Cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic disease characterized by synovial inflammation that leads to the destruction of cartilage and bone. In the last decade, there was a lot of successful research in the field of cytokine expression and regulation. It has become clear that pro- and anti-inflammatory cytokines, derived predominantely from cells of macrophage lineage, play a major role in the initiation and perpetuation of the chronic inflammatory process in the RA synovial membrane. Monokines are abundant in rheumatoid synovial tissue, whereas low amounts of lymphokines are found. The involvement of pro-inflammatory cytokines, particularly interleukin (IL)-1 and tumor necrosis factor-alpha, in the pathogenesis of RA is well accepted. Recent data provide evidence that the pro-inflammatory cytokine IL-18 plays a crucial role in the development and sustenance of inflammatory joint diseases. There also appears to be a compensatory anti-inflammatory response in RA synovial membrane. It has become clear in the last few years that T cell-derived cytokines expressed preferentially by Th1 cells contribute to joint destruction and inflammation in RA. However, products from Th2 cells may be protectiv

Differential role of interleukin-6 in lung inflammation induced by lipoteichoic acid and peptidoglycan from Staphylococcus aureus

Lipoteichoic acids (LTA) and peptidoglycans (PepG) are major components of the cell walls of gram-positive bacteria that trigger inflammatory responses in vitro. To study the in vivo effects of LTA and PepG from Staphylococcus aureus in lungs and to determine the role of interleukin (IL)-6 herein, these compounds were intranasally administered to IL-6 gene deficient (IL-6(-/-)) and wild type (IL-6(+/+)) mice. In IL-6(+/+) mice, LTA and PepG induced acute pulmonary inflammation in a dose-dependent way, characterized by neutrophilic influx and IL-6 production in the bronchoalveolar lavage fluid. Endogenously produced IL-6 attenuated inflammation induced by 10 mug LTA, as reflected by enhanced neutrophil influx, and increased tumor necrosis factor-alpha, macrophage inflammatory protein-1-alpha, and cytokine-induced neutrophil chemoattractant (KC) release into bronchoalveolar lavage fluid of IL-6(-/-) mice, compared with IL-6(+/+) mice. By contrast, pulmonary inflammation induced by 100 mug LTA was similar (neutrophil influx) or even tended to be attenuated (cytokine and chemokine release) in IL-6(-/-) mice. Endogenous IL-6 increased inflammation induced by PepG, as reflected by decreased neutrophil influx into lungs of IL-6(-/-) mice, compared with IL-6-(+/+) mice. These data suggest that IL-6 plays an antiinflammatory role during LTA-induced pulmonary inflammation, which is dependent on the severity of the inflammatory challenge, and a proinflammatory role in peptidoglycan-induced acute lung inflammation. Thus, the contribution of IL-6 to lung inflammation may vary with the stimulus use

Electrical stimulation of the splenic nerve bundle ameliorates dextran sulfate sodium-induced colitis in mice

Background: Vagus nerve stimulation has been suggested to affect immune responses, partly through a neuronal circuit requiring sympathetic innervation of the splenic nerve bundle and norepinephrine (NE) release. Molecular and cellular mechanisms of action remain elusive. Here, we investigated the therapeutic value of this neuromodulation in inflammatory bowel disease (IBD) by applying electrical splenic nerve bundle stimulation (SpNS) in mice with dextran sulfate sodium (DSS)-induced colitis. Methods: Cuff electrodes were implanted around the splenic nerve bundle in mice, whereupon mice received SpNS or sham stimulation. Stimulation was applied 6 times daily for 12 days during DSS-induced colitis. Colonic and splenic tissues were collected for transcriptional analyses by qPCR and RNA-sequencing (RNA-seq). In addition, murine and human splenocytes were stimulated with lipopolysaccharide (LPS) in the absence or presence of NE. Single-cell RNA-seq data from publicly available data sets were analyzed for expression of β-adrenergic receptors (β-ARs). Results: Colitic mice undergoing SpNS displayed reduced colon weight/length ratios and showed improved Disease Activity Index scores with reduced Tumor Necrosis Factor α mRNA expression in the colon compared with sham stimulated mice. Analyses of splenocytes from SpNS mice using RNA-seq demonstrated specific immune metabolism transcriptome profile changes in myeloid cells. Splenocytes showed expression of β-ARs in myeloid and T cells. Cytokine production was reduced by NE in mouse and human LPS-stimulated splenocytes. Conclusions: Together, our results demonstrate that SpNS reduces clinical features of colonic inflammation in mice with DSS-induced colitis possibly by inhibiting splenic myeloid cell activation. Our data further support exploration of the clinical use of SpNS for patients with IBD

Restoring the Balance of the Autonomic Nervous System as an Innovative Approach to the Treatment of Rheumatoid Arthritis

The immunomodulatory effect of the autonomic nervous system has raised considerable interest over the last decades. Studying the influence on the immune system and the role in inflammation of the sympathetic as well as the parasympathetic nervous system not only will increase our understanding of the mechanism of disease, but also could lead to the identification of potential new therapeutic targets for chronic immune-mediated inflammatory diseases, such as rheumatoid arthritis (RA). An imbalanced autonomic nervous system, with a reduced parasympathetic and increased sympathetic tone, has been a consistent finding in RA patients. Studies in animal models of arthritis have shown that influencing the sympathetic (via α- and β-adrenergic receptors) and the parasympathetic (via the nicotinic acetylcholine receptor α7nAChR or by electrically stimulating the vagus nerve) nervous system can have a beneficial effect on inflammation markers and arthritis. The immunosuppressive effect of the parasympathetic nervous system appears less ambiguous than the immunomodulatory effect of the sympathetic nervous system, where activation can lead to increased or decreased inflammation depending on timing, doses and kind of adrenergic agent used. In this review we will discuss the current knowledge of the role of both the sympathetic (SNS) and parasympathetic nervous system (PNS) in inflammation with a special focus on the role in RA. In addition, potential antirheumatic strategies that could be developed by targeting these autonomic pathways are discussed