Human antimicrobial peptide LL-37 is present in atherosclerotic plaques and induces death of vascular smooth muscle cells: a laboratory study

BACKGROUND: Death of smooth muscle cells in the atherosclerotic plaques makes the plaques more prone to rupture, which can initiate an acute ischemic event. The development of atherosclerosis includes the migration of immune cells e.g. monocytes/macrophages and T lymphocytes into the lesions. Immune cells can release antimicrobial peptides. One of these, human cathelicidin antimicrobial peptide hCAP-18, is cleaved by proteinase 3 generating a 4.5 kDa C-terminal fragment named LL-37, which has been shown to be cytotoxic. The aim of the study was to explore a potential role of LL-37 in the pathophysiology of atherosclerosis. METHODS: We investigated the presence of LL-37 in human atherosclerotic lesions obtained at autopsy using immunohistochemistry. The direct effects of LL-37 on cultured vascular smooth muscle cells and isolated neutrophil granulocytes were investigated with morphological, biochemical and flow cytometry analysis. RESULTS: The neointima of atherosclerotic plaques was found to contain LL-37-like immunoreactivity, mainly in macrophages. In cultured smooth muscle cells, LL-37 at 30 μg/ml caused cell shrinkage, membrane blebbing, nuclear condensation, DNA fragmentation and an increase in caspase-3 activity as studied by microscopy, ELISA and enzyme activity assay, respectively. Flow cytometry demonstrated that LL-37 in a subset of the cells caused a small but rapidly developing increase in membrane permeability to propidium iodide, followed by a gradual development of FITC-annexin V binding. Another cell population stained heavily with both propidium iodide and FITC-annexin V. Neutrophil granulocytes were resistant to these effects of LL-37. CONCLUSION: This study shows that LL-37 is present in atherosclerotic lesions and that it induces death of vascular smooth muscle cells. In a subset of cells, the changes indicate the development of apoptosis triggered by an initial mild perturbation of plasma membrane integrity. The findings suggest a role for LL-37 as a mediator of immune cell-induced death of vascular smooth muscle cells in atherosclerosis

Subcutaneous fat accumulation and BMI associated with risk for pulmonary embolism in patients with proximal deep vein thrombosis: a population study based on 23,796 consecutive autopsies

Objective. Although deep vein thrombosis (DVT) and pulmonary embolism (PE) are manifestations of the same disease, far from all patients develop PE. Our objective was to investigate risk-modifying factors. Setting, subjects and design. Between 1970 and 1982, 23 796 autopsies, representing 84% of all in-hospital deaths in the Malmo City population, were performed, using a standardized procedure. In a case-control study nested in a population-based cohort of patients with proximal DVT, the relationship between PE and body mass index (BMI), thoracic and abdominal subcutaneous (SC) fat thickness was evaluated. Results. Proximal DVT was found in 15%, of which 58% were women. Mean age in men was 4.5 years lower than in women (P < 0.001). Fifty per cent of the patients had PE, half of which were fatal. Similar age- and gender distribution was found in cases and controls. Patients in the upper tertile of BMI, abdominal and thoracic SC fat thickness had, in comparison with mid-tertile, and independent of age, gender and death from cancer disease, an increased odds (95% CI) for PE of 1.24 (1.04-1.47) (P = 0.014), 1.28 (1.07-1.53) (P = 0.006) and 1.35 (1.13-1.61) (P = 0.001), respectively, whereas in patients of the lower tertiles, a negative association was found. Conclusions. We found no differences in age- and gender distribution between PE cases and controls. BMI and SC fat thickness were markers of disease progression from proximal DVT to PE. The highly significant and independent association indicates that SC obesity may be of greater importance in venous thromboembolism as compared with cardiovascular diseases related to visceral (abdominal) obesity with lipid- and glucose metabolic disturbances

Prevalence and risk of pulmonary embolism in patients with intracardiac thrombosis: a population-based study of 23,796 consecutive autopsies

Aims White right intracardiac thrombosis (IT) is a potential cause of pulmonary embolism (PE) similar to that of stroke in left-sided IT, its prevalence and prognostic significance has not been studied in the general population. The aim of this study was to assess the age- and gender-specific prevalence of IT and its relation to PE in a population-based autopsy cohort. Methods and Results Between 1970 and 1982, 23 796 autopsies, representing 84% of all in-hospital deaths in the Malmo city population, were performed, using a standardized procedure. The relationship between IT and PE was evaluated by cohort analyses and nested case-control studies. IT was present in 1706 (7.2%) patients, 727 and 747 of whom had right and left atrial IT, respectively. PE prevalence in patients with isolated left IT, isolated right IT, and combined IT was 28.5, 35.6, and 48.9%, with RR (95% CI) of 1.5 (1.3-1.8), 2.0 (1.6-2.5), and 3.5 (2.7-4.7), respectively, compared with age- and gender-matched controls. Patients dying from ischaemic heart disease had a 3.2 (2.7-3.6) times higher risk of right IT, which was associated with 43% PE prevalence. Of all patients with PE at autopsy, right IT was found in 354 (6.5%), and the only detected source of PE in 220 (4.0%). Conclusion Right cardiac thrombosis, though difficult to assess clinically, is as common as left cardiac thrombosis and is associated with an increased risk of PE. The diagnosis should be considered in all cases of PE, especially in patients with atrial. fibrillation or myocardial infarction and in the absence of confirmed deep vein thrombosis

Trousseau's syndrome - what is the evidence? A population-based autopsy study

Despite numerous studies documenting the association between cancer and venous thromboembolism (VTE), the reason for the excessive risk in certain cancers remains obscure. No large-scale studies have yet investigated the independent effects of cancer type, site and growth pattern. Between 1970 and 1982, 23,796 standardised autopsies were performed, representing 84% of all in-hospital deaths in an urban Swedish population. The relationship between cancer and PE was evaluated with logistic regression. The overall PE prevalence was 23%, and 10% of the population had a fatal PE. Forty-two per cent of pancreatic cancer patients had PE (OR 2.55; 95% CI 2.10-3.09) (p < 0.001); gall bladder, gastric, colorectal and pulmonary adenocarcinomas were similarly independently associated with PE. In comparison with squamous cell lung cancer, patients with pulmonary adenocarcinoma had 1.65 times higher odds for PE (95% CI 1.20-2.29). Adenocarcinoma and metastatic cancer were independently associated with PE risk (OR 1.27; 95% CI 1.16 - 1.40; P < 0.001, and OR 1.10; 95% CI 1.01 - 1.20; p=0.024, respectively) but when controlling for cancer type and spread, pancreatic cancer was still associated with an OR of 2.10 (95% CI 1.71-2.58) of PE (p < 0.001).We conclude that the risk of PE in cancer patients depends not only on the cancer site and spread but also on the histological type. The excess independent risk in pancreatic cancer is intriguing and should warrant further research

The prevalence of renal amyloidosis of the AA-type in a series of 1,158 consecutive autopsies

To determine the prevalence of renal amyloidosis of the AA-type in a defined population, formalin-fixed specimens from the kidneys of all the cases autopsied in 1983 at The General Hospital of Malmö, Sweden, were investigated using immunohistochemical techniques. Amyloid deposits of protein AA were found in 10 of 1,158 investigated cases and the calculated prevalence was 0.86 per cent. The mean age at death of the individuals with the AA-type of amyloidosis was 79 years. Six of the cases with amyloidosis had rheumatoid arthritis. The avidin-biotin-peroxidase complex technique was found to be superior to the immunofluorescence method and a high sensitivity and specificity was achieved when sequence-specific antibodies against a synthetized nonapeptide corresponding to a hydrophilic segment of the polypeptide chain of protein AA were used in the assay. Nine cases with other types of amyloid deposits in the kidneys were also detected. None of these cases showed any AA immunoreactivity but all of them demonstrated Congophilic deposits which were immunohistochemically stained by antibodies against the amyloid P-component. The prevalence of renal amyloidosis comprising all types of amyloid protein deposits was 1.64 per cent