How does obesity cause osteoarthritis? By “inflammaging”
Research in medicine does not stand still. Frequently we update our articles because a wave of new studies appear on a specific subject, such is the case in the relationship between obesity and inflammation.
What is “inflammaging”?
“Inflammaging,” is a combination word consisting of “inflammation” and “aging.” Doctors now regularly use this term to describe the harmful aspects of chronic low grade inflammation in aging people. A new paper (December 2017) in the medical journal Frontiers in immunology, published by doctors at the University of Miami and University of Chieti-Pescara, helps explain this problem.(1)
Here is what the researchers said:
- “Obesity superimposed on aging drastically increases chronic low-grade inflammation (inflammaging), which is an important link between obesity, insulin resistance, and age-associated diseases.” To make matters worse is the emerging problem that aging obese patients do not have good clinical response to the medications they are taking. If you are overweight and you are trying to convince people that your medications are not helping, you may have an argument that your obesity is a hindrance.
While this paper focuses on many disorders of aging including type-2 diabetes, rheumatoid arthritis, cognitive impairment, and dementia, where obesity plays a significant role, we will focus on the aspects of obesity and osteoarthritis.
A quick point though, as stated in this research and another new study (December 2017) from university research teams in Italy published in Clinical and molecular allergy, (2) the increase of obesity inspired pro-inflammatory cytokines (small proteins that send pro-inflammatory and anti-inflammatory messages through out the body) is associated with dementia, Parkinson’s disease, atherosclerosis, diabetes type 2, sarcopenia (bone loss) and a high risk of morbidity (disease) and mortality (death). Coming up with a treatment for inflammaging is obvious paramount to the patient’s health.
Study highlights from the University of Miami and University of Chieti-Pescara team:
- Despite the fact that osteoarthritis directly correlates with age, the real cause of this association is not clear, and osteoarthritis development can be separated into aging-dependent (breakdown associated with aging) and aging-independent (breakdown associated with injury, wear and tear demands of sports and heavy labor) processes.
- Both aging-dependent and aging-independent osteoarthritis developments increase production of matrix metalloproteinases (enzymes that breakdown and destroy tissue) and cytokines.
- Both aging-dependent and aging-independent osteoarthritis increase production of Reactive oxygen species (ROS) induced age-related changes in chondrocytes (cartilage cells). Simply Reactive oxygen species (ROS) is a chemical reaction that leads to oxidant damage.
- Weigh loss
- Obesity accelerates progression of osteoarthritis
- Exercise and loss of at least 10% of body weight can effectively lead to improvement in symptoms, pain relief, and physical function.
- Physical activity may reactivate a regenerative process by mobilizing stem cells and increase proteoglycan (proteins) production that restore cartilage structure.
The last statement warrants a few articles on its own, and we have them. These articles will help you understand how physical activity and weight loss help heal damaged joints even advanced joint degeneration. Please see How stem cells heal degenerative joint disease after years of cortisone and painkillers, and Excessive weight and joint pain – the inflammation connection.
Doctors working with nutrition and metabolism are among those researchers who are bringing attention to osteoarthritis as a whole joint disease and in fact a whole body disease.
This is a title of an August 31, 2017 study: “Obesity-associated metabolic syndrome spontaneously induces infiltration of pro-inflammatory macrophage in synovium and promotes osteoarthritis.” Before we go onto to discuss this research these are the keywords that should stick out: spontaneously, pro-inflammatory, promotes osteoarthritis.
This study lead by researchers at the Queensland University of Technology, the University of Southern Queensland, and The Prince Charles Hospital in Australia begins with acknowledging that obesity is an important risk factor for osteoarthritis however how obesity causes osteoarthritis remains largely unknown.
Before you read on you may think that the answer is obvious, excessive weight is causing pressure and load on joints. Studies as we have shown in companion articles on this website, are actually looking at how obesity causes inflammation without weight load being a factor. We are going to pull in that research here later in this article.
Back to the Australian researchers: obesity is creating a toxic inflammatory environment spontaneously
The researchers fed Wistar rats a high-carbohydrate, high-fat diet for period of 8 and 16 weeks. The study showed that, obesity induced by this diet is associated with spontaneous and local inflammation of the synovial membranes in the rats even before the cartilage degradation.
- Comment: The obesity is creating a toxic inflammatory environment spontaneously, meaning it is not waiting for degenerative joint disease to occur to produce the classic symptoms of swelling and painful inflammation. This is an amazing reversal of roles – inflammation before degeneration.
The researchers noted increased synovitis and increased macrophage infiltration (immune cells are now invading the areas causing swelling and edema) into the synovium (the protective joint membrane) and a predominant elevation of pro-inflammatory M1 macrophages (A specific type of immune cell) is occurring.
- Comment: The toxic elements created by obesity, and nowhere is wear and tear or load discussed, is the inflammation it creates. Obesity is pro-inflammatory, promotes osteoarthritis.
This study concludes that future therapeutic strategies targeted at the synovial macrophage phenotype (an obesity causing classification of inflammation) may be the key to break the link between obesity and osteoarthritis.(3)
- In other words the joint environment has becoming a diseased joint environment via obesity induced joint inflammation. It can be managed by managing obesity.
When we write our articles, we like to “connect the dots,” this means looking at multiple studies and finding the common thread. This line of thinking takes us over to the Netherlands who one week earlier published their article “Metabolic dysregulation accelerates injury-induced joint degeneration, driven by local inflammation; an in vivo rat study.” The keywords we will be looking at here are accelerates injury-induced joint degeneration.
The growing evidence for the existence of an obesity causing type of osteoarthritis
In this study from researchers at the University Medical Center Utrecht, the doctors wrote of the growing evidence for the existence of an obesity-related phenotype of osteoarthritis in which low-grade inflammation and a disturbed metabolic profile play a role. (A phenotype is a classification, what these doctors are trying to show is that osteoarthritis caused by obesity is a special type of osteoarthritis, caused by inflammation, not wear and tear or rheumatoid factors.)
In a Rat model study, the scientists were able to link together a devastating progression of quick and rapid joint degeneration.
- Forty Wistar rats were divided intow two groups
- Group A a standard/balanced diet
- Group B a high-fat diet.
- After 12 weeks, in 14 out of 20 rats in each group, cartilage was mechanically damaged in the right knee joint. The remaining six animals in each group served as controls.
- Comment: The researchers damaged the cartilage to see how the immune system would respond to injury in an over fed high fat diet test rat.
- After a subsequent 12 weeks, serum was collected for metabolic state (disease or healing environment), subchondral bone changes (bone spurs or bone degeneration), osteoarthritis severity determined by histology (microscopic evaluation), and macrophage presence (Our friends from the immune system the macrophage which cleans up injury debris to make way for healing.)
- The high-fat diet rats showed increased statistically relevant metabolic parameters, resulting in a dysmetabolic state and subsequent synovial inflammation, whereas cartilage degeneration was hardly influenced.
- The high-fat condition in combination with mechanical cartilage damage resulted in a clear statistically significant progression of the osteoarthritic features, with increased synovitis and multiple large osteophytes (bone spur development).
- It is concluded that a metabolic dysbalance due to a high-fat diet increases joint inflammation without cartilage degeneration.
- The dysmetabolic state (obesity causing toxic environment) clearly accelerates progression of osteoarthritis upon cartilage damage.(4)
If you have cartilage damage from wear and tear – obesity accelerates that damage to osteoarthritis
What else can you say? If you have cartilage damage from wear and tear – obesity accelerates that damage to osteoarthritis and more so and the need for knee replacement. If you have somehow been spared wear and tear damage in your joints, the obesity induced inflammation will damage it on its own. Researchers cannot make a more powerful statement.
Other articles on this obesity, inflammation and joint disease
Here is more research from our other articles:
- Metabolic syndrome and osteoarthritis joint pain
- In this article a highlighted study is on the connection between insulin, inflammation, and joint pain here are the bullet points of their findings.
- Excessive weight and joint pain – the inflammation connection
- In this article a highlighted study is from Ohio State University published in the medical journal Pain. The study goal was to evaluate if and how a diet of foods with anti-inflammatory properties affected pain and other problems of inflammation in joints.
- How diet, Type II diabetes and obesity compromise tendon healing
- Obesity and Back Pain
Do you have questions about obesity and osteoarthritis? You can get help and information from our Caring Medical staff.
1 Frasca D, Blomberg BB, Paganelli R. Aging, obesity and inflammatory age-related diseases. Frontiers in immunology. 2017;8:1745. [Google Scholar]
2 Ventura MT, Casciaro M, Gangemi S, Buquicchio R. Immunosenescence in aging: between immune cells depletion and cytokines up-regulation. Clinical and Molecular Allergy. 2017 Dec;15(1):21. [Google Scholar]
3 Sun AR, Panchal SK, Friis T, Sekar S, Crawford R, Brown L, Xiao Y, Prasadam I. Obesity-associated metabolic syndrome spontaneously induces infiltration of pro-inflammatory macrophage in synovium and promotes osteoarthritis. PLoS One. 2017 Aug 31;12(8):e0183693. [Google Scholar]
4 de Visser HM, Mastbergen SC, Kozijn AE, Coeleveld K, Pouran B, van Rijen MH, Lafeber FP, Weinans H. Metabolic dysregulation accelerates injury‐induced joint degeneration, driven by local inflammation; an in vivo rat study. Journal of Orthopaedic Research. 2017 Aug 25. [Google Scholar]