INTRODUCTION:
Definition of terms:
Chronic inflammation
is inflammation of prolonged duration (weeks or years) in which continuing
inflammation, tissue injury, and healing, often by fibrosis, proceed
simultaneously.
Characteristics of
inflammation:
Chronic inflammation is characterized by a different set of
reactions:
1.
Infiltration with mononuclear cells, including
macrophages, lymphocytes, and plasma cells.
2.
Tissue destruction, largely induced by the
products of the inflammatory cells.
3.
Repair, involving new vessel proliferation
(angiogenesis) and fibrosis.
Malignancy can be
defined as a tendency to progress
in virulence. In popular usage, it is any condition
that, if uncorrected, tends to worsen so as to cause serious illness
or death. Cancer is the best known example.
Deregulated inflammatory response plays a pivotal role in
the initiation, development and progression of tumours. Potential molecular
mechanism(s) that drive the establishment of an inflammatory-tumour
microenvironment is not entirely understood owing to the complex cross-talk
between pro-inflammatory and tumorigenic mediators such as cytokines,
chemokines, oncogenes, enzymes, transcription factors and immune cells.
Factors affecting
activation and deactivation of molecular mediators:
These molecular mediators are critical linchpins between
inflammation and cancer, and their activation and/or deactivation are
influenced by;
1. Extrinsic (i.e. environmental and lifestyle)
2. Intrinsic (i.e. hereditary) factors.
At present, the research pertaining to
inflammation-associated cancers is accumulating at an exponential rate.
Interest stems from hope that new therapeutic strategies against molecular
mediators can be identified to assist in cancer treatment and patient
management.
In a sense, tumours act as wounds that fail to heal (2).The hallmarks of
cancer-related inflammation include the presence of inflammatory cells and
inflammatory mediators (for example, chemokines, cytokines and prostaglandins)
in tumour tissues, tissue remodelling and angiogenesis (
growth of new blood vessels) similar to that seen in chronic
inflammatory responses, and tissue repair.
Other terms:
Cytokines: A small protein released by cells
that has a specific effect on the interactions between cells, on communications
between cells or on the behavior of cells. The cytokines includes the
interleukins, lymphokines and cell signal molecules, such as tumor necrosis
factor and the interferons, which trigger inflammation and respond to
infections.
Chemokine: One of a large group of proteins that act as lures
and were first found attracting white blood cells. The chemokines are involved
in a wide variety of processes including acute and chronic types of
inflammation, infectious diseases, and cancer. Chemokines may lure cancer cells
and help determine the sites to which cancer cells spread by metastasis.
Prostaglandin: One of a number of hormone-like substances that
participate in a wide range of body functions such as the contraction and
relaxation of smooth muscle, the dilation and constriction of blood vessels,
control of blood pressure, and modulation of inflammation. Prostaglandins are
derived from a chemical called arachidonic acid.
