[Tendinopathy in rheumatic diseases]

Reactive oxygen species in tendon injury and repair

Reactive oxygen species (ROS) are chemical moieties that in physiological concentrations serve as fast-acting signaling molecules important for cellular homeostasis. However, their excess either due to overproduction or inability of the antioxidant system to inactivate them results in oxidative stress, contributing to cellular dysfunction and tissue damage. In tendons, which are hypovascular, hypocellular, and composed predominantly of extracellular matrix (ECM), particularly collagen I, ROS likely play a dual role: regulating cellular processes such as inflammation, proliferation, and ECM remodeling under physiological conditions, while contributing to tendinopathy and impaired healing when dysregulated. This review explores the sources of ROS in tendons, including NADPH oxidases and mitochondria, and their role in key processes such as tissue adaptation to mechanical load and injury repair, also in systemic conditions such as diabetes. In addition, we integrate the emerging perspective that calcium signaling-mediated by mechanically activated ion channels-plays a central role in tendon mechanotransduction under daily mechanical loads. We propose that mechanical overuse (overload) may lead to hyperactivation of calcium channels, resulting in chronically elevated intracellular calcium levels that amplify ROS production and oxidative stress. Although direct evidence linking calcium channel hyperactivity, intracellular calcium dysregulation, and ROS generation under overload conditions is currently circumstantial, this review aims to highlight these connections and identify them as critical avenues for future research. By framing ROS within the context of both adaptive and maladaptive responses to mechanical load, this review provides a comprehensive synthesis of redox biology in tendon injury and repair, paving the way for future work, including development of therapeutic strategies targeting ROS and calcium signaling to enhance tendon recovery and resilience.

The role of inflammatory periocular, ocular surface and systemic diseases in involutional ectropion

BACKGROUND

This study investigated the association between involutional ectropion and chronic inflammatory diseases of the eyelid and ocular surface, and other systemic diseases.

METHODS

This case-control study was conducted using electronic medical records from Clalit Health Services in Israel, 2001-2022. Patients diagnosed with involutional ectropion were compared to two control groups: one with senile cataracts and another with other ophthalmic diseases. The groups were matched 1:3 by birth year, sex, and ethnicity. Mixed models were used to assess differences in demographics, periocular, ocular, and systemic diseases between the groups. Conditional logistic regression was used to estimate the odds ratios (OR) and adjust for confounders.

RESULTS

A total of 1786 patients with involutional ectropion and 5358 matched individuals in each control group were included. The average age of the patients with involutional ectropion was 77 ± 10 years, and 60% were men. Significant associations were found between involutional ectropion and several inflammatory diseases: blepharitis (OR 4.25, 95% confidence interval [CI]: 3.68-4.91), chalazion (OR 3.01, 95% CI: 2.3-3.94), hordeolum (OR 2.27, 95% CI: 1.8-2.86), dermatitis of the eyelid (OR 1.69, 95% CI: 1.16-2.47), chronic conjunctivitis (OR 3.49, 95% CI: 2.86-4.26), pterygium (OR 2.21, 95% CI: 1.71-2.86), hypertension (OR 1.5, 95% CI: 1.31-1.72), dyslipidaemia (OR 1.46, 95% CI: 1.3-1.64), and rheumatic disease (OR 1.9, 95% CI: 1.5-2.4).

CONCLUSIONS

Periocular, ocular surface, and systemic inflammatory diseases are independent risk factors for involutional ectropion. Further research is necessary to fully understand these associations.

Effects of hyaluronic acid injections on pain and functioning in patients affected by tendinopathies: A narrative review

BACKGROUND

Tendinopathies are overuse tendon injuries showing load-dependant pain, stiffness, weakness of movement in the affected area, and impairment in the movements. The scientific interest on the role of Hyaluronic Acid (HA) for the management of tendinopathies has been increased due to its anti-inflammatory and lubricative properties.

OBJECTIVE

To collect evidence regarding the effectiveness and safety of HA injections in reducing pain in patients affected by tendinopathies.

METHODS

A scientific literature search was conducted using the PubMed, Medline and PEDro electronic databases. The databases were searched since their inception until July 2021. The search was limited to English language articles. Different combinations of the terms and MeSH terms "tendinopathy", "tendinosis", "tendinitis", "hyaluronic acid", "hyaluronate", "infiltration", "hyaluronic injections", "viscosupplementation" connected with various boolean operators were used for other electronic databases.

RESULTS

One hundred and one records were identified from the selected databases plus three additional papers identified by the authors through other sources. After removing duplicated papers and title/abstract screening, 19 studies were included in our review (eight papers on shoulder, three on elbow, four on hand, one on knee, and three on ankle).

CONCLUSION

The results showed that none of the studies report severe adverse effects and most of them support the use of HA injections in tendinopathies, with a special attention to pain reduction and functional assessment. Further studies are warranted to better investigate effects and methods of administration of HA in tendinopathies.

Infliximab prevents systemic bone loss and suppresses tendon inflammation in a collagen-induced arthritis rat model

Reduced Bone Mineral Density (BMD) and tendon abnormalities, such as tenosynovitis and enthesitis, are prevalent comorbidities in patients with rheumatoid arthritis (RA). The aim of the present study was to investigate the effect of chronic treatment with infliximab on BMD and tendon inflammation in an animal model of inflammatory arthritis. Collagen-Induced Arthritis (CIA) was induced in rats, followed by long-term intraperitoneal administration of infliximab. Two additional groups of animals received methotrexate either as a monotherapy or as a co-treatment to infliximab. BMD was evaluated by Micro-Computed Tomography (Micro-CT) and bone histological examination. Tendon inflammation was assessed histologically and by quantitative ELISA analysis of pro-inflammatory cytokines in tendon tissues. Both methotrexate and infliximab treatment alleviated joint inflammation and reduced paw edema. Infliximab-treated animals exhibited an improved trabecular microarchitecture on micro-CT and histological analysis compared to both non-treated and methotrexate-treated animals. Infliximab almost reversed the pathological changes in tendons induced by CIA. Finally, we observed statistically significant declines in tendon TNF-a and IL-23 levels after infliximab treatment. Our study provides evidence that infliximab prevents arthritis-related osteoporosis and suppresses tendon inflammation in an animal model of inflammatory arthritis, in addition to controlling disease activity. These findings offer perspectives for the management of osteoporosis and enthesitis in RA.