnosed by cardiac catheterization, and both patients underwent Coronary Artery Bypass Grafting successfully. Notably, patients' baseline ECGs were normal, and they were maintained on Rivaroxaban 10 mg following their viral illness.

CONCLUSION

Despite advances in the preventive measures for COVID-19 complications, its pathophysiologic impact on vasculature and atherosclerosis is still incompletely understood. Further clinical trials must be conducted to study this association between Wellens' syndrome and this virus to prevent life-threatening complications.

Atherosclerosis, Cardiovascular Disorders and COVID-19: Comorbid Pathogenesis

The article describes how atherosclerosis and coronavirus disease 19 (COVID-19) may affect each other. The features of this comorbid pathogenesis at various levels (vascular, cellular and molecular) are considered. A bidirectional influence of these conditions is described: the presence of cardiovascular diseases affects different individuals' susceptibility to viral infection. In turn, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can have a negative effect on the endothelium and cardiomyocytes, causing blood clotting, secretion of pro-inflammatory cytokines, and thus exacerbating the development of atherosclerosis. In addition to the established entry into cells via angiotensin-converting enzyme 2 (ACE2), other mechanisms of SARS-CoV-2 entry are currently under investigation, for example, through CD147. Pathogenesis of comorbidity can be determined by the influence of the virus on various links which are meaningful for atherogenesis: generation of oxidized forms of low-density lipoproteins (LDL), launch of a cytokine storm, damage to the endothelial glycocalyx, and mitochondrial injury. The transformation of a stable plaque into an unstable one plays an important role in the pathogenesis of atherosclerosis complications and can be triggered by COVID-19. The impact of SARS-CoV-2 on large vessels such as the aorta is more complex than previously thought considering its impact on vasa vasorum. Current information on the mutual influence of the medicines used in the treatment of atherosclerosis and acute COVID-19 is briefly summarized.

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.

Targeting CSF-1R represents an effective strategy in modulating inflammatory diseases

Colony-stimulating factor-1 receptor (CSF-1R), also known as FMS kinase, is a type I single transmembrane protein mainly expressed in myeloid cells, such as monocytes, macrophages, glial cells, and osteoclasts. The endogenous ligands, colony-stimulating factor-1 (CSF-1) and Interleukin-34 (IL-34), activate CSF-1R and downstream signaling pathways including PI3K-AKT, JAK-STATs, and MAPKs, and modulate the proliferation, differentiation, migration, and activation of target immune cells. Over the past decades, the promising therapeutic potential of CSF-1R signaling inhibition has been widely studied for decreasing immune suppression and escape in tumors, owing to depletion and reprogramming of tumor-associated macrophages. In addition, the excessive activation of CSF-1R in inflammatory diseases is consecutively uncovered in recent years, which may result in inflammation in bone, kidney, lung, liver and central nervous system. Agents against CSF-1R signaling have been increasingly investigated in preclinical or clinical studies for inflammatory diseases treatment. However, the pathological mechanism of CSF-1R in inflammation is indistinct and whether CSF-1R signaling can be identified as biomarkers remains controversial. With the background information aforementioned, this review focus on the dialectical roles of CSF-1R and its ligands in regulating innate immune cells and highlights various therapeutic implications of blocking CSF-1R signaling in inflammatory diseases.

Predicting roles of IL-27 and IL-32 in determining the severity and outcome of COVID-19

OBJECTIVE

Immune changes play fundamental roles in the pathogenesis and severity of coronavirus disease 2019 (COVID-19). Previous studies have revealed alterations in immune responses of patients with non-severe and severe COVID-19. Therefore, this study investigated whether interleukin-27 (IL-27) and interleukin-32 (IL-32) levels may be considered as predicting factors for determining the severity and outcome of COVID-19.

METHODS

The blood samples were collected from 50 non-severe and severe patients infected with COVID-19 and 25 healthy subjects. The serum samples were isolated from the whole blood. The levels of IL-27 and IL-32 were measured by enzyme-linked immunosorbent assay and percentages of some immune cells were studied by cell counter.

RESULTS

The levels of IL-27 and IL-32 were significantly higher in COVID-19 patients than healthy subjects (p < 0.0001-0.01). IL-27 was significantly reduced in severe COVID-19 patients who needed to undergo ICU therapy (p < 0.05). Disease severity was significantly associated with IL-27 level in patients with COVID-19 (p < 0.05), unlike IL-32 level. There was a significant association between IL-27 and IL-32 in participants (p < 0.0001, odds ratio (OR) = 0.9873; 95% confidence interval (CI) = 0.9998 to 1.000; p < 0.05, OR = 0.4462; 95% CI = 0.08,579 to 0.7802; p < 0.01, OR = 0.6640, 95% CI = 0.3007-0.8590). IL-27 level was significantly higher in the recovered subjects than dead cases (p < 0.0001). IL-27 and IL-32 levels in patients who had fever were significantly higher than those who did not have (p < 0.01-0.05), unlike patients who suffered from cough (p < 0.001-0.01). The IL-27 level in patients with non-severe COVID-19 was directly correlated with CRP value (p < 0.05, OR = 0.5,722,357, 95% CI = 0.06,807,176-0.8,435,928). IL-27 and IL-32 levels in non-severe patients were positively associated with NLR (p < 0.01, OR = 0.7292; 95% CI = 0.2809 to 0.9163; p < 0.01, OR = 0.6537, 95% CI = 0.1425-0.8896). Patients with severe COVID-19 had a significant increase in NLR (p < 0.0001-0.05). NLR was significantly correlated with the disease severity (p < 0.0001-0.05). Survivors had a significant reduction in NLR compared with those who succumbed to COVID-19 (p < 0.05).

CONCLUSION

Change in IL-27 level along with the frequencies of some immune cells may serve as a predictor of the severity and outcome of COVID-19.

The role of IL-35 and IL-37 in breast cancer - potential therapeutic targets for precision medicine

Breast cancer is still a major concern due to its relatively poor prognosis in women, although there are many approaches being developed for the management of breast cancer. Extensive studies demonstrate that the development of breast cancer is determined by pro versus anti tumorigenesis factors, which are closely related to host immunity. IL-35 and IL-37, anti-inflammatory cytokines, play an important role in the maintenance of immune homeostasis. The current review focuses on the correlation between clinical presentations and the expression of IL-35 and IL-37, as well as the potential underlying mechanism during the development of breast cancer in vitro and in vivo. IL-35 is inversely correlated the differentiation and prognosis in breast cancer patients; whereas IL-37 shows dual roles during the development of breast cancer, and may be breast cancer stage dependent. Such information might be useful for both basic scientists and medical practitioners in the management of breast cancer patients.

Sex Differences in Coronary Artery Disease and Diabetes Revealed by scRNA-Seq and CITE-Seq of Human CD4+ T Cells

Despite the decades-old knowledge that males and people with diabetes mellitus (DM) are at increased risk for coronary artery disease (CAD), the reasons for this association are only partially understood. Among the immune cells involved, recent evidence supports a critical role of T cells as drivers and modifiers of CAD. CD4+ T cells are commonly found in atherosclerotic plaques. We aimed to understand the relationship of CAD with sex and DM by single-cell RNA (scRNA-Seq) and antibody sequencing (CITE-Seq) of CD4+ T cells. Peripheral blood mononuclear cells (PBMCs) of 61 men and women who underwent cardiac catheterization were interrogated by scRNA-Seq combined with 49 surface markers (CITE-Seq). CAD severity was quantified using Gensini scores, with scores above 30 considered CAD+ and below 6 considered CAD-. Four pairs of groups were matched for clinical and demographic parameters. To test how sex and DM changed cell proportions and gene expression, we compared matched groups of men and women, as well as diabetic and non-diabetic subjects. We analyzed 41,782 single CD4+ T cell transcriptomes for sex differences in 16 women and 45 men with and without coronary artery disease and with and without DM. We identified 16 clusters in CD4+ T cells. The proportion of cells in CD4+ effector memory cluster 8 (CD4T8, CCR2+ Em) was significantly decreased in CAD+, especially among DM+ participants. This same cluster, CD4T8, was significantly decreased in female participants, along with two other CD4+ T cell clusters. In CD4+ T cells, 31 genes showed significant and coordinated upregulation in both CAD and DM. The DM gene signature was partially additive to the CAD gene signature. We conclude that (1) CAD and DM are clearly reflected in PBMC transcriptomes, and (2) significant differences exist between women and men and (3) between subjects with DM and non-DM.

The Role of IL-37 and IL-38 in Colorectal Cancer

Colorectal cancer (CRC) is a major killer. Dysregulation of IL-37 and IL-38, both anti-inflammatory cytokines, is observed in auto-immune diseases. The precise regulatory mechanisms of IL-37/IL-38 during the development of CRC remains unclear, but chronic intestinal inflammation is involved in the carcinogenesis of CRC. Constitutive production of colonic IL-37 and IL-38 is substantially reduced in CRC, consistent with an inverse correlation with CRC differentiation. Reduced colonic IL-37 and IL-38 is relating to CRC invasion and distant metastasis, suggesting a protective role for IL-38 within the tumor micro-environment. IL-38 is reduced in right-sided CRC compared to left-sided CRC, which is in line with multiple risk factors for right-sided CRC, including the embryonic development of the colon, and genetic differences in CRC between these two sides. Finally, colonic IL-37 and tumor associated neutrophils (TAN) seem to be independent biomarkers of prognostic value, whereas colonic IL-38 seems to be a reliable and independent biomarker in predicting the 5-year survival post-surgery in CRC. However, there is room for improvement in available studies, including the extension of these studies to different regions/countries incorporating different races, evaluation of the role of multi-drug resistance, and different subsets of CRC. It would be useful to determine the kinetics of circulating IL-38 and its relationship with drug resistance/targeted therapy. The measurement of colonic IL-38 at the molecular and cellular level is required to explore the contribution of IL-38 pathways during the development of CRC. These approaches could provide insight for the development of personalized medicine.

Interleukin-37: A Link Between COVID-19, Diabetes, and the Black Fungus

The COVID-19 pandemic involved millions of people and diabetes was identified as an associated comorbidity. Initiation of systemic corticosteroids in patients suffering from severe COVID-19 was associated with lower mortality. A surge of invasive fungal infections of the maxillofacial region, namely mucormycosis, was linked to a deadly infection known as black fungus. Black fungus, diabetes, corticosteroids, and coronavirus disease 2019 (COVID-19) all have a dysregulated immune response in common, which partly could also be attributed to interleukin 37 (IL-37). IL-37, a new cytokine of the IL-1 family, known for broadly reducing innate inflammation as well as acquired immune responses. The use of corticosteroids in diabetic COVID-19 patients, crowded hospitals, and lack of medical oxygen should be carefully considered to reduce COVID-associated secondary infections.

Polarized Macrophages in Periodontitis: Characteristics, Function, and Molecular Signaling

Periodontitis (PD) is a common chronic infectious disease. The local inflammatory response in the host may cause the destruction of supporting periodontal tissue. Macrophages play a variety of roles in PD, including regulatory and phagocytosis. Moreover, under the induction of different factors, macrophages polarize and form different functional phenotypes. Among them, M1-type macrophages with proinflammatory functions and M2-type macrophages with anti-inflammatory functions are the most representative, and both of them can regulate the tendency of the immune system to exert proinflammatory or anti-inflammatory functions. M1 and M2 macrophages are involved in the destructive and reparative stages of PD. Due to the complex microenvironment of PD, the dynamic development of PD, and various local mediators, increasing attention has been given to the study of macrophage polarization in PD. This review summarizes the role of macrophage polarization in the development of PD and its research progress.