My discovery that capsaicin blocks my hayfever has led me into other avenues of investigation:
1: Proc Natl Acad Sci U S A. 2007 Jun 12;104(24):10146-51. Epub 2007 Jun 4. Links
Central histamine H3 receptor signaling negatively regulates susceptibility to autoimmune inflammatory disease of the CNS.Teuscher C, Subramanian M, Noubade R, Gao JF, Offner H, Zachary JF, Blankenhorn EP.
Departments of Medicine and Pathology, University of Vermont, Burlington, VT 05405, USA.
c.teuscher@uvm.edu
Histamine (HA), a biogenic amine with a broad spectrum of activities in both physiological and pathological settings, plays a key regulatory role in experimental allergic encephalomyelitis, the autoimmune model of multiple sclerosis. HA exerts its effect through four G protein-coupled receptors designated HA receptor H1, H2, H3, and H4. We report here that, compared with wild-type animals, mice with a disrupted HA H3 receptor (H3RKO), the expression of which is normally confined to cells of the nervous system, develop more severe disease and neuroinflammation. We show that this effect is associated with dysregulation of blood-brain barrier permeability and increased expression of MIP-2, IP-10, and CXCR3 by peripheral T cells. Our data suggest that pharmacological targeting of the H3R may be useful in preventing the development and formation of new lesions in multiple sclerosis, thereby significantly limiting the progression of the disease.
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1: J Immunol. 2006 Jan 1;176(1):17-26. Links
A key regulatory role for histamine in experimental autoimmune encephalomyelitis: disease exacerbation in histidine decarboxylase-deficient mice.Musio S, Gallo B, Scabeni S, Lapilla M, Poliani PL, Matarese G, Ohtsu H, Galli SJ, Mantegazza R, Steinman L, Pedotti R.
Immunology and Muscular Pathology Unit, National Neurological Institute "C. Besta," Milan, Italy.
Histamine can modulate the cytokine network and influence Th1 and Th2 balance and Ab-isotype switching. Thus, pharmacological blockade or genetic deletion of specific histamine receptors has been shown to reduce the severity of experimental autoimmune encephalomyelitis (EAE), a prototypic Th1-mediated disease with similarities to human multiple sclerosis. To study the comprehensive contribution of endogenous histamine to the expression of EAE, we attempted to induce EAE in histidine decarboxylase-deficient mice, which are genetically unable to make histamine. In this study, we show that EAE is significantly more severe in HDC-/-, histamine-deficient mice, with diffuse inflammatory infiltrates, including a prevalent granulocytic component, in the brain and cerebellum. Unlike splenocytes from wild-type mice, splenocytes from HDC-/- mice do not produce histamine in response to the myelin Ag, whereas production of IFN-gamma, TNF, and leptin are increased in HDC-/- splenocytes in comparison to those from wild-type mice. Endogenous histamine thus appears to regulate importantly the autoimmune response against myelin and the expression of EAE, in this model, and to limit immune damage to the CNS. Understanding which receptor(s) for histamine is/are involved in regulating autoimmunity against the CNS might help in the development of new strategies of treatment for EAE and multiple sclerosis.
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capsaicin modulates histamine release in stressed rats:
1: Neurosci Lett. 1999 Aug 6;270(3):181-4. Links
Activation of sensory nerves participates in stress-induced histamine release from mast cells in rats.Huang ZL, Mochizuki T, Watanabe H, Maeyama K.
Department of Pharmacology, Ehime University School of Medicine, Onsen-gun, Japan.
To elucidate the mechanism by which stress induces rapid histamine release from mast cells, Wistar rats, pretreated as neonates with capsaicin, were subjected to immobilization stress for 2 h, and histamine release was measured in paws of anesthetized rats by using in vivo microdialysis after activation of sensory nerves by electrical or chemical stimulation. Immobilization stress studies indicated that in control rats stress induced a 2.7-fold increase in the level of plasma histamine compared to that in freely moving rats. Whereas pretreatment with capsaicin significantly decreased stress-induced elevation of plasma histamine. Microdialysis studies showed that electrical stimulation of the sciatic nerve resulted in a 4-fold increase of histamine release in rat paws. However, this increase was significantly inhibited in rats pretreated with capsaicin. Furthermore, injection of capsaicin into rat paw significantly increased histamine release in a dose-dependent manner. These results suggest that activation of sensory nerves participates in stress-induced histamine release from mast cells.
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1: Adv Exp Med Biol. 2007;601:423-30.Links
Mast cells, T cells, and inhibition by luteolin: implications for the pathogenesis and treatment of multiple sclerosis.Theoharides TC, Kempuraj D, Iliopoulou BP.
Department of Pharmacology, Internal Medicine and Biochemistry, Immunology Program, Tufts University School of Medicine, Tufts-New England Medical Center, Boston, MA, USA.
theoharis.theoharides@tufts.edu
Multiple sclerosis (MS) is a demyelinating disease of the central nervous system (CNS) mainly mediated by Th1, but recent evidence indicates that Th2 T cells, mostly associated with allergic reactions, are also involved. Mast cells are involved in allergic and inflammatory reactions because they are located perivascularly and secrete numerous proinflammatory cytokines. Brain mast cells are critically placed around the blood-brain barrier (BBB) and can disrupt it, a finding preceding any clinical or pathological signs of MS. Moreover, mast cells are often found close to MS plaques, and the main MS antigen, myelin basic protein (MBP), can activate human cultured mast cells to release IL-8, TNF-alpha, tryptase, and histamine. Mast cells could also contribute to T cell activation since addition of mast cells to anti-CD3/anti-CD28 activated T cells increases T cell activation over 30-fold. This effect requires cell-to-cell contact and TNF, but not histamine or tryptase. Pretreatment with the flavone luteolin totally blocks mast cell stimulation and T cell activation. Mast cells could constitute a new unique therapeutic target for MS.
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1: Neurology. 2006 Feb 28;66(4):572-5. Links
Allergy, histamine 1 receptor blockers, and the risk of multiple sclerosis.Alonso A, Jick SS, Hernán MA.
Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA.
aalogut@alumni.unav.es
BACKGROUND: It is unclear whether allergic diseases are associated with multiple sclerosis (MS), but histamine 1 receptor blockers, used in the treatment of allergic conditions, decreased the severity of experimental autoimmune encephalomyelitis (an animal model of MS). OBJECTIVE: To assess the association of allergy history and use of histamine 1 receptor blockers with the risk of MS. METHODS: Using a case-control study nested in the United Kingdom-based General Practice Research Database cohort, the authors identified 163 incident cases of MS with at least 3 years of follow-up before their first symptoms (index date). Up to 10 controls matched to the cases by age, sex, general practice, and time in the cohort were selected. Previous history of allergic disease and use of histamine 1 receptor blockers in the 3 years before the index date were assessed through computerized medical records. RESULTS: History of any allergic condition in the 3 years before the index date was not associated with MS risk (adjusted odds ratio [OR] 1.2, 95% CI 0.8 to 1.
. However, use of sedating histamine 1 receptor blockers was associated with decreased MS risk (adjusted OR 0.2, 95% CI 0.1 to 0.
. CONCLUSION: These results do not support a strong link between allergic conditions and multiple sclerosis (MS) risk but suggest a possible beneficial effect of antihistamines on the onset of MS.
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1: Int J Immunopathol Pharmacol. 2005 Oct-Dec;18(4):771-8.Links
A pilot, open label, clinical trial using hydroxyzine in multiple sclerosis.Logothetis L, Mylonas IA, Baloyannis S, Pashalidou M, Orologas A, Zafeiropoulos A, Kosta V, Theoharides TC.
Department of Neurology, Aristotle University, AHEPA Hospital, Thessaloniki, Greece.
Multiple sclerosis (MS) is an autoimmune disorder of myelin destruction. Blood-brain-barrier (BBB) disruption precedes pathological or clinical findings and could involve mediators from perivascular brain mast cells, such as histamine and vascular endothelial growth factor (VEGF). Mast cells could be activated by many triggers, including acute stress that has been correlated with MS exacerbations. We considered that the histamine-1 (H1) receptor antagonist hydroxyzine, which also partially inhibits brain mast cells and has anxiolytic properties, may reduce MS symptoms. This open label, pilot, clinical trial investigated the effect on MS of an oral solution of hydroxyzine (100 mg per day), together with caffeine (200 mg per day) to reduce sedation. Twenty patients (8 males; 12 females) with relapsing-remitting or relapsing-progressive MS completed the study (12 +/- 1 months) and were evaluated using disability scales. Most patients on hydroxyzine (75%) remained stable or improved neurologically and all but one showed improved mood. Hydroxyzine could be used as an adjuvant in MS, but the small number of patients enrolled and the short duration of the study precludes any definitive conclusions. A double-blind, placebo-controlled study is warranted.
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1: Proc Natl Acad Sci U S A. 2003 Feb 18;100(4):1867-72. Epub 2003 Feb 7. Links
Multiple elements of the allergic arm of the immune response modulate autoimmune demyelination.Pedotti R, DeVoss JJ, Youssef S, Mitchell D, Wedemeyer J, Madanat R, Garren H, Fontoura P, Tsai M, Galli SJ, Sobel RA, Steinman L.
Department of Neurology and Neurological Science, Stanford University Medical Center, Stanford, CA 94305, USA.
Analysis of mRNA from multiple sclerosis lesions revealed increased amounts of transcripts for several genes encoding molecules traditionally associated with allergic responses, including prostaglandin D synthase, histamine receptor type 1 (H1R), platelet activating factor receptor, Ig Fc epsilon receptor 1 (Fc epsilon RI), and tryptase. We now demonstrate that, in the animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), mediated by T helper 1 (Th1) T cells, histamine receptor 1 and 2 (H1R and H2R) are present on inflammatory cells in brain lesions. Th1 cells reactive to myelin proteolipid protein expressed more H1R and less H2R than Th2 cells. Pyrilamine, an H1R antagonist, blocked EAE, and the platelet activating factor receptor antagonist CV6209 reduced the severity of EAE. EAE severity was also decreased in mice with disruption of the genes encoding Ig Fc gamma RIII or both Fc gamma RIII and Fc epsilon RI. Prostaglandin D synthase and tryptase transcripts were elevated in EAE brain. Taken together, these data reveal extensive involvement of elements of the immune response associated with allergy in autoimmune demyelination. The pathogenesis of demyelination must now be viewed as encompassing elements of both Th1 responses and "allergic" responses.
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From wikipedia, pyrilamine is an old (off-patent?) anti-histamine!
Mepyramine (INN, also known as pyrilamine) [1] is a first generation antihistamine, targeting the H1 receptor. However, it rapidly permeates the brain and so often causes drowsiness as a side effect.
It is used in over-the-counter combination products for colds and menstrual symptoms.[2]
Side effects may include sedation/drowsiness, muscle weakness, and insomnia.
upregulating histamine receptor 2 may be another useful tack:
1: Neuroreport. 2002 Aug 7;13(11):1407-10. Links
Activation of histamine H2 receptors ameliorates experimental allergic encephalomyelitis.Emerson MR, Orentas DM, Lynch SG, LeVine SM.
Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
Experimental allergic encephalomyelitis (EAE), a model of multiple sclerosis, is an autoimmune, demyelinating disease of the CNS. Pro-inflammatory cytokines (e.g. tumour necrosis factor-alpha (TNF-alpha) and interleukin (IL)-12) and reactive oxygen species are implicated in promoting EAE. Since histamine H(2) receptor activation suppresses production of O(2)*-, TNF-alpha, and IL-12 by inflammatory cells, we tested the hypothesis that dimaprit, an H(2) agonist, would reduce the clinical severity and pathology of EAE. Dimaprit treatment significantly reduced clinical signs compared to vehicle in both C57BL/6 and iNOS deficient EAE mice. Furthermore, dimaprit significantly reduced CNS staining for lectin-positive macrophages and decreased extravasated albumin staining, an indicator of blood-brain barrier leakage. These data provide a rationale for exploring H2 receptor activation for therapeutic value in multiple sclerosis.
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Somewhere above there's an abstract which shows that capsaicin dramatically reduces mast cells in rats and this might be useful;
1: Int J Immunopharmacol. 2000 Sep;22(9):673-84. Links
Hydroxyzine inhibits experimental allergic encephalomyelitis (EAE) and associated brain mast cell activation.Dimitriadou V, Pang X, Theoharides TC.
Department of Pharmacology and Experimental Therapeutics, Tufts University School of Medicine, Boston, MA 02111, USA.
Experimental allergic encephalomyelitis (EAE) has been used as an animal model for the human demyelinating disease multiple sclerosis (MS). In acute MS or EAE, early disruption in the integrity of the blood-brain-barrier (BBB) precedes brain infiltration by inflammatory cells or any clinical evidence of disease. BBB permeability could be affected by vasoactive mediators and cytokines released from perivascular brain mast cells. We investigated the number and degree of activation of brain mast cells in EAE and the effect of the heterocyclic histamine-1 receptor antagonist hydroxyzine, a piperazine compound known to also block mast cells. Acute EAE was induced in Lewis rats by immunization with whole guinea pig spinal cord homogenate and complete Freund's adjuvant (CFA). A second group of animals were treated orally with hydroxyzine for one day before immunization and then continuously for 14 days. Control rats were treated with CFA or hydroxyzine alone. The clinical progression of EAE was assessed on days 10, 12 and 14 after immunization. The number of metachromatic mast cells and the degree of degranulation was assessed in the thalamus with light microscopy. At day 14, there was a three-fold increase in the number of brain mast cells with EAE, as compared to controls. These cells were positive for the immunoglobulin E binding protein (FcepsilonRI), while those from control rats were not. Over 40% of all thalamic mast cells studied in EAE showed partial staining or extruded secretory granule indicative of secretion. Hydroxyzine treatment inhibited (p<0.05) the progression and severity of EAE by 50% and the extent of mast cell degranulation by 70% (p<0.05). These findings indicate that brain mast cells are associated with EAE development and that inhibition of their activation correlates positively with the clinical outcome.
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