Let us take a moment to imagine that we are suffering from immunosuppression—our immune system is becoming weaker, and its efficacy is decreasing. Isn't it disturbing to know that the body is now prone to all kinds of diseases? Well, a significant portion of our population suffers from this condition induced by a simple act—drinking arsenic-laden water. Is arsenic that dangerous, you ask? A study by researchers from the Indian Institute of Toxicology Research (IITR), Lucknow and Central Drug Research Institute, Lucknow, claims so!
A report by the World Health Organisation says that at least 140 million people in 50 countries have been drinking water containing arsenic at levels above the WHO provisional guideline value of 10 μg/L. In this study, published in the journal Scientific Reports, the researchers have investigated the effect of arsenic exposure on the immune system, specifically on the T-cells—a type of white blood cells that play a central role in the body’s immune system.
In our body, the T-cells grow to become specialised cells known as CD4—helper cells that lead the attack against infections, and CD8—suppressor cells that regulate the immune response. The study investigates the impact of arsenic exposure on CD4, CD8 and the regulatory T-cells, which moderate the immune system and prevent the occurrence autoimmune diseases.
The researchers conducted the study on male mice as the immune system of mice is very similar to humans. They exposed the mice to Mycobacterium fortuitum—a group of bacteria found in natural and processed water, sewage, and dirt and cause infections of the skin, lymph nodes, and joints, and evaluated the extent of weakening of the immune system.
The study revealed that arsenic exposure disrupts the delicate balance between CD4 and CD8 cells and increases the incidence of infections like tuberculosis. When the researchers exposed the mice to arsenic, an increased number of T-cells in the mice grew to become CD4 cells, while the number of CD8 cells remained unaffected. On moving to the spleen, an organ of the body that filters the blood, an increased number of CD4 cells transformed into regulatory T-cells, and impacted the other immune cells. This imbalance reduced the overall functionality of the immune system.
The study also showed that arsenic affected the secretion of cytokines—a group of proteins secreted by the immune system as part of its response to fight infections, thereby making the body more susceptible to infections. The mice exposed to M. fortuitum were highly susceptible to infections like skin, joint and lymph node infections. The study also inferred a higher risk of tuberculosis due to weakened immune system. Exposure to arsenic, however, does not affect other parameters like the body weight and liver and kidney function, making it difficult to notice its impact.
“In conclusion, the present study clearly showed that exposure to environmentally relevant doses of arsenic disturbs thymocyte differentiation as reflected by enhanced commitment into CD4 lineage in the thymus. It has also been clearly demonstrated that arsenic exposure affected T-cell cytokine secretion by up-regulating Treg population thereby induced immunosuppression”, say the authors in their study.
So, can this exposure be countered? The study says that treatment with wortmannin, a drug used to treat cancer, could help. Wortmannin can bring down the arsenic-induced increase in regulatory T-cells, thereby helping recover immunity.
The study is yet another evidence to show how arsenic-induced groundwater can play havoc on the body—a condition that many, especially in the states of West Bengal, Jharkhand, Bihar and Uttar Pradesh, are exposed to in India. So if you are living in an arsenic-affected area, wortmannin could come in for help, of course under the supervision of your doctor!