Polarization of rheumatoid macrophages is regulated by the CDKN2B-AS1/ MIR497/TXNIP axis

Single-cell characterisation of tissue homing CD4 + and CD8 + T cell clones in immune-mediated refractory arthritis

BACKGROUND

Immune-mediated arthritis is a group of autoinflammatory diseases, where the patient's own immune system attacks and destroys synovial joints. Sustained remission is not always achieved with available immunosuppressive treatments, warranting more detailed studies of T cell responses that perpetuate synovial inflammation in treatment-refractory patients.

METHODS

In this study, we investigated CD4 + and CD8 + T lymphocytes from the synovial tissue and peripheral blood of patients with treatment-resistant immune-mediated arthritis using paired single-cell RNA and TCR-sequencing. To gain insights into the trafficking of clonal families, we compared the phenotypes of clones with the exact same TCRß amino acid sequence between the two tissues.

RESULTS

Our results show that both CD4 + and CD8 + T cells display a more activated and inflamed phenotype in the synovial tissue compared to peripheral blood both at the population level and within individual T cell families. Furthermore, we found that both cell subtypes exhibited clonal expansion in the synovial tissue.

CONCLUSIONS

Our findings suggest that the local environment in the synovium drives the proliferation of activated cytotoxic T cells, and both CD4 + and CD8 + T cells may contribute to tissue destruction and disease pathogenesis.

Targeting different phenotypes of macrophages: A potential strategy for natural products to treat inflammatory bone and joint diseases

BACKGROUND

Macrophages, a key class of immune cells, have a dual role in inflammatory responses, switching between anti-inflammatory M2 and pro-inflammatory M1 subtypes depending on the specific environment. Greater numbers of M1 macrophages correlate with increased production of inflammatory chemicals, decreased osteogenic potential, and eventually bone and joint disorders. Therefore, reversing M1 macrophages polarization is advantageous for lowering inflammatory factors. To better treat inflammatory bone disorders in the future, it may be helpful to gain insight into the specific mechanisms and natural products that modulate macrophage polarization.

OBJECTIVE

This review examines the impact of programmed cell death and different cells in the bone microenvironment on macrophage polarization, as well as the effects of natural products on the various phenotypes of macrophages, in order to suggest some possibilities for the treatment of inflammatory osteoarthritic disorders.

METHODS

Using 'macrophage polarization,' 'M1 macrophage' 'M2 macrophage' 'osteoporosis,' 'osteonecrosis of femoral head,' 'osteolysis,' 'gouty arthritis,' 'collagen-induced arthritis,' 'freund's adjuvant-induced arthritis,' 'adjuvant arthritis,' and 'rheumatoid arthritis' as search terms, the relevant literature was searched using the PubMed, the Cochrane Library and Web of Science databases.

RESULTS

Targeting macrophages through different signaling pathways has become a key mechanism for the treatment of inflammatory bone and joint diseases, including HIF-1α, NF-κB, AKT/mTOR, JAK1/2-STAT1, NF-κB, JNK, ERK, p-38α/β, p38/MAPK, PI3K/AKT, AMPK, AMPK/Sirt1, STAT TLR4/NF-κB, TLR4/NLRP3, NAMPT pathway, as well as the programmed cell death autophagy, pyroptosis and ERS.

CONCLUSION

As a result of a search of databases, we have summarized the available experimental and clinical evidence supporting herbal products as potential treatment agents for inflammatory osteoarthropathy. In this paper, we outline the various modulatory effects of natural substances targeting macrophages in various diseases, which may provide insight into drug options and directions for future clinical trials. In spite of this, more mechanistic studies on natural substances, as well as pharmacological, toxicological, and clinical studies are required.

Heme oxygenase-1 ameliorates endotoxin-induced acute lung injury by modulating macrophage polarization via inhibiting TXNIP/NLRP3 inflammasome activation

Acute lung injury (ALI) remains a global public health issue without specific and effective treatment options available in the clinic. Alveolar macrophage polarization is involved in the initiation, development and progression of ALI; however, the underlying mechanism remains poorly understood. Heme oxygenase-1 (HO-1) acts as an antioxidant in pulmonary inflammation and has been demonstrated to be linked with the severity and prognosis of ALI. In this study, the therapeutic effects of HO-1 were examined, along with the mechanisms involved, mainly focusing on alveolar macrophage polarization. HO-1 depletion induced higher iNOS and CD86 (M1 phenotype) expression but was significantly decreased in Arg-1 and CD206 (M2 phenotype) expression in BALF alveolar macrophages after equivalent LPS stimulation. We also found that HO-1 deletion distinctly accelerated the expression of inflammasome-associated components NLRP3, ASC and caspase-1 in vivo and in vivo and in vitro. Moreover, on the basis of LPS for MH-S cells, levels of TXNIP, NLRP3, ASC and caspase-1 were increased and HO-1 depletion exacerbated these changes, whereas double depletion of HO-1 and TXNIP partially mitigated these elevations. Also, HO-1 knockdown induced more M1 phenotype and less M2 phenotype compared with LPS alone, whereas double silence of HO-1 and TXNIP partially changed the polarization state. Taken together, we demonstrated that HO-1 could modulate macrophage polarization via TXNIP/NLRP3 signaling pathway, which could be a potential therapeutic target for ALI treatment.

Protein arginine deiminase 2 (PAD2) modulates the polarization of THP-1 macrophages to the anti-inflammatory M2 phenotype

Background

Macrophages are effector cells of the innate immune system that undergo phenotypical changes in response to organ injury and repair. These cells are most often classified as proinflammatory M1 and anti-inflammatory M2 macrophages. Protein arginine deiminase (PAD), which catalyses the irreversible conversion of protein-bound arginine into citrulline, is expressed in macrophages. However, the substrates of PAD and its role in immune cells remain unclear. This study aimed to investigate the role of PAD in THP-1 macrophage polarization to the M1 and M2 phenotypes and identify the citrullinated proteins and modified arginines that are associated with this biological switch using mass spectrometry.

Results

Our study showed that PAD2 and, to a lesser extent, PAD1 and PAD4 were predominantly expressed in M1 macrophages. We showed that inhibiting PAD expression with BB-Cl-amidine decreased macrophage polarization to the M1 phenotype (TNF-α, IL-6) and increased macrophage polarization to the M2 phenotype (MRC1, ALOX15). This process was mediated by the downregulation of proteins involved in the NF-κβ pathway. Silencing PAD2 confirmed the activation of M2 macrophages by increasing the antiviral innate immune response and interferon signalling. A total of 192 novel citrullination sites associated with inflammation, cell death and DNA/RNA processing pathways were identified in M1 and M2 macrophages.

Conclusions

We showed that inhibiting PAD activity using a pharmacological inhibitor or silencing PAD2 with PAD2 siRNA shifted the activation of macrophages towards the M2 phenotype, which can be crucial for designing novel macrophage-mediated therapeutic strategies. We revealed a major citrullinated proteome and its rearrangement following macrophage polarization, which after further validation could lead to significant clinical benefits for the treatment of inflammation and autoimmune diseases.

Thioredoxin-interacting protein: A new therapeutic target in bone metabolism disorders?

Target identification is essential for developing novel therapeutic strategies in diseases. Thioredoxin-interacting protein (TXNIP), also known as thioredoxin-binding protein-2, is a member of the α-arrestin protein family and is regulated by several cellular stress factors. TXNIP overexpression coupled with thioredoxin inhibits its antioxidant functions, thereby increasing oxidative stress. TXNIP is directly involved in inflammatory activation by interacting with Nod-like receptor protein 3 inflammasome. Bone metabolic disorders are associated with aging, oxidative stress, and inflammation. They are characterized by an imbalance between bone formation involving osteoblasts and bone resorption by osteoclasts, and by chondrocyte destruction. The role of TXNIP in bone metabolic diseases has been extensively investigated. Here, we discuss the roles of TXNIP in the regulatory mechanisms of transcription and protein levels and summarize its involvement in bone metabolic disorders such as osteoporosis, osteoarthritis, and rheumatoid arthritis. TXNIP is expressed in osteoblasts, osteoclasts, and chondrocytes and affects the differentiation and functioning of skeletal cells through both redox-dependent and -independent regulatory mechanisms. Therefore, TXNIP is a potential regulatory and functional factor in bone metabolism and a possible new target for the treatment of bone metabolism-related diseases.

Viola yedoensis Makino formula alleviates DNCB-induced atopic dermatitis by activating JAK2/STAT3 signaling pathway and promoting M2 macrophages polarization

BACKGROUND

Atopic dermatitis (AD), a common inflammatory skin disorder, severely affects the life quality of patients and renders heavy financial burden on patient's family. The Chinese medicine Viola yedoensis Makino formula (VYAC) has been widely used for treating various skin disorders. Previous studies have reported that VYAC is effective in relieving DNCB-induced AD and inflammation. However, the anti-inflammatory mechanism of VYAC is still ill-defined and poorly understood. This study aims to investigate the therapeutic effects of VYAC on DNCB-induced AD and to elucidate the underlying anti-inflammatory mechanisms.

METHODOLOGY

VYAC were extracted with 70% ethanol and lyophilized for use. AD mice were established by DNCB. The therapeutic effects of VYAC were evaluated by oral administration VYAC (150, 300 and 600 mg/kg) daily in vivo. The histopathological and immunohistochemistry were used to analyze skin lesion and macrophages infiltration, RT-qPCR and Elisa were used to analyze the inflammatory factors in skin tissues and serum. To explore the underlying mechanism of VYAC against AD in vitro. RAW264.7 cells and bone-marrow-derived macrophages (BMDMs) were employed for macrophage polarization analysis. Flow cytometer, immunofluorescence and western blot were used to analyze M2 macrophages markers. STAT3 siRNA were transfected into both cells to validate the effects of VYAC-induced macrophages M2 polarization via JAK2/STAT3 signaling pathway.

RESULTS

VYAC ameliorated skin lesion of DNCB-induced AD mice by decreased clinical scores and epidermal thickness, decreased the level of pro-inflammatory factors (IL-1β, TNF-α and IL-18) and enhanced IL-10 anti-inflammatory factor level, inhibited macrophages infiltration and promoted M2 macrophages polarization in vivo. VYAC significantly promoted M2 macrophages polarization in vitro. It is observed that VYAC not only inhibited the phosphorylation of JAK2 and STAT3 in RAW264.7 cells and BMDMs, but also accelerated the translocation to the nucleus. What's more, VYAC reduced the polarization of M2 macrophage by activating JAK2/STAT3 signaling pathway was observed in both cells.

CONCLUSIONS

Our findings demonstrate that VYAC significantly ameliorates skin lesion of DNCB-induced AD mice and reduces the levels of inflammatory factors by activating JAK2/STAT3 signaling pathway and promoting M2 macrophages polarization.