Interleukin-18 gene polymorphism and markers of subclinical atherosclerosis. The Cardiovascular Risk in Young Finns Study

Increased Expression of Interleukin-18 mRNA is Associated with Carotid Artery Stenosis

Background:

Carotid artery stenosis is the atherosclerotic narrowing of the proximal internal carotid artery and one of the primary causes of stroke. Elevated expression of the pleiotropic proinflammatory cytokine interleukin-18 has been demonstrated in human atherosclerotic plaques.

Aims:

To investigate whether the mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 −137 G/C (rs187238) variants are associated with carotid artery stenosis development.

Study Design:

Case-control study.

Methods:

The mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 rs187238 variants were evaluated by quantitative real-time polymerase chain reaction and real-time polymerase chain reaction, respectively, in the peripheral blood mononuclear cells of 70 patients with carotid artery stenosis (36 symptomatic, 34 asymptomatic) and 75 healthy controls.

Results:

Interleukin-18 mRNA expression was significantly increased in carotid artery stenosis patients compared to that in healthy controls (p=0.01). However, no significant difference was observed between interleukin-18-binding protein mRNA expression levels in patients with carotid artery stenosis and those in controls (p=0.101). Internal carotid artery stenosis severity was significantly higher in symptomatic patients than that in asymptomatic patients (p<0.001). A significant relationship was identified between interleukin-18 expression and internal carotid artery stenosis severity in patients with carotid artery stenosis (p=0.051). Interleukin-18 rs187238 polymorphism genotype frequencies did not significantly differ between patients with carotid artery stenosis and controls (p=0.246). A significant difference was identified between interleukin-18-binding protein gene expression and symptomatic and asymptomatic patients (p=0.026), but there was no difference in interleukin-18 expression between the symptomatic and asymptomatic subgroups (p=0.397).

Conclusion:

Interleukin-18 mRNA expression may affect carotid artery stenosis etiopathogenesis and internal carotid artery stenosis severity and also may play a mechanistic role in the pathogenesis of carotid artery stenosis, influencing the appearance of symptoms.

Increased IL18 mRNA levels in peripheral artery disease and its association with triglyceride and LDL cholesterol levels: a pilot study

Peripheral artery disease (PAD) typically refers to lower limb vessel ischemia caused by atherosclerotic stenosis of lower extremity arteries. IL18 is a pleiotropic pro-inflammatory cytokine reported to function as an inflammatory biomarker in cardiovascular diseases. IL18 activity is balanced by high-affinity naturally occurring IL18-binding protein (IL18BP). This study aimed to determine whether IL18, IL18 BP mRNA levels and -137 G/C (rs187238) polymorphism, which was previously associated with IL18 gene transcriptional activity, were associated with PAD etiology. IL18, IL18BP mRNA levels from peripheral blood mononuclear cells and -137 G/C (rs187238) polymorphism were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and RT-PCR, respectively, in 55 PAD patients (26 aorta-iliac, 29 femoro-popliteal) and 61 disease-free controls. IL18 mRNA levels were increased in PAD patients compared with healthy controls (p = 0.09); however, did not reach a statistical significant level, also did not significantly differ between aorta-iliac and femoro-popliteal occlusive PAD subgroups (p = 0.285). However, IL18BP mRNA levels were significantly lower in PAD group compared with controls (p < 0.001). Genotype frequencies of rs187238 polymorphism did not significantly differ between PAD patients and controls (p = 0.385). IL18 mRNA levels were significantly correlated with triglycerides and LDL cholesterol levels in PAD patients (p = 0.003, p = 0.014, respectively). HDL cholesterol levels were negatively correlated with IL18 mRNA levels in controls (p = 0.05). This report is a preliminary study to show an association between IL18, IL18BP mRNA levels and PAD and suggests that the IL18 gene may have a significant relationship with triglyceride and LDL cholesterol levels in PAD patients.

Association between the polymorphisms in intercellular adhesion molecule-1 and the risk of coronary atherosclerosis: a case-controlled study

Intercellular adhesion molecule-1 (ICAM-1), an important immune adhesion molecule, is related to the atherosclerosis. We explored the association between the polymorphisms of the ICAM-1 gene and coronary atherosclerotic stenosis to determine whether any risk factors correlate with genetic polymorphisms in Chinese patients with coronary atherosclerosis. Using the SNaPshot assay, we examined six SNPs of rs5491, rs281428, rs281432, rs5496, rs5498 and rs281437 in 604 patients diagnosed with coronary atherosclerotic stenosis by angiography and in 468 controls. We found that AG genotype of rs5498 had higher frequency in the coronary atherosclerotic stenosis patients (41.56% to 34.19%, P = 0.017, OR = 1.368,95%CI 1.057–1.770) and that the haplotype A_rs5491C_rs281428G_rs281432 had higher frequency in patients (13.8% to 12.1%, P = 0.048). When analyzing the clinical risk factors for coronary atherosclerosis, we found that the rs5498 locus was associated with the levels of apolipoprotein A (APOA) (P = 0.0002) and triglycerides (TG) (P = 0.002). Furthermore, the levels of triglycerides (TG) were also associated with rs281432 (P = 0.040). Additionally, the TT genotype of rs281437 was associated with a higher level of apolipoprotein A (APOA) (P = 0.039) and apolipoprotein B (APOB) (P = 0.003). Finally, among those with coronary atherosclerosis, we found no differences in the haplotype analysis of polymorphisms of the ICAM-1 gene from individuals with hypertension or those who smoked. According to our results, the ICAM-1 polymorphisms were associated with risk of coronary atherosclerotic stenosis in Chinese individuals.

The effects of Eculizumab on the pathology of malignant atrophic papulosis

Background

Degos disease is a frequently fatal and incurable occlusive vasculopathy most commonly affecting the skin, gastrointestinal tract and brain. Vascular C5b-9 deposition and a type I interferon (IFN) rich microenvironment are held to be pathogenetically important in the evolution of the vascular changes. We recently discovered the use of eculizumab as a salvage drug in the treatment of near fatal Malignant atrophic papulosis (MAP). The effects of eculizumab on the pathology of MAP are explored.

Methods

Archival skin and gastrointestinal biopsy material was procured over a 2.5-year period before and after eculizumab therapy in our index case. Routine light microscopy and immunohistochemical assessment for C3d, C4d, C5b-9, MxA and caspase 3 were examined. Direct immunofluorescent studies were also conducted on select biopsy material.

Results

The patient had received eculizumab as a emergent life saving measure and following rapid improvement he continued with biweekly infusions for 4 years. Although improved he continues to have signs and symptoms of persistent abdominal disease. Pre-Eculizumab biopsies showed an active thrombotic microangiopathy associated with a high type I interferon signature and extensive vascular deposits of C5b-9 in skin and gastrointestinal biopsies. Endothelial cell apoptosis as revealed by Caspase 3 expression was noted. Inflammation comprising lymphocytes and macrophages along with mesenchymal mucin was observed as well. Post-eculizumab biopsies did not show active luminal thrombosis but only chronic sequelae of prior episodes of vascular injury. There was no discernible caspase 3 expression. After 12 months of therapy, C5b-9 was no longer detectable in tissue. The high type I IFN signature and inflammation along with mucin deposition was not altered by the drug. In addition, there was little effect of the drug on the occlusive fibrointimal arteriopathy which appears to be one characterized by extensive myofibroblastic expansion of the intima potentially as revealed by staining for smooth muscle actin without immunoreactivity for desmin and myogenin.

Conclusions

Complement activation and enhanced endothelial cell apoptosis play an important role in the thrombotic complications of MAP. However, the larger vessel proliferative intimal changes appear to be independent of complement activation and may be on the basis of other upstream mechanisms. Monitoring C5b-9 deposition in tissue is likely not of great value in assessing treatment response to eculizumab given the persistence of C5b-9 in tissue for several months despite clinically effective C5 blocking therapy. A more integrated approach addressing upstream and downstream pathways in addition to those attributable to complement activation are critical for the successful treatment of MAP. Eculizumab may be used as salvage therapy in critically ill patients with thrombotic microangiopathy.

The influence of innate and adaptive immune responses on atherosclerosis

Both the chronic development of atherosclerotic lesions and the acute changes in lesion phenotype that lead to clinical cardiovascular events are significantly influenced by the innate and adaptive immune responses to lipoprotein deposition and oxidation in the arterial wall. The rapid pace of discovery of mechanisms of immunologic recognition, effector functions, and regulation has significantly influenced the study of atherosclerosis, and our new knowledge is beginning to affect how we treat this ubiquitous disease. In this review, we discuss recent advances in our understanding of how innate and adaptive immunity contribute to atherosclerosis, as well as therapeutic opportunities that arise from this knowledge.