Rheumatoid arthritis (RA) is an inflammatory autoimmune disease potentially leading to disability, with about 30 % of patients unable to work after 3 years of disease. The disease affects predominantly small joints such as hands, wrists and feet.
The causes and development of rheumatoid arthritis, similar to development of a majority of inflammatory and autoimmune disorders, is largely due to an inadequate immune response to environmental agents. Among these agents, infectious organisms are the leaders. An impressive list of microorganisms suspected of provoking the disease has formed, and the list is still growing.
Infections might not trigger rheumatoid arthritis in all cases. For example, co-occurence with psychological stress or chronic joint tissue microtrauma. might be needed. Smoking and ageing are also risk factors for RA. Because RA and periodontitis are complex diseases characterized by common pathogenetic mechanisms of chronic inflammation and bone destruction, it has been suggested that periodontitis is linked to the development of RA, specifically its causative agent Porphyromonas gingivalis.
Gut bacteria and other microorganisms play a crucial role in influencing innate and acquired immune responses and thus interfere with the fragile balance inflammation versus tolerance. Link between gut bacteria composition and the severity of inflammation have been confirmed in inflammatory bowel diseases. More recently similar changes in the gut microbiota have been reported in patients with spondyloarthritis and rheumatoid arthritis.2
There is a growing awareness that different drugs such as antibiotic and immunosuppressant can both influence and to be influenced by microbiota diversity and composition. Although the impact of antibiotics on microbiome is mostly temporary, their frequent use or administration during early infancy can exert permanent effects. It is known that anti-cancer therapy frequently used also in treating chronic inflammatory arthritis, such as methotrexate and cyclophosphamide, changes dramatically the gut microflora. After these treatments often occurs a general depletion of the gut microbiota, the drop in bacteria diversity is accompanied by a reduction in the commensal species in favor of potential pathogens that can lead to a deterioration of the gut barrier and bacteria enetring body tissues and bloodstream.
In case of viral infections such as observed with herpes viruses, the immune system limits viral infection by producing proinflammatory agents (interferon). Incapacity to control the inflammatory reactions is one of the major factors provoking RA development.
There is strong evidence that the highest joint inflammation level may be observed early (75 % erosions within the first 2 years) and that timely treatment is able to slow down the progression of bone and join damage measured by radiographic scanning. A case of long-lasting recovery after periodontal treatment, in a male patient with newly onset of RA and PD has been recently reported, suggesting that in selected early RA cases, prompt periodontal infection treatment may induce disease regression, thus avoiding the development of a chronic and progressive arthritis.
Systemic and localized extra-CNS bacterial infections are collectively and independently associated with an increased risk of developing dementia among older US veterans. Extra-CNS bacterial infections such as cellulitis, urinary tract infections, blood poisoning, osteomyelitis, and septic arthritis can trigger, worsen and contribute to the development and spread of dementia, cause cognitive impairments, and possibly increase the risk for dementia among humans. Sepsis significantly increased risk for dementia among intensive care recipients. Hospitalization for pneumonia has also been associated with a significantly increased risk for subsequent dementia.3
- How Rheumatoid Arthritis Can Result from Provocation of the Immune System by Microorganisms and Viruses. Marina I. Arleevskaya,1,* Olga A. Kravtsova,2 Julie Lemerle,3 Yves Renaudineau,3 and Anatoly P. Tsibulkin1 Front Microbiol. 2016; 7: 1296.
- Microbiota and chronic inflammatory arthritis: an interwoven link
Andrea Picchianti Diamanti,corresponding author#1,3 M. Manuela Rosado,#2 Bruno Laganà,1 and Raffaele D’Amelio1 J Transl Med. 2016; 14: 233.
- Systemic and localized extra-central nervous system bacterial infections and the risk of dementia among US veterans: A retrospective cohort study
Francis Mawanda,a Robert B. Wallace,a,b Kimberly McCoy,c and Thad E. Abramsa,b,c,∗ Journal ListAlzheimers Dement (Amst)v.4; 2016