Tocilizumab Increases Body Weight and Serum Adipokine Levels in Patients with Rheumatoid Arthritis Independently of Their Treatment Response: a Retrospective Cohort Study

The bidirectional immune crosstalk in metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an unabated risk factor for end-stage liver diseases with no available therapies. Dysregulated immune responses are critical culprits of MASLD pathogenesis. Independent contributions from either the innate or adaptive arms of the immune system or their unidirectional interplay are commonly studied in MASLD. However, the bidirectional communication between innate and adaptive immune systems and its impact on MASLD remain insufficiently understood. Given that both innate and adaptive immune cells are indispensable for the development and progression of inflammation in MASLD, elucidating pathogenic contributions stemming from the bidirectional interplay between these two arms holds potential for development of novel therapeutics for MASLD. Here, we review the immune cell types and bidirectional pathways that influence the pathogenesis of MASLD and highlight potential pharmacologic approaches to combat MASLD based on current knowledge of this bidirectional crosstalk.

Physiological role of cytokines in the regulation of mammalian metabolism

The innate cytokine system is involved in the response to excessive food intake. In this review, we highlight recent advances in our understanding of the physiological role of three prominent cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF), in mammalian metabolic regulation. This recent research highlights the pleiotropic and context-dependent functions in the immune-metabolic interplay. IL-1β is activated in response to overloaded mitochondrial metabolism, stimulates insulin secretion, and allocates energy to immune cells. IL-6 is released by contracting skeletal muscle and adipose tissue and directs energy from storing tissues to consuming tissues. TNF induces insulin resistance and prevents ketogenesis. Additionally, the therapeutic potential of modulating the activity of each cytokine is discussed.

Effect of biological disease-modifying antirheumatic drugs on body composition in patients with rheumatoid arthritis: a systematic review and meta-analysis

Background

Rheumatoid arthritis (RA) generates an inflammatory profile that predisposes to total and visceral fatty accumulation and reduced fat free mass (FFM). This metabolic disorder contributes to poor functionality, increased cardiovascular risk and higher mortality. This study aimed to address a systematic review with meta-analysis to determine the effect of biological and targeted synthetic disease-modifying antirheumatic drugs (bDMARDs and tsDMARDs) on body composition (BC) of patients with RA.

Methods

The search was conducted at the electronic databases PubMed, Cochrane Library, Embase, Lilacs and grey literature. This investigation was carried until July 2021. Outcomes of interest were total weight, body mass index (BMI), fat mass (FM) and FFM. A meta-analysis comparing these outcomes in RA patients under bDMARD treatment versus controls was performed.

Results

Out of 137 studies reviewed, 18 were selected: fifteen prospective cohorts, two retrospective cohorts, and one cross-sectional study. The studies comprised 1221 patients, 778 on bDMARD treatment and 443 controls, which included RA patients under conventional synthetic DMARD (csDMARD). No study addressing BC analysis in patients using tsDMARD was found. The mean age and duration of the disease was 56.7 years and 6.77 years, respectively. Ten studies demonstrated a significant increase of total weight in 88.2% of patients and 42.3% for BMI. In studies that analyzed BC by double X-ray absorptiometry (DXA), the increase in total weight and BMI correlated positively to the increase in FFM. The meta-analysis carried out in five studies showed no significant difference of the mean difference for total weight 0.12 kg (95% CI − 5.58, 5.82), BMI 0.08 kg/m2 (95% CI − 1.76, 1.92), FM − 0.08 kg (95% IC − 5.31, 5.14), and FFM − 2.08 kg (95% CI − 7.37, 3.21).

Conclusion

This systematic review suggests a possible impact of bDMARDs on BC of RA patients, even though, the meta-analysis carried out in a small part of these studies was not able to confirm significant variation in BC components.

Trial registration: PROSPERO code: CRD42020206949.

Systemic effects of IL-6 blockade in rheumatoid arthritis beyond the joints

Interleukin (IL)-6 is produced locally in response to an inflammatory stimulus, and is able to induce systemic manifestations at distance from the site of inflammation. Its unique signaling mechanism, including classical and trans-signaling pathways, leads to a major expansion in the number of cell types responding to IL-6. This pleiotropic cytokine is a key factor in the pathogenesis of rheumatoid arthritis (RA) and is involved in many extra-articular manifestations that accompany the disease. Thus, IL-6 blockade is associated with various biological effects beyond the joints. In this review, the systemic effects of IL-6 in RA comorbidities and the consequences of its blockade will be discussed, including anemia of chronic disease, cardiovascular risks, bone and muscle functions, and neuro-psychological manifestations.

Adiponectin Deregulation in Systemic Autoimmune Rheumatic Diseases

Deregulation of adiponectin is found in systemic autoimmune rheumatic diseases (SARDs). Its expression is downregulated by various inflammatory mediators, but paradoxically, elevated serum levels are present in SARDs with high inflammatory components, such as rheumatoid arthritis and systemic lupus erythematosus. Circulating adiponectin is positively associated with radiographic progression in rheumatoid arthritis as well as with cardiovascular risks and lupus nephritis in systemic lupus erythematosus. However, in SARDs with less prominent inflammation, such as systemic sclerosis, adiponectin levels are low and correlate negatively with disease activity. Regulators of adiponectin gene expression (PPAR-γ, Id3, ATF3, and SIRT1) and inflammatory cytokines (interleukin 6 and tumor necrosis factor α) are differentially expressed in SARDs and could therefore influence total adiponectin levels. In addition, anti-inflammatory therapy could also have an impact, as tocilizumab treatment is associated with increased serum adiponectin. However, anti-tumor necrosis factor α treatment does not seem to affect its levels. Our review provides an overview of studies on adiponectin levels in the bloodstream and other biological samples from SARD patients and presents some possible explanations why adiponectin is deregulated in the context of therapy and gene regulation.

Adipokines and Autoimmunity in Inflammatory Arthritis

Adipokines are adipose tissue-derived factors not only playing an important role in metabolism but also influencing other central processes of the body, such as inflammation. In autoimmune diseases, adipokines are involved in inflammatory pathways affecting different cell types. Many rheumatic diseases belong to the group of autoimmune diseases, for example rheumatoid arthritis (RA) and psoriatic arthritis. Due to the autoimmune responses, a chronic inflammatory milieu develops, which affects the whole body, including adipose tissue. Metabolic alterations such as obesity influence inflammatory responses in autoimmune diseases. Adipokines are bioactive mediators mainly produced by adipose tissue. Due to alterations of systemic adipokine levels, their role as biomarkers with diagnostic potential has been suggested in the context of rheumatic diseases. In the affected joints of RA patients, different synoviocytes but also osteoclasts, osteoblasts, and chondrocytes produce several adipokines, contributing to the unique inflammatory microenvironment. Adipokines have been shown to be potent modulatory effectors on different cell types of the immune system but also local cells in synovial tissue, cartilage, and bone. This review highlights the most recent findings on the role of adipokines in the pathophysiology of inflammatory arthritis with a distinct focus on RA in the quickly developing research field.