PKM2 promotes proinflammatory macrophage activation in ankylosing spondylitis

IDO1-mediated M2 macrophage polarization alleviates the progression of ankylosing spondylitis

Indoleamine 2,3-dioxygenase 1 (IDO1) plays an anti-inflammatory role in autoimmune disease. However, its specific function in ankylosing spondylitis (AS) remain unclear. This study aimed to investigate the potential role of IDO1 in AS. Immunofluorescence, RT-qPCR, and western blot assays were employed to measure gene expression, while ELISA was used to quantify the release of M1 macrophage and M2 macrophage markers. CCK-8, EdU, flow cytometry, ALP staining, and Alizarin red staining (ARS) assays were conducted for functional analysis. JASPAR predicted the binding sites between PPARγ and the promoter, which were further validated by luciferase and ChIP assays. Our findings revealed that the expression of IDO1 was markedly elevated in AS patients. IDO1 overexpression promoted the proliferation of THP-1 cells and M2 macrophage polarization. Conversely, IDO1 knockdown facilitated the osteogenic differentiation of BMSCs. Furthermore, IDO1-mediated upregulation of PPARγ modulated RUNX2 transcription. PPARγ overexpression counteracted the effects of IDO1 knockdown, thereby inhibiting the osteogenic differentiation of BMSCs. In conclusion, the IDO1/PPARγ/RUNX2 signaling pathway may protect against AS by promoting M2 macrophage polarization and inhibiting osteogenic differentiation.

IL-33-Induced TREM2+ Macrophages Promote Pathological New Bone Formation Through CREG1-IGF2R Axis in Ankylosing Spondylitis

Pathological new bone formation is the main cause of disability in ankylosing spondylitis (AS), and so far, it lacks a targeted therapy. Macrophages are central orchestrators of inflammation progression and tissue remodeling, but their contribution to pathological new bone formation has largely not been explored. Here, it is identified that TREM2+ macrophages predominated within the sites of new bone formation and adjacent to osteogenic precursor cells. In vivo, both depletion of macrophages and knockout of Trem2 significantly reduced pathological new bone formation in a collagen antibody-induced arthritis (CAIA) model. Specifically, TREM2+ macrophages promoted osteogenic differentiation of ligament-derived progenitor cells (LDPCs) by secreting CREG1, a secretory glycoprotein involved in cell differentiation and normal physiology. CREG1-IGF2R-PI3K-AKT signaling pathway is involved in TREM2+ macrophage-mediated pathological new bone formation. In addition, it is found that IL-33 promoted TREM2+ macrophage differentiation through phosphorylation of STAT6. Targeting the above signalings alleviated new bone formation in the CAIA model. The findings highlight the critical role of IL-33-induced TREM2+ macrophages in pathological new bone formation and provide potential therapeutic targets for halting spinal ankylosis in AS.

Sweet regulation - The emerging immunoregulatory roles of hexoses

BACKGROUND

It is widely acknowledged that dietary habits have profound impacts on human health and diseases. As the most important sweeteners and energy sources in human diets, hexoses take part in a broad range of physiopathological processes. In recent years, emerging evidence has uncovered the crucial roles of hexoses, such as glucose, fructose, mannose, and galactose, in controlling the differentiation or function of immune cells.

AIM OF REVIEW

Herein, we reviewed the latest research progresses in the hexose-mediated modulation of immune responses, provided in-depth analyses of the underlying mechanisms, and discussed the unresolved issues in this field.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Owing to their immunoregulatory effects, hexoses affect the onset and progression of various types of immune disorders, including inflammatory diseases, autoimmune diseases, and tumor immune evasion. Thus, targeting hexose metabolism is becoming a promising strategy for reversing immune abnormalities in diseases.

METTL17-Mediated Inhibition of M1 Macrophage Polarization Alleviates the Progression of Ankylosing Spondylitis

RNA methylation is involved in the pathogenesis of ankylosing spondylitis (AS). This study aimed to investigate the potentials of METTL17 in AS. mRNA expression was detected using RT-qPCR. RNA methylation was detected using MeRIP assay. Protein expression was detected using western blot. Cell proliferation was detected using EdU assay. Macrophage functions was detected using flow cytometry. METTL17 was upregulated after exposure to LPS. However, METTL17 knockdown promoted inflammatory response. Moreover, METTL17 knockdown promoted M1 macrophage polarization. Mechanically, METTL17 regulate RNA methylation. Mechanically, METTL17 promoted the RNA methylation of STAT1, inhibiting the mRNA and protein stability of STAT1. In summary, METTL17 inhibits inflammatory response and M1 macrophage polarization via mediating the RNA methylation of STAT1. Therefore, targeting METTL17/STAT1 may be a promising strategy for AS.

Compound 3K attenuates isoproterenol-induced cardiac hypertrophy by inhibiting pyruvate kinase M2 (PKM2) pathway

AIM

Chronic sympathetic stimulation has been identified as a primary factor in the pathogenesis of cardiac hypertrophy (CH). However, there is no appropriate treatment available for the management of CH. Recently, it has been revealed that pyruvate kinase M2 (PKM2) plays a significant role in cardiac remodeling, fibrosis, and hypertrophy. However, the therapeutic potential of selective PKM2 inhibitor has not yet been explored in cardiac hypertrophy. Thus, in the current study, we have studied the cardioprotective potential of Compound 3K, a selective PKM2 inhibitor in isoproterenol-induced CH model.

METHODS

To induce cardiac hypertrophy, male Wistar rats were subcutaneously administered isoproterenol (ISO, 5 mg/kg/day) for 14 days. Compound 3K at dosages of 2 and 4 mg/kg orally was administered to ISO-treated rats for 14 days to explore its effects on various parameters like ECG, ventricular functions, hypertrophic markers, histology, inflammation, and protein expression were performed.

RESULTS

Fourteen days administration of ISO resulted in the induction of CH, which was evidenced by alterations in ECG, ventricular dysfunctions, increase in hypertrophy markers, and fibrosis. The immunoblotting of hypertrophy heart revealed the significant rise in PKM2 and reduction in PKM1 protein expression. Treatment with Compound 3K led to downregulation of PKM2 and upregulation of PKM1 protein expression. Compound 3K showed cardioprotective effects by improving ECG, cardiac functions, hypertrophy markers, inflammation, and fibrosis. Further, it also reduced cardiac expression of PKM2-associated splicing protein, HIF-1α, and caspase-3.

CONCLUSION

Our findings suggest that Compound 3K has a potential cardioprotective effect via PKM2 inhibition in isoproterenol-induced CH.

Exploring causal correlations between inflammatory cytokines and ankylosing spondylitis: a bidirectional mendelian-randomization study

Background

The impact of inflammatory factors on the development of Ankylosing Spondylitis (AS) is widely recognized, but the exact causal relationship remains unclear.

Methods

The bidirectional mendelian-randomization study utilized genetic data from a genome-wide association study (GWAS) of 186 AS cases and 456,162 controls of European ancestry. Inflammatory cytokines were obtained from a GWAS summary of 8,293 healthy participants. Causal associations were primarily investigated using the inverse variance-weighted method, supplemented by MR Egger, weighted median and weighted mode analyses. Heterogeneity in the results was assessed using the Cochrane Q test. Horizontal pleiotropy was evaluated through the MR-Egger intercept test and the MR pleiotropy residual sum and outliers (MR-PRESSO) test. Sensitivity analysis was conducted through leave-one-out analysis.

Results

The results suggest a genetically predicted potential association between beta-nerve growth factor (βNGF), Interleukin-1-beta (IL-1β), and TNF-related apoptosis inducing ligand (TRAIL) with the risk of AS (OR: 2.17, 95% CI: 1.13-4.16; OR: 0.41, 95% CI: 0.18-0.95,; OR: 1.47, 95% CI: 1.02-2.13).Additionally, Interleukin-12p70 (IL-12p70), Interleukin-17 (IL-17), Interleukin-6 (IL-6), Interleukin-4 (IL-4), Stromal-cell-derived factor 1 alpha (SDF-1α), Macrophage inflammatory protein 1β (MIP1β), Monocyte chemoattractant protein-3 (MCP-3), Platelet-derived growth factor bb (PDGFbb), Granulocyte-colony stimulating factor (GCSF), Fibroblast growth factor basic (bFGF), TNF-related apoptosis inducing ligand (TRAIL), and Interferon-gamma (IFN -γ) are suggested as consequences of AS in genetically prediction.No evidence of horizontal pleiotropy or heterogeneity between the genetic variants was found (P>0.05), and a leave-one-out test confirmed the stability and robustness of this association.

Conclusion

These findings suggest that βNGF, IL-1β, and TRAIL may play a crucial role in the pathogenesis of AS. Additionally, AS may impact the expression of cytokines such as IL-12p70, IL-17, IL-6, IL-4, SDF-1α, MIP1β, MCP-3, PDGFbb,GCSF, bFGF,TRAIL,and IFN-γ. Further investigations are warranted to determine whether these biomarkers can be utilized for the prevention or treatment of AS.

The role of inflammation in autoimmune disease: a therapeutic target

Autoimmune diseases (AIDs) are immune disorders whose incidence and prevalence are increasing year by year. AIDs are produced by the immune system's misidentification of self-antigens, seemingly caused by excessive immune function, but in fact they are the result of reduced accuracy due to the decline in immune system function, which cannot clearly identify foreign invaders and self-antigens, thus issuing false attacks, and eventually leading to disease. The occurrence of AIDs is often accompanied by the emergence of inflammation, and inflammatory mediators (inflammatory factors, inflammasomes) play an important role in the pathogenesis of AIDs, which mediate the immune process by affecting innate cells (such as macrophages) and adaptive cells (such as T and B cells), and ultimately promote the occurrence of autoimmune responses, so targeting inflammatory mediators/pathways is one of emerging the treatment strategies of AIDs. This review will briefly describe the role of inflammation in the pathogenesis of different AIDs, and give a rough introduction to inhibitors targeting inflammatory factors, hoping to have reference significance for subsequent treatment options for AIDs.