Asbestos fibers

Chronic exposure to asbestos fibers is a major risk factor for development of mesothelioma. How asbestos induces asbestos-related disease, including mesothelioma, is being investigated and probably involves several mechanisms.

Sharp asbestos fibers damage cells

Damaging asbestos fibers appear to be sharp. They appear to induce cell death in some of the cells lining the chest cavity (mesothelium comprised of mesothelial cells). These dying cells induce the neighboring cells to fill the holes and the adjacent cells proliferate or make more cells,1 like patching a hole on the elbow of a favorite jacket. Some cells damaged by asbestos don’t die but have damaged DNA. One of these damaged cells transforms to cancer and grows into mesothelioma in approximately 4% of people who were chronically exposed to asbestos for decades.2

Exposure to damaging asbestos fibers usually triggers inflammation. As the cells are damaged, signals are sent to recruit white blood cells, such as neutrophils, that help clean up the damaged cells. Neutrophils comprise about 40% to 75% of the white blood cells. Neutrophils arrive quickly, and are a main component of pus from an infection or splinter. Although platelets are known to bind damaged blood vessels and form a clot to plug a leak, platelets also can amplify the inflammatory signals.3

Chronic inflammation and shorter overall survival

Chronic exposure to asbestos fibers can sustain chronic inflammation, which occurs in approximately 36% to 81% of mesothelioma patients. Chronic inflammation eventually can damage the surrounding normal tissue. The level of chronic inflammation is often measured by one or more of the five scores shown in Table 1. Surprisingly, some markers are more sensitive and find inflammation in more mesothelioma patients.

Table 1. Parameters that correlate with chronic inflammation

Parameter Abbreviation Value that corresponds to higher inflammation Percentage of mesothelioma patients with high inflammation by the marker
Neutrophil-to-Lymphocyte Ratio NLR >5 38%
Platelet-to-Lymphocyte Ratio PLR ≥ 300 36%
C-reactive Protein CRP ≥ 10 (high levels) 77%
Albumin ≤ 35 (very low levels; hypoalbuminemia) 45%
Modified Glascow Prognostic Score mGPS ≥1, a composite score that includes CRP and albumin 81%

Pinato et al showed that some mesothelioma patients had high inflammation detected by high neutrophil-to-lymphocyte ratios (NLR) and high mGPS.4 Mesothelioma patients with high inflammation defined by NLR or mGPS scores lived significantly shorter than those who had had normal markers.4, 5 Thus chronic inflammation was associated with a shorter lifespan in mesothelioma patients.

Chronic inflammation and non-small-cell lung cancer (NSCLC)

Likewise, inflammation markers can also be used to predict the risk of regrowth of a type of lung cancer. Approximately 30% of patients with non-small cell lung cancer that had been surgically removed can have a return of the lung cancer within 5 years. NSCLC patients who have high neutrophil-to-lymphocyte ratios (NLR) often have shorter survival times (by 2 years) than those with a normal NLR.6

Is all inflammation bad?

No. Inflammation is the first step in healing a wound. Under normal circumstances, the wound heals and the body uses lipid-based molecules to turn off the inflammatory process.

For example, omega-3 fatty acids found in oily fish, walnuts, flaxseeds, and many green vegetables provide the building blocks (precursors) for the three mediators that turn off inflammation. These off switches or dimmer switches for inflammation are called maresins, resolvins and protectins.7

Interestingly, curcurmin, an antioxidant present in curry, can induce an inflammatory type of cell death (pyroptosis) in human mesothelioma cells in tissue culture. It’s also a potent antioxidant.8

Tips that can help reduce chronic inflammation