Question

Why is autoimmunity sometimes associated with infection and how would you test if it is the cause?

Answer 1

AUTOIMMUNITY is the system of immune responses of an organism against its own healthy cells and issues.Any immune that results from such an immune response is termed as ' autoimmune disease".Like all adaptive immune responses , it is focused on specific antigens by T- cell receptors and B-cell receptors.The antigens recognized by these cells are processed from proteins within target organ and this drives a chronic inflammatory process that disrupts the normal function of the tissue.

In human disease the trigger for this process cannot usually be determined. There is evidence that autoimmunity can follow infection, but that more than one infection can initiate disease.

Autoimmunity occurs when the immune system recognizes and attacks host tissue.In addition to genetic factors , environmental factors also like bacteria,viruses and other pathogens are thought to play a major role in triggering autoimmune disease.Multiple arms of immune system may be involved in autoimmune pathology.Antigens are taken up by antigen presenting cells (APCs) such as dendritic cells and processed into peptides which are loaded onto major hospitality complex (MHC) molecules for presenting to T cells via T cell receptors.Tc cells can directly lyse a target while Th cells release cytokines that activate macrophages, monocytes and B cells.B cells themselves have surface receptors that can bind surface antigens.Upon receiving signals from Th cells, the B cells secretes antibodies specific for antigens.Antibody may bind to and activate the macrophages or its specific target via Fc receptor.

There are multiple mechanisms by which host infection by a pathogen can lead to autoimmunity.The pathogens may carry elements similar to amino acid sequence or structure to self antigen, the pathogen acts as a self mimic.In this way the immune response to a pathogen, causes damage to self tissue.Antigens released from damaged tissue are taken up by ACPs and this initiates a self specific immune response.Infection may lead autoimmunity through the processing and presentation of cryptic antigen.The cryptic antigens are invisible to the immune system.The inflammatory environment that arises after infection can induce increased protease production and differential processing of releases self epitopes.

CAN INFECTIONS LEAD TO AUTOIMMUNE DISORDERS ?

Some evidences suggest that bacterial and viral infections may play a part in the development of autoimmune disease.

Autoimmune disorders occur when the body's immune system that helps protect the body against infections instead turns against the body's own organs and tissues.

Some researchers believe that people who have infections may be at higher risk of developing several types of autoimmune disorders.In fact scientific evidence has linked autoimmune disorders with infection for over a century.

INFECTION AND AUTOIMMUNE DISEASES :

Since bacteria and viruses trigger a similar immune response, some researchers have suggested that antibodies produced in response to certain infections may also attack some of the normal cells because they resemble the bacteria that caused the infection.Some say that infections may actually damage the immune system, leading to the development of autoimmune disorders.During research,, scientists have found that in many cases both genetic susceptibility and an environmental trigger must be present for autoimmune disorders to develop.

No single infection has been found to be responsible for the development of autoimmunity, infact many different infections may be linked to a single autoimmunity disease.Some of the autoimmune diseases include : Rheumatoid arthritis, Lupus, Myocarditis , Myasthenia gravis . Ofcoarse not everyone who gets these infections will develop an autoimmune disorder , since it seems that in addition to the infection, some sort of genetic disposition is also involved in the development of such conditions.Many other infections may also be related to the development of autoimmunity because these infections occur before any autoimmune disorder associated symptoms develop, it can be difficult to determine a link between one infection and a specific autoimmune disorder.

Usually the infections increase the risk of developing autoimmunity, but not always during an autoimmunity the infections occur.

TEST FOR AUTOIMMUNE DISORDER :

It is not easy to diagnose an infections caused by autoimmunity.Several blood tests are done to diagnose this condition :

1. Auto-antibody tests : There are blood tests that can look for the presence of auto-antibodies in the blood. Auto antibodies are the antibodies produced by your own immune system that cause it to attack your own cells,tissues and organs.

2. Inflammation and organ function tests : Since certain autoimmune disorders may cause your organs to disfunction, the tests may be performed to see if the organs are working properly.

Hope the answer was helpful.

Thanks ;)