Autoimmune Diseases and Microplastic Pollution: Joining the Dots

INTRODUCTION Plastic pollution is one of the biggest environmental challenges of the 21st century. Plastics include a wide range of synthetic/semi-synthetic materials that use polymers as their main component. Most disposable plastic products are slowly degraded to microplastics (MPs) and nanoplastics, posing additional environmental hazards. MPs refer to plastic fragments and particles with diameter < 5 mm. Depending on their origin, MPs can be classified into two categories: primary and secondary MPs. Primary MPs correspond to plastics produced directly as microparticles for use in personal care products such as facial cleansers and cosmetics. Secondary MPs correspond to the fragmentation of larger plastic debris (>5 mm).[1] MODES OF ENTRY : These micro/nanoplastics can enter our body via primary contacts leading to Inflammation and triggering autoimmune diseases in human body. Some of those modes are defined below: [Figure 1]Figure 1: Mechanism of inflammation due to micro/nanoplastics Food ingestionSeafood has been found to be contaminated with MPs, such as commercial processed fish and sea salt. Honey, beer, and food products are contaminated due to processing materials/packaging. This is the most common way plastic pollutes the human body, and it can affect the intestinal gut microbiota, eventually causing inflammatory bowel disease.[1]Inhalation of air and dust particlesMPs ≤10 mm are cleared by mucociliary clearance, while MPs <1 mm penetrate through bronchial epithelial cells and contact endothelial cells.[1]SkinExposure to face cleansers/face cream or the use of protective mobile phone cases can cause the entering of MPs through cutaneous wounds, sweat glands, or hair follicles.[1] MECHANISM Bisphenol A – It is xenoestrogen and is used primarily for manufacturing of polycarbonate plastic. It has xenoestrogenic activity, i.e., estrogen-mimicking effects. Bisphenol A can activate mediated immune effects, thereby inducing pro-inflammatory pathways[2] Hyperprolactinemia – It is the result of estrogen stimulation of hypothalamic–pituitary–adrenal (HPA) axis. It is associated with autoimmune diseases such as antiphospholipid syndrome, multiple sclerosis, systemic lupus erythematosus (SLE), rheumatoid arthritis, autoimmune thyroid disease, diabetes mellitus type I, Graves’ disease, and celiac disease[3] Bisphenol A acts as a thyroid receptor antagonist, having inverse relationship with free thyroxine 4 and thyroid-stimulating hormone level. It can modify DNA methylation patterns, histone acetylation, and microRNA profile, thereby altering the expression of immune function-related genes such as Toll-like receptors which are commonly implicated in the pathogenesis of multiple autoimmune disorders[4] At a cellular level, the damage is due to oxidative stress, mitochondrial or endoplasmic reticulum dysfunction, or lipid peroxidation.[4] SPECIAL SCENARIOS Rheumatoid arthritis It is characterized by synovial inflammation and bony erosions. MPs detected in fibroblast-like synoviocytes have shown implication as a new pollutant causing inflammation and structural damage of the joints.[5] Type 1 diabetes For manufacturing of plastics, phthalates are used which can act on HPA axis and beta-cells of the pancreas. Urinary levels of such products were found to be high in new-onset type 1 diabetes.[5] Systemic lupus erythematosus With the global environmental factors having a significant role in contributing towards development of lupus, the exact mechanism of miro and nanoplastics in doing the same is yes to be ascertained. In a recent study, it was seen that MPs led to lupus like symptoms in various models of mice.[5] CONCLUSIONS The risk of MP exposure and autoimmune diseases is real. Although further large-scale studies are required for better understanding, awareness among physicians is of paramount importance to be on the lookout for these diseases and such associations. Financial support and sponsorship None. Conflicts of interest There are no conflicts of interest.