Effects of Prolonged Fasting during Inpatient Multimodal Treatment on Pain and Functional Parameters in Knee and Hip Osteoarthritis: A Prospective Exploratory Observational Study

Fasting activates optineurin-mediated mitophagy in chondrocytes to protect against osteoarthritis

Mitochondrial homeostasis plays a crucial role in the pathogenesis of osteoarthritis (OA), a chronic musculoskeletal disorder characterized by articular cartilage degeneration and chondrocyte apoptosis. However, molecular mechanisms underlying the association between mitophagy and OA remain unclear. Here, we aimed to investigate the role of the autophagy receptor protein optineurin (OPTN) in OA, and explore the effects of dietary intervention on OA symptoms and its relationship with OPTN-mediated mitophagy. Our findings showed the downregulation of OPTN in patients with OA. Using an Optn-knockout mouse model, we demonstrated that OPTN deficiency leads to impaired mitophagy, resulting in the accumulation of damaged mitochondria, increased production of reactive oxygen species, and chondrocyte apoptosis. Furthermore, fasting prevented OA progression by activating OPTN-mediated mitophagy and maintaining mitochondrial homeostasis in mice. The present study revealed a novel mechanism by which OPTN-mediated mitophagy influences chondrocytes and the OA phenotype in Optn-knockout mice, suggesting that OPTN-mediated mitophagy plays a crucial role in OA development and progression. This study provides new insights into the pathogenesis of OA and offers a potential avenue for the development of novel drugs targeting OPTN to mitigate OA progression.

[Nutrition and fasting]

BACKGROUND

Patients with rheumatic diseases often enquire about the options for nutritional therapy. Nutritional factors have been empirically described that are associated with the occurrence of inflammatory rheumatic diseases or flare-ups or improved disease states. A growing number of epidemiological and clinical studies deal with the evaluation of nutrition and dietary restriction in rheumatology.

OBJECTIVE

Narrative presentation of the evidence of nutritional interventions and fasting and its clinical implications.

RESULTS AND DISCUSSION

Only limited data from smaller clinical studies are available for evidence assessment. A benefit in terms of symptoms and quality of life in rheumatoid arthritis was shown for the Mediterranean and plant-based diet as well as the anti-inflammatory diet. The effect sizes are small to moderate and the effectiveness in the context of complex lifestyle programs is probably sustainable. The evidence for elimination diets is weak. Initial clinical studies indicate a moderate benefit of plant-based nutrition for osteoarthritis in the context of the metabolic syndrome. There is moderate evidence for the benefit of dietary weight normalization in psoriasis. There is clear experimental evidence of a significant anti-inflammatory effect of prolonged fasting. Several clinical studies demonstrated a symptomatic benefit of prolonged modified fasting (therapeutic fasting) in rheumatoid arthritis (RA). If fasting is followed by a vegan and vegetarian diet, lasting effects of up to 1 year have been documented. Cardiometabolic but not antirheumatic effects have been proven for intermittent fasting. Nutrition and fasting can be classified as a possible useful addition to conventional treatment but are currently only rarely taken into account in practice.

Fasting in Science and Clinics: A Report on Proceedings from the International Scientific Symposium and Conference on Fasting in Berlin (June 2023)

BACKGROUND

A fasting conference and scientific symposium on fasting were held in Berlin in June 2023. Researchers and clinicians from around the world shared new findings, clinical insights, and work in progress during a 3-day program.

SUMMARY

Different fasting regimens, including prolonged, short-term, intermittent fasting, and time-restricted eating were discussed for preventive and therapeutic settings. Experimental and clinical findings shared ranged from biochemical and cellular fasting responses to fasting-mimicking agents, the role of the gut microbiome, and immunological effects. Clinically, a special focus was placed upon metabolic, autoimmune, neurodegenerative, and oncological diseases. The discussion also covered how modern technologies, practical adaptations to traditional protocols, and a supportive network of specialized physicians can assist in the practical application of fasting, among other subjects.

KEY MESSAGES

Dose-response relationships, gender aspects, and the subjective experience of fasting seem promising for future research, while further investigation of religious fasting may offer deeper insights into motivational and health aspects.

World's Longest Medically Documented Repeated Fasting History in a 92 Years Old Man Who Fasted 21 Days Yearly for 45 Years: A Case Report

Case presentation: Scientific documentation on lifelong repeated cycles of long-term fasting doesn't exist. We report the case of a 92-year-old man who fasted 3 weeks yearly for 45 years. Results: Body weight and clinical parameters showed cyclic variations, returning to baseline after food reintroduction. Biological age analysis indicated that the patient was 5.9 years younger than his chronological age. Mental and physical health tests documented the absence of frailty, that the patient could function independently, had excellent cognitive functions, and a good mobility. Conclusion: It can be reasonably assumed that this subject have had protective effects from his yearly fasting.

Sirtuin 1 in osteoarthritis: Perspectives on regulating glucose metabolism

Osteoarthritis (OA) is a degenerative disease characterised by articular cartilage destruction, and its complex aetiology contributes to suboptimal clinical treatment outcomes. A close association exists between glucose metabolism dysregulation and OA pathogenesis. Owing to the unique environment of low oxygen and glucose concentrations, chondrocytes rely heavily on their glycolytic capacity, exhibiting distinct spatiotemporal differences. However, under pathological stimulation, chondrocytes undergo excessive glycolytic activity while mitochondrial respiration and other branches of glucose metabolism are compromised. This metabolic change induces cartilage degeneration by reprogramming the inflammatory responses. Sirtuins, a highly conserved family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases, regulate glucose metabolism in response to energy fluctuations in different cellular compartments，alleviating metabolic stress. SIRT1, the most extensively studied sirtuin, participates in maintaining glucose homeostasis in almost all key metabolic tissues. While actively contributing to the OA progression and displaying diverse biological effects in cartilage protection, SIRT1's role in regulating glucose metabolism in chondrocytes has not received sufficient attention. This review focuses on discussing the beneficial role of SIRT1 in OA progression from a metabolic regulation perspective based on elucidating the primary characteristics of chondrocyte glucose metabolism. We also summarise the potential mechanisms and therapeutic strategies targeting SIRT1 in chondrocytes to guide clinical practice and explore novel therapeutic directions.