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Patient questions: Is mast cell disease autoimmune?

Autoimmune disease is when your body has an abnormal immune response to something that is a normal part of the body. There are more than eighty currently identified autoimmune diseases and they affect a significant population worldwide. At least 2% of women are estimated to have at least one autoimmune condition. Multiple sclerosis, rheumatoid arthritis and lupus are examples of autoimmune disease. Autoimmune diseases can affect small areas or multiple organs or targets throughout the body.

There are a number of possible causes of autoimmune disease. Some well supported theories include:
1. Molecular mimicry. This occurs when the body is exposed to an external danger and direct antibodies and immune defense against this danger. However, once the danger has been resolved, the antibodies and immune defense are directed toward damaging some normal part of the body that by happenstance looks like the dangerous thing. A classic example of this is development of rheumatic fever, PANDAS and other complications after a Streptococcus infection. The body makes antibodies to fight Strep, the Strep is killed and infection resolved, but the antibodies then attack things in the body that look like strep to the antibodies.
2. Genetic predisposition. Mutations and improper expression of genes that mediate tolerance, like HLA genes, can result in autoimmune disease. In these patients, these anomalies cause the body to fail to recognize itself as “safe”.
3. Cryptic determinants. This refers to the situation in which a hidden part of a normal structure in the body is not usually “seen” by the rest of the body. When that hidden part is exposed to the rest of the body, the immune system does not recognize it and attacks it, thinking it is dangerous. I imagine this as a waterway in a year of drought. A river has many small black rocks on the bottom. When the water is high, like most years, you cannot see these rocks. In a year of drought, the water level drops and you can the black rocks on the bottom. They were always a natural part of the riverbed, and they were always there, you just couldn’t see them. This can happen inside the body too. Sometimes your immune system sees things that were always there but not seen by it before.

The key feature unifying autoimmune diseases is that the immune system directly targets a part of the body that is normal and healthy. In lupus, the body makes antibodies that target the DNA inside our cells, which is not just normal but critically important to survival. It doesn’t target defective DNA, it targets regular old, keeps us alive, DNA.

Mast cell diseases are not autoimmune diseases. Mast cell diseases are not directly their attacks to a normal, healthy part of the body. In mast cell disease, mast cells are dysregulated and behave inappropriately. While this can damage parts of the body, this damage occurs due to the general inflammatory environment rather than because mast cells specifically targeted those parts of the body. Aberrant mast cells aren’t saying, “Quick, there’s an intruder in the liver! Let’s go get them!” when it’s just your regular liver hanging out. They are just so activated that mediator release could damage some cells in the liver, and in other places at the same time. The mast cell activation does not specifically target the liver in this scenario.

A confusing aspect of mast cell disease is that MCAS can occur secondary to autoimmune disease and many MCAS patients have autoimmune disease. In this patient population, the MCAS is probably induced by the inflammation caused by the autoimmune disease. Even still, while the primary autoimmune disease targets specific parts of the body, MCAS does not target specific parts of the body to attempt to destroy them.

Interplay between mast cells and hormones: Part 5 of 8

Hormone Location released Major functions Interaction with mast cells Reference
Inhibin Testes, ovaries, placenta, pituitary Inhibits production of FSH No known interaction with mast cells
Insulin Pancreas Promotes transfer of glucose from blood to liver and muscle

Promotes production of glycogen in liver

Promotes liberation of glucose stores in liver

 Increases growth and survival of mast cells

Increases degranulation and mediator release

 Lessmann E, et al. Insulin and insulin-like growth factor-1 promote mast cell survival via activation of the phosphatidylinositol-3-kinase pathway. Experimental Hematology 2006: 34(11), 1532-1541.
Insulin like growth factor Liver Modulates cell growth and development

Behaves like insulin

 Increases growth and survival of mast cells

Increases degranulation and mediator release

 Lessmann E, et al. Insulin and insulin-like growth factor-1 promote mast cell survival via activation of the phosphatidylinositol-3-kinase pathway. Experimental Hematology 2006: 34(11), 1532-1541.
Leptin Adipose tissue Decrease of appetite Activates inflammatory cells and T cell responses

Increases production of TNF, IL-2 and IL-6

Decreases mediator production due to activation of IgE receptor

Suppresses secretion of ghrelin

 Taildeman J, et al. Human mast cells express leptin and leptin receptors. Histochem Cell Biol 2009: 131(6), 703-711.
Luteinizing hormone (LH) Pituitary Stimulates ovulation and formation of corpus luteum

Stimulates testosterone production

 Histamine decreases LH release by acting at H1 receptor.

Histamine increases release of luteinizing hormone releasing hormone (LHRH), also by acting at H1 receptor.

 Miayke A, et al. Involvement of H1 histamine receptor in basal and estrogen-stimulated luteinizing hormone-releasing hormone secretion in rats in vitro. Neuroendocrinology 1987: 45(3), 191-196.

Pontiroli AE, et al. The effect of histamine and H1 and H2 receptors on prolactin and luteinizing hormone release in humans: sex differences and the role of stress. J Clin Endocrinol Metab 1981: 52(5), 924-928.
Melanocyte stimulating hormone (MSH) Pituitary Stimulates melanin production and release

Increases during pregnancy

 MSH can induce apoptosis in mast cells

Dose dependent increase in histamine relief, but not in IL-1, IL-6, IL-8, TGFb or TNF

 Sarkar A, et al. alpha-Melanocyte-stimulating hormone induces cell death in mast cells: involvement of NF-kappaB. FEBS Lett 2003: 549(1-3), 87-93.

Grutzkau A, et al. alpha-Melanocyte stimulating hormone acts as a selective inducer of secretory functions in human mast cells. Biochem Biophys Res Commun 2000: 278(1), 14-19.
Melatonin Pineal gland, immune system Induces sleep and lowers body temperature Mast cells produce and release melatonin regardless of activation state Maldonado MD, et al. Evidence of melatonin synthesis and release by mast cells. Possible modulatory role on inflammation. Pharmacol Res 2010: 62(3), 282-287.

 

Interplay between mast cells and hormones: Part 4 of 8

Hormone Location released Major functions Interaction with mast cells Reference
Ghrelin Stomach, jejunum, duodenum, colon, brain, lungs, liver, adipose tissue, placenta, lymphatic system Stimulate appetite

Can cross BBB

 Induced mast cell degranulation

Dose dependently induced histamine release

Inhibits many inflammatory molecules, like TNF, IL-8, MCP-1, IL-1b, IL-6, CRP, IL-12, VCAM-1, MMP2, MMP9, GM-CSF and IL-17

Opposes action of leptin, a mast cell mediator

Level is increased by lack of sleep, promoting excessive hunger.

 Hirayama T, et al. Ghrelin and obestatin promote the allergic action in rat peritoneal mast cells as basic secretagogues. Peptides 2010: 31(11), 2109-2113.

Baatar D, et al. The effects of ghrelin on inflammation and the immune system. Molecular and Cellular Endocrinology 2011: 340(1), 44-58.
Glucagon Pancreas Regulates amount of available glucose

Triggers breakdown of glycogen and production of glucose in liver, raising blood sugar

Released when blood sugar is too low

Can increase level of cAMP in myocardium to overcome effect of beta blockers

Anecdotal reports that glucagon may be able to relax esophagus sphincter to pass impacted food

 

 

 In anaphylaxis patients on beta blockers, glucagon can be used to reduce resistance to epinephrine and increase blood pressure

May be considered to treat Kounis Syndrome where epinephrine is contraindicated

Histamine H3 receptor may regulate glucagon release from pancreas

 

 Nakamura T, et al. Role of histamine H3 receptor in glucagon secreting aTC1.6 cells. FEBS Open Bio 2015: 5, 36-41.

Thomas M, Crawford I. Glucagon infusion in refractory anaphylactic shock in patients on beta blockers. Emerg Med J 2005: 22, 272-276.
Glucagon-like peptide 1 (GLP-1) Small intestine Increases release of insulin and nausea

Decreases release of glucagon, desire to eat and amount of food consumed

Increases anxiety

 

 Possible relationship   between GLP-1 and histamine in the brain, but still unclear

GLP-1 level is modulated by leptin, a mast cell mediator Increases ACTH and cortisol

 Gotoh K, et al. Glucagon-like peptide-1, corticotropin-releasing hormone, and hypothalamic neuronal histamine interact in the leptin-signaling pathway to regulate feeding behavior. FASEB J 2005: 19(9), 1131-1133.
Gonadotropin releasing hormone Hypothalamus Stimulate FSH and LH release from pituitary

Part of HPG axis

Drive secondary sex characteristics

Regulate sex hormone release

 Histamine induces GnRH release in some studies Noris G, et al. Histamine directly stimulates gonadotropin-releasing hormone secretion from GT1-1 cells via H1 receptors coupled to phosphoinositide hydrolysis. Endrocrinology 1995: 136(7), 2967-2974.
Growth hormone releasing hormone Hypothalamus Stimulate growth hormone release from pituitary

Regulates bone growth

Regulates metabolism of proteins, carbohydrates and lipids

 Induces mast cell degranulation and release of serotonin and histamine, causing low blood pressure Macia RA, et al. Hypotension induced by growth hormone releasing peptide is mediated by mast cell serotonin release in the rat. Toxicology and Applied Pharmacology 1990: 104(3), 403-410.
Hepcidin Liver Decreases iron absorption in intestines

Decreases iron release by macrophages

 Chronic inflammation causes elevated hepcidin, making iron less available. This is called anemia of chronic inflammation. Weiss G. Anemia of chronic disorders: new diagnostic tools and new treatment strategies. Seminars in Hematology 2015: 52(4), 313-320.
Human chorionic gonadotropin (HCG) Placenta Maintains hormone release in ovaries during pregnancy

Inhibition of immune defense against fetus

 Not known to directly affect mast cell activation or histamine release Schumacher A, et al. Endocrine factors modulating immune responses in pregnancy. Front Immunol 2014: 5, 196.

 

Interplay between mast cells and hormones: Part 3 of 8

Hormone Location released Major functions Interaction with mast cells Reference
Dopamine Hypothalamus

Adrenal gland (medulla)

 Inhibit prolactin released from pituitary

Increase heart rate and blood pressure

Inhibit norepinephrine release

 

 

 Enhances mast cell degranulation

Perpetuates immediate and late phase hypersensitivity reactions

H3 receptor activation inhibits dopamine production

Dopamine is released by mast cells

H1 inverse agonists increase dopamine release

Histamine increases dopamine release

 Mori T, et al. D1-like dopamine receptors antagonist inhibits cutaneous immune reactions mediated by Th2 and mast cells. Journal of Dermatological Science 2013: 71, 37-44.

Xue L, et al. The effects of D3R on TLR4 signaling involved in the regulation of METH-mediated mast cell activation. International Immunopharmacology 2016: 36. 187-198.
Endothelin Stomach Promotes smooth muscle contraction of stomach

Very potent vasoconstrictor

 Activates mucosal mast cells

Mast cells regulate endothelin levels to prevent loss of blood flow to tissues

 Boros M, et al. Endothelin-1 induces mucosal mast cell degranulation and tissue injury via ETA receptors. Clin Sci (Lond) 2007: 103(48), 31S-34S.

Hultner L, Ehrenreich H. Mast cells and endothelin-1: a life-saving biological liaison. Trends Immunol 2005: 26(5), 235-238.

 
Epinephrine/ adrenaline Adrenal gland (medulla), sympathetic nervous system Fight or flight response

Increases heart rate, force of heart contraction, blood pressure, energy breakdown, production of ACTH, bloodflow and energy to the brain and muscles

Suppresses nonessential functions and significantly decreases GI motility and excretion of urine and stool

 Epinephrine inhibits IgE mediated released of histamine, prostaglandins and TNF

Epinephrine inhibits mast cell proliferation, adhesion and movement within the body SCF reduces action of epinephrine on mast cells by decreasing B2 adrenergic receptors

 

 

 Cruse G, et al. Counterregulation of beta(2)-adrenoceptor function in human mast cells by stem cell factor. J Allergy Clin Immunol 2010: 125(1), 257-263.

Scanzano A, Cosentino M. Adrenergic regulation of innate immunity: a review. Front Pharmacol 2015.
Erythropoietin Kidney Stimulate red blood cell production

Protects nerve cells and tissues

 During low oxygen events, mast cells express receptors for erythropoietin

Erythropoietin can bind at the CKIT receptor

Decreases inflammatory response to infection (decreases IL-6 and TNF)

 Wiedenmann T, et al. Erythropoietin acts as an anti-inflammatory signal on murine mast cells. Mol Immunol 2015: 65(1), 68-76.
Estradiol and other estrogens Ovaries, placenta, adipose tissue, testes Drive female secondary sex characteristics

Increase metabolism, uterine and endometrial growth, bone production, and the release of cholesterol in bile

Increase production of proteins in liver, cortisol, sex hormone binding globulin, somatostatin, clotting factors II, VII, IX, X, antithrombin III and plasminogen, HDL, triglycerides

Decrease LDL, production of adipose tissue, GI motility

 

 

Modulate salt and water retention

Inhibits programmed cell death of germ cells

 E2 is a very potent mast cell degranulator

E2 drives mast cell degranulation in ovaries to trigger ovulation

Enhances IgE mediated degranulation

Increased production of leukotrienes

Increases mast cell density in ovaries

 Zaitsu M, et al. Estradiol activates mast cells via a non-genomic estrogen receptor-a and calcium influx. Mol Immunol 2007: 44(8), 1977-1985.

Zierau O, et al. Role of female sex hormones, estradiol and progesterone, in mast cell behavior. Front Immunol 2012: 3, 169.
Follicle stimulating hormone (FSH) Pituitary Stimulates maturation of ovarian follicles

Stimulates maturation of seminiferous tubules, production of sperm and production of androgen binding protein

 Triggers mast cell degranulation

Increases mast cell density in ovaries

 Theoharides TC, Stewart JM. Genitourinary mast cells and survival. Transl Androl Urol 2015: 4(5), 579-586.

Jaiswal K, Krishna A. Effects of hormones on the number, distribution and degranulation of mast cells in the ovarian complex of mice. Acta Physiol Hung 1996: 84(2), 183-190.
Gastric inhibitory polypeptide/ glucose-dependent insulinotropic polypeptide (GIP) Duodenum, jejunum Triggers release of insulin

Involved in fatty acid metabolism

Involved in bone formation

 May suppress release of stomach acid triggered by histamine McIntosh CHS, et al. Chapter 15 Glucose-Dependent Insulinotropic Polypeptide (Gastric Inhibitory Polypeptide; GIP). Vitamins & Hormones 2009: 80, 409-471.
Gastrin Stomach, duodenum, pancreas Release of gastric acid

Release of pepsinogen, the precursor to pepsin

Triggers secretion of pancreatic enzyme

Triggers emptying of gallbladder

Increases stomach motility

 Triggers release of histamine in enterochromaffin-like cells to trigger gastric acid secretion

Triggers mast cell degranulation

Gastrin releasing peptide, which induces gastrin release, triggers histaminergic itching response

 Akiyama T, et al. Roles of glutamate, substance P, and gastrin-releasing peptide as spinal neurotransmitters of histaminergic and nonhistaminergic itch. Pain 2014: 155, 80-92.

 

Mood disorders and inflammation: Neurologic effects and treatment (Part 4 of 4)

TNF blockers like Enbrel and infliximab can lower depression independent of improvements with physical symptoms. 62% of patients with treatment resistant depression saw improvement on infliximab versus 33% with standard therapies. Infliximab also improved sleep, allowing patients to stay asleep longer. Infliximab successfully improved depression symptoms in patients with inflammatory disease as well as controls who had elevated CRP and TNF but not on controls with normal CRP and TNF. Patients who were not effectively treated with SSRIs were found to have higher IL-6 and TNF.

Chronic inflammation can cause structural and functional changes in the brain, interfering with its ability to make new connections and damaging existing function. Activation of microglial cells in the nervous system is associated with maladaptive behaviors and decreased brain function seen in bipolar disorder, major depressive disorder and other mood conditions. They also protect neurologic function in multiple sclerosis, Huntington’s and Alzheimer’s. Minocycline, an antibiotic, also has significant anti-inflammatory and neuroprotective effects.

In some encephalitis models, DMARDs can actually restore stem cells of the nervous system, reducing tissue and myelin damage. DMARDs, often used for autoimmune diseases, improve mood symptoms in rheumatoid arthritis patients. They can also mitigate hyperactivity from amphetamines. Clinical trials are currently investigating the full effects of these medications on psychiatric conditions.

Mood stabilizers often have anti-inflammatory effects. In bipolar disorder patients, lithium and valproate decreased IL-6. Medications that act on serotonin and dopamine receptors decrease production of inflammatory molecules like TNF, IL-6 and PGE2. Escitalopram, an SSRI antidepressant, can decrease cortisol production and IL-11.  ACTH production can be induced by fluoxetine.

References:

Furtado M, Katzman MA. Examining the role of neuroinflammation in major depression. Psychiatry Research 2015: 229, 27-36.

Rosenblat JD, et al. Inflamed moods: a review of the interactions between inflammation and mood disorders. Progress in Neuro-Psychopharmacology & Biological Psychiatry 2014; 53, 23-34.

Clinical trial data for midostaurin (PKC412) in advanced systemic mastocytosis has been published

Hey, everyone –

I know a lot of people have been waiting with bated breath for the outcome of the trial assessing the use of midostaurin (PKC412) in advanced systemic mastocytosis (a term describing aggressive systemic mastocytosis, mast cell leukemia, and systemic mastocytosis with associated clonal hematologic non-mast cell lineage disease).

A press release described the outcome of the phase II trial. Read it here.

Data from the phase II trial was also published. Read it here.

Please note that because of my job, I cannot answer questions about this medication.

The effects of cortisol on mast cells: Part 3 of 3

In some cases, glucocorticoids can immediately treat issues with immune activation. This immediate action is not well understood.  In animal models, glucocorticoids can stop allergic reactions in five minutes and significantly decrease short term histamine release. Mostly though, glucocorticoids mitigate mast cell activation through delayed actions. This is one of the reasons why premedication with steroids prior to surgery or procedures is recommended to start the day before.

Glucocorticoids affect gene expression, which is one of the reasons they take time to work. Gene expression is very complicated and is highly regulated by cells. Genes are part of your DNA. Think of each gene as a message.  When your cell wants to make something using a gene, like a protein, it makes a copy of the message in the gene and then takes it to another part of the cell to make the protein. There are many molecules that affect how easy it is to make something from a gene.  Some molecules make it easier and others make it harder.  Transcription factors are molecules that sit by genes that make it easier for their message to be made. Interfering with making the message and getting it to the part of the cell where it can make something, like the protein, can drastically alter the behavior of a cell.

One of the major ways that glucocorticoids interfere with making the message is with glucocorticoid receptors. Many people know that receptors are often on the outside of a cell and they are activated when a molecule fits into the receptor like a key into a lock.  Glucocorticoid receptors do not work like that.  They are small molecules inside cells that are changed when glucocorticoids bind to them.

Cortisol, or other glucocorticoids, bind to the glucocorticoid receptors inside mast cells. When this happens, they interfere with the transcription factors so it is really hard to use the genes. Some of these transcription factors are called NF-kB and AP-1.  When glucocorticoid receptors have been activated in the mast cell, the transcription factors can’t help to use the genes.

Cytokines are molecules that cells use to “talk” to each other. Another kind of signal.  Glucocorticoids directly interfere with use of cytokine genes so that they aren’t made.  Mast cells make many cytokines and they are responsible for a lot of late phase allergic symptoms.  Manufacture of IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, GM-CSF, TNF and IFN-g (interferon gamma) can all be suppressed with glucocorticoids.

If the cytokine genes have already been used, glucocorticoids can still prevent them from being made. When you use a gene to make something, it creates a messenger RNA (mRNA) that carries the message.  If the mRNA falls apart, nothing will be made from the gene. Glucocorticoids make the messages fall apart before making anything for many cytokines, including IL-1, IL-2, IL-6, IL-8, TNF and GM-CSF.

References:

Oppong E, et al. Molecular mechanisms of glucocorticoid action in mast cells. Molecular and Cellular Endocrinology 2013: 380, 119-126.

Varghese R, et al. Association among stress, hypocortisolism, systemic inflammation and disease severity in chronic urticaria. Ann Allergy Asthma Immunol 2016: 116, 344-348.

Zappia CD, et al. Effects of histamine H1 receptor signaling on glucocorticoid receptor activity. Role of canonical and non-canonical pathways. Scientific Reports 2015: 5.

Coutinho AE, Chapman KE. The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights. Mol Cell Endocrinol 2011: 335(1), 2-13.

Sinniah A, et al. The role of the Annexin-A1/FPR2 system in the regulation of mast cell degranulation provoked by compound 48/80 and in the inhibitory action of nedocromil. International Immunopharmacology 2016: 32, 87-95.

Mood disorders and inflammation: Inflammatory conditions and treatment (Part 3 of 4)

A number of inflammatory conditions coincide with mood disorders. Women with chronic health issues who pursue diagnosis are commonly labeled as having anxiety and the physical symptoms as a result of that. However, there is a significant body of evidence pointing to mood disorders as being organic symptoms of the inflammation rather than the psychological reaction to the changes that come with chronic illness. What we often frame as behavioral or psychiatric symptoms are perceived by some researchers as “sickness behavior” that promotes healing. Low energy, appetite and mood, along with sleeping more, redirect energy from less important functions to immune defense or wound repair.

Patients with autoimmune disease, diabetes, metabolic syndrome, asthma and allergies all experience mood disorders. Psoriasis dramatically increases the frequency of depressive symptoms. Cardiovascular disease patients are more likely to have major depressive disorder or bipolar disorder than the general population. Major depressive disorder increases risk of coronary artery and poorer prognosis with cardiovascular disease.

In one study with ISM and CM patients, 75% reported symptoms of depression. In a different study, 60% reported depressive symptoms and anxiety. Asthma and wheezing are independently associated with major depressive episodes in a massive study with almost 250,000 people from 57 countries.

Depression patients who have attempted suicide show increased TNF and IL-6, along with low IL-2, compared to depression patients who have not attempted suicide. Elevated CRP is also associated with depression. Alexithymia, in which the patient feels no emotions, affects 39-46% of patients with major depressive disorder. These patients also demonstrate very high CRP levels which can decrease cognitive functions.

Treatment of chronic illnesses can also improve associated mood disorders. Aspirin is currently being trialed as a treatment for bipolar disorder. Use of aspirin with an SSRI produced better response than just the SSRI.  Use of COX-2 inhibitors like celecoxib with antidepressants improves symptoms and decreases levels of IL-6 and IL-1b. NSAIDs, which also interfere with COX-2, reduce depression when compared to placebo.

Omega-3 polyunsaturated fatty acids have been found to be potent antidepressants. These molecules also decrease the production of prostaglandins and cytokines. Omega-3 polyunsaturated fatty acids interfere with the COX-2 enzyme that produces prostaglandins.  Curcumin also decreases cytokine production, as well as normalizing activity from the HPA axis and improving mood.

References:

Furtado M, Katzman MA. Examining the role of neuroinflammation in major depression. Psychiatry Research 2015: 229, 27-36.

Rosenblat JD, et al. Inflamed moods: a review of the interactions between inflammation and mood disorders. Progress in Neuro-Psychopharmacology & Biological Psychiatry 2014; 53, 23-34.

Effect of vitamin D on mast cells

Vitamin D is an essential fat soluble vitamin that functions as a hormone. Its primary function is to promote intestinal absorption of calcium, magnesium, phosphate, iron and zinc. It also has a variety of anti-inflammatory and immunoregulatory effects. Deficiency of vitamin D3 has been linked previously to a number of inflammatory conditions, like asthma, diabetes mellitus, eczema and other atopic disorders.

A significant portion of vitamin D is produced in the skin when exposed to sunlight. The precursor 7-dehydrocholesterol in the skin is changed to form cholecalciferol, vitamin D3, when irradiated with UVB light. In the liver, cholecalciferol (vitamin D3) is metabolized to form 25-dihydroxyvitamin D3. In the kidney, it is further metabolized to 1,25-dihydroxyvitamin D3. Vitamin D2 and D3 supplements may also be taken orally.  They will be processed by the liver in a similar fashion. Vitamin D3 is much more active than vitamin D2.

Vitamin D3 can exert a number of effects on mast cells. Though the mechanism is unclear, vitamin D3 seems to regulate the action of COX, the enzyme that produces prostaglandins.  Accordingly, vitamin D3 can disrupt prostaglandin production.

It interferes with the production of cytokines, and chemokines, including Il-1, IL-6, IL-33, and TNF. It inhibits release of IL-6 and CRP.  It is thought that vitamin D affects the stability of the mRNA for these molecules.  This means that the genes for these molecules are not being used appropriately and so they cannot be made.

Vitamin D3 can also induce production of anti-inflammatory mediators. IL-4 and IL-10 are mast cell mediators that regulate inflammation.  Vitamin D3 is required for their production and release.  IL-10 can mitigate inflammation resulting from IgE activation.  A single application of vitamin D3 to the skin decreased the immediate skin response to an IgE allergen.  It decreased production of leukotrienes and histamine.  Mast cells have vitamin D receptors (VDRs) inside their cells and close to where the genes are stored.  Mast cell VDRs must be present to see these effects.

Long term use of vitamin D3 (30-40 days) was found to cause mast cell apoptosis (programmed cell death) in a cell model. Vitamin D3 also directly impeded the differentiation and maturation of mast cell precursors.

There is a lot we do not know about how vitamin D3 interacts with mast cells but it is generally considered to have an anti-inflammatory and anti-allergic effect.

References:

Yip KH, et al. Mechanisms of vitamin D3 metabolite repression of IgE-dependent mast cell activation. Journal of Allergy and Clinical Immunology 2014: 13395), 1356-1364.e14

Conti P, Kempuraj D. Impact of vitamin D on mast cell activity, immunity and inflammation. Journal of Food and Nutrition Research 2016: 4(1), 33-39.

The effects of cortisol on mast cells: Part 2 of 3

Glucocorticoids, like cortisol, can affect mast cells in many ways. As I discussed in my previous post, there are many ways for mast cells to release mediators when activated. In all of these pathways, there are many molecules involved that carry the signal, like people passing the Olympic torch. In mast cells, one of the molecules that suppresses inflammatory activation signal is called SLAP (yes, really).  Cortisol increases the amount of SLAP in mast cells so inflammatory activation signals are suppressed.

An important step in degranulation is changing the amount of calcium inside the cell and moving it to different parts of the cell. In some studies, glucocorticoids can affect this movement of calcium. Other studies have found that in some pathways, glucocorticoids don’t affect calcium movement, but instead interfere with things like the IgE receptor.

Cortisol is also thought to directly inhibit stem cell factor (SCF) binding to the CKIT receptor. When SCF binds to the CKIT receptor, this sends a signal to the mast cell to stay live.  This means that taking glucocorticoids can let mast cells die at the appropriate time. SCF also tells mast cells to go to inflamed spaces.  By blocking this signal, glucocorticoids suppress inflammation.

One of the ways that molecules carry a signal is by changing the next molecule in the pathway. A big way that cells changing molecules is by chopping off a piece of them called a phosphate group.  This is done by special enzymes called phosphatases.  Glucocorticoids affect the availability of phosphatases so they aren’t able to get to the right part of the cell to carry the signal.  When this happens, there is less activation and less histamine release.

Arachidonic acid is the molecule modified to make eicosanoids (leukotrienes, thromboxanes and prostaglandins.) Glucocorticoids directly interfere with the production of these molecules in multiple ways.  The first way is by interfering with COX-2, one of the enzymes that makes prostaglandins.  Another way is by preventing arachidonic acid from being released to a place where they can be turned into leukotrienes, thromboxanes and prostaglandins.  This occurs because glucocorticoids increase the amount of a powerful anti-inflammatory molecule called annexin-I.  Annexin-I inhibits the molecule that releases the arachidonic acid, called phospholipase A2.

Annexin-I was the subject of an important paper earlier this year. In trying to identify exactly how mast cell stabilizers like ketotifen and cromolyn work, the researchers discovered that treatment with mast cell stabilizers decreased degranulation and increased annexin-I made by mast cells.  They also found that glucocorticoids had the same effect.

References:

Oppong E, et al. Molecular mechanisms of glucocorticoid action in mast cells. Molecular and Cellular Endocrinology 2013: 380, 119-126.

Varghese R, et al. Association among stress, hypocortisolism, systemic inflammation and disease severity in chronic urticaria. Ann Allergy Asthma Immunol 2016: 116, 344-348.

Zappia CD, et al. Effects of histamine H1 receptor signaling on glucocorticoid receptor activity. Role of canonical and non-canonical pathways. Scientific Reports 2015: 5.

Coutinho AE, Chapman KE. The anti-inflammatory and immunosuppressive effects of glucocorticoids, recent developments and mechanistic insights. Mol Cell Endocrinol 2011: 335(1), 2-13.

Sinniah A, et al. The role of the Annexin-A1/FPR2 system in the regulation of mast cell degranulation provoked by compound 48/80 and in the inhibitory action of nedocromil. International Immunopharmacology 2016: 32, 87-95.