Inflammatory Information and Courses from MediaLab, Inc.

The H & E section of the brain biopsy (left frame)revealed edema of the parencymya with the accumulation of inflammatory cells in the perivascular spaces. The close in view of the exudate (right) frame reveals that the inflammatory exudate is comprised primarily of polymorphonuclear luekocytes. The histologic diagnosis therefore is suppurative meningitis, with culture results necessary to establish the etiologic agent.

Atherosclerosis is a clogging, narrowing and hardening of the body's large and medium-sized blood vessels. Atherosclerosis can lead to hypertension, stroke, myocardial infarction (heart attack), renal problems, etc. Not surprisingly, cardiovascular risk markers tend to reflect a person's degree of atherosclerosis.Atherosclerosis is actually a chronic inflammatory response within the walls of arteries. Small lipoproteins like LDL are able to diffuse through the endothelial wall of blood vessels and accumulate. The inflammatory component of atherosclerosis results from the migration of leukocytes (mainly macrophages) that enter the blood vessel walls. These macrophages seek to remove the deposited LDL as well as intermediate-density lipoproteins (IDL). As macrophages phagocytose these lipoproteins, they become foam cells that get trapped in the endothelial space. This eventually leads to "hardening" or "furring" of the arteries and plaque formation. Arteriosclerosis is a general term describing any hardening (loss of elasticity) of medium or large arteries whereas atherosclerosis is a hardening of an artery specifically due to plaque. The risk to patients with significant atherosclerosis is that eventually a narrowing of the artery (stenosis) can cause a reduction in oxygen delivery to tissues and plaque rupture can lead to an acute coronary event.

Recall that the inflammatory events leading to atherosclerosis are due to the presence of LDL particles which diffuse through the endothelium and into the vessel wall. It makes sense that the more LDL particles there are, the more risk there would be for LDL depositing in the vessel wall. It would seem therefore that measuring the number of LDL particles could be more useful than measuring the cholesterol content of the particles. Traditional measurements of LDL-C quantify the amount of cholesterol associated with all the LDL in a patient sample; they don't tell us how many LDL particles there are. An analogy can be made with battleships. If you wanted to measure the size of a navy that was sailing for your shores, it makes more sense to count the number of ships than to count the amount of cargo the ships carry in order to estimate the number of ships. Of course, it is intuitive that the more LDL-C there is, the greater the number of LDL particles. In that sense, LDL particle number should correlate to LDL cholesterol, and this is indeed true. However, studies now show that measurement of the number of LDL particles is a more powerful predictor of cardiovascular risk. The exact relationship between LDL particle number and cholesterol content actually varies due to the fact that the lipoproteins vary in size and in the ratio of triglycerides to cholesterol. So, although cholesterol is related to LDL particle number, it is not in perfect proportion.How can we then measure LDL particle number? The most obvious way would be to measure apolipoprotein B100 (often abbreviated ApoB). Each LDL particle has one molecule of ApoB attached to it. Therefore, if we measured ApoB, we would be measuring the number of LDL particles, not the contents of those particles, and number appears to be more important with regard to adverse outcomes.

The traditional CRP test has a typical reference range of < 8 mg/dL. The hs-CRP test, with its increased sensitivity has a reference or optimal range of < 3 mg/dL. As with most risk markers, the results of hs-CRP testing are generally interpreted on a relative scale; the higher the value, the higher the risk of a future cardiovascular event.The American Heart Association and Centers for Disease Control and Prevention has defined risk groups with hs-CRP as follows: Low risk: < 1.0 mg/L Average risk: 1.0 to 3.0 mg/L High risk: > 3.0 mg/L It is important to note that hs-CRP assays are measuring the same protein as traditional CRP assays. Thus, in patients with active inflammation (such as chronic, active arthritis; lupus; infection; etc.) hs-CRP values would be expected to be high and would not necessarily implicate cardiovascular risk. If values greater than 10 mg/L are seen in repeated measurements, a non-cardiovascular cause should be considered. Taking anti-inflammatory drugs (NSAIDs, aspirin, etc.) or the statin-class of cholesterol-lowering drugs may reduce CRP levels in patients. This is not an artifact, but is thought to be an effect of treating the underlying inflammatory process.

Atherosclerosis. U.S. Department of Health & Human Services National Institutes of Health. Available at http://www.nhlbi.nih.gov/health/dci/Diseases/Atherosclerosis/Atherosclerosis_WhatIs.htmlAccessed June 23, 2009.Daniels LB, Barrett-Connor E, Sarno M, Laughlin GA,Bettencourt R, Wolfert RL. Lipoprotein-associated phospholipase A2 (Lp-PLA2) independently predicts incident coronary heart disease (CHD) in an apparently healthy older population: The Rancho Bernardo study. J Am Coll Cardiol. 2008;51:913-919.Executive Summary of the third report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). JAMA. 2001; 285:2486-2497. Frostegard, J, Wu R, Lemne C, Thulin T, Witztum JL and de Faire U. Circulating oxidized low-density lipoprotein is increased in hypertension, Clin Sci 2003; 105, 615.Garza CA, Montoir VM, McConnell JP, et al. Association between lipoprotein-associated phospholipase A2 and cardiovascular disease: a systematic review. Mayo Clin Proc. 2007;82(2):159-165.Interpretive Handbook, (MC0440rev0407) Mayo Clinic, Rochester MN;2007. Maksimowicz-McKinnon K, Bhatt DL, Calabrese LH: Recent advances in vascular inflammation: C-reactive protein and other inflammatory biomarkers. Curr Opin Rheumatol. 2004;16:18-24.Mora S, Szklo M, Otvos JD, et al. LDL particle subclasses, LDL particle size, and carotid atherosclerosis in the multi-ethnic study of atherosclerosis. Atherosclerosis. 2007;192:211-217.NACB Laboratory Medicine Practice Guidelines. Emerging biomarkers of cardiovascular disease and stroke. National Academy of Clinical Biochemistry Laboratory Medicine Practice Guidelines. 2006.PLACtest animation, diaDexus. http://www.plactest.com/laboratorians/action.php Accessed June 23, 2009.Rifai N, Warnick GR. Lipids, lipoproteins, apolipoproteins, and other cardiovascular risk factors. In: Burtis CA, Ashwood ER. Bruns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St. Louis, MO: Elsevier Saunders: 2006; chap. 26.Ridker PM, Rifai N, Rose L, et al. Comparison of C-reactive protein and low-density lipoprotein cholesterol levels in the prediction of first cardiovascular events. N Engl J Med. 2002;347:1557-1565.Sniderman AD. Differential response of cholesterol and particle measures of atherogenic lipoproteins to LDL-lowering therapy: Implications for clinical practice. J Clin Lipidol 2008;2:36-42.Tsimikas, S, Brilakis ES, Miller ER, et al. Oxidized phospholipids, Lp(a) lipoprotein, and coronary artery disease, N Engl J Med: 2005;353:46.Tsimikas S, Bergmark C, Beyer RW, et al. Temporal increases in plasma markers of oxidized low-density lipoprotein strongly reflect the presence of acute coronary syndromes. J Am Coll Cardiol. 2003; 41: 360.Tsimikas, S, Lau HK, Han KR, et al. Percutaneous coronary intervention results in acute increases in oxidized phospholipids and lipoprotein(a): Short-term and long-term immunologic responses to oxidized low-density lipoprotein. Circulation. 2004;109, 3164.Tsimikas S, Witztum JL, Miller ER, Sasiela WJ, et al. High-dose atorvastatin reduces total plasma levels of oxidized phospholipids and immune complexes present on apolipoprotein B-100 in patients with acute coronary syndromes in the MIRACL trial, Circulation: 2004;110, 1406. Walldius G, Jungner I, Holme I, et al. High apolipoprotein B, low apolipoprotein A-I, and improvement in the prediction of fatal myocardial infarction (AMORIS study): a prospective study. Lancet. 2001;358:2026-2033.Yusuf S, Hawken S, Ounpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:937-952.

Transferrin saturation (TS) is usually reported along with the SI and TIBC. TS indicates the percent of iron binding sites on transferrin that are carrying iron. TS is derived from a calculation using the formula:TS =(SI/TIBC) x 100TS results are reported as percentages. Typical reference intervals for TS are 20% to 55% for males and 15% to 50% for females. TS is generally considered to be the most sensitive laboratory test for detecting altered iron metabolism in hereditary hemochromatosis (HH). It may be elevated prior to significant deposition of tissue iron. TS levels increase as additional iron is accumulated.A drawback to using the TS is that it is dependent on performing both the SI and TIBC. The UIBC (see section below) may be a lower cost alternative.The optimal TS criterion for detecting HH is controversial. Using a TS of >60% for males and >50% for females has been found highly accurate in detecting abnormal iron metabolism in persons with HH. Others studies suggest using lower TS levels, e.g. 45%, as a criterion indicating further testing is warranted. Current guidelines from the American College of Physicians include a TS cutoff level of >55% for identifying iron overload. (11)Patients with initially increased TS should be followed by performing a second TS from a fasting morning specimen. The patient should also be advised not to take vitamins supplemented with iron or oral contraceptives for several days prior to the repeated test. TS levels may be affected by diurnal variation, dietary factors, and co-existing disease states such as inflammation and hepatitis. Patients with HH may have falsely normal TS if chronic blood loss or inflammatory disease is present.

Eosinophils have a circulating half-life of approximately 18 hours and a tissue life span of at least 6 days.They are capable of locomotion and phagocytosis and can enter inflammatory sites, but do so less readily than neutrophils.In tissues the primary location for eosinophils is in the epithelial barriers to the outside world such as, lungs, skin and GI tract.They are capable of returning to the circulating blood and bone marrow after they enter the tissues.

The cytoplasm of eosinophils is evenly filled by numerous orange-red granules of uniform size. They do not overlie the nucleus. The eosinophil granules contain numerous enzymes including peroxidase, phospholipase D, catalase, acid phosphatase, and vitamin B12-binding proteins. Their ability to kill bacteria is less than that of neutrophils. Their main purpose is to counteract parasitic infections and to participate in immune allergic reactions. They may also be increased in a variety of nonimmunologic inflammatory responses from bacteria and fungi causing chronic infections. Malignancies, collagen vascular diseases, and myeloproliferative disorders may also may be settings for prominent eosinophils.