Simvastatin exerts its anti-inflammatory effect in hypercholesterolaemic patients by decreasing the serum levels of monocyte chemoattractant protein-1

Key Chemokine Pathways in Atherosclerosis and Their Therapeutic Potential

The search to improve therapies to prevent or treat cardiovascular diseases (CVDs) rages on, as CVDs remain a leading cause of death worldwide. Here, the main cause of CVDs, atherosclerosis, and its prevention, take center stage. Chemokines and their receptors have long been known to play an important role in the pathophysiological development of atherosclerosis. Their role extends from the initiation to the progression, and even the potential regression of atherosclerotic lesions. These important regulators in atherosclerosis are therefore an obvious target in the development of therapeutic strategies. A plethora of preclinical studies have assessed various possibilities for targeting chemokine signaling via various approaches, including competitive ligands and microRNAs, which have shown promising results in ameliorating atherosclerosis. Developments in the field also include detailed imaging with tracers that target specific chemokine receptors. Lastly, clinical trials revealed the potential of various therapies but still require further investigation before commencing clinical use. Although there is still a lot to be learned and investigated, it is clear that chemokines and their receptors present attractive yet extremely complex therapeutic targets. Therefore, this review will serve to provide a general overview of the connection between various chemokines and their receptors with atherosclerosis. The different developments, including mouse models and clinical trials that tackle this complex interplay will also be explored.

Targeting the chemokine network in atherosclerosis

Chemokines and their receptors represent a potential target for immunotherapy in chronic inflammation. They comprise a large family of cytokines with chemotactic activity, and their cognate receptors are expressed on all cells of the body. This network dictates leukocyte recruitment and activation, angiogenesis, cell proliferation and maturation. Dysregulation of chemokine and chemokine receptor expression as well as function participates in many pathologies including cancer, autoimmune diseases and chronic inflammation. In atherosclerosis, a lipid-driven chronic inflammation of middle-sized and large arteries, chemokines and their receptors participates in almost all stages of the disease from initiation of fatty streaks to mature atherosclerotic plaque formation. Atherosclerosis and its complications are the main driver of mortality and morbidity in cardiovascular diseases (CVD). Hence, exploring new fields of therapeutic targeting of atherosclerosis is of key importance. This review gives an overview of the recent advances on the role of key chemokines and chemokine receptors in atherosclerosis, addresses chemokine-based biomarkers at biochemical, imaging and genetic level in human studies, and highlights the clinial trials targeting atherosclerosis.

Statin modulation of monocyte phenotype and function: implications for HIV-1-associated neurocognitive disorders

HIV-1-associated neurocognitive disorder (HAND) remains a persistent problem despite antiretroviral therapy (ART), largely a result of continued inflammation in the periphery and the brain and neurotoxin release from activated myeloid cells in the CNS. CD14+CD16+ inflammatory monocytes, expanded in HIV infection, play a central role in the pathogenesis of HAND and have parallels with monocyte-dependent inflammatory mechanisms in atherosclerosis. Statins, through their HMG-CoA reductase inhibitor activity, have pleiotropic immunomodulatory properties that contribute to their benefit in atherosclerosis beyond lipid lowering. Here, we investigated whether statins would modulate the monocyte phenotype and function associated with HIV-1 neuropathogenesis. Treatment ex vivo with simvastatin and atorvastatin reduced the proportion of CD16+ monocytes in peripheral blood mononuclear cells, as well as in purified monocytes, especially CD14++CD16+ "intermediate" monocytes most closely associated with neurocognitive disease. Statin treatment also markedly reduced expression of CD163, which is also linked to HAND pathogenesis. Finally, simvastatin inhibited production of monocyte chemoattractant protein-1 (MCP-1) and other inflammatory cytokines following LPS stimulation and reduced monocyte chemotaxis in response to MCP-1, a major driver of myeloid cell accumulation in the CNS in HAND. Together, these findings suggest that statin drugs may be useful to prevent or reduce HAND in HIV-1-infected subjects on ART with persistent monocyte activation and inflammation.

Simvastatin ameliorates experimental autoimmune encephalomyelitis by inhibiting Th1/Th17 response and cellular infiltration

AIM

Experimental autoimmune encephalomyelitis (EAE) is a CD4(+)-mediated autoimmune pathology of the central nervous system (CNS) that is used as a model for the study of the human neuroinflammatory disease, multiple sclerosis. During the development of EAE, auto-reactive Th1 and Th17 CD4(+) T cells infiltrate the CNS promoting inflammatory cells recruitment, focal inflammation and tissue destruction. In this sense, statins, agents used to lower lipid levels, have recently shown to exert interesting immunomodulatory function. In fact, statins promote a bias towards a Th2 response, which ameliorates the clinical outcome of EAE. Additionally, simvastatin can inhibit Th17 differentiation. However, many other effects exerted on the immune system by statins have yet to be clarified, in particular during neuroinflammation. Thus, the aim of this study was to investigate the effects of simvastatin on the development of experimental autoimmune encephalomyelitis.

METHODS

Mice were immunized with MOG(35-55) and EAE severity was assessed daily and scored using a clinical scale. Cytokine secretion by mononuclear cells infiltrating the CNS was evaluated by flow cytometry.

RESULTS

Simvastatin (5 mg/kg/day) improved clinical outcome, induced an increase in TGF-β mRNA expression and inhibited IL-6, IL-12p40, IL-12p70, RANTES and MIP-1β secretion (p < 0.05). This was accompanied by a significant decrease in CNS inflammatory mononuclear cell infiltration, with reduced frequencies of both Th1 and Th17 cells. Simvastatin inhibited the proliferation of T lymphocytes co-cultured with primary microglial cells.

CONCLUSIONS

Simvastatin treatment promotes EAE clinical amelioration by inhibiting T cell proliferation and CNS infiltration by pathogenic Th1 and Th17 cells.

Simvastatin improves morphological and functional recovery of sciatic nerve injury in Wistar rats

AIM

The purpose of this work is to investigate the effects of simvastatin on sciatic nerve regeneration in male Wistar Rats.

MATERIALS AND METHODS

Forty animals were allocated into four groups: (1) control (C); (2) control+simvastatin (CS); (3) lesioned animals+sterile PBS (LC) and (4) lesioned animals+simvastatin (LS). Lesioned animals were submitted to crushing lesion of right sciatic nerve. Simvastatin (20mg/kg/day, i.p.) was administered for five days. Footprints were obtained weekly for evaluation of functional locomotor recovery by means of the Sciatic Function Index (SFI). Blood samples were obtained weekly for quantifying circulating leukocytes. Animals were sacrificed after 21 days for histological analyses of sciatic nerve and spleen.

RESULTS

LS Animals presented increased SFI scores, decreased areas of oedema and mononuclear cell infiltration during Wallerian degeneration and nerve regeneration (7,14 and 21 days; P<0.05). Spleen weight and white pulp areas was increased in LC animals after 21 days. Increased numbers of circulating neutrophils were observed in simvastatin treated animals (CS e LS) at seven, 14 and 21 days, compared to non-treated groups (C and LC).

CONCLUSION

The study suggests that simvastatin accelerates the morphological and functional recovery process of the peripheral nervous system interfering with innate and acquired immunity.

Randomised study of ezetimibe, start doses of original statins, and their combination in patients with coronary heart disease and hyperlipidemia Part 2. Therapy effects on the levels of C-reactive protein and proinflammatory cytokines

Aim. To assess the effects of original statins as monotherapy or in combination with ezetimibe on the levels of proinflammatory cytokines and high-sensitive C-reactive protein (hsCRP) in patients with coronary heart disease (CHD) and hyperlipidemia (HLP). Material and methods. The study included 60 male and female patients with CHD, primary polygenic HLP, and the levels of low-density lipoprotein cholesterol (LDL-CH) of 2,9-4,9 mmol/l. Monotherapy with original statins or ezetimibe lasted for 6 months, while the combination therapy lasted for 3 months. In all randomised patients, the levels of hsCRP, interleukin 6 (IL-6), and monocyte chemotactic protein-1 (MCP-1) were measured at baseline, 12 and 24 weeks after the therapy started. Results. At baseline, median hsCRP levels in the groups of Ezetrol, Zocor, Liprimar, and Crestor monotherapy were 0,5-0,88 mg/l, with no significant dynamics after 3 months of the treatment. Baseline IL-6 levels across the monotherapy groups were 1,94-2,54 pg/ml; at 3 months, there was a non-significant reduction by 7-32 %. After 3 months of the therapy, the decrease in MCP-1 levels was not statistically significant (-1,3-7,7 %). The combined therapy did not result in a significant dynamics of hsCRP concentrations, with the exception of the group receiving Ezetrol and Liprimar. Although the combined therapy further reduced MCP-1 levels (by 30-78 pg/ml), these changes were not statistically significant. No significant difference was observed across statin and Ezetrol groups in terms of their effects on IL-6 and MCP-1 levels. Conclusion. The comparison of the three treatment schemes demonstrated similar, but not statistically significant reduction on the levels of hsCRP, IL-6, and MCP-1. No marked benefits were observed for either monotherapy or combination therapy over 12-24 weeks of the follow-up.

The effects of statin monotherapy and low-dose statin/ezetimibe on lipoprotein-associated phospholipase A₂

BACKGROUND

Many of the pleiotropic effects of statins remain to be elucidated.

HYPOTHESIS

Different statin regimens with similar lipid-lowering efficacy may have different effects on biomarkers of atherothrombosis including lipoprotein-associated phospholipase A₂ (Lp-PLA₂ ).

METHODS

After a 4-week dietary lead-in, 82 hypercholesterolemic patients were randomized to 1 of 2 treatment groups: atorvastatin 20 mg or atorvastatin/ezetimibe 5 mg/5 mg. After 8 weeks of drug treatment, the groups were compared for percent change in lipid parameters, Lp-PLA₂ , interleukin-6 (IL-6), monocyte chemoattractant protein-1, and fibrinogen.

RESULTS

Low-density lipoprotein cholesterol (LDL-C) lowering was comparable between the 2 groups (-47% ± 11% and -49% ± 7% in the atorvastatin and combination groups, respectively). Although Lp-PLA₂ was reduced in both groups, the reduction was greater in the atorvastatin group (-42% and -9% [median], respectively, P = 0.03). Although IL-6 was decreased only in the atorvastatin group, IL-6 changes were not significantly different between the 2 groups. The changes in monocyte chemoattractant protein-1 and fibrinogen were similar in each group.

CONCLUSIONS

Atorvastatin monotherapy was stronger at reducing plasma Lp-PLA₂ than the low-dose atorvastatin/ezetimibe combination after equivalent LDL-C lowering. This result may provide evidence of potential statin effects beyond the lowering of LDL-C.

Effects of Curcuma comosa on the expression of atherosclerosis-related cytokine genes in rabbits fed a high-cholesterol diet

AIM OF THE STUDY

Curcuma comosa has been known to have potential use in cardiovascular diseases, but its immunoregulatory role in atherosclerosis development and liver toxicity has not been well studied. We therefore investigated the effects of Curcuma comosa on the expression of atherosclerosis-related cytokine genes in rabbits fed a high-cholesterol diet.

MATERIALS AND METHODS

Twelve male New Zealand White rabbits were treated with 1.0% cholesterol for one month and were subsequently treated with 0.5% cholesterol either alone, or in combination with 5mg/kg/day of simvastatin or with 400mg/kg/day of Curcuma comosa powder for three months. The expression of IL-1, MCP-1, TNF-α, IL-10, and TGF-β in the isolated abdominal aorta and liver were determined by real-time RT-PCR. Liver toxicity was determined by hepatic enzyme activity.

RESULTS

Curcuma comosa significantly decreased the expression of pro-inflammatory cytokines, leading to a stronger reduction in IL-1, MCP-1, and TNF-α expression compared to that was suppressed by simvastatin treatment. However, neither Curcuma comosa nor simvastatin affected the expression of anti-inflammation cytokines. In the liver, Curcuma comosa insignificantly decreased the expression of pro-inflammatory cytokines and significantly increased the expression of the anti-inflammatory cytokine IL-10 without altering the activity of hepatic enzymes. In contrast, simvastatin significantly increased the MCP-1 and TNF-α expressions and serum ALT level, without affecting the expression of anti-inflammatory cytokines.

CONCLUSIONS

In this study, we demonstrated that Curcuma comosa exerts anti-inflammatory activity in the aorta and liver without causing liver toxicity, indicating that Curcuma comosa is a potential candidate as an alternative agent in cardiovascular disease therapy.

CCL3 (MIP-1 alpha) levels are elevated during acute coronary syndromes and show strong prognostic power for future ischemic events

As chemokines are considered instrumental in thrombotic plaque rupture and erosion as well as in ischemia-reperfusion injury processes, we aimed to identify previously unknown chemokines associated with acute coronary syndromes. Plasma of 44 patients with acute myocardial infarction (AMI) and 22 controls were profiled for a panel of chemokines by multiplex analysis. Levels of CCL3 were prospectively verified in 54 patients with unstable angina pectoris (UAP). An AMI mouse model was used to assess the relationship between differentially expressed chemokines and myocardial ischemia. CCL3 levels were significantly elevated in AMI vs. controls (P=0.02) albeit, that adjustment for confounding factors attenuated this association. In support of a direct association with cardiac ischemia CCL3 levels were also seen to be elevated in patients with UAP at baseline and significantly down-regulated after 180 days (P<0.001). Importantly, baseline upper quartile levels were strongly correlated with future acute coronary syndromes (Likelihood Ratio 11.5; P<0.01). Furthermore circulating levels of CCL3 were significantly enhanced after AMI in mice (P=0.02), while CCR5(+) T-cell numbers were increased as well, suggestive of CCL3 driven T-cell homing towards the ischemic area. CCL3 levels are elevated during ACS and released upon ischemia. Since CCL3 specifically predicts future cardiovascular events, it may serve as a predictive biomarker.