Defensins are defined to have antimicrobial properties as they prevent the entry of pathogens and can kill them by attacking their membranes. The defensins affect the membrane, increases the influx of water in the cells that results in the death of microbes. The most commonly occurring category of defensin in humans are beta-defensins, which are present in four forms, whereas others (alpha and theta defensins) are present at low levels. The beta-defensins can be found in the airway epithelia, which are human β-defensin-1 (HBD-1) and human β-defensin-2 (HBD-2). Cystic fibrosis is a condition in which the faulty CFTR gene results in a malformed CFTR protein, which is a membrane protein. The transport is affected due to which thick mucus accumulates in the lungs, making it prone to infections. Cystic fibrosis has no treatment, but the beta-defensins helps to lower the complexities to make breathing effortless. The beta-defensins act on the respiratory pathogens and kills them so that they do not cause infection in the mucus. Protegrin-1 and iseganan are few examples of defensins that have been proved effective in killing the respiratory pathogens in cystic fibrosis patients and are in the clinical trial phase.
The classes of peptides or proteins that are a part of neutrophils and have cytotoxic or antimicrobial properties are known as defensins. These are the antibiotic polypeptides that cause cell damage by destroying the cell membrane. They can be also be defined as the natural defensive cells which have a role in the immune response by killing the microbes either directly or indirectly. There are two forms of human defensins known as alpha and beta-defensins that are made up of 30 amino acids and differ due to differences in disulfide bond linkage. These cells are majorly produced by the immune cells, such as lymphocytes and phagocytic cells, but also by the epithelial cells present in the lining of the gastrointestinal tracts. Along with humans, the defensins are also found in plants and fungi where they are produced in different tissues of the body. There are various important roles of defensins, such as:
It is present in mother milk and helps to develop immunity in infants.
The defensins have been proven effective against HIV because it acts on the viral particles and prevents their entry in target cells.
In immature animals, it fights against the pathogens because the immune system is underdeveloped.
Cystic fibrosis causes and effects:
Various genetic disorders are found in humans, which occur when the faulty genes on either the X chromosome or Y chromosome get transferred to the offspring. The faulty genes are caused due to mutations that lead to addiction, deletion, or substitution of base pairs. This gene forms malformed proteins that cause abnormalities. CFTR protein experiences mutation by the deletion of a single amino acid at the 508 positions. CFTR protein is required for the transport of ions across the membrane because CFTR is a membrane protein and regulates the formation of saliva, tears, and mucus. Defects in this gene lead to a condition called cystic fibrosis in which the membrane protein is malformed, and thus, transportation is abrupted. This leads to the formation and deposition of thicker mucus that accumulates in the lungs and catches an infection, making breathing difficult. This disease is a recessive genetic disease, and both the carrier (normal) parents will give rise to a baby having cystic fibrosis.
