About this Research Topic
Despite many shared mechanisms and pathologies, there is growing evidence that different types of arthritis are subject and react differently to endocrinological effects. Rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), and temporomandibular joint (TMJ) disorders (TMD) all present unique opportunities to study these effects independently and in relation to each other.
RA is a chronic autoimmune disease that affects females three times more frequently than males. Notably, the risk of developing RA increases in women who are lactating after their first pregnancy, recurrence in the early postpartum period, and is reduced in women using oral contraceptives. Interestingly, gender differences in the prevalence of RA diminish in older age groups. These phenomena could be partially attributed to the altered expression of an array of multipotent sex hormones.
Similar to RA, TMDs are approximately twice as prevalent and more severe in women than in men, while pregnant women generally have fewer TMD symptoms than non-pregnant women. Thus, the hormone storm during pregnancy may benefit TMD management. For instance, both progesterone and 17β-estradiol have been known to reduce TMJ inflammation, demonstrating their potential as candidates for TMD treatment.
In addition, for OA, although there are no suitable treatments to halt its progression, hormonal and reproductive factor levels are correlated with the incidence of total knee arthroplasty. This indicates a potential direction for OA management.
On the other hand, patients with PsA are more likely to develop endocrine disorders than the general population. Indeed, in comparison with a control group, significantly more patients with PsA had osteoporosis (9.1% vs 13.2%; P < 0.0001), hypothyroidism (8.6% vs 12.7%; P < 0.0001), diabetes mellitus (20.7% vs 27.9%; P < 0.0001), and Cushing disease (0.1% vs 0.3%; P < 0.0001).
In addition to sex hormones, the crosstalk between the gastrointestinal endocrine axis and the immune system is known to regulate the progression and outcome of arthritis. For example, as a trigger for RA development, the proinflammatory cytokine tumor necrosis factor-alpha (TNF-α) could alter the secretion and action of gut hormones that are important for appetite maintenance. As a result, the blockade of TNF-α not only ameliorates rheumatoid inflammation but also modulates body composition and energy expenditure as well as alters muscle catabolism and bone remodeling. However, the therapeutic usage of these gut hormones is not well explored, nor is it clear if these gut hormones will also actively orchestrate the development of other types of arthritis.
Taken together, uncovering the influence of different hormones on cartilage, synovium, ligament, and the joint disk is critical for understanding the interaction between endocrinology and arthritic diseases, and will directly benefit the identification and development of potential treatments for each kind of arthritis.
This Research Topic aims to give an overview of recent advances in the study of endocrinological effects on RA, OA, PsA, and TMD. In particular but not limited to the following areas:
• The cellular mechanisms and influence of different hormones on cartilage, synovium, ligament, and joint disk as they relate to the aforementioned types of arthritis;
• Correlation between the expression of sex hormones (such as progesterone and 17 β-estradiol) and that of the pro-arthritic molecules among different types of arthritis;
• Expression and activity of the gastrointestinal hormones related to different types of arthritis;
• Cross-talking between pro-inflammatory cytokines (such as TNF-α) and gastrointestinal hormones during the progression of the aforementioned arthritic diseases.
Distinguishing the role of specific hormones on different kinds of arthritis will reveal why one treatment strategy is not effective on all kinds of arthritis and will provide new targets for precision medicines of each kind of arthritis. Positive and negative results in original research and reviews are welcome.
Keywords: arthritis, osteoarthritis, psoriatic arthritis, rheumatoid arthritis, temporomandibular joint disorder
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.