WikiBiomeThe human microbiome encyclopediaRanked matches across titles, topics, categories, and article introductions, filtered to mechanism.
An acidic microenvironment is a local drop in pH — typically into the 4.5–6.5 range — inside a tissue, organ, or ecological niche. Acidification arises from three recurring sources: bacterial fermentative metabolism that releases short-chain fatty acids and lactate (lou…
Aromatase (CYP19A1) is the cytochrome P450 enzyme that catalyzes the final and rate-limiting step of estrogen biosynthesis — the conversion of androgens (testosterone, androstenedione) to estrogens (estradiol, estrone). It is expressed in the ovaries, placenta, adipose …
Autophagy (from Greek, "self-eating") is the cellular process of degrading and recycling damaged organelles, misfolded proteins, and intracellular pathogens through lysosomal digestion. It is the cell's primary quality control mechanism -- a housekeeping system that bec…
Viruses that exclusively infect bacteria. Bacteriophages -- phages for short -- are the most abundant biological entities on Earth, outnumbering bacteria in most environments by ratios of 1:1 to 10:1. In the human gut, the phageome represents a powerful but underexplore…
Bile acids are cholesterol-derived amphipathic molecules synthesized in the liver, secreted into the duodenum, and extensively modified by gut bacteria. The host-microbe co-metabolism of bile acids creates a signaling network with profound effects on lipid metabolism, g…
CagA is an effector protein produced by some strains of helicobacter pylori. Its name derives from “cytotoxin-associated gene A.” CagA is delivered into gastric epithelial cells through the bacterium's type IV secretion system and is therefore different from a freely se…
The major copper-carrying protein in human blood, binding approximately 95% of circulating copper. Ceruloplasmin is far more than a passive transport vehicle -- it is a multicopper oxidase with ferroxidase activity, an acute-phase reactant that rises with inflammation, …
Perhaps the most pervasive metallomic finding across human disease: copper is elevated in nearly every pathological condition examined in this wiki -- cancer (pan-cancer), PCOS, cardiovascular disease, depression, schizophrenia, IBD, and rheumatoid arthritis. Simultaneo…
Cyclooxygenase-2 (COX-2) is the inducible enzyme that converts arachidonic acid to prostaglandin H₂ — the precursor of prostaglandin E₂ (PGE₂), prostacyclin, and thromboxane. Unlike COX-1 (constitutive, homeostatic), COX-2 is transcriptionally induced by nf kappa b duri…
A distinct form of regulated cell death caused by excess intracellular copper binding to lipoylated proteins in the TCA cycle, first characterized by Tsvetkov et al. in Science (2022). Unlike ferroptosis (iron-dependent lipid peroxidation) or apoptosis (caspase-dependen…
Direct DNA damage is the primary carcinogenic mechanism for chromium but is notably absent or minor for nickel and arsenic. This distinction is fundamental to understanding why these three metals cause cancer through such different pathways.
Drug repurposing (also called drug repositioning) is the strategy of identifying new therapeutic uses for existing approved drugs. It dramatically accelerates the path from bench to bedside because safety, pharmacokinetics, and manufacturing are already established. In …
Epigenetics is the study of heritable changes in gene expression that occur without alterations to the DNA sequence itself. These changes -- primarily DNA methylation, histone modifications, and non-coding RNA regulation -- represent a molecular memory system that can b…
Epithelial-mesenchymal transition (EMT) is a cellular program in which polarized epithelial cells lose their cell-cell adhesion and acquire migratory, mesenchymal properties. While essential during embryonic development and wound healing, aberrant EMT activation drives …
The estrobolome is the aggregate of enteric bacterial genes whose products are capable of metabolizing estrogens. First proposed by Plottel and Blaser (2011), the concept describes how the gut microbiome acts as an endocrine organ, modulating circulating estrogen levels…
Estrogen recirculation is the recycling loop by which conjugated estrogens excreted in bile are deconjugated by gut bacterial beta glucuronidase, reabsorbed across the intestinal epithelium, and returned to systemic circulation uzuner 2023 bidirectional relationship end…
The Fenton reaction is the iron-catalyzed generation of hydroxyl radicals (OH.) from hydrogen peroxide -- the most reactive oxygen species in biology. Discovered by H.J.H. Fenton in 1894, this reaction is the mechanistic bridge between metal accumulation and oxidative t…
Ferroptosis is a form of iron-dependent regulated cell death driven by the accumulation of lipid peroxides on cellular membranes pendergrass 2026 microbial metallomics parkinsons ferroptosis, riederer 2021 iron concert master parkinsons. Unlike apoptosis or necrosis, fe…
The gut-prostate axis describes the bidirectional communication between the gut microbiome and the prostate gland. Gut-derived microbial metabolites, inflammatory mediators, and immune signals influence prostatic health, while prostatic disease states alter systemic inf…
[NiFe] hydrogenases are the second major nickel-dependent virulence factor class in human pathogens. Less widespread than urease but critical for energy metabolism in gastric, enteric, and intracellular pathogens. The discovery that H. pylori hydrogenase powers CagA tra…
Hypoxia refers to a state of low oxygen tension (partial pressure of O₂ < 5% in tissue, vs. ~21% in air). In the context of microbiome metallomics, hypoxia is a critical ecological determinant that reshapes bacterial community structure by favoring obligate and facultat…
Immunotherapy harnesses the patient's own immune system to fight disease, most notably cancer. Immune checkpoint inhibitors (ICIs) -- antibodies that block PD-1, PD-L1, or CTLA-4 -- have revolutionized oncology since their introduction in the 2010s, producing durable re…
Interleukin-22 (IL-22) is an immune signaling protein that helps coordinate host responses at epithelial surfaces. In the gut evidence represented by WikiBiome, group 3 innate lymphoid cells (ILC3s) are a prominent source, while Th17-associated responses can also includ…
Lipid peroxidation is the oxidative degradation of polyunsaturated fatty acids (PUFAs) in cell membranes by reactive oxygen species (ROS). The process generates toxic aldehydes — malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) — that damage proteins, DNA, and mitocho…
Matrix metalloproteases are a family of zinc-dependent endopeptidases that degrade components of the extracellular matrix (ECM). They are central to tissue remodeling in both health and disease and sit at a critical intersection in the wiki: zinc as the essential cataly…
The ability of certain metals to cause cancer has been known since the 19th century. The three metals covered in this wiki — nickel, arsenic, and chromium — represent distinct mechanistic paradigms that collectively illustrate the diversity of metal-induced carcinogenes…
A metal ion that activates estrogen receptors and mimics the biological effects of estradiol. Metalloestrogens represent a distinct class of endocrine-disrupting compounds where the active agent is an inorganic metal rather than an organic xenoestrogen like BPA or phtha…
Metalloestrogens are metal ions that activate estrogen receptors and mimic the biological effects of estradiol, the primary endogenous estrogen. They represent a category of endocrine-disrupting compounds where the active agent is an inorganic metal rather than an organ…
Metallomics is the systematic study of metals and metalloids in a biological system. The metallome is the set of metal and metalloid species present in a defined organism, tissue, cell, fluid, or microbial community; metallomics is the measurement and interpretation of …
A family of small (6-7 kDa), cysteine-rich proteins that bind heavy metals with extraordinary affinity. Metallothioneins (MTs) are the cell's primary chemical defense against metal toxicity -- they sequester cadmium, mercury, lead, and other toxic metals, preventing the…
The fungal component of the human microbiome, comprising ~0.1-1% of the total gut microbial community by abundance but disproportionately active in immune signaling and cross-kingdom interactions. While bacterial communities dominate microbiome research, emerging eviden…
Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) is a family of transcription factors that regulate inflammation, immune responses, cell survival, and proliferation. NF-kB is a convergence point where metal toxicity, pathogen signaling, and chronic…
The oral microbiome is the second most complex microbial community in the human body after the gut, harboring ~700 species across distinct niches (tongue, buccal mucosa, gingival crevice, saliva, dental plaque). While traditionally studied in the context of dental disea…
Polyamines -- putrescine, spermidine, spermine, and cadaverine -- are small polycationic molecules produced by both the host and the gut microbiome. They regulate cell growth, differentiation, apoptosis, and immune function. In the gut ecosystem, polyamines are metaboli…
Shotgun metagenomics is a sequencing approach that fragments and sequences all DNA in a sample -- bacterial, archaeal, fungal, viral, and host -- without prior amplification of a specific gene target. Unlike 16S rRNA amplicon sequencing, which identifies "who is there" …
Statins (HMG-CoA reductase inhibitors) are the most widely prescribed drug class globally, used primarily for cholesterol lowering and cardiovascular risk reduction. Over 200 million people take statins worldwide. Beyond their canonical mechanism of inhibiting cholester…
A synbiotic is a combination of a probiotic (live beneficial microorganism) and a prebiotic (substrate that selectively feeds beneficial microbes), designed to work synergistically — the prebiotic supports the survival and colonization of the probiotic organism. Synbiot…
The virome is the collection of all viruses inhabiting a given ecosystem -- in the gut, this means primarily bacteriophages (phages), which constitute ~90% of the intestinal virome. While microbiome research has historically focused on bacteria, mounting evidence shows …