‘Yin and Yang’ in inflammation: duality in innate immune cell function and tumorigenesis

Abstract

Background: The two stages of the acute inflammatory process are apoptosis (‘Yin’) and wound healing or resolution (‘Yang’). Inflammation defends the host against unwanted elements. Objective/methods: To present a discussion of pleiotropic roles of innate immune cells possessing ‘tumoricidal’ and/or ‘tumorigenic’ properties in inflammation-induced dysfunction of the immune system and the genesis of chronic inflammatory diseases, hyperplasia, precancer/neoplasia or tumor and angiogenesis. Results/conclusions: Loss of maintenance of the balance between apoptosis and wound healing and co-existence of death and growth factors in tissues could create ‘immunological chaos’ with accumulation of ‘immune response mismatches’. Unresolved inflammation plays a role in the genesis of chronic inflammatory and autoimmune diseases and cancer. Identification of accumulated ‘mismatched’ death and growth factors during the developmental phases of immune dysfunction in target tissues or cancer microenvironment presents challenges and opportunities for future studies on diagnosis, prevention and therapy of these diseases.

Keywords::

• ageing
• Alzheimer's
• angiogenesis
• apoptosis
• atherosclerosis
• B cell
• cancer
• cardiovascular disease
• chemokines
• conjunctiva
• cytokines
• dendritic cells
• dual functions
• eosinophils
• hyperplasia
• hypertention
• inflammatory diseases
• innate and adoptive immune cells
• interferons
• interleukins
• leaky mast cells
• lupus
• lymphoid hyperplasia
• macrophages
• mast cells
• natural killers
• neoplasia
• neutrophils
• ocular inflammation
• pleiotropic
• resolution of inflammation
• T cell
• tumoricidal
• tumorigenesis
• tumorigenic
• wound healing

Acknowledgements

The experimental studies on inflammatory diseases were established in collaboration with Dr John H Rockey and his team at the University of Pennsylvania, School of Medicine in 1980s/90s. Concepts and hypotheses in promoting the role of inflammatory mediators in cancer research and designs of cohort clinical studies were developed at the National Cancer Institute, National Institutes of Health (NIH) since 1998. The author is grateful to Mr Alan Hoofring at NIH Medical Arts Department for his expert work on production of images.

Notes