This group also showed that stimulation of mouse macrophages with the bacterial toxin, lipopolysaccharide (i.e., LPS, also termed endotoxin), increased their production and secretion of itaconate.

These publications were followed by numerous others focused on the biology of itaconate and certain itaconate-like compounds as regulars of various cellular responses in animals and possibly humans.

[24] Unlike other types of itaconate-forming cells, however, these neutrophils, which are phagocytes, tend to retain rather than release itaconate to the extracellular space.

[26] Itaconate is a by-product of the tricarboxylic acid cycle, consisting of eight successive enzyme-catalyzed biochemical reactions that occur in the cell's mitochondria.

[36][37] These findings indicate that itaconate stimulates human HEK 293 and mouse respiratory epithelial cells by activating their OXGR1 receptors.

Future studies need to determine the extent to which OXGR1 contributes to the various actions of itaconate and itaconate-like compounds (see next section) as well as the potencies of each of these agents in activating OXGR1.

Based on the average consumption of bread and bread-related baked goods in Germany, the daily intake of itaconate plus its two isomers was estimated to be from 7 to 20 micrograms.

Nrf2: a) inhibits its target genes from expressing their pro-inflammatory cytokines, Interleukin 1 beta, i.e., IL-1β (which is enzymatically cleaved to its active form by caspase 1[54]) and tumor necrosis factor; b) inhibits its target genes expression of hypoxia-inducible factor 1-alpha which is converted enzymatically to an active form[55] that stimulates the pro-inflammatory actions of macrophages (i.e., by inducing them to assume the MI macrophage subtype), dendritic cells, T cells, and neutrophils;[56] and c) increases the cellular and tissue levels of pro-inflammatory reactive oxygen species.

And, in a model of LPS-induced septic shock, mice injected intraperitoneally with LPS plus 4-octyl itaconate had fewer physical symptoms of shock, lower serum levels of the pro-inflammatory cytokines, IL-1β and tumor necrosis factor, unchanged levels of the anti-inflammatory cytokine interleukin 10, and longer survival times compared to mice treated with LPS but not 4-octyl itaconate.

[23][54][58] In one study, cultured bone marrow-derived mouse macrophages were treated with LPS for 3 hours, 4-octyl itaconate or buffer for the next 45 minutes, nigericin or adenosine triphosphate (both agents activate NLRP3) for the next 45 minutes, and then assayed for extracellular IL-1β, interleukin 18, gasdermin D, and a protein not released by cells unless they had died, lactate dehydrogenase.

Similar results occurred in studies on mononuclear cells isolated from the blood of persons who did or did not have the cryopyrin-associated periodic syndrome, i.e., CAPS.

4-Octyl itaconate inhibited the release of IL-1β from LPS- or Pam3CSK4-stimulated (Pam3CSK4a mimics LPS's actions[59]), nigericin-activated mononuclear cells isolated from the blood of persons who did or did not have CAPS.

Injection of 4-octyl itaconate along with the uric acid crystals significantly reduced this inflammation response as indicated by the lower levels of IL-1β and another pro-inflammatory cytokine, interleukin 6 (i.e., IL-6), and fewer inflammation-inducing neutrophils in the peritoneum compared to 4-octyl itaconate-untreated mice.

[20][23][61] Studies have shown that: a) Atf3 gene knockout embryonic mouse fibroblasts[7] and bone marrow-derived mouse macrophages[62] (these cells lack ATF3 protein) had higher levels of IκBζ and pro-inflammatory cytokines (including IL-6 in the macrophage study) than control (i.e., ATF3 protein-expressing) fibroblasts and macrophages; b) Irg1 gene knockout peritoneal macrophages (i.e., macrophages lacking the itaconate-forming enzyme, IRK1) had lower levels of ATF3 than control mice but 4-oleyl itaconate treatment increased their ATF3 levels; c) dimethyl itaconate inhibited the ability of LPS to increase the levels of IκBζ protein and IL-6 in mouse bone marrow-derived macrophages;[61] d) Atf3 gene knockout mice with experimentally-induced inflammation of their hearts caused by either myocardial infarction due to the ligation of their left anterior descending coronary artery or by intraperitoneal injections of the heart-injuring drug, doxorubicin, developed greater levels of cardiac tissue inflammation, larger cardiac infarction (i.e., dead tissue) sizes, more cardiac fibrosis, poorer cardiac function, and higher blood serum levels of IL-6 than ATF3-expressing control mice; and e) 4-octyl itaconate reduced the IL-6 serum levels, cardiac inflammation, cardiac fibrosis, infarction size, and cardiac dysfunction caused by myocardial infarction or doxorubicin in Atf3 gene knockout mice.

[7][64][61] Tet methylcytosine dioxygenase 2 (i.e., TET2) is an enzyme that is activated by the tricarboxylic acid cycle intermediate metabolite, α-ketoglutarate.

[43][65][66][67] Studies have shown that: a) itaconate blocked α-ketoglutarate from binding to and thereby activating the isolated TET2 protein in a cell-free system; b) TET2 gene knockout bone marrow-derived macrophages (i.e., BMDMs) had far lower levels of hydroxymethylcytosine in their DNA than control macrophages; c) itaconate and 4-octyl itaconate lowered the amount of hydroxymethylcytosine in the DNA of control but not in TET2 gene knockout BMDMs; d) LPS stimulation of mouse macrophage RAW264.7 cells (these cells express TET2) caused increases in their levels of the messenger RNA (and presumably therefore the protein levels) of three proinflammatory chemokines (i.e., proteins that among other functions mobilize inflammation-promoting leukocytes), CXCL9, CXCL10, and CXCL11, but did not do so in Tet2 gene knockout RAW264.7 cells; e) itaconate reduced the ability of LPS to stimulate rises in the messenger RNA levels for IL-6 and IL-1β in RAW264.7 cells; f) 4-octyl itaconate reduced the ability of LPS to raise the messenger RNA levels of IκBζ, Il-6, CXCL9, CXCL10, and CXCL11 in the RAW264 cells; g) in a model of LPS-induced septic shock, LPS-treated Irg1 gene knockout mice (i.e., mice lacking the itaconate-forming protein, IRG1), had higher serum levels of IL-6, greater lung damage, and poorer survival times than control (i.e. IRG1-expressing) LPS-treated mice; h) compared to LPS-treated control mice, LPS-treated mice that were made to express an inactive TET2 protein (termed Tet2HxD) in place of active TET2 protein had lower serum levels of pro-inflammatory cytokines IL-6 and tumor necrosis factor, lower serum levels of the proinflammatory chemokine CXCL9, lower serum levels of alanine transaminase and aspartate transaminase (i.e., liver proteins that are released in the circulation by damaged livers), less severe pulmonary edema and lung tissue injury, and longer survival times; and i) the intraperitoneal injection of itaconate 12 hours before LPS treatment of in mice expressing active TET2 likewise had lower serum levels of IL-6, tumor necrosis factor, CXCL9, alanine transaminase, and aspartate transaminase, less severe pulmonary edema and lung tissue injury, and longer survival times.

[64][61] Elevated levels of IL-17 (assumed to be IL-17A unless future studies define it as another IL-17 subtype) occur in the cells involved in other human autoimmune inflammatory disorders besides psoriasis.

[45][46] The effects of itaconate or one of its analogs in animal models of these autoimmune diseases should be examined in a manner similar to the studies in psoriasis.

[75] Itaconate inhibits isocitrate lyase and thereby the functioning of the glycolate cycle and the growth of cultured and/or phagocytosed Staphylococcus aureus (including multiple drug resistant Staphyoocccus aureus), Vogesella indigofera (also termed Pseudomonas indigofera), Legionella pneumophila, Mycobacterium avium, Salmonella enterica, Coxiella burnetii, Francisella tularensis, and Acinetobacter baumannii.

[23][29] It should be noted, however, that Staphylococcus aureus and at least one other bacterial species, Pseudomonas aeruginosa, can use host cell-derived itaconate to form a biofilm that covers their surfaces and thereby increases their survival and pathogenicity.

However, the virus can cause severe nervous system birth defects in babies when it is transmitted from infected mothers to their embryos.

These "congenital zika syndrome" defects include microcephaly, craniosynostosis (i.e., premature closure of the skull's fontanels), cerebellar hypoplasia, ventriculomegaly, and various other nervous system malformations.

Further studies strongly suggested that these anti-viral actions of 4-octyl itaconate were due to its stimulating increases in the activity of the Nrf2 transcription factor (see the above section termed "Inhibit KEAP1").

They also support further preclinical studies to determine if itaconate-like compounds suppress human inflammation-related colon cancers.

These results indicate that 4-octyl itaconate selectively kills multiple drug resistant Y79-CR cells that are cultured or implanted in mice and does so by triggering ferroptosis.

In more advanced cases, it is commonly treated with platinum-based antineoplastic drugs and lenvatinib, an inhibitor of vascular endothelial growth factor receptors.

[20][86] These findings suggest that dimethyl itaconate inhibits the proliferation of Ty82 mouse cells by suppressing the activity of their mTOR protein and I3K/AKT/mTOR pathway.

The products made from itaconate include synthetic styrene-butadiene-based rubber, synthetic latexes, various plastics, superabsorbent polymers that absorb large amounts of liquids (for use in, e.g., baby diapers), unsaturated polyester resins that are used to make glass fiber-reinforced plastics (e.g., fiberglass), detergents,[5] and biofuels (i.e., fuels made from organic materials such as itaconic acid).

Fields using the products of itaconate include those that manufacture paint, lacquers (i.e., coatings for covering the surfaces of various objects), plasticizers, plastics, chemical fibers, hygienic materials, construction materials,[5] and environmentally-friendly fuels that can be substituted for pollution-causing, non-renewable fuels such as coal, oil, and natural gas.

[5] The demand for itaconic acid has grown to such an extent that it is projected to reach a market value of 177 million dollars per year in United States of American currency by 2028.