The N-Formyl Peptide Receptors and Rheumatoid Arthritis: A Dangerous Liaison or Confusing Relationship?

Formyl peptide receptor 1 and its antagonist T0080 in atherosclerosis

Focal inflammation and arterial damage driven by macrophages are key pathogenic processes in atherosclerosis. However, the mechanisms that regulate these processes remain poorly understood. In this study, we demonstrate that formyl peptide receptor 1 (FPR1) agonist, a mitochondrial N-formyl peptide, is elevated in the blood of patients with atherosclerosis and correlates with carotid stenosis. Macrophages expressing FPR1 were found in atherosclerotic lesions. Conditional deletion of Fpr1 in macrophages reduced plaque formation, local inflammation, and aortic atherosclerosis in apolipoprotein E (ApoE)-/- mice. FPR1 activates protein kinase C (PKC) in macrophages, promoting the production of reactive oxygen species (ROS), tumor necrosis factor alpha (TNF-α) and interleukin-1beta (IL-1β), which accelerates the apoptosis of endothelial cells and smooth muscle cells. To inhibit FPR1 bioactivity, we developed an antagonist, T0080. Therapeutic administration of T0080 attenuates atherosclerotic progression in ApoE-/- mice. Our findings highlight the pivotal role of FPR1 in macrophage-mediated atherosclerotic plaque formation and support further investigation of T0080-mediated FPR1 inhibition as a potential treatment for atherosclerosis.

Clinical and Pathophysiological Tangles Between Allergy and Autoimmunity: Deconstructing an Old Dichotomic Paradigm

Allergic and autoimmune disorders are characterised by dysregulation of the immune responses to otherwise inert environmental substances and autoantigens, leading to inflammation and tissue damage. Their incidence has constantly increased in the last decades, and their co-occurrence defies current standards in patient care. For years, allergy and autoimmunity have been considered opposite conditions, with IgE and Th2 lymphocytes cascade driving canonical allergic manifestations and Th1/Th17-related pathways accounting for autoimmunity. Conversely, growing evidence suggests that these conditions not only share some common inciting triggers but also are subtended by overlapping pathogenic pathways. Permissive genetic backgrounds, along with epithelial barrier damage and changes in the microbiome, are now appreciated as common risk factors for both allergy and autoimmunity. Eosinophils and mast cells, along with autoreactive IgE, are emerging players in triggering and sustaining autoimmunity, while pharmacological modulation of B cells and Th17 responses has provided novel clues to the pathophysiology of allergy. By combining clinical and therapeutic evidence with data from mechanistic studies, this review provides a state-of-the-art update on the complex interplay between allergy and autoimmunity, deconstructing old dichotomic paradigms and offering potential clues for future research.

Neutrophil exhaustion and impaired functionality in psoriatic arthritis patients

Background

Neutrophils (polymorphonuclear leukocytes, PMNs) are the most abundant subtype of white blood cells and are among the main actors in the inflammatory response. Psoriatic arthritis (PsA) is a chronic inflammatory disease affecting both the axial and peripheral joints. Typically associated with psoriasis, PsA can also affect multiple systems and organs, including the nails and entheses. Despite the involvement of PMNs in PsA, their specific role in the disease remains poorly understood. This study aimed to characterize the biological functions of PMNs and neutrophil-related mediators in PsA patients.

Materials and methods

31 PsA patients and 22 healthy controls (HCs) were prospectively recruited. PMNs were isolated from peripheral blood and subjected to in vitro stimulation with lipopolysaccharide (LPS), N-Formylmethionyl-leucyl-phenylalanine (fMLP), tumor necrosis factor (TNF), phorbol 12-myristate 13-acetate (PMA), or control medium. Highly purified peripheral blood PMNs (>99%) were evaluated for activation status, reactive oxygen species (ROS) production, phagocytic activity, granular enzyme and neutrophil extracellular traps (NETs) release. Serum levels of matrix metalloproteinase-9 (MMP-9), myeloperoxidase (MPO), TNF, interleukin 23 (IL-23), and interleukin 17 (IL-17) were measured by ELISA. Serum Citrullinated histone H3 (CitH3) was measured as a NET biomarker.

Results

Activated PMNs from PsA patients displayed reduced activation, decreased ROS production, and impaired phagocytic activity upon stimulation with TNF, compared to HCs. PMNs from PsA patients also displayed reduced granular enzyme (MPO) and NET release. Serum analyses revealed elevated levels of MMP-9, MPO, TNF, IL-23, IL-17, and CitH3 in PsA patients compared to HCs. Serum CitH3 levels positively correlated with MPO and TNF concentrations, and IL-17 concentrations were positively correlated with IL-23 levels in PsA patients. These findings indicate that PMNs from PsA patients show reduced in vitro activation and function, and an increased presence of neutrophil-derived mediators (MMP-9, MPO, TNF, IL-23, IL-17, and CitH3) in their serum.

Conclusions

Taken together, our findings suggest that PMNs from PsA patients exhibit an "exhausted" phenotype, highlighting their plasticity and multifaceted roles in PsA pathophysiology.

Aquaporin-8 promotes human dermal fibroblasts to counteract hydrogen peroxide-induced oxidative damage: A novel target for management of skin aging

The skin is subjected to various external factors that contribute to aging including oxidative stress from hydrogen peroxide (H2O2). This study investigated the distribution of aquaporin-8 (AQP8), a protein that transports H2O2 across biological membranes, in skin cells, and its effects in mitigating H2O2-induced oxidative damage. Human dermal fibroblasts were treated with increasing concentrations of H2O2 to evaluate oxidative damage. Cell viability, reactive oxygen species (ROS) generation, and the expression of specific genes associated with skin aging (IL-10, FPR2, COL1A1, KRT19, and Aggrecan) were evaluated and AQP8 expression was assessed via quantitative polymerase chain reaction and western blotting. Small-interfering RNA was used to silence the AQP8 gene and evaluate its significance. The results show that H2O2 treatment reduces cell viability and increases ROS generation, leading to oxidative damage that affects the expression of target molecules. Interestingly, H2O2-treated cells exhibit high levels of AQP8 expression and gene silencing of AQP8 reverses high levels of ROS and low levels of COL1A1, KRT19, and Aggrecan expression in stressed cells, indicating that AQP8 plays a vital role in preventing oxidative damage and consequent aging. In conclusion, AQP8 is upregulated in human dermal fibroblasts during H2O2-induced oxidative stress and may help prevent oxidative damage and aging. These findings suggest that AQP8 could be a potential therapeutic target for skin aging. Further research is necessary to explore the feasibility of using AQP8 as a preventive or therapeutic strategy for maintaining skin health.

The Benefits of Water from Nitrodi's Spring: The In Vitro Studies Leading the Potential Clinical Applications

Natural products (water, plants, and minerals) have been studied for diverse applications in health and disease. Since there has been a growing interest in the introduction of thermal water as a clinical complementary approach in the treatment of low-grade inflammation and stress-related conditions, this review focuses on the oldest spa in the world: Nitrodi's spring. Substantial studies in the 1960s showed that both the internal and external use of Nitrodi's water yielded several benefits in physiological processes and in treating certain disorders, mainly allergic and autoimmune inflammatory conditions. More recently, a novel interest in Nitrodi's water has prompted researchers to further explore the effects of this water and shed light on the molecular mechanisms sustaining its therapeutic efficacy. In different epithelial cell models, Nitrodi's water had strong promotional effects on proliferation, cell migration, cell viability, and fibroblast to myofibroblast transition, all of which essential for wound healing and tissue remodeling. Moreover, Nitrodi's water exhibited anti-oxidant and anti-inflammatory properties through the inhibition of ROS production and protein S-nitrosylation. Here, we have collected the clinical and basic data on Nitrodi's water and reviewed articles that have discussed its use as a potential treatment for several inflammatory and autoimmune diseases and age-related skin deterioration.

Roles of the Siglec family in bone and bone homeostasis

Tremendous progress has been seen in the study of the role of sialic acid binding im-munoglobulin type lectins (Siglecs) in osteoimmunology in the past two decades. Interest in Siglecs as immune checkpoints has grown from the recognition that Siglecs have relevance to human disease. Siglecs play important roles in inflammation and cancer, and play key roles in immune cell signaling. By recognizing common sialic acid containing glycans on glycoproteins and glycolipids as regulatory receptors for immune cell signals, Siglecs are expressed on most immune cells and play important roles in normal homeostasis and self-tolerance. In this review, we describe the role that the siglec family plays in bone and bone homeostasis, including the regulation of osteoclast differentiation as well as recent advances in inflammation, cancer and osteoporosis. Particular emphasis is placed on the relevant functions of Siglecs in self-tolerance and as pattern recognition receptors in immune responses, thereby potentially providing emerging strategies for the treatment of bone related diseases.

Calcinosis Cutis and Calciphylaxis in Autoimmune Connective Tissue Diseases

Calcinosis represents a severe complication of several autoimmune disorders. Soft-tissue calcifications have been classified into five major types: dystrophic, metastatic, idiopathic, iatrogenic, and calciphylaxis. Autoimmune diseases are usually associated with dystrophic calcifications, including calcinosis cutis, occurring in damaged or devitalized tissues in the presence of normal serum levels of calcium and phosphate. In particular, calcinosis cutis has been described in dermatomyositis, polymyositis, juvenile dermatomyositis, systemic sclerosis, systemic lupus erythematosus, primary Sjögren's syndrome, overlap syndrome, mixed connective tissue disease, and rheumatoid arthritis. Calciphylaxis, a severe and life-threatening syndrome presenting with vascular calcifications and thrombosis, has also been associated with some autoimmune conditions. Due to the potentially disabling character of calcinosis cutis and calciphylaxis, physicians' awareness about the clinical presentation and management of these diseases should be increased to select the most appropriate treatment option and avoid long-term complications. In this review, we aim to analyze the clinical features of calcinosis cutis and calciphylaxis associated with autoimmune diseases, and the main treatment strategies evaluated up to now for treating this potentially disabling disease.

Evaluation of 18F-FAPI-04 Imaging in Assessing the Therapeutic Response of Rheumatoid Arthritis

PURPOSE

Fibroblast activating protein (FAP) is highly expressed in the synovial tissues of rheumatoid arthritis (RA) patients. The aim of this study was to determine the feasibility of PET imaging with an Al[¹⁸F] F-NOTA-labeled FAP inhibitor 04(¹⁸F-FAPI-04) for the evaluation of arthritic progression and therapeutic response in experimental arthritis.

METHODS

Fibroblast-like synoviocytes (FLSs) were obtained from patients with RA or osteoarthritis (OA), and the relationship between ¹⁸F-FAPI-04 uptake and the inflammatory activity of RA FLSs was investigated. Collagen-induce arthritis (CIA) mice models were established and treated with methotrexate (MTX) or etanercept (ETC). Then, PET imaging was performed 24 h following ¹⁸F-FAPI-04 injection. The imaging results were compared by assessing macroscopic arthritis scores and histological staining.

RESULTS

¹⁸F-FAPI-04 uptake was obvious in RA FLSs that characterizing FAP activation. The higher the uptake of ¹⁸F-FAPI-04, the more severity of the inflammatory phenotype in RA FLS. Furthermore, the uptake of ¹⁸F-FAPI-04 in inflamed joints could be found even before the deformity of the parental joints could be observed by histological examination. Both MTX and ETC were effective in inhibiting the progression of arthritis in CIA mice was confirmed by macroscopic, histological, and radiographic pathology scores. Importantly, ¹⁸F-FAPI-04 uptake declined accordingly in CIA models following MTX and ETC treatment.

CONCLUSIONS

These findings suggest that PET imaging of ¹⁸F-FAPI-04 can be used to monitor treatment response in RA, and is more sensitive in disease speculation than macroscopic arthritis scoring.

Water from Nitrodi’s Spring Induces Dermal Fibroblast and Keratinocyte Activation, Thus Promoting Wound Repair in the Skin: An In Vitro Study

The Romans knew of Nitrodi’s spring on the island of Ischia more than 2000 years ago. Although the health benefits attributed to Nitrodi’s water are numerous, the underlying mechanisms are still not understood. In this study, we aim to analyze the physicochemical properties and biological effects of Nitrodi’s water on human dermal fibroblasts to determine whether the water exerts in vitro effects that could be relevant to skin wound healing. The results obtained from the study indicate that Nitrodi’s water exerts strong promotional effects on dermal fibroblast viability and a significant stimulatory activity on cell migration. Nitrodi’s water induces alpha-SMA expression in dermal fibroblasts, thus promoting their transition to myofibroblast-protein ECM deposition. Furthermore, Nitrodi’s water reduces intracellular reactive oxygen species (ROS), which play an important role in human skin aging and dermal damage. Unsurprisingly, Nitrodi’s water has significant stimulatory effects on the cell proliferation of epidermal keratinocytes and inhibits the basal ROS production but enhances their response to the oxidative stress caused by external stimuli. Our results will contribute to the development of human clinical trials and further in vitro studies to identify inorganic and/or organic compounds responsible for pharmacological effects.

Detecting potential mechanism of vitamin D in treating rheumatoid arthritis based on network pharmacology and molecular docking

Aim: Vitamin D plays a vital role in Rheumatoid arthritis (RA). However, the mechanism of vitamin D and rheumatism is still unclear. Therefore, a strategy based on network pharmacology and molecular docking was used to explore the mechanism of vitamin D and RA.

Methods: The targets of RA were obtained from the GeneCards database and Therapeutic Targets Database, and the targets of vitamin D were obtained from the Drugbank database and STITCH database. Next, overlapping genes were identified by Venny, and further Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and molecular docking analyses were performed.

Results: A total of 1,139 targets of RA and 201 targets of vitamin D were obtained. A total of 76 overlapping genes were identified by Venny. The enrichment analysis showed that cell proliferation, immune response, and apoptotic process were the critical biological processes of vitamin D in treating RA. Antifolate resistance, osteoclast differentiation, and the nuclear factor-kappa B (NF-κB) signalling pathway are fundamental mechanisms of vitamin D in treating RA. According to further molecular docking, ALB, TNF, CASP3, and TP53 may be important punctuation points or diagnostic markers for future RA treatment.

Conclusion: By analysing overlapping genes of diseases and drugs, this study confirmed that ALB, TNF, CASP3, and TP53 may be essential markers or diagnostic markers for future RA treatment.

LncRNA ZNF667-AS1 alleviates rheumatoid arthritis by sponging miR-523-3p and inactivating the JAK/STAT signalling pathway

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease, which compromises the synovial membrane resulting in chronic inflammation. Increasing evidence has demonstrated that long non-coding RNAs (lncRNAs) are implicated in the pathogenesis of RA. This study investigated the role of lncRNA ZNF667-AS1 in RA progression.

METHODS

Synovial tissues and fibroblast-like synoviocytes (FLSs) were obtained from patients with RA. Gene expression was measured using RT-qPCR. Chondrocytes were treated with lipopolysaccharide (LPS) to establish in vitro models of OA. Cell counting kit-8 (CCK-8), western blot, and enzyme-linked immunosorbent assay (ELISA) were used to examine the proliferation and inflammatory cytokine production in chondrocytes. Animal models of OA were established in SD rats. Peripheral blood mononuclear cells (PBMCs) were isolated from the OA rats. Flow cytometry was used to measure the changes of the inflammatory T-helper cell 17 (Th17) cells. The relationship between ZNF667-AS1 and miR-523-3p was verified by luciferase reporter assay.

RESULTS

ZNF667-AS1 was downregulated in RA-FLSs and LPS-stimulated chondrocytes. ZNF667-AS1 overexpression significantly promoted cell proliferation and inhibited the production of IL-6, IL-17 and TNF-α in LPS-stimulated chondrocytes. Additionally, ZNF667-AS1 overexpression reduced the generation of CD4 + IL-17+ cells. In mechanism, ZNF667-AS1 acted a sponge for miR-523-3p. MiR-523-3p overexpression reversed the ZNF667-AS1-mediated regulation of cell proliferation and inflammation. Furthermore, miR-523-3p overexpression abolished the inhibitory effects of ZNF667-AS1 on the JAK/STAT signalling activation.

CONCLUSION

ZNF667-AS1 exerts protective effects during RA development by sponging miR-523-3p and inactivating the JAK/STAT signalling.