Toll-like receptorToll-like receptors (TLRs) are a class of proteins that play a key role in the innate immune system. They are single-pass membrane-spanning receptors usually expressed on sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes. Once these microbes have reached physical barriers such as the skin or intestinal tract mucosa, they are recognized by TLRs, which activate immune cell responses. The TLRs include TLR1, TLR2, TLR3, TLR4, TLR5, TLR6, TLR7, TLR8, TLR9, TLR10, TLR11, TLR12, and TLR13.
MelaninMelanin (ˈmɛlənɪn; ) is a broad term for a group of natural pigments found in most organisms. The melanin pigments are produced in a specialized group of cells known as melanocytes. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types — brown eumelanin and black eumelanin. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization.
Staphylococcus aureusStaphylococcus aureus is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive for catalase and nitrate reduction and is a facultative anaerobe that can grow without the need for oxygen. Although S. aureus usually acts as a commensal of the human microbiota, it can also become an opportunistic pathogen, being a common cause of skin infections including abscesses, respiratory infections such as sinusitis, and food poisoning.
StaphylococcusStaphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical (cocci), and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms (capable of growth both aerobically and anaerobically). The name was coined in 1880 by Scottish surgeon and bacteriologist Alexander Ogston (1844–1929), following the pattern established five years earlier with the naming of Streptococcus.
Signal transductionSignal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Most commonly, protein phosphorylation is catalyzed by protein kinases, ultimately resulting in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway.
Innate immune systemThe innate, or nonspecific, immune system is one of the two main immunity strategies (the other being the adaptive immune system) in vertebrates. The innate immune system is an alternate defense strategy and is the dominant immune system response found in plants, fungi, insects, and primitive multicellular organisms (see Beyond vertebrates).
InflammationInflammation (from inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and initiate tissue repair.
Methicillin-resistant Staphylococcus aureusMethicillin-resistant Staphylococcus aureus (MRSA) is a group of gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus. MRSA is responsible for several difficult-to-treat infections in humans. It caused more than 100,000 deaths attributable to antimicrobial resistance in 2019. MRSA is any strain of S. aureus that has developed (through natural selection) or acquired (through horizontal gene transfer) a multiple drug resistance to beta-lactam antibiotics.
Staphylococcus epidermidisStaphylococcus epidermidis is a Gram-positive bacterium, and one of over 40 species belonging to the genus Staphylococcus. It is part of the normal human microbiota, typically the skin microbiota, and less commonly the mucosal microbiota and also found in marine sponges. It is a facultative anaerobic bacteria. Although S. epidermidis is not usually pathogenic, patients with compromised immune systems are at risk of developing infection. These infections are generally hospital-acquired. S.
Interleukin 15Interleukin-15 (IL-15) is a protein that in humans is encoded by the IL15 gene. IL-15 is an inflammatory cytokine with structural similarity to Interleukin-2 (IL-2). Like IL-2, IL-15 binds to and signals through a complex composed of IL-2/IL-15 receptor beta chain (CD122) and the common gamma chain (gamma-C, CD132). IL-15 is secreted by mononuclear phagocytes (and some other cells) following infection by virus(es). This cytokine induces the proliferation of natural killer cells, i.e.
