Mycotoxins: Citrinin and Gliotoxin
*This article is not medical advice. Before starting on any health related regimen, seek the advice of your Primary Care Physician or an M.D.
Citrinin and Gliotoxin
Citrinin affects the bone marrow as well as the liver, kidney, and mitochondrial respiratory chain. Citrinin and Gliotoxin both inhibit the anti-inflammatory cytokine, IL-10. This is concerning because IL-10 has the ability to block TNFA and IL-6, both of which are important pro-inflammatory pathways. Certain genetic variations of IL-10 are implicated in intestinal inflammatory issues, notably with emulsifiers in food and supplements linked to IBD.
Citrinin causes malfunction of the respiratory system, as well as inhibition of mitochondrial complex I, which results in superoxide (free radical) production. Citrinin has been significantly associated with neutrophilia, squamous cell carcinoma, Fanconi anemia, leukemia, hepatoblastoma, and fatty liver disease.
“Citrinin has been shown to be nephrotoxic and hepatotoxic to humans. The kidney is the major target organ of Citrinin. Citrinin is commonly found along with ochratoxin, and an additive or synergic effect has been shown to increase the toxicity, causing kidney disease in humans. Other than the kidney, the target organs of Citrinin include the liver, mitochondrial respiratory chain, and bone marrow.”
Why read this article?
You may find this article valuable if you’re interested in:
What citrin is and what effects it has on the body
What gliotoxin is and what effects it has on the body
What detox pathways are involved in clearing citrinin and gliotoxin
What binders may helpful if exposed to citrinin and gliotoxin
Brief Summary of Citrinin:
Citrinin is a poisonous secondary metabolite made by various fungi, particularly Aspergillus, Penicillium, and Monascus species. It is found in soil, rotting vegetation, food storage systems, and water damaged buildings. This mycotoxin can also be found in various foods, including fermented sausages, wheat, corn, and rice, as well as foods colored using pigments from rice that has been fermented with Monascus species.
Citrinin can have deleterious effects on the body:
Citrinin affects all major organs, including the bone marrow, liver, kidney, and mitochondrial respiratory chain
Citrinin and Gliotoxin both inhibit IL-10. This is concerning because, as an important anti-inflammatory cytokine, IL-10 is known to block TNFA and IL-6, both of which are involved in pro-inflammatory pathways. Certain genetic variations of IL-10 are implicated in intestinal inflammatory issues, notably with emulsifiers in food and supplements linked to IBD
Citrinin causes malfunction of respiratory system, as well as inhibition of mitochondrial complex I, resulting in superoxide (free radical) production
Citrinin alters the expression of the aryl hydrocarbon receptor (AhR), the androgen receptor (AR), and aromatase, a member of the cytochrome P450 superfamily (more information on this below)
Citrinin has been associated with neutrophilia, squamous cell carcinoma, Fanconi anemia, leukemia, hepatoblastoma, and fatty liver disease
Brief Summary of Gliotoxin:
The fungus most closely associated with gliotoxin is Aspergillus fumigatus. Exposure to A. fumigates has the potential to cause a range of life-threatening respiratory and systemic infections in patients with compromised immunity. Gliotoxin is detectable in the serum of patients with Invasive Aspergillosis (IA), and in the lungs and serum of mice with experimentally induced IA.
Gliotoxin modulates the secretion of IL-6, IL-10, and TNF-α from lipopolysaccharide (LPS)-stimulated human MM6 monocytes in vitro
Gliotoxin targets NF-κB signaling to promote immune suppression
Dendritic cells are capable of innate recognition of pathogens, and they also present antigens to naive T cells during adaptive immunity. Gliotoxin induced caspase-3 activation and apoptosis in CD83+ monocyte-derived dendritic cells, which led to inhibition of human T cell function
Gliotoxin has been shown to inhibit NADPH oxidase in human neutrophils (NADPH oxidative bursts are used to kill some fungi)
Binders for Citrinin and Gliotoxin
Binders for Citrinin
MOS Prebiotic (found in Jarrow Sacchromyves Boulardii)Mannan oligosaccharides (MOS) are prebiotics derived from the outer cell wall of S. cerevisiae
Glucomannan (a dietary fiber supplement made from the root of the konjac plant)
Binders for Gliotoxin
Clay binders
Glucomannan
N-acetyl cysteine (NAC)
Sacchromyces boulardii
Psyllium husk
Detoxification Pathways for Citrinin and Gliotoxin
Phase 1 CYP450 Enzymes for Citrinin detoxification include CYP1A2, CYP2D6, CYP2C9, CYP3A4 [5]
Phase 2 Detox Pathways For Citrinin: unknown at this time
Phase 1 CYP450 Enzymes For Gliotoxin: unknown at this time
Phase 2 Detox Pathways For Gliotoxin: unknown at this time
Additional Details on Citrinin:
"Citrinin has been identified in various foods such as meals colored with Monascus pigments, fermented sausages, wheat, corn, and rice. The mycotoxin citrinin, one of the toxic secondary metabolites produced by various species of fungi, was first identified in the filamentous fungus Penicillium citrinum in 1931. Citrinin has been linked to human genotoxic, embryotoxic, teratogenic, carcinogenic, and mycotoxin nephropathy consequences."[1]
"Numerous human cell lines and animal species have been used to study the toxicity of citrinin, and in tissues, kidney injury and changes in the metabolism of the liver have also been reported. The DNA adduct C-C8dG-OTA was formed as a result of the co-exposure to citrinin and ochratoxin A. Citrinin’s mechanism of action on mitochondrial metabolism has been elucidated, and it has been observed that in the liver and kidney mitochondria of rats, citrinin inhibits several enzymes, including malate dehydrogenase and glutamate dehydrogenase, as well as the ATP synthase complex involved in the respiratory chain. Through the transcription factors Skn7 and Yap1, citrinin has been shown to boost a dose-dependent enhanced expression of GRE2 or SOD2 promoters with stress-sensitive promoter characteristics."[1]
"The toxin affects all the main organs, including the bone marrow, liver, kidney, and mitochondrial respiratory chain. The negative consequences are thought to be caused by altered enzymatic antioxidative responses and the effects of oxidative stress. Altering the gene expression of jun B and tbx2a in Zebrafish causes decreased blood flow and heartbeat, as well as male infertility. Citrinin accelerated apoptotic processes, reduced total cell counts, and interfered with oocyte maturation, fertilization, and embryonic development in mouse blastocysts. Given that citrinin is a common food contaminant found in human food all over the world, it is logical to assume that humans are exposed to it far more frequently than is usually believed. Due to its poisonous, mutagenic, and carcinogenic characteristics, citrinin contamination is one of the biggest hazards to food safety and human health. "[1]
"Citrinin is a secondary metabolite made by some fungal strains, particularly Aspergillus, Penicillium, and MonascusCitri species. This natural poison is extremely prevalent and is mostly found in soil, rotting vegetation, and food storage systems. Due to its poisonous, mutagenic, and carcinogenic characteristics, citrinin contamination is one of the most significant risks to food safety and human health..... Further, citrinin’s potential toxicity in humans was elucidated by an in silico approach based on gene and protein toxicity targets and implicated transcription factors."[1]
".... citrinin is mutagenic, carcinogenic, and hepatotoxic and alters the expression of targets such as the aryl hydrocarbon receptor (AhR), the androgen receptor (AR), and aromatase, a member of the cytochrome P450 superfamily. The aryl hydrocarbon receptor is a transcription factor that is normally inactive, but once it binds to xenobiotics, it alters the gene expression of several enzymes important for differentiation. All three targets together alter the expression of genes involved in differentiation, androgen production, and cancer incidence. Previously, it was shown that mycotoxins activated AhR, which later influenced immunogenicity and epithelial organization during stress and inflammation in an aromatase-dependent manner."[1]
".....Citrinin is predicted to be well absorbed and access the brain (in the egg white) and Pgp nonsubstrate (red dot), and not pumped out of the brain. Furthermore, based on the excellent solubility values, we hypothesize that citrinin could be effectively absorbed orally after food consumption in the small intestine."[1]
"Citrinin, a potential carcinogen, demonstrates its harmful effects through upregulating MAP kinase activity, miRNA transcription, protein kinase B signaling, DNA damage response signal transduction by P53, a stress-activated protein kinase signaling cascade, netrin–UNC5B signaling, and an immunological response. The transcription factors involved were E2F1, HSF1, SIRT1, RELA, NFKB, JUN, and MYC. Citrinin was substantially related to neutrophilia, squamous cell carcinoma, Fanconi anemia, leukemia, hepatoblastoma, and fatty liver disorders. The netrin–UNC5B signaling pathway, lipids and atherosclerosis, thyroid cancer, and modulation of PTEN gene transcription were the top five functional descriptions discovered using data mining on citrinin targets."[1]
"The two basic mechanisms of CIT-mediated harmful effects in biological systems are assumed to be the effects of oxidative stress and altered enzymatic antioxidative responses (e.g., epithelial glutathione and transhydrogenase). In the respiratory chain, CIT has been discovered to promote the creation of reactive oxygen species (ROS) and boost the synthesis of superoxide anions. These bioactivities could explain lipid peroxidation and cell death associated with mitochondrial malfunction. The activation of caspases-3, -6, -7, and -9 has been linked to CIT triggered apoptosis in kidney PK15 cells and human promyelocytic leukemia (HL-60) cells. CIT (108, 324, and 970 ppm) has been shown in several studies to cause harmful consequences in varieties of yeast cells by inducing oxidative stress and upregulating genes from oxidative stress response such as AADs, OYE3, FLR1, GRE2, and MET17."[1]
"CIT has previously been shown to accumulate in the budding yeast mitochondria, and exposure with CIT causes malfunction of respiratory system as well as mitochondrial complex I inhibition. Dysfunction in mitochondria caused by suppression of mitochondrial complex I resulted in superoxide anion (O2−) production. ... CIT treatment (1000 µM) of cells (107 mL−1) for 60 min at pH 4.5 resulted in a considerable rise in peroxides and total ROS as well as a 3-fold increase in glutathione concentration, with no change in superoxide or hydroxyl radical levels. CIT treatment raised ROS levels in hepatocarcinoma HepG2 cells (10–30 µM) for 60 min and in single cells from the murine skin suspensions at 50 µM for 12–72 h. This suggests that CIT-induced ROS generation is required for apoptosis and antioxidant system activation, as well as for adaptive responses, which are mediated through the activation of ROS-sensitive transcription factors. A decrease in GSH due to conjugation with patulin as well as molecular interactions of CIT with the free sulfhydryl groups of integrative membrane proteins lead to cell death. CIT may affect the plasma membrane by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme in a time-dependent, irreversible manner. Long-term exposure to a reductase disrupts the synthesis of the cholesterol/ testosterone (and ergosterol) pathway, resulting in hypocholesterolemia. In acute testing, CIT inhibited growth, cell proliferation, viability, cytotoxicity, and many other measured parameters in a dose- and time-dependent manner, regardless of the kind of cells used. In chronic tests, CIT I inhibited one of the key enzymes involved in cholesterol synthesis (resulting in lower serum testosterone levels and hypocholesterolemia), had multiple immune modulator effects , and caused nephropathy, hepato- and fetotoxicity, and renal adenoma formation in various animal models."[1]
"CIT has been shown to be nephrotoxic and hepatotoxic to humans. The kidney is the major target organ of CIT. CIT is commonly found along with ochratoxin, and an additive or synergic effect has been shown to increase the toxicity, causing kidney disease in humans. Other than the kidney, the target organs of CIT include the liver, mitochondrial respiratory chain, and bone marrow. This nephrotoxin is also considered as one possible reason for porcine nephropathy. In the absence of adequate exposure data, the risk of CIT as a food contaminant was assessed based on an estimate of the critical CIT concentrations in grains and grain-based products that would result in nephrotoxicity. Furthermore, CIT is quickly absorbed and transported, particularly to the liver and kidney. A recent human CIT toxic kinetic study revealed that 40% of CIT was eliminated in the urine, implying that 40% of CIT was absorbed."[2]
"Citrinin, also a ubiquitous environmental contaminant, affects the expression of casp3, TNF, IL10, IL1B, BAG3, CCNB1, CCNE1, and CDC25A genes...........A previous study reported induction of apoptosis in HL-60 cells by stimulating cytochrome c release followed by activation of multiple caspases with citrinin exposure..........Another study reported that low exposure doses of citrinin (10 μg/mL) and gliotoxin (100 ng/mL) inhibited IL-10 and led to an increased risk of an inflammatory response with relative overproduction of TNF-α and IL-6............"[3]
"Citrinin was significantly associated with neutrophilia, squamous cell carcinoma, Fanconi anemia, leukemia, hepatoblastoma, and fatty liver diseases, and the transcription factors implicated were E2F1, HSF1, SIRT1, RELA, NFKB, JUN, and MYC. The top five functional descriptions obtained with data mining on citrinin targets were a cellular response to an organic cyclic compound, the netrin–UNC5B signaling pathway, lipids and atherosclerosis, thyroid cancer, and regulation of PTEN gene transcription. In mammalian cells, the stress-activated protein kinases (SAPKs), including RK/p38/CSBP kinase, and c-Jun N-terminal kinase (JNK), all together play very important roles in response to environmental stresses. Upon activation, these stress-related protein kinases phosphorylate and activate the transcription factors ATF2, c-Jun, and Elk-1, to respond to the stress."[3]
“Previously, a possible mechanism was hypothesized for quercetin protection against CCL4 toxicity in the rat brain. The NF-κB pathway has long been recognized as a classic proinflammatory signaling pathway. Increased NF-B activity indirectly encourages the development of neutrophil extracellular traps (NET), one of neutrophils’ antimicrobial defense mechanisms. It has been demonstrated that Sirtuin 1 (SIRT1) binds to HSF1 and controls the acetylation status of HSF1 to act as a regulator of HSF1 DNA-binding activity. Taken together, our results showed that citrinin toxicity mechanisms are attenuated via attenuation of the top five stress-related pathways in a protein kinase-, NF-κB-, and SIRT1-dependent manner, and that RELA, JUN, and MYC are involved in this process."[3]
Additional Details on Gliotoxin
"Numerous studies have suggested that the toxicity of ETP toxins and gliotoxin in particular may be, in part, underpinned by redox cycling of the disulphide bridge which can generate damaging reactive oxygen species (ROS) and drive the formation of mixed disulphide bonds with host proteins (Chai and Waring, 2000). Although gliotoxin was first characterized in the fungal genus Gliocladium (Weindling and Emerson, 1936; Weindling, 1941), the fungus most closely associated with gliotoxin is A. fumigatus, which causes a range of life-threatening respiratory and systemic infections in patients with compromised immunity. Gliotoxin is detectable in the serum of patients with IA and in the lungs and serum of mice with experimentally induced IA (Lewis et al., 2005) suggesting an association with active infection."[4]
"The germination of A. fumigatus conidia and subsequent invasion into the respiratory epithelium is a critical step which promotes infection. Gliotoxin promotes cytoskeletal remodeling in human alveolar epithelial cells in vitro which facilitates the internalization of A. fumigatus conidia. Fungal burdens present in the lung tissue of immunosuppressed mice infected with an A. fumigatus gliPΔ mutant unable to produce gliotoxin were significantly reduced compared with wild-type fungus, and the invasive capacity of the gliPΔ mutant was partially restored following the addition of exogenous gliotoxin which correlated with increased mortality. .....The application of gliotoxin or exhausted culture medium from wild-type A. fumigatus but not a gliotoxin-defective mutant induces apoptosis in human bronchial epithelial cells, and in murine fibroblasts and alveolar epithelial cells in a c-Jun N-terminal kinase (JNK) pathway-dependent manner."[4]
"Gliotoxin induces apoptosis and cytoskeletal changes that affect macrophage function. Macrophages exposed to 0.3–3 μM gliotoxin in vitro undergo DNA fragmentation and apoptosis within 5 h."[4]
"Recent research has highlighted a critical role for macrophages in toxin surveillance and the maintenance of barrier function in the distal colon. Murine colonocytes are protected from the toxicity of gliotoxin, T-2 toxin and candidalysin by a population of CD11chigh subepithelial macrophages which form specialized “balloon-like” protrusions (BLPs) in response to local fungi, and use them to interact with the distal colonic epithelium where they limit the absorption of toxic materials. Strikingly, in mice that are depleted for these macrophages, the distal colonic epithelium continues to absorb toxin-containing fluids and undergoes apoptosis concomitant with a loss of barrier integrity. These observations suggest that the BLPs enable colonic epithelial cells to differentiate between harmless and harmful substances and identify CD11chigh subepithelial macrophages as central mediators of colonic barrier function and local responses to fungal toxins in vivo."[4]
"Neutrophils play a major role in the control of fungal infection. Human neutrophils treated with concentrations (92–306 nM) of gliotoxin found in the blood of patients with IA were unable to phagocytose zymosan or serum-opsonised zymosan and exhibited cytoskeletal re-organization. Similarly, isolated polymorphonuclear leukocytes exposed to 107 nM gliotoxin exhibited reduced production of ROS within 30 min"[4]
"The production of neutrophil extracellular traps (NETs) occurs in response to the presence of invading fungi that are too large to be phagocytosed, and the NADPH oxidative burst promotes the formation of NETs in an in vivo model of pulmonary aspergillosis. Gliotoxin has been shown to inhibit assembly of the NADPH oxidase in human neutrophils."[4]
"In vivo, immunosuppressed neutropenic mice infected with an A. fumigatus ΔgliZ mutant unable to produce gliotoxin exhibited a non-significant improvement in survival after seven days when compared with wild-type controls. Additionally, a significant increase in the survival of neutropenic mice was observed following disruption of the A. fumigatus transcriptional regulator LaeA, which was associated with decreased production of gliotoxin and an increased susceptibility to phagocytosis. No difference in survival was observed between groups of neutropenic mice infected with wild-type A. fumigatus conidia or a ΔgliP mutant unable to produce gliotoxin. In contrast, immunosuppressed, non-neutropenic mice infected with the same strains exhibited significantly improved survival. Indeed, a ΔgliP mutant unable to produce gliotoxin exhibited attenuated virulence in non-neutropenic murine models of invasive pulmonary aspergillosis, but exhibited normal virulence in models rendered neutropenic. These observations suggest that non-neutropenic mice are more susceptible to the effects of gliotoxin in a model of IA and highlight neutrophils as a primary target of the toxin."[4]
"Dendritic cells are capable of innate recognition of pathogens and also present antigens to naive T cells during adaptive immunity. Gliotoxin (0.1 μM) induced caspase-3 activation and apoptosis in CD83+ monocyte-derived dendritic cells while concentrations between 0.15 and 1.5 μM inhibited human T cell function in vitro."[4]
"Nuclear factor kappa-B (NF-κB) signaling plays a role in numerous aspects of innate immunity including immune cell survival and the production of pro-inflammatory M1 macrophages. Multiple studies have demonstrated that gliotoxin targets NF-κB signaling to promote immune suppression.
“Treatment of Jurkat T cells with 306 nM gliotoxin abolished NF-κB signaling by preventing the degradation of the regulatory subunit IκB-α. NF-κB is also implicated in gliotoxin-induced apoptosis of eosinophils. Eosinophils that received TNF-α and 306 nM gliotoxin stabilised IκB-α, resulting in NF-κB inhibition, a significant increase in apoptosis and a decrease in the production of IL-8."[4]
A Word of Encouragement
If you would like to review your genetics, nutrition, or discuss testing options for citrinin or gliotoxin, please contact me to set up an appointment. I encourage you to explore the references listed below for additional context and details. Of all the mycotoxins, Citrinin and Gliotoxin have much less research related to detoxification and biotransformation.
References:
1. Food Toxicity of Mycotoxin Citrinin and Molecular Mechanisms of Its Potential Toxicity Effects through the Implicated Targets Predicted by Computer-Aided Multidimensional Data Analysis. Seema Zargar, Conceptualization, Formal analysis1,* and Tanveer A. Wani2Life (Basel). 2023 Apr; 13(4): 880. Published online 2023 Mar 26. doi: 10.3390/life13040880
2. Citrinin Mycotoxin Contamination in Food and Feed: Impact on Agriculture, Human Health, and Detection and Management Strategies. By Madhu Kamle, Dipendra Kumar Mahato. Toxins 2022, 14(2), 85; https://doi.org/10.3390/toxins14020085
3. Food Toxicity of Mycotoxin Citrinin and Molecular Mechanisms of Its Potential Toxicity Effects through the Implicated Targets Predicted by Computer-Aided Multidimensional Data Analysis. Seema Zargar, Conceptualization, Formal analysis1,* and Tanveer A. Wani. Life (Basel). 2023 Apr; 13(4): 880. Published online 2023 Mar 26. doi: 10.3390/life13040880
4. Fungal Toxins and Host Immune Responses. Rhys Brown , Emily Priest. Front. Microbiol., 13 April 2021. Sec. Microbial Immunology. Volume 12 - 2021 | https://doi.org/10.3389/fmicb.2021.643639
5. Cytochrome P450 mediates the formation of four new citrinin metabolites