Interactions of Nanomaterial's with the Immune System, an Overview
- Peter Hoet, Leuven
Thursday, March 14, 4:10 PM - Physics and Astronomy Colloquium
Biomedical & Physical Sciences Bldg., Rm. 1415
The exploration of the immunomodulating potential of nanoparticles (NPs), has only recently been a major focus of research into the health effects of nanomaterials. Therefore, only little data are available on the mechanisms involved in such effects.
An in-depth evaluation of such effects with both accidental exposure (e.g., environmental and occupational) and therapeutic exposure (vaccinations, drug delivery tools) is required. Questions such as how nanomaterials (NPs) can interact with the immune system and which effects are expected in both the short and long term remain unanswered. In this seminar the focus is on modulation of the immune response after exposure to biopersistent nanomaterials, with emphasis on key factors that participate in the final outcome of the immune response. The modulation of immune-sensitive respiratory disorders, such as asthma, by NPs will be discussed.
Immune system components and their specific modulation by NPs
The primary function of the immune system is to prevent or protect against foreign material, mostly micro-organisms, but also dust and particles, entering and/or affecting the organism. In the defense against foreign intruders, several lines of protection, both specific and nonspecific, are integrated. The lines of defense are divided into the innate and adaptive immune response.
Innate (non-specific) immunity refers to the basic disease resistance the organism possesses and comprises 4 different protective barriers: 1) anatomic or physical, blocking the material from entering the organism (skin/surface of mucous membranes); 2) physiologic, increasing blood flow, degradation of material and activation of the immune system (by temperature, pH, oxygen tension or soluble factors such as lysozyme, interferon [IFN], and complement); 3) endocytic and/or phagocytic, active uptake of the material by specialized cells; and 4) inflammatory, recruitment of different cells (mainly macrophages and neutrophils).
The phagocytes also form the connection between innate and acquired (adaptive) immunity by, for example, presenting specific antigens to specialized cells or by secreting chemotactic peptides that recruit lymphocytes. The main feature of the adaptive immune system is its specific, inducible response. Phagocytic cells are general-purpose effector cells capable of handling a wide variety of stressors, whereas lymphocytes (acquired immunity) are specific to a single stressor.
Both systems (innate and acquired) strongly interact, and drawing a line between the two is often impossible. At first contact, cells of the immune system interact with the foreign materials, through direct interaction or with the help of antigen-presenting cells. This process is accompanied by the production of different cytokines, which act as inflammatory and/or immunological mediators. These cytokines or chemokines can shape the immune response toward a pro-inflammatory or an anti-inflammatory outcome.