Inflammation and cardiac outcome

FXR ligands protect against hepatocellular inflammation via SOCS3 induction

Because of the anti-inflammatory actions of farnesoid X receptor (FXR) agonists, FXR has received much attention as a potential therapeutic target. However, the molecular mechanisms of actions have not yet been elucidated. In the present study, we reported that in the animal model of LPS-induced liver injury, administration of the FXR natural ligand CDCA could attenuate hepatocyte inflammatory damage, reduce transaminase activities, suppress inflammation mediators (IL-6, TNF-α and ICAM-1) expression and inhibit STAT3 phosphorylation. These protective effects of FXR were accompanied by an increased expression of suppressor of cytokine signaling 3 (SOCS3), which is a negative feedback regulator of cytokine-STAT3 signaling. We then demonstrated that the beneficial effects of FXR agonist in STAT3 activation were weakened by small interfering RNA-mediated SOCS3 knockdown in hepacytes. Moreover we observed both natural ligand CDCA and synthetic ligand GW4064 could upregulate SOCS 3 expression by enhancing the promoter activity in hepatocytes. These results suggest modulation of SOCS3 expression may represent a novel mechanism through which FXR activation could selectively affect cytokine bioactivity in inflammation response. FXR ligands may be potentially therapeutic in the treatment of liver inflammatory diseases via SOCS3 induction.

Inflammation, endoplasmic reticulum stress, autophagy, and the monocyte chemoattractant protein-1/CCR2 pathway

Numerous inflammatory cytokines have been implicated in the pathogenesis of cardiovascular diseases. Monocyte chemoattractant protein (MCP)-1/CCL2 is expressed by mainly inflammatory cells and stromal cells such as endothelial cells, and its expression is upregulated after proinflammatory stimuli and tissue injury. MCP-1 can function as a traditional chemotactic cytokine and also regulates gene transcription. The recently discovered novel zinc-finger protein, called MCPIP (MCP-1-induced protein), initiates a series of signaling events that causes oxidative and endoplasmic reticulum (ER) stress, leading to autophagy that can result in cell death or differentiation, depending on the cellular context. After a brief review of the basic processes involved in inflammation, ER stress, and autophagy, the recently elucidated role of MCP-1 and MCPIP in inflammatory diseases is reviewed. MCPIP was found to be able to control inflammatory response by inhibition of nuclear factor-κB activation through its deubiquitinase activity or by degradation of mRNA encoding a set of inflammatory cytokines through its RNase activity. The potential inclusion of such a novel deubiquitinase in the emerging anti-inflammatory strategies for the treatment of inflammation-related diseases such as cardiovascular diseases and type 2 diabetes is briefly discussed.

The Cardiomyocyte as a Source of Cytokines in Cardiac Injury

Fibrosis induced by prolonged inflammation is a major pathophysiological feature of adverse left ventricular remodeling after myocardial infarction and pathological cardiac hypertrophy. Recent reports strongly suggest that the interaction between leukocytes, non-myocytes (mainly cardiac fibroblasts) and cardiomyocytes, possibly mediated by cytokine signaling, plays an important role in controlling the inflammatory reaction after cardiac injury. Therefore, controlling cytokine secretion from resident cardiomyocytes is one plausible strategy for preventing tissue damage.

Treatment of patients with intermediate cardiovascular risk: Are clinical measures enough?

AIM

Clinical measures of cardiovascular disease risk (CVD) are important tools for establishing therapy to lower CVD risk. Risk assessment has come under criticism because clinical measures can underestimate or overestimate CVD risk. We assessed CVD risk in 252 subjects without evidence of CVD to establish therapy of one or more risk factors from clinical indications. The subjects all had intermediate CVD risk using the Framingham score.

RESULTS

Average age was 59.1 years. 23.8% were smokers, 59.1% were hypertensive, 65.1% had hyperlipidemia. BMI was greater than 30 kg/M(2) in 56% and diabetes was present in 43.7%. In this cohort, 86.9% required therapy for hypertension or hyperlipidemia, and this proportion increased to 95.6% when subjects with diabetes were included. Of the remaining 4.4% (11 subjects), 7 reached intermediate risk based on cigarette smoking and 4 based on age >65 years old. Among diabetics, 94/110 had another risk factor and would require statin and ACE or ARB therapy.

CONCLUSIONS

Of subjects at intermediate risk for CVD, 98.4% would not require further testing to decide on therapy to lower CVD risk. Although 16 diabetic subjects had no other risk factors, current guidelines suggest that these subjects should be treated to reduce CVD risk.

The social environment and IL-6 in rats and humans

Inflammatory cytokine levels predict a wide range of human diseases including depression, cardiovascular disease, type 2 diabetes, autoimmune disease, general morbidity, and mortality. Stress and social experiences throughout the lifecourse have been associated with inflammatory processes. We conducted studies in humans and laboratory rats to examine the effect of early life experience and adult social position in predicting IL-6 levels. Human participants reported family homeownership during their childhood and current subjective social status. Interleukin-6 (IL-6) was measured from oral mucosal transudate. Rats were housed in groups of three, matched for quality of maternal care received. Social status was assessed via competition for resources, and plasma IL-6 was assessed in adulthood. In both humans and rats, we identified an interaction effect; early social experience moderated the effect of adult social status on IL-6 levels. Rats that experienced low levels of maternal care and people with low childhood socioeconomic status represented both the highest and lowest levels of IL-6 in adulthood, depending on their social status as young adults. The predicted interaction held for non-Hispanic people, but did not occur among Hispanic individuals. Adversity early in life may not have a monotonically negative effect on adult health, but may alter biological sensitivity to later social experiences.