Inflammation

The body’s natural immune response to injury, infection or foreign bodies is inflammation. This is a protective mechanism.

Acute inflammation often causes pain, redness and swelling.

In the absence of injury, infection or presence of foreign bodies, prolonged, low-grade chronic inflammation can cause harm to the body and result in chronic disease.¹

Before looking at chronic inflammation, let’s briefly review the immune system, the immune response and innate and acquired immunity.

What and where is the Immune System

The US National Centre for Biotechnology Information² states ‘the organs of the immune system include skin and mucous membranes, blood and the organs of the lymphatic system’. There are also specialized organs which make infection-fighting white blood cells called lymphocytes, i.e. the bone marrow, the thymus gland in the centre of our chest, our small and large bowel, lymph nodes and spleen. This illustrates the immune system is not one discrete organ, but an integrated collaboration by a group of systems, organs and tissues.

Focusing on specific cells of the immune system…

- - White blood cells originate in the bone marrow from stem cells. Generally, released into the blood stream at maturity, occasionally the release of white blood cells occurs before maturity. Though only occurring in small numbers, immature white blood cells found in the bloodstream are known as blasts.
  - White blood cells are either of myeloid or lymphoid lineage
  - Myeloid cells include non-lymphocyte white cells, e.g. basophils, eosinophils, neutrophils and macrophages. These cells contain enzymes capable of destroying invaders. Neutrophils are the most common type of white blood cell, responding in great numbers to the site of a tissue injury following chemical signalling from the host or metabolic activity of the invading organism.
  - Lymphoid cells include T lymphocytes which mature in the thymus gland, B lymphocytes which mature in the bone marrow and also killer cells. Mature lymphocytes are found in blood and lymph tissue throughout the body, for example the spleen, tonsils and lymph nodes.
3,4,5

Mak and Saunders³explain the immune system evolved to protect the body from entities that are regarded as ‘non-self’, also known as antigens. This might include living organisms such as bacteria, viruses and parasites, but also inert matter such as splinters.

They go on to say that despite an environment teeming with disease-causing antigens, known as pathogens, few healthy people suffer lasting consequences from infection. This is entirely down to the immune response orchestrated by the cells and tissues of the immune system which recognise and destroy foreign invaders.

Innate and Acquired Immunity

Neutrophilic activity, as described above, is the first line of defence and part of the innate immune response.

T lymphocytes and B lymphocytes are part of the acquired immune response.

Both the innate and acquired immune systems work together to rid the body of antigens.

Through DNA randomisation there are many, many different T cells, each effective against a specific antigen. On identification of the antigen, a cytotoxic T cell will copy itself many times to ‘fight’ the invader. T helper cells sending signals to other cytotoxic T cells, B cells and macrophages for backup, so to speak. Once threat from the antigen has passed, some of the T cells become memory cells. These memory cells can be quickly activated if the same antigen invades again.

B cells make proteins called antibodies which destroy specific antigens. B cells may become activated by T helper cells as described above. Once threat from the antigen has passed, some of the B cells become memory cells. These memory cells can be quickly activated if the same antigen invades again.

Chronic Inflammation

…is where the immune response has become stuck and is not being turned off. The immune system is responding when there is no pathogen and no resolution, so the pilot light is still lit. Rather than attacking foreign invaders the immune system’s target is the body’s own tissue. In the long term this can result in chronic disease.

Certain autoimmune diseases such as rheumatoid arthritis and psoriasis, as well as other diseases like Parkinsons disease, asthma and Crohn’s disease are linked with chronic inflammation. As too are heart disease and Type 2 diabetes.

Aspects of daily living can be a common cause of some cases of low grade, persistent inflammation. Whilst it may not be possible to modify all causes, for example ageing, taking steps to mitigate the following may help to reduce the inflammation…

Insufficient physical activity
Prolonged stress
Obesity
An imbalance of the microbes within the gut microbiome
A diet high in ultra-processed foods
Poor sleep
Smoking tobacco
Excessive alcohol consumption

Though there are other tests, one common blood test for inflammation is C-Reactive Protein (CRP). CRP is a protein made by the liver. High levels indicate there is active inflammation somewhere within the body. ⁷

How to reduce chronic inflammation

Here is a link to a shortened version (14 mins) of an hour long ZOE podcast. Professor Phillip Calder is an expert on how our diet influences our immune system. Philip Calder advises the following dietary changes will help reduce inflammation…

omega-3s
vitamin C
Polyphenols
fibre-rich foods

ZOE Inflammation expert: How to beat chronic inflammation – Professor Philip Calder

References

Cleveland Clinic, Health Library [Internet]. Ohio, US; 2024. Inflammation; Available from: https://my.clevelandclinic.org/health/symptoms/21660-inflammation
org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. In brief: What are the organs of the immune system? [Updated 2023 Aug 14].Available from: https://www.ncbi.nlm.nih.gov/books/NBK279395/
Dean L. Blood Groups and Red Cell Antigens [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2005. Chapter 1, Blood and the cells it contains.Available from: https://www.ncbi.nlm.nih.gov/books/NBK2263/
Mak, T. W. and Saunders, M. E. (2005)The Immune Response: Basic and Clinical Principles. London: Academic Press
Cleveland Clinic, Health Library [Internet]. Ohio, US; 2023. T Cells; Available from: https://my.clevelandclinic.org/health/body/24630-t-cells
Cleveland Clinic, Health Library [Internet]. Ohio, US; 2023. B Cells; Available from: https://my.clevelandclinic.org/health/body/24669-b-cells
Cleveland Clinic, Health Library [Internet]. Ohio, US; 2024. Inflammation; Available from: https://my.clevelandclinic.org/health/symptoms/21660-inflammation