Use of Dipeptidyl Peptidase-4 Inhibitors and New-onset Rheumatoid Arthritis in Patients with Type 2 Diabetes.Epidemiology. 2018;29:904-912. [PMID: 30028343 DOI: 10.1097/EDE.0000000000000891]

Association of Dipeptidylpeptidase 4 (CD26) With Chondrocyte Senescence and Radiographic Progression in Knee Osteoarthritis

OBJECTIVE

To evaluate the association of dipeptidylpeptidase 4 (DPP-4; also known as CD26) with cellular senescence of human cartilage and progression of knee osteoarthritis (OA).

METHODS

Articular cartilage sections and chondrocytes were acquired from 35 individuals undergoing total knee replacement for OA to evaluate the following: 1) the association between OA severity and established senescence markers (senescence-associated β-galactosidase activity and p16), which was quantified using immunohistochemistry and flow cytometry (n = 19 samples); 2) the coexpression of DPP-4 with established senescence markers, which was assessed using flow cytometry; and 3) expression levels of anabolic and catabolic genes, senescence-related genes, and senescence-associated secretory phenotypes in DPP-4+ and DPP-4- cells, which were isolated using fluorescence-activated cell sorting or magnetic-activated cell sorting (n = 16 samples). The concentration of soluble DPP-4 was measured in samples of synovial fluid and samples of plasma from the Prediction of Osteoarthritis Progression cohort and then evaluated for association with the severity of radiographic knee OA at baseline (n = 65 samples) and the progression of structural radiographic OA (n = 57 samples) over a 3-year period.

RESULTS

DPP-4 expression was associated with higher senescence-associated β-galactosidase activity, p16 expression, senescence-related gene and catabolic gene (ADAMTS5, MMP13, IL6, and IL8) expression, higher senescence-associated secretory phenotype secretion, and lower anabolic gene (COL2A1 and ACAN) expression in primary chondrocytes. Synovial fluid DPP-4 concentration was associated with radiographic OA progression (odds ratio 105.32; P = 0.015), proteases (synovial fluid matrix metalloproteinase 1 and matrix metalloproteinase 3), aggrecan degradation (synovial fluid sulfated glycosaminoglycan), indicators of activated macrophages (synovial fluid CD14 and CD163), and inflammation (synovial fluid interleukin-6).

CONCLUSION

Our study identifies DPP-4 as a key surface marker in senescent chondrocytes and a predictor of radiographic OA progression.

Glucose as a Potential Key to Fuel Inflammation in Rheumatoid Arthritis

Glucose is the most important source of energy and homeostasis. Recent investigations are clarifying that glucose metabolism might be altered in rheumatoid arthritis (RA), which would play a role in the inflammatory phenotype of rheumatoid synovial fibroblasts. It may also play a role in a variety of autoimmune diseases’ pathophysiology by modulating immune responses and modifying autoantigen expressions. The research into glucose and its metabolism could lead to a better understanding of how carbohydrates contribute to the occurrence and duration of RA and other autoimmune diseases.

Emerging Role of Dipeptidyl Peptidase-4 in Autoimmune Disease

Dipeptidyl-peptidase IV (DPP4), originally identified as an aminopeptidase in 1960s, is an ubiquitously expressed protease presented as either a membrane-bound or soluble form. DPP4 cleaves dipeptide off from the N-terminal of its substrates, altering the bioactivity of its substrates. Subsequent studies reveal that DPP4 is also involved in various cellular processes by directly binding to a number of ligands, including adenosine deaminase, CD45, fibronectin, plasminogen, and caveolin-1. In recent years, many novel functions of DPP4, such as promoting fibrosis and mediating virus entry, have been discovered. Due to its implication in fibrotic response and immunoregulation, increasing studies are focusing on the potential role of DPP4 in inflammatory disorders. As a moonlighting protein, DPP4 possesses multiple functions in different types of cells, including both enzymatic and non-enzymatic functions. However, most of the review articles on the role of DPP4 in autoimmune disease were focused on the association between DPP4 enzymatic inhibitors and the risk of autoimmune disease. An updated comprehensive summary of DPP4’s immunoregulatory actions including both enzymatic dependent and independent functions is needed. In this article, we will review the recent advances of DPP4 in immune regulation and autoimmune rheumatic disease.

Type 2 diabetes mellitus, glycaemic control, associated therapies and risk of rheumatoid arthritis: a retrospective cohort study

OBJECTIVE

To compare the incident risk of RA in patients with type 2 diabetes mellitus (T2DM) and to explore the role of glycaemic control and associated therapeutic use in the onset of RA.

METHODS

This study was a retrospective cohort study using patients derived from the IQVIA Medical Research Data (IMRD-UK) database between 1995 and 2019. A total of 224 551 newly diagnosed patients with T2DM were matched to 449 101 patients without T2DM and followed up to assess their risk of RA. Further analyses investigated the effect of glycaemic control, statin use and anti-diabetic drugs on the relationship between T2DM and RA using a time-dependent Cox regression model.

RESULTS

During the study period, the incidence of RA was 8.1 and 10.6 per 10 000 person-years in the exposed and unexposed groups, respectively. The adjusted hazard ratio (aHR) was 0.73 (95% CI 0.67, 0.79). In patients who had not used statins in their lifetime, the aHR was 0.89 (95% CI 0.69, 1.14). When quantifying the effects of glycaemic control, anti-diabetic drugs and statins using time-varying analyses, there was no association with glycaemic control [aHR 1.00 (95% CI 0.99, 1.00)], use of metformin [aHR 1.00 (95% CI 0.82, 1.22)], dipeptidyl peptidase-4 inhibitors [DPP4is; aHR 0.94 (95% CI 0.71, 1.24)] and the development of RA. However, statins demonstrated a protective effect for progression of RA in those with T2DM [aHR 0.76 (95% CI 0.66, 0.88)], with evidence of a duration-response relationship.

CONCLUSION

There is a reduced risk of RA in patients with T2DM that may be attributable to the use of statins.

Dipeptidyl peptidase-4 inhibitor-induced autoimmune diseases: Current evidence

Dipeptidyl peptidase-4 inhibitors (DPP-4i) have an important place in the management of type 2 diabetes. The DPP-4 enzyme is ubiquitously distributed throughout the human body and has multiple substrates through which it regulates several important physiological functions. DPP-4 regulates several immune functions, including T-cell activation, macrophage function, and secretion of cytokines. Studies have reported an increase in autoimmune diseases like bullous pemphigoid, inflammatory bowel disease, and arthritis with DPP-4i use. The relationship of DPP-4i and autoimmune diseases is a complex one and warrants further research into the effect of DPP-4 inhibition on the immune system to understand the pathogenesis more clearly. Whether a particular cluster of autoimmune diseases is associated with DPP-4i use remains an important contentious issue. Nevertheless, a heightened awareness from the clinicians is required to identify and treat any such diseases. Through this review, we explore the clinical and pathophysiological characteristics of this association in light of recent evidence.

DPP4 reduces proinflammatory cytokine production in human rheumatoid arthritis synovial fibroblasts

Rheumatoid arthritis (RA) is an autoimmune disorder that is characterized by increasing levels of proinflammatory cytokines. The ubiquitous enzyme dipeptidyl peptidase-4 (DPP4, also known as CD26) regulates different immune disorders, although the effects of DPP4 in RA are uncertain. Here, we found lower levels of DPP4 in RA synovial tissues compared with normal tissues. DPP4 levels were also lower in a rat collagen-induced arthritis model than in control (healthy) rats. Overexpression of DPP4 or exogenous treatment of RA synovial fibroblasts with DPP4 reduced levels of proinflammatory interleukin (IL)-1β, IL-6, and IL-13, and increased anti-inflammatory IL-10 synthesis, while DPP4 inhibitors sitagliptin and vildagliptin increased proinflammatory cytokine production, indicating an enhanced risk of RA development. The evidence suggests that increasing DPP4 expression is a novel strategy for RA disease.

Use of dipeptidyl peptidase-4 inhibitors is associated with a lower risk of rheumatoid arthritis in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of cohort studies

BACKGROUND AND AIMS

Case reports have described occurrence of rheumatoid arthritis (RA) after initiation of Dipeptidyl Peptidase-4 Inhibitors (DPP4i), suggesting a possible adverse effect of the medications. However, the findings from subsequent cohort studies suggest the opposite as they indicate that T2DM patients who used DPP4i tended to have a lower risk of RA. We aimed to investigate the association between use of DPP4i and incident RA in patients with type 2 diabetes mellitus (T2DM) using systematic review and meta-analysis.

METHODS

Potentially eligible studies were identified from Medline and EMBASE databases from inception to May 2020 using search strategy that comprised of terms for "Dipeptidyl peptidase-4 inhibitor" and "Rheumatoid arthritis". Eligible study must be cohort study consisting of one cohort of patients with T2DM who were DPP4i users and another cohort of comparators with T2DM who did not receive DPP4i. Then, the study must report effect estimates with 95% confidence intervals (95% CIs) comparing incident RA between DPP4i users versus comparators. Point estimates with standard errors retrieved from each study were combined together using the generic inverse variance method.

RESULTS

A total of 709 articles were identified. After systematic review, four retrospective cohort studies met the eligibility criteria and were included into the meta-analysis. DPP4i users had a significantly lower risk of incident RA compared with comparators with the pooled hazard ratio of 0.72 (95% CI, 0.54-0.96; I² 75%).

CONCLUSION

This systematic review and meta-analysis found a significant association between DPP4i use and a lower risk of incident RA.

How should rheumatologists manage glucocorticoid-induced hyperglycemia?

Glucocorticoid-induced hyperglycemia (GIH) is an important complication to be managed by rheumatologists as it can affect morbidity and mortality of patients. Before administration of glucocorticoids, risk for the development of GIH should be assessed in every patient. A meta-analysis identified male gender, older age, family history of diabetes mellitus, current smoking history, past history of hypertension, higher body mass index, higher fasting plasma glucose (PG) and higher hemoglobin A1c (HbA1c) levels as risk factors for GIH. Then, rheumatologists need to carefully monitored PG levels including 2-h after meals because glucocorticoids particularly affect postprandial glucose metabolism. Fasting PG level ≥ 126 mg/dL and/or post-meal PG level ≥ 200 mg/dL are considered as GIH regardless of HbA1c level. Treatment strategy for GIH should center on insulin injection since the effectiveness of oral hypoglycemic agents for GIH has been uncertain. But, rheumatologists may try oral hypoglycemic agents in advance of insulin therapy for mild GIH, whereas diabetologists should be consulted in case of intractable GIH. More strict control of GIH could be possible using intensive insulin protocol. Rheumatologists are encouraged to be interested in the management of GIH for providing patients superior care, working closely with diabetologists.

Dipeptidyl peptidase 4 inhibitors and their potential immune modulatory functions

Dipeptidyl peptidase 4 (DPP4) inhibitors (DPP4is) are oral anti-diabetic drugs (OADs) for the treatment of type 2 diabetes mellitus (T2DM) through inhibiting the degradation of incretin peptides. Numerous investigations have been focused on the effects of DPP4is on glucose homeostasis. However, there are limited evidences demonstrating their Potential modulatory functions in the immune system. DPP4, originally known as the lymphocyte cell surface protein CD26, is widely expressed in many types of immune cells including CD4(+) and CD8(+) T cells, B cells, NK cells, dendritic cells, and macrophages; and regulate the functions of these cells. In addition, DPP4 is capable of modulating plenty of cytokines, chemokines and peptide hormones. Accordingly, DPP4/CD26 is speculated to be involved in various immune/inflammatory diseases and DPP4is may become a new drug class applied in these diseases. This review focuses on the regulatory effects of DPP4is on immune functions and their possible underlying mechanisms. Further clinical studies will be necessitated to fully evaluate the administration of DPP4is in diabetic patients with or without immune diseases.

Methodological considerations when analysing and interpreting real-world data

In the absence of relevant data from randomized trials, nonexperimental studies are needed to estimate treatment effects on clinically meaningful outcomes. State-of-the-art study design is imperative for minimizing the potential for bias when using large healthcare databases (e.g. claims data, electronic health records, and product/disease registries). Critical design elements include new-users (begin follow-up at treatment initiation) reflecting hypothetical interventions and clear timelines, active-comparators (comparing treatment alternatives for the same indication), and consideration of induction and latent periods. Propensity scores can be used to balance measured covariates between treatment regimens and thus control for measured confounding. Immortal-time bias can be avoided by defining initiation of therapy and follow-up consistently between treatment groups. The aim of this manuscript is to provide a non-technical overview of study design issues and solutions and to highlight the importance of study design to minimize bias in nonexperimental studies using real-world data.