Interleukin-38 in atherosclerosis

AMPK/autophagy-mediated alleviation of tendinopathy by IL-38: A novel strategy for the treatment of obesity-related tendinopathy

The effect of interleukin-38 (IL-38), a recently identified member of the IL-1 family with potential applications in various inflammation-related conditions, on ER stress has not been explored. Furthermore, its role in obesity-associated tendinopathy has not been investigated. In this study, human primary tenocytes were treated with palmitate (200 or 400 μM) and palmitate plus IL-38 (0-50 ng/mL) for 24 h. Western blotting was used to assess ER stress and tendinopathogenic markers in tenocytes. Monodansylcadaverine (MDC) staining was used to evaluate autophagosomes. Apoptosis was determined by cell viability assays, caspase 3 activity assays and TUNEL assays. Cell migration was evaluated by a cell scratch assay. Small interfering (si) RNA transfection was used for target gene silencing. Treatment of tenocytes with IL-38 attenuated apoptosis, restored the balance between MMPs and TIMP-1, and alleviated ER stress under palmitate conditions. IL-38 treatment enhanced AMPK phosphorylation and promoted the expression of autophagy markers related to LC3 conversion, p62 degradation, and autophagosome formation in cultured tenocytes. The effects of IL-38 on ER stress, apoptosis, and MMP-9, MMP-13, and TIMP-1 expression in palmitate-treated tenocytes were abrogated by AMPK siRNA or 3-methyladenine (3MA). These results suggest that IL-38 alleviates ER stress through the AMPK/autophagy pathway, thereby reducing apoptosis and preventing extracellular matrix (ECM) degradation in tenocytes under hyperlipidemic conditions. This study provides a promising therapeutic avenue for treating obesity-related tendinopathy using an endogenous compound such as IL-38.

Emerging functions and therapeutic targets of IL-38 in central nervous system diseases

Interleukin (IL)-38 is a newly discovered cytokine of the IL-1 family, which binds various receptors (i.e., IL-36R, IL-1 receptor accessory protein-like 1, and IL-1R1) in the central nervous system (CNS). The hallmark physiological function of IL-38 is competitive binding to IL-36R, as does the IL-36R antagonist. Emerging research has shown that IL-38 is abnormally expressed in the serum and brain tissue of patients with ischemic stroke (IS) and autism spectrum disorder (ASD), suggesting that IL-38 may play an important role in neurological diseases. Important advances include that IL-38 alleviates neuromyelitis optica disorder (NMOD) by inhibiting Th17 expression, improves IS by protecting against atherosclerosis via regulating immune cells and inflammation, and reduces IL-1β and CXCL8 release through inhibiting human microglial activity post-ASD. In contrast, IL-38 mRNA is markedly increased and is mainly expressed in phagocytes in spinal cord injury (SCI). IL-38 ablation attenuated SCI by reducing immune cell infiltration. However, the effect and underlying mechanism of IL-38 in CNS diseases remain inadequately characterized. In this review, we summarize the biological characteristics, pathophysiological role, and potential mechanisms of IL-38 in CNS diseases (e.g., NMOD, Alzheimer's disease, ASD, IS, TBI, and SCI), aiming to explore the therapeutic potential of IL-38 in the prevention and treatment of CNS diseases.

IL-38 alleviates atherogenic responses via SIRT6/HO-1 signaling: A promising strategy against obesity-related atherosclerosis

Interleukin-38 (IL-38), a member of the IL-1 family, is known for its anti-inflammatory properties mediated through ligand signaling in various disease models. It plays a significant role in atherosclerosis development, forming a theoretical basis for therapeutic strategies. However, the direct effects of IL-38 on atherogenic responses in the vascular endothelium and monocytes remain unclear. In this investigation, IL-38 treatment reduced THP-1 monocyte adhesion to HUVECs, decreased the expression of vascular adhesion molecules, and mitigated inflammation in the presence of palmitate. IL-38 treatment upregulated SIRT6 expression and enhanced autophagy markers such as LC3 conversion and p62 degradation. The effects of IL-38 were nullified by siRNA-mediated suppression of SIRT6 or heme oxygenase-1 (HO-1) in HUVECs and palmitate-treated THP-1 cells. These findings reveal that IL-38 mitigates inflammation through the SIRT6/HO-1 pathway, offering a potential therapeutic approach for addressing obesity-related atherosclerosis.

Evolving concepts in the pathophysiology of atherosclerosis: from endothelial dysfunction to thrombus formation through multiple shades of inflammation

Atherosclerosis is the anatomo-pathological substrate of most cardio, cerebro and vascular diseases such as acute and chronic coronary syndromes, stroke and peripheral artery diseases. The pathophysiology of atherosclerotic plaque and its complications are under continuous investigation. In the last 2 decades our understanding on the formation, progression and complication of the atherosclerotic lesion has greatly improved and the role of immunity and inflammation is now well documented and accepted. The conventional risk factors modulate endothelial function determining the switch to a proatherosclerotic phenotype. From this point, lipid accumulation with an imbalance from cholesterol influx and efflux, foam cells formation, T-cell activation, cytokines release and matrix-degrading enzymes production occur. Lesions with high inflammatory rate become vulnerable and prone to rupture. Once complicated, the intraplaque thrombogenic material, such as the tissue factor, is exposed to the flowing blood, thus inducing coagulation cascade activation, platelets aggregation and finally intravascular thrombus formation that leads to clinical manifestations of this disease. Nonconventional risk factors, such as gut microbiome, are emerging novel markers of atherosclerosis. Several data indicate that gut microbiota may play a causative role in formation, progression and complication of atherosclerotic lesions. The gut dysbiosis-related inflammation and gut microbiota-derived metabolites have been proposed as the main working hypothesis in contributing to disease formation and progression. The current evidence suggest that the conventional and nonconventional risk factors may modulate the degree of inflammation of the atherosclerotic lesion, thus influencing its final fate. Based on this hypothesis, targeting inflammation seems to be a promising approach to further improve our management of atherosclerotic-related diseases.