Periodontitis is a complex disease: (a) various causative factors play a role simultaneously and interact with each other; and (b) the disease is episodic in nature, and bursts of disease activity can be recognized, ie, the disease develops and cycles in a nonlinear fashion. We recognize that various causative factors determine the immune blueprint and, consequently, the immune fitness of a subject. Normally, the host lives in a state of homeostasis or symbiosis with the oral microbiome; however, disturbances in homeostatic balance can occur, because of an aberrant host response (inherited and/or acquired during life). This imbalance results from hyper- or hyporesponsiveness and/or lack of sufficient resolution of inflammation, which in turn is responsible for much of the disease destruction seen in periodontitis. The control of this destruction by anti-inflammatory processes and proresolution processes limits the destruction to the tissues surrounding the teeth. The local inflammatory processes can also become systemic, which in turn affect organs such as the heart. Gingival inflammation also elicits changes in the ecology of the subgingival environment providing optimal conditions for the outgrowth of gram-negative, anaerobic species, which become pathobionts and can propagate periodontal inflammation and can further negatively impact immune fitness. The factors that determine immune fitness are often the same factors that determine the response to the resident biofilm, and are clustered as follows: (a) genetic and epigenetic factors; (b) lifestyle factors, such as smoking, diet, and psychosocial conditions; (c) comorbidities, such as diabetes; and (d) local and dental factors, as well as randomly determined factors (stochasticity). Of critical importance are the pathobionts in a dysbiotic biofilm that drive the viscious cycle. Focusing on genetic factors, currently variants in at least 65 genes have been suggested as being associated with periodontitis based on genome-wide association studies and candidate gene case control studies. These studies have found pleiotropy between periodontitis and cardiovascular diseases. Most of these studies point to potential pathways in the pathogenesis of periodontal disease. Also, most contribute to a small portion of the total risk profile of periodontitis, often limited to specific racial and ethnic groups. To date, 4 genetic loci are shared between atherosclerotic cardiovascular diseases and periodontitis, ie, CDKN2B-AS1(ANRIL), a conserved noncoding element within CAMTA1 upstream of VAMP3, PLG, and a haplotype block at the VAMP8 locus. The shared genes suggest that periodontitis is not causally related to atherosclerotic diseases, but rather both conditions are sequelae of similar (the same?) aberrant inflammatory pathways. In addition to variations in genomic sequences, epigenetic modifications of DNA can affect the genetic blueprint of the host responses. This emerging field will yield new valuable information about susceptibility to periodontitis and subsequent persisting inflammatory reactions in periodontitis. Further studies are required to verify and expand our knowledge base before final cause and effect conclusions about the role of inflammation and genetic factors in periodontitis can be made.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/prd.12297

The role of inflammation and genetics in periodontal disease.

Challenges in the treatment of Rheumatoid Arthritis.

Objectives Biologic disease-modifying antirheumatic drugs (bDMARDs) have revolutionised treatment and outcomes for rheumatoid arthritis (RA). The expanding repertoire allows the option of switching bDMARD if current treatment is not effective. For some patients, even after switching, disease control remains elusive. This analysis aims to quantify the frequency of, and identify factors associated with, bDMARD refractory disease. Methods Patients with RA starting first-line tumour necrosis factor inhibitor in the British Society for Rheumatology Biologics Register for RA from 2001 to 2014 were included. We defined patients as bDMARD refractory on the date they started their third class of bDMARD. Follow-up was censored at last follow-up date, 30 November 2016, or death, whichever came first. Switching patterns and stop reasons of bDMARDs were investigated. Cox regression identified baseline clinical factors associated with refractory disease. Multiple imputation of missing baseline data was used. Results 867 of 13 502 (6%) patients were bDMARD refractory; median time to third bDMARD class of 8 years. In the multivariable analysis, baseline factors associated with bDMARD refractory disease included patients registered more recently, women, younger age, shorter disease duration, higher patient global assessment, higher Health Assessment Questionnaire score, current smokers, obesity and greater social deprivation. Conclusions This first national study has identified the frequency of bDMARD refractory disease to be at least 6% of patients who have ever received bDMARDs. As the choice of bDMARDs increases, patients are cycling through bDMARDs quicker. The aetiopathogenesis of bDMARD refractory disease requires further investigation. Focusing resources, such as nursing support, on these patients may help them achieve more stable, controlled disease.

https://ard.bmj.com/content/annrheumdis/77/10/1405.full.pdf

Biologic refractory disease in rheumatoid arthritis: results from the British Society for Rheumatology Biologics Register for Rheumatoid Arthritis.

Despite nearly three decades of advances in the management of rheumatoid arthritis (RA), a substantial minority of patients are exposed to multiple DMARDs without necessarily benefitting from them; a group of patients variously designated as having 'difficult to treat', 'treatment-resistant' or 'refractory' RA. This Review of refractory RA focuses on two types of patients: those for whom multiple targeted therapies lack efficacy and who have persistent inflammatory pathology, which we designate as persistent inflammatory refractory RA (PIRRA); and those with supposed refractory RA who have continued disease activity that is predominantly independent of objective evidence of inflammation, which we designate as non-inflammatory refractory RA (NIRRA). These two types of disease are not mutually exclusive, but identifying those individuals with predominant PIRRA or NIRRA is important, as it informs distinct treatment and management approaches. This Review outlines the clinical differences between PIRRA and NIRRA, the genetic and epigenetic mechanisms and immune pathways that might contribute to the immunopathogenesis of recalcitrant synovitis in PIRRA, and a possible basis for non-inflammatory symptomatology in NIRRA. Future approaches towards the definition of refractory RA and the application of single-cell and integrated omics technologies to the identification of refractory RA endotypes are also discussed.

Persistent inflammatory and non-inflammatory mechanisms in refractory rheumatoid arthritis.

Rheumatoid arthritis (RA) is a systemic inflammatory disorder, with the most common extra-articular manifestation of RA being lung involvement. While essentially any of the lung compartments can be affected and manifest as interstitial lung disease (ILD), pleural effusion, cricoarytenoiditis, constrictive or follicular bronchiolitis, bronchiectasis, pulmonary vasculitis, and pulmonary hypertension, RA-ILD is a leading cause of death in patients with RA and is associated with significant morbidity and mortality. In this review, we focus on the common pulmonary manifestations of RA, RA-ILD and airway disease, and discuss evolving concepts in the pathogenesis of RA-associated pulmonary fibrosis, as well as therapeutic strategies, and have revised our previous review on the topic. A rational clinical approach for the diagnosis and management of RA-ILD, as well as an approach to patients with clinical worsening in the setting of treatment with disease-modifying agents, is included. Future directions for research and areas of unmet need in the realm of RA-associated lung disease are raised.

https://err.ersjournals.com/content/errev/30/160/210011.full.pdf

Rheumatoid arthritis-interstitial lung disease: manifestations and current concepts in pathogenesis and management.

Rheumatoid arthritis (RA) is a chronic inflammatory disease caused by both genetic and environmental factors. Smoking has been implicated as one of the most important extrinsic risk factors for its development and severity. Recent developments have shed light on the pathophysiology of RA in smokers, including oxidative stress, inflammation, autoantibody formation and epigenetic changes. The association of smoking and the development of RA have been demonstrated through epidemiologic studies, as well as through in vivo and animal models of RA. With increased use of biological agents in addition to standard disease-modifying antirheumatic drugs (DMARDs), there has been interest in how smoking affects drug response in RA treatment. Recent evidence suggests the response and drug survival in people treated with anti-tumour necrosis factor (anti-TNF) therapy is poorer in heavy smokers, and possible immunological mechanisms for this effect are presented in the current paper.

https://www.mdpi.com/1422-0067/15/12/22279/pdf

So Min Yang

Papers

Smoking and rheumatoid arthritis.