Functional adaptation to oxidative stress by memory T cells: An analysis of the role in the cardiovascular disease process

Air pollution and its effects on the immune system

A well-functioning immune system is vital for a healthy body. Inadequate and excessive immune responses underlie diverse pathologies such as serious infections, metastatic malignancies and auto-immune conditions. Therefore, understanding the effects of ambient pollutants on the immune system is vital to understanding how pollution causes disease, and how that pathology could be abrogated. The immune system itself consists of multiple types of immune cell that act together to generate (or fail to generate) immune responses and in this article we review evidence of how air pollutants can affect different immune cell types such as particle-clearing macrophages, inflammatory neutrophils, dendritic cells that orchestrate adaptive immune responses and lymphocytes that enact those responses. Common themes that emerge are of the capacity of air pollutants to stimulate pro-inflammatory immune responses across multiple classes of immune cell. Air pollution can enhance T helper lymphocyte type 2 (Th2) and T helper lymphocyte type 17 (Th17) adaptive immune responses, as seen in allergy and asthma, and dysregulate anti-viral immune responses. The clinical effects of air pollution, in particular the known association between elevated ambient pollution and exacerbations of asthma and chronic obstructive pulmonary disease (COPD), are consistent with these identified immunological mechanisms. Further to this, as inhaled air pollution deposits primarily on the respiratory mucosa this review focuses on mechanisms of respiratory disease. However, as discussed in the article, air pollution also affects the wider immune system for example in the neonate and gastrointestinal tract. Whilst the many identified actions of air pollution on the immune system are notably diverse, immunological research does suggest potential strategies to ameliorate such effects, for example with vitamin D supplementation. An in-depth understanding of the immunological effects of ambient pollutants should hopefully yield new ideas on how to reduce the adverse health effects of air pollution.

Simultaneous quantification of mitochondrial DNA damage and copy number in circulating blood: a sensitive approach to systemic oxidative stress

Systemic oxidative stress is associated with a wide range of pathological conditions. Oxidative DNA damage is frequently measured in circulating lymphocytes. Mitochondrial DNA (mtDNA) is known to be more sensitive to oxidative damage than nuclear DNA but is rarely used for direct measurement of DNA damage in clinical studies. Based on the supercoiling-sensitive real-time PCR method, we propose a new approach for the noninvasive monitoring of systemic oxidative stress by quantifying the mtDNA structural damage and copy number change in isolated lymphocytes in a single test. We show that lymphocytes have significantly less mtDNA content and relatively lower baseline levels of damage than cancer cell lines. In an ex vivo challenge experiment, we demonstrate, for the first time, that exogenous H₂O₂ induces a significant increase in mtDNA damage in lymphocytes from healthy individuals, but no repair activity is observed after 1 h recovery. We further demonstrate that whole blood may serve as a convenient alternative to the isolated lymphocytes in mtDNA analysis. Thus, the blood analysis with the multiple mtDNA end-points proposed in the current study may provide a simple and sensitive test to interrogate the nature and extent of systemic oxidative stress for a broad spectrum of clinical investigations.