Mucins protect against Streptococcus pneumoniae virulence by suppressing pneumolysin expression

The skin and mucous membranes serve as the primary line of defense against pathogens by providing both physical and chemical protection. These barriers are essential in preventing the entry and establishment of microbes, thereby maintaining the integrity of the host.
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...

Peptic ulcer disease, commonly called PUD, represents a multifaceted condition characterized by disruptions in the lining of the gastrointestinal (GI)  tract. Central to the protection of the gastrointestinal lining is the mucosal-bicarbonate barrier. This physiological defense mechanism is a formidable shield against the corrosive effects of gastric acid and pepsin secretion in the stomach. Its role is pivotal in maintaining the structural integrity of the stomach's inner lining.

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...

The gastric glands contain parietal cells that secrete hydrochloric acid (HCl) for digestion. The cells secrete HCl because it is highly corrosive and essential for breaking down food. To achieve this, they secrete hydrogen and chloride ions into the lumen of the gastric glands, which combine to form HCl.
Within parietal cells, carbonic acid is first formed through the reaction of water and carbon dioxide. The dissociation of carbonic acid releases bicarbonate and hydrogen ions. The bicarbonate...

Natural flora, body system defenses, and inflammation are natural barriers of the body against infectious agents regardless of previous exposure. Normal floras of the human body refer to the microbial population that colonizes the skin and mucous membranes.
In addition, many body organ systems have unique defenses against infection. The skin is an intact, multilayered surface preventing invasion by microorganisms unless impaired. Mucous membranes lining the mouth, nose, and eyelids are barriers...

Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...