Interleukin-17A expression in human synovial mast cells in rheumatoid arthritis and osteoarthritis

Mast Cell Involvement in the Pathogenesis of Selected Musculoskeletal Diseases

In recent years, there has been a noteworthy revival of interest in the function of mast cells (MCs) in the human body. It is now acknowledged that MCs impact a wide array of processes beyond just allergies, leading to a shift in research direction. Unfortunately, some earlier conclusions were drawn from animal models with flawed designs, particularly centered around the receptor tyrosine kinase (Kit) pathway. Consequently, several subsequent findings may have been unreliable. Thus, what is now required is a re-examination of these earlier findings. Nevertheless, the remaining data are fascinating and hold promise for a better comprehension of numerous diseases and the development of more effective therapies. As the field continues to progress, many intriguing issues warrant further investigation and analysis. For instance, exploring the bidirectional action of MCs in rheumatoid arthritis, understanding the extent of MCs' impact on symptoms associated with Ehlers-Danlos syndrome, and unraveling the exact role of the myofibroblast-mast cell-neuropeptides axis in the joint capsule during post-traumatic contractures are all captivating areas for exploration. Hence, in this review, we summarize current knowledge regarding the influence of MCs on the pathogenesis of selected musculoskeletal diseases, including rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, gout, muscle and joint injuries, tendinopathy, heterotopic ossification, and Ehlers-Danlos syndrome. We believe that this review will provide in-depth information that can guide and inspire further research in this area.

Phenotype Diversity of Macrophages in Osteoarthritis: Implications for Development of Macrophage Modulating Therapies

Chronic inflammation is implicated in numerous human pathologies. In particular, low-grade inflammation is currently recognized as an important mechanism of osteoarthritis (OA), at least in some patients. Among the signs of the inflammatory process are elevated macrophage numbers detected in the OA synovium compared to healthy controls. High macrophage counts also correlate with clinical symptoms of the disease. Macrophages are central players in the development of chronic inflammation, pain, cartilage destruction, and bone remodeling. However, macrophages are also involved in tissue repair and remodeling, including cartilage. Therefore, reduction of macrophage content in the joints correlates with deleterious effects in OA models. Macrophage population is heterogeneous and dynamic, with phenotype transitions being induced by a variety of stimuli. In order to effectively use the macrophage inflammatory circuit for treatment of OA, it is important to understand macrophage heterogeneity and interactions with surrounding cells and tissues in the joint. In this review, we discuss functional phenotypes of macrophages and specific targeting approaches relevant for OA treatment development.

Roles of mast cells in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory arthritis, and the complex interaction and activation of innate and adaptive immune cells are involved in RA pathogenesis. Mast cells (MCs) are one of the tissue-resident innate immune cells, and they contribute to RA pathogenesis. In the present review, the evidence of the pathologic role of MC in RA is discussed based on human and animal data. In addition, the potential role of MC in RA pathogenesis and the research area that should be focused on in the future are suggested.

Association between the polymorphism of IL-17A and IL-17F gene with knee osteoarthritis risk: a meta-analysis based on case-control studies

Background

Knee osteoarthritis is a joint disease which is characterized by degeneration of articular cartilage and subsequent subchondral bone changes. Polymorphisms of IL-17A/F gene were the recognized candidate genes associated with knee osteoarthritis risk although the results were conflicting. The aim of this study was to determine whether IL-17A(rs2275913) and IL-17F(rs763780) polymorphisms confer susceptibility to knee osteoarthritis.

Method

Literature search was performed in PubMed, Medline, Cochrane Library, Web of science, Embase, and Google Scholar (last search was updated on June 20, 2019), and assessing this association was performed by calculating odds ratios with 95% confidence intervals. Statistical heterogeneity was quantitatively evaluated by using the Q statistic with its p value and I² statistic.

Result

Six case-control based studies were included involving IL-17A(rs2275913) (2134 cases and 2306 controls) and IL-17F(rs763780) (2134 cases and 2426 controls). The overall analysis suggested that the A allele of the rs2275913 polymorphism, and the C allele of the rs763780 polymorphism in the IL-17 gene may increase the risk of OA. However, subgroup analysis revealed that no association between IL-17A(rs2275913) gene and knee OA risk was found in Caucasian population.

Conclusions

This meta-analysis revealed that the IL-17A(rs2275913) gene polymorphisms may increase the risk of knee OA in Asians, and the IL-17F(rs763780) gene polymorphisms may increase the risk of knee OA both in Asians and Caucasians. However, because of the limitations of the present study, additional larger studies are needed to confirm our findings in the future.

The pathogenicity of Th17 cells in autoimmune diseases

IL-17-producing T helper (Th17) cells have been implicated in the pathogenesis of many inflammatory and autoimmune diseases. Targeting the effector cytokines IL-17 and GM-CSF secreted by autoimmune Th17 cells has been shown to be effective for the treatment of the diseases. Understanding a molecular basis of Th17 differentiation and effector functions is therefore critical for the regulation of the pathogenicity of tissue Th17 cells in chronic inflammation. Here, we discuss the roles of proinflammatory cytokines and environmental stimuli in the control of Th17 differentiation and chronic tissue inflammation by pathogenic Th17 cells in humans and in mouse models of autoimmune diseases. We also highlight recent advances in the regulation of pathogenic Th17 cells by gut microbiota and immunometabolism in autoimmune arthritis.

[Effect of intra-articular injection of platelet-rich plasma on interleukin-17 expression in synovial fluid and venous plasma of knee osteoarthritis patients]

Objective

To investigate the interleukin-17 (IL-17) levels changes in both synovial fluid and venous plasma of patients with primary knee osteoarthritis (OA) after intra-articular injection of platelet-rich plasma (PRP).

Methods

Between January 2015 and January 2016, 30 patients with primary knee OA were treated by intra-articular injection of PRP once a week for 3 weeks (trial group). Thirty healthy individuals were recruited into the study as control. There was no significant difference in gender, age, and body mass index between 2 groups ( P>0.05). Visual analogue scale (VAS) score and Knee Society Score (KSS) were used to evaluate pain level and function of the knee for patients with OA. The IL-17 levels in both venous plasma and synovial fluid were measured before injection and at 1, 3, 6, and 12 months after injection in trial group and the IL-17 levels in venous plasma were measured in control group. The levels were determined using ELISA method.

Results

There was no knee joint swelling, fever, local infection, or other uncomfortable symptoms for all patients in process of PRP injection. All patients were followed up 13.5 months on average (range, 12-15 months). In trial group, the VAS scores at different time points after injection were significantly lower than that before injection ( P<0.05). And the KSS scores at different time points after injection were significantly higher than that before injection ( P<0.05). There was no significant difference in VAS and KSS scores between different time points after injection ( P>0.05). The IL-17 levels in venous plasma before and after injection in trial group were significantly higher than that in control group ( P<0.05). The IL-17 levels in venous plasma at each time point after injection were significantly lower than that before injection ( P<0.05). There was no significant difference in IL-17 levels in both venous plasma and synovial fluid between different time points after injection ( P>0.05).

Conclusion

Intra-articular injection of PRP can significantly release the pain symptoms, improve joint function, and reduce IL-17 levels in both synovial fluid and venous plasma of the patients with knee OA, but IL-17 levels can not reduce to normal level.

An Inflammation-Centric View of Neurological Disease: Beyond the Neuron

Inflammation is a complex biological response fundamental to how the body deals with injury and infection to eliminate the initial cause of cell injury and effect repair. Unlike a normally beneficial acute inflammatory response, chronic inflammation can lead to tissue damage and ultimately its destruction, and often results from an inappropriate immune response. Inflammation in the nervous system (“neuroinflammation”), especially when prolonged, can be particularly injurious. While inflammation per se may not cause disease, it contributes importantly to disease pathogenesis across both the peripheral (neuropathic pain, fibromyalgia) and central [e.g., Alzheimer disease, Parkinson disease, multiple sclerosis, motor neuron disease, ischemia and traumatic brain injury, depression, and autism spectrum disorder] nervous systems. The existence of extensive lines of communication between the nervous system and immune system represents a fundamental principle underlying neuroinflammation. Immune cell-derived inflammatory molecules are critical for regulation of host responses to inflammation. Although these mediators can originate from various non-neuronal cells, important sources in the above neuropathologies appear to be microglia and mast cells, together with astrocytes and possibly also oligodendrocytes. Understanding neuroinflammation also requires an appreciation that non-neuronal cell—cell interactions, between both glia and mast cells and glia themselves, are an integral part of the inflammation process. Within this context the mast cell occupies a key niche in orchestrating the inflammatory process, from initiation to prolongation. This review will describe the current state of knowledge concerning the biology of neuroinflammation, emphasizing mast cell-glia and glia-glia interactions, then conclude with a consideration of how a cell's endogenous mechanisms might be leveraged to provide a therapeutic strategy to target neuroinflammation.

The emerging role of mast cells in liver disease

The depth of our knowledge regarding mast cells has widened exponentially in the last 20 years. Once thought to be only important for allergy-mediated events, mast cells are now recognized to be important regulators of a number of pathological processes. The revelation that mast cells can influence organs, tissues, and cells has increased interest in mast cell research during liver disease. The purpose of this review is to refresh the reader's knowledge of the development, type, and location of mast cells and to review recent work that demonstrates the role of hepatic mast cells during diseased states. This review focuses primarily on liver diseases and mast cells during autoimmune disease, hepatitis, fatty liver disease, liver cancer, and aging in the liver. Overall, these studies demonstrate the potential role of mast cells in disease progression.

Neuroinflammation, Mast Cells, and Glia: Dangerous Liaisons

The perspective of neuroinflammation as an epiphenomenon following neuron damage is being replaced by the awareness of glia and their importance in neural functions and disorders. Systemic inflammation generates signals that communicate with the brain and leads to changes in metabolism and behavior, with microglia assuming a pro-inflammatory phenotype. Identification of potential peripheral-to-central cellular links is thus a critical step in designing effective therapeutics. Mast cells may fulfill such a role. These resident immune cells are found close to and within peripheral nerves and in brain parenchyma/meninges, where they exercise a key role in orchestrating the inflammatory process from initiation through chronic activation. Mast cells and glia engage in crosstalk that contributes to accelerate disease progression; such interactions become exaggerated with aging and increased cell sensitivity to stress. Emerging evidence for oligodendrocytes, independent of myelin and support of axonal integrity, points to their having strong immune functions, innate immune receptor expression, and production/response to chemokines and cytokines that modulate immune responses in the central nervous system while engaging in crosstalk with microglia and astrocytes. In this review, we summarize the findings related to our understanding of the biology and cellular signaling mechanisms of neuroinflammation, with emphasis on mast cell-glia interactions.