Corticotropin-releasing hormone induces skin vascular permeability through a neurotensin-dependent process

Association between augmented levels of the gut pro-hormone Proneurotensin and subclinical vascular damage

Elevated levels of the gut pro-hormone Proneurotensin (proNT) have been found to predict development of cardiovascular disease. However, it is still unknown whether higher proNT levels are associated with subclinical vascular damage. Herein, we investigated the relationship between higher proNT concentrations and augmented pulse pressure (PP) and carotid intima-media thickness (cIMT), indicators of increased arterial stiffness and subclinical atherosclerosis, respectively. Clinical characteristics, PP and cIMT were evaluated in 154 non-diabetic individuals stratified into tertiles according to fasting serum proNT concentrations. We found that, subjects with higher proNT levels exhibited a worse lipid profile and insulin sensitivity, increased C-reactive protein levels, along with higher values of PP and cIMT as compared to the lowest proNT tertile. Prevalence of elevated PP (≥ 60 mmHg) and subclinical carotid atherosclerosis (IMT > 0.9 mm) was increased in the highest tertile of proNT. In a logistic regression analysis adjusted for several confounders, subjects with higher proNT levels displayed a fivefold raised risk of having elevated PP values (OR 5.36; 95%CI 1.04-27.28; P = 0.05) and early carotid atherosclerosis (OR 4.81; 95%CI 1.39-16.57; P = 0.01) as compared to the lowest proNT tertile. In conclusion, higher circulating levels of proNT are a biomarker of subclinical vascular damage independent of other atherosclerotic risk factors.

Mast cells in the autonomic nervous system and potential role in disorders with dysautonomia and neuroinflammation

Mast cells (MC) are ubiquitous in the body, and they are critical for not only in allergic diseases but also in immunity and inflammation, including having potential involvement in the pathophysiology of dysautonomias and neuroinflammatory disorders. MC are located perivascularly close to nerve endings and sites such as the carotid bodies, heart, hypothalamus, the pineal gland, and the adrenal gland that would allow them not only to regulate but also to be affected by the autonomic nervous system (ANS). MC are stimulated not only by allergens but also many other triggers including some from the ANS that can affect MC release of neurosensitizing, proinflammatory, and vasoactive mediators. Hence, MC may be able to regulate homeostatic functions that seem to be dysfunctional in many conditions, such as postural orthostatic tachycardia syndrome, autism spectrum disorder, myalgic encephalomyelitis/chronic fatigue syndrome, and Long-COVID syndrome. The evidence indicates that there is a possible association between these conditions and diseases associated with MC activation. There is no effective treatment for any form of these conditions other than minimizing symptoms. Given the many ways MC could be activated and the numerous mediators released, it would be important to develop ways to inhibit stimulation of MC and the release of ANS-relevant mediators.

The peripheral corticotropin releasing factor family's role in vasculitis

Corticotropin releasing factor family peptides (CRF peptides) include 4 members, corticotropin releasing hormone (CRH), Urocortin (UCN1), UCN2 and UCN3. CRF peptides function via the two distinct receptors, CRF1 and CRF2. Among them, CRH/CRF1 has been recognized to influence immunity/inflammation peripherally. Both pro- and anti-inflammatory effects of CRH are reported. Likewise, UCNs, peripherally in cardiovascular system have been documented to have both potent protective and harmful effects, with UCN1 acting on both CRF1 & CRF2 and UCN2 & UCN3 on CRF2. We and others also observe protective and detrimental effects of CRF peptides/receptors on vasculature, with the latter of predominantly higher incidence, i.e., they play an important role in the development of vasculitis while in some cases they are found to counteract vascular inflammation. The pro-vasculitis effects of CRH & UCNs include increasing vascular endothelial permeability, interrupting endothelial adherens & tight junctions leading to hyperpermeability, stimulating immune/inflammatory cells to release inflammatory factors, and promoting angiogenesis by VEGF release while the anti-vasculitis effects may be just the opposite, depending on many factors such as different CRF receptor types, species and systemic conditions. Furthermore, CRF peptides' pro-vasculitis effects are found to be likely related to cPLA2 and S1P receptor signal pathway. This minireview will focus on summarizing the peripheral effects of CRF peptides on vasculature participating in the processes of vasculitis.

Mast Cells in Autism Spectrum Disorder-The Enigma to Be Solved?

Autism Spectrum Disorder (ASD) is a disturbance of neurodevelopment with a complicated pathogenesis and unidentified etiology. Many children with ASD have a history of "allergic symptoms", often in the absence of mast cell (MC)-positive tests. Activation of MCs by various stimuli may release molecules related to inflammation and neurotoxicity, contributing to the development of ASD. The aim of the present paper is to enrich the current knowledge on the relationship between MCs and ASD by discussing key molecules and immune pathways associated with MCs in the pathogenesis of autism. Cytokines, essential marker molecules for MC degranulation and therapeutic targets, are also highlighted. Understanding the relationship between ASD and the activation of MCs, as well as the involved molecules and interactions, are the main points contributing to solving the enigma. Key molecules, associated with MCs, may provide new insights to the discovery of drug targets for modeling inflammation in ASD.

Neurotensin counteracts hair growth inhibition induced by chronic restraint stress

Stress has been considered as a potential trigger for hair loss through the neuroendocrine-hair follicle (HF) axis. Neurotensin (NTS), a neuropeptide, is known to be dysregulated in the inflammatory-associated skin diseases. However, the precise role of NTS in stress-induced hair loss is unclear. To investigate the function and potential mechanisms of NTS in stress-induced hair growth inhibition, we initially detected the expression of neurotensin receptor (Ntsr) and NTS in the skin tissues of stressed mice by RNA-sequencing and ELISA. We found chronic restraint stress (CRS) significantly decreased the expression of both NTS and Ntsr in the skin tissues of mice. Intracutaneous injection of NTS effectively counteracted CRS-induced inhibition of hair growth in mice. Furthermore, NTS regulated a total of 1093 genes expression in human dermal papilla cells (HDPC), with 591 genes being up-regulated and 502 genes being down-regulated. GO analysis showed DNA replication, cell cycle, integral component of plasma membrane and angiogenesis-associated genes were significantly regulated by NTS. KEGG enrichment demonstrated that NTS also regulated genes related to the Hippo signalling pathway, axon guidance, cytokine-cytokine receptor interaction and Wnt signalling pathway in HDPC. Our results not only uncovered the potential effects of NTS on stress-induced hair growth inhibition but also provided an understanding of the mechanisms at the gene transcriptional level.

Neurotensin and Neurotensin Receptors in Stress-related Disorders: Pathophysiology & Novel Drug Targets

Neurotensin (NT) is a 13-amino acid neuropeptide widely distributed in the CNS that has been involved in the pathophysiology of many neural and psychiatric disorders. There are three known neurotensin receptors (NTSRs), which mediate multiple actions, and form the neurotensinergic system in conjunction with NT. NTSR1 is the main mediator of NT, displaying effects in both the CNS and the periphery, while NTSR2 is mainly expressed in the brain and NTSR3 has a broader expression pattern. In this review, we bring together up-to-date studies showing an involvement of the neurotensinergic system in different aspects of the stress response and the main stress-related disorders, such as depression and anxiety, post-traumatic stress disorder (PTSD) and its associated symptoms, such as fear memory and maternal separation, ethanol addiction, and substance abuse. Emphasis is put on gene, mRNA, and protein alterations of NT and NTSRs, as well as behavioral and pharmacological studies, leading to evidence-based suggestions on the implicated regulating mechanisms as well as their therapeutic exploitation. Stress responses and anxiety involve mainly NTSR1, but also NTSR2 and NTSR3. NTSR1 and NTSR3 are primarily implicated in depression, while NTSR2 and secondarily NTSR1 in PTSD. NTSR1 is interrelated with substance and drug abuse and NTSR2 with fear memory, while all NTSRs seem to be implicated in ethanol consumption. Some of the actions of NT and NTSRs in these pathological settings may be driven through interactions between NT and corticotrophin releasing factor (CRF) in their regulatory contribution, as well as by NT's pro-inflammatory mediating actions.

Potential Role of Moesin in Regulating Mast Cell Secretion

Mast cells have existed for millions of years in species that never suffer from allergic reactions. Hence, in addition to allergies, mast cells can play a critical role in homeostasis and inflammation via secretion of numerous vasoactive, pro-inflammatory and neuro-sensitizing mediators. Secretion may utilize different modes that involve the cytoskeleton, but our understanding of the molecular mechanisms regulating secretion is still not well understood. The Ezrin/Radixin/Moesin (ERM) family of proteins is involved in linking cell surface-initiated signaling to the actin cytoskeleton. However, how ERMs may regulate secretion from mast cells is still poorly understood. ERMs contain two functional domains connected through a long α-helix region, the N-terminal FERM (band 4.1 protein-ERM) domain and the C-terminal ERM association domain (C-ERMAD). The FERM domain and the C-ERMAD can bind to each other in a head-to-tail manner, leading to a closed/inactive conformation. Typically, phosphorylation on the C-terminus Thr has been associated with the activation of ERMs, including secretion from macrophages and platelets. It has previously been shown that the ability of the so-called mast cell "stabilizer" disodium cromoglycate (cromolyn) to inhibit secretion from rat mast cells closely paralleled the phosphorylation of a 78 kDa protein, which was subsequently shown to be moesin, a member of ERMs. Interestingly, the phosphorylation of moesin during the inhibition of mast cell secretion was on the N-terminal Ser56/74 and Thr66 residues. This phosphorylation pattern could lock moesin in its inactive state and render it inaccessible to binding to the Soluble NSF attachment protein receptors (SNAREs) and synaptosomal-associated proteins (SNAPs) critical for exocytosis. Using confocal microscopic imaging, we showed moesin was found to colocalize with actin and cluster around secretory granules during inhibition of secretion. In conclusion, the phosphorylation pattern and localization of moesin may be important in the regulation of mast cell secretion and could be targeted for the development of effective inhibitors of secretion of allergic and inflammatory mediators from mast cells.

Effect of Allergen-Specific Immunotherapy on Transcriptomic Changes in Canine Atopic Dermatitis

Canine atopic dermatitis (cAD) is a genetic, chronic, and recurrent inflammatory and pruritic skin disorder. Allergen-specific immunotherapy (ASIT) is presently recognized as the only clinically effective disease-modifying treatment for allergies. The aim of our study was to analyze the changes in gene expression observed in the peripheral blood nuclear cells of cAD patients subjected to ASIT. Blood samples designated for transcriptomic analyses were collected from AD dogs twice, before and six months after ASIT, and also from healthy dogs. Statistical analysis revealed 521 differentially expressed transcripts, among which 241 transcripts represented genes with well-described functions. Based on the available literature, we chose nine differentially expressed genes (RARRES2, DPP10, SLPI, PLSCR4, MMP9, NTSR1, CBD103, DEFB122, and IL36G) which may be important in the context of the dysregulated immune response observed in cAD patients. The expressions of five out of the nine described genes (DPP10, PLSCR4, NTSR1, DEFB122, and IL36G) changed after the application of ASIT. The expressions of three of these genes returned to the level observed in the healthy control group. The genes listed above need further investigation to determine details of their role in the molecular mechanism of immune tolerance induction in response to allergen-specific immunotherapy.

Role of SARS-CoV-2 Spike-Protein-Induced Activation of Microglia and Mast Cells in the Pathogenesis of Neuro-COVID

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). About 45% of COVID-19 patients experience several symptoms a few months after the initial infection and develop post-acute sequelae of SARS-CoV-2 (PASC), referred to as "Long-COVID," characterized by persistent physical and mental fatigue. However, the exact pathogenetic mechanisms affecting the brain are still not well-understood. There is increasing evidence of neurovascular inflammation in the brain. However, the precise role of the neuroinflammatory response that contributes to the disease severity of COVID-19 and long COVID pathogenesis is not clearly understood. Here, we review the reports that the SARS-CoV-2 spike protein can cause blood-brain barrier (BBB) dysfunction and damage neurons either directly, or via activation of brain mast cells and microglia and the release of various neuroinflammatory molecules. Moreover, we provide recent evidence that the novel flavanol eriodictyol is particularly suited for development as an effective treatment alone or together with oleuropein and sulforaphane (ViralProtek®), all of which have potent anti-viral and anti-inflammatory actions.

Mast Cell Cytokines in Acute and Chronic Gingival Tissue Inflammation: Role of IL-33 and IL-37

Much evidence suggests autoimmunity in the etiopathogenesis of periodontal disease. In fact, in periodontitis, there is antibody production against collagen, DNA, and IgG, as well as increased IgA expression, T cell dysfunction, high expression of class II MHC molecules on the surface of gingival epithelial cells in inflamed tissues, activation of NK cells, and the generation of antibodies against the azurophil granules of polymorphonuclear leukocytes. In general, direct activation of autoreactive immune cells and production of TNF can activate neutrophils to release pro-inflammatory enzymes with tissue damage in the gingiva. Gingival inflammation and, in the most serious cases, periodontitis, are mainly due to the dysbiosis of the commensal oral microbiota that triggers the immune system. This inflammatory pathological state can affect the periodontal ligament, bone, and the entire gingival tissue. Oral tolerance can be abrogated by some cytokines produced by epithelial cells and activated immune cells, including mast cells (MCs). Periodontal cells and inflammatory-immune cells, including mast cells (MCs), produce cytokines and chemokines, mediating local inflammation of the gingival, along with destruction of the periodontal ligament and alveolar bone. Immune-cell activation and recruitment can be induced by inflammatory cytokines, such as IL-1, TNF, IL-33, and bacterial products, including lipopolysaccharide (LPS). IL-1 and IL-33 are pleiotropic cytokines from members of the IL-1 family, which mediate inflammation of MCs and contribute to many key features of periodontitis and other inflammatory disorders. IL-33 activates several immune cells, including lymphocytes, Th2 cells, and MCs in both innate and acquired immunological diseases. The classic therapies for periodontitis include non-surgical periodontal treatment, surgery, antibiotics, anti-inflammatory drugs, and surgery, which have been only partially effective. Recently, a natural cytokine, IL-37, a member of the IL-1 family and a suppressor of IL-1b, has received considerable attention for the treatment of inflammatory diseases. In this article, we report that IL-37 may be an important and effective therapeutic cytokine that may inhibit periodontal inflammation. The purpose of this paper is to study the relationship between MCs, IL-1, IL-33, and IL-37 inhibition in acute and chronic inflamed gingival tissue.

Neurotensin and xenin stimulates pancreatic exocrine secretion through the peripheral cholinergic nerves in conscious sheep

The present study aimed to clarify the effects of neurotensin and xenin on pancreatic exocrine secretion in conscious sheep and their mechanism of actions. The animals were equipped with two silastic cannulae in the common bile duct to separately collect pancreatic fluid and bile, and a silastic cannula in the proximal duodenum to continuously return the mixed fluids. NT and xenin were intravenously injected at range of 0.01-3.0 nmol/kg during the phase I of duodenal migrating motor complex. A single intravenous NT injection significantly and dose-dependently increased pancreatic fluid, protein, and bicarbonate outputs. The effect of NT at 1 nmol/kg was completely inhibited by a background intravenous infusion of atropine methyl nitrate at a dose of 10 nmol/kg/min, however, the effect was not altered by a prior injection of the neurotensin receptor subtype (NTR)-1 antagonist SR 48692 at 60 nmol/kg. Moreover, a single intravenous xenin-25 injection significantly and dose-dependently increased pancreatic fluid and protein output, whereas the effect of xenin-25 did not clearly show dose-dependence. The prior SR 48692 injection at 30 nmol/kg did not significantly alter the effects of xenin-25 at 0.3 nmol/kg, while the atropine infusion significantly inhibited the increase in fluid secretion. Under the atropine infusion, xenin-25 at 0.3 nmol/kg did not increase protein and bicarbonate outputs, whereas the inhibitory effect of the atropine was not significant compared to that of the single injection of xenin-25. A single intravenous injection of NTR-2 agonist levocabastine at 0.1-3 nmol/kg did not alter pancreatic exocrine secretion. These results suggest that both NT and xenin-25 effectively stimulates pancreatic exocrine secretion through the peripheral cholinergic system in sheep and that NTR-2 is not involved in the regulation of pancreatic exocrine secretion, however, we did not precisely determine the role of NTR-1 in the actions of both the peptides on pancreatic exocrine secretion.

Transient Opening of the Blood-Brain Barrier by Vasoactive Peptides to Increase CNS Drug Delivery: Reality Versus Wishful Thinking?

BACKGROUND

The blood-brain barrier inhibits the central nervous system penetration of 98% of small molecule drugs and virtually all biologic agents, which has limited progress in treating neurologic disease. Vasoactive peptides have been shown in animal studies to transiently disrupt the blood-brain barrier and regadenoson is currently being studied in humans to determine if it can improve drug delivery to the brain. However, many other vasoactive peptides could potentially be used for this purpose.

METHODS

We performed a review of the literature evaluating the physiologic effects of vasoactive peptides on the vasculature of the brain and systemic organs. To assess the likelihood that a vasoactive peptide might transiently disrupt the blood-brain barrier, we devised a four-tier classification system to organize the available evidence.

RESULTS

We identified 32 vasoactive peptides with potential blood-brain barrier permeabilityaltering properties. To date, none of these are shown to open the blood-brain barrier in humans. Twelve vasoactive peptides increased blood-brain barrier permeability in rodents. The remaining 20 had favorable physiologic effects on blood vessels but lacked specific information on permeability changes to the blood-brain barrier.

CONCLUSION

Vasoactive peptides remain an understudied class of drugs with the potential to increase drug delivery and improve treatment in patients with brain tumors and other neurologic diseases. Dozens of vasoactive peptides have yet to be formally evaluated for this important clinical effect. This narrative review summarizes the available data on vasoactive peptides, highlighting agents that deserve further in vitro and in vivo investigations.

Varied Composition and Underlying Mechanisms of Gut Microbiome in Neuroinflammation

The human gut microbiome has been implicated in a host of bodily functions and their regulation, including brain development and cognition. Neuroinflammation is a relatively newer piece of the puzzle and is implicated in the pathogenesis of many neurological disorders. The microbiome of the gut may alter the inflammatory signaling inside the brain through the secretion of short-chain fatty acids, controlling the availability of amino acid tryptophan and altering vagal activation. Studies in Korea and elsewhere highlight a strong link between microbiome dynamics and neurocognitive states, including personality. For these reasons, re-establishing microbial flora of the gut looks critical for keeping neuroinflammation from putting the whole system aflame through probiotics and allotransplantation of the fecal microbiome. However, the numerosity of the microbiome remains a challenge. For this purpose, it is suggested that wherever possible, a fecal microbial auto-transplant may prove more effective. This review summarizes the current knowledge about the role of the microbiome in neuroinflammation and the various mechanism involved in this process. As an example, we have also discussed the autism spectrum disorder and the implication of neuroinflammation and microbiome in its pathogenesis.

Corticotropin releasing hormone promotes inflammatory bowel disease via inducing intestinal macrophage autophagy

Psychosocial stress is a vital factor contributing to the pathogenesis and progression of inflammatory bowel disease (IBD). The contribution of intestinal macrophage autophagy to the onset and development of IBD has been widely studied. Herein, we investigated the underlying mechanism of psychosocial stress in an IBD mouse model pertaining to macrophage autophagy. Corticotropin releasing hormone (CRH) was peripherally administrated to induce psychosocial stress. For in vivo studies, dextran sulfate sodium (DSS) was used for the creation of our IBD mouse model. For in vitro studies, lipopolysaccharide (LPS) was applied on murine bone marrow-derived macrophages (BMDMs) as a cellular IBD-related challenge. Chloroquine was applied to inhibit autophagy. We found that CRH aggravated the severity of DSS-induced IBD, increasing overall and local inflammatory reactions and infiltration. The levels of autophagy in intestinal macrophages and murine BMDMs were increased under these IBD-related inflammatory challenges and CRH further enhanced these effects. Subsequent administration of chloroquine markedly attenuated the detrimental effects of CRH on IBD severity and inflammatory reactions via inhibition of autophagy. These findings illustrate the effects of peripheral administration of CRH on DSS-induced IBD via the enhancement of intestinal macrophage autophagy, thus providing a novel understanding as well as therapeutic target for the treatment of IBD.

Between two storms, vasoactive peptides or bradykinin underlie severity of COVID-19?

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to be a world-wide pandemic with overwhelming socioeconomic impact. Since inflammation is one of the major causes of COVID-19 complications, the associated molecular mechanisms have been the focus of many studies to better understand this disease and develop improved treatments for patients contracting SARS-CoV-2. Among these, strong emphasis has been placed on pro-inflammatory cytokines, associating severity of COVID-19 with so-called "cytokine storm." More recently, peptide bradykinin, its dysregulated signaling or "bradykinin storm," has emerged as a primary mechanism to explain COVID-19-related complications. Unfortunately, this important development may not fully capture the main molecular players that underlie the disease severity. To this end, in this focused review, several lines of evidence are provided to suggest that in addition to bradykinin, two closely related vasoactive peptides, substance P and neurotensin, are also likely to drive microvascular permeability and inflammation, and be responsible for development of COVID-19 pathology. Furthermore, based on published experimental observations, it is postulated that in addition to ACE and neprilysin, peptidase neurolysin (Nln) is also likely to contribute to accumulation of bradykinin, substance P and neurotensin, and progression of the disease. In conclusion, it is proposed that "vasoactive peptide storm" may underlie severity of COVID-19 and that simultaneous inhibition of all three peptidergic systems could be therapeutically more advantageous rather than modulation of any single mechanism alone.

Neurolysin substrates bradykinin, neurotensin and substance P enhance brain microvascular permeability in a human in vitro model

Increased brain microvascular permeability and disruption of blood-brain barrier (BBB) function are among hallmarks of several acute neurodegenerative disorders, including stroke. Numerous studies suggest the involvement of bradykinin (BK), neurotensin (NT) and substance P (SP) in BBB impairment and oedema formation after stroke; however, there is paucity of data in regard to the direct effects of these peptides on the brain microvascular endothelial cells (BMECs) and BBB. The present study aimed to evaluate the direct effects of BK, NT and SP on the permeability of BBB in an in vitro model based on human induced pluripotent stem cell (iPSC)-derived BMECs. Our data indicate that all three peptides increase BBB permeability in a concentration-dependent manner in an in vitro model formed from two different iPSC lines (CTR90F and CTR65M) and widely used hCMEC/D3 human BMECs. The combination of BK, NT and SP at a sub-effective concentration also resulted in increased BBB permeability in the iPSC-derived model indicating potentiation of their action. Furthermore, we observed abrogation of BK, NT and SP effects with pretreatment of pharmacological blockers targeting their specific receptors. Additional mechanistic studies indicate that the short-term effects of these peptides are not mediated through alteration of tight-junction proteins claudin-5 and occludin, but likely involve redistribution of F-actin and secretion of vascular endothelial growth factor. This is the first experimental study to document the increased permeability of the BBB in response to direct action of NT in an in vitro model. In addition, our study confirms the expected but not well-documented, direct effect of SP on BBB permeability and adds to the well-recognised actions of BK on BBB. Lastly, we demonstrate that peptidase neurolysin can neutralise the effects of these peptides on BBB, suggesting potential therapeutic implications.

The impact of psychological stress on mast cells

OBJECTIVE

Atopic diseases worsen with psychological stress, but how stress contributes to their pathogenesis is still not clear. We review the evidence supporting the premise that stress contributes to allergic and inflammatory processes through stimulation of mast cells (MCs) by neuroimmune stimuli.

DATA SOURCES

PubMed was searched between 1950 and 2019 using the following terms: allergies, atopic diseases, corticotropin-releasing hormone, inflammation, hypothalamic-pituitary-adrenal axis, mast cells, mastocytosis, neuropeptides, psychological stress, neurotensin, and substance P.

STUDY SELECTIONS

Only articles published in English were selected based on their relevance to stress and MCs, especially those that discussed potential mechanisms of action.

RESULTS

Psychological stress worsens many diseases, especially asthma, atopic dermatitis, and mastocytosis. This effect is mediated through MCs stimulated by neuropeptides, especially corticotropin-releasing hormone, neurotensin, and substance P, a process augmented by interleukin-33.

CONCLUSION

Understanding how stress stimulates MCs to release proinflammatory mediators is important in advancing treatments for diseases that worsen with stress.

Effect of Stress on Neuroimmune Processes

PURPOSE

Psychological stress worsens many diseases, especially those with inflammatory components, such as atopic dermatitis (AD) and autism spectrum disorder (ASD), conditions that are significantly correlated in large epidemiologic studies. However, how stress contributes to these conditions is still poorly understood. This narrative review of the relevant literature advances the premise that stress affects inflammatory processes in AD and ASD via stimulation of mast cells (MCs).

METHODS

MEDLINE was searched between 1980 and 2019 using the terms allergies, atopic dermatitis, autism spectrum disorder, brain, corticotropin-releasing hormone, inflammation, hypothalamic-pituitary-adrenal axis, mast cells, neuropeptides, stress, neurotensin, and substance P.

FINDINGS

Exposure to psychological stress is associated with onset and/or exacerbation of AD and ASD. This association could be attributable to activation of MCs, which are ubiquitous in the body, including the brain, and could contribute to inflammation.

IMPLICATIONS

Understanding and addressing the connection between stress and MCs is important in clarifying the pathogenesis and developing effective treatments for diseases that worsen with stress and involve inflammation, such as AD and ASD.

Injury of Muscular but not Cutaneous Nerve Drives Acute Neuropathic Pain in Rats

Acute pain is a common complication after injury of a peripheral nerve but the underlying mechanism is obscure. We established a model of acute neuropathic pain via pulling a pre-implanted suture loop to transect a peripheral nerve in awake rats. The tibial (both muscular and cutaneous), gastrocnemius-soleus (muscular only), and sural nerves (cutaneous only) were each transected. Transection of the tibial and gastrocnemius-soleus nerves, but not the sural nerve immediately evoked spontaneous pain and mechanical allodynia in the skin territories innervated by the adjacent intact nerves. Evans blue extravasation and cutaneous temperature of the intact skin territory were also significantly increased. In vivo electrophysiological recordings revealed that injury of a muscular nerve induced mechanical hypersensitivity and spontaneous activity in the nociceptive C-neurons in adjacent intact nerves. Our results indicate that injury of a muscular nerve, but not a cutaneous nerve, drives acute neuropathic pain.

Autonomic nerve dysfunction and impaired diabetic wound healing: The role of neuropeptides

Lower extremity ulcerations represent a major complication in diabetes mellitus and involve multiple physiological factors that lead to impairment of wound healing. Neuropeptides are neuromodulators implicated in various processes including diabetic wound healing. Diabetes causes autonomic and small sensory nerve fibers neuropathy as well as inflammatory dysregulation, which manifest with decreased neuropeptide expression and a disproportion in pro- and anti- inflammatory cytokine response. Therefore to fully understand the contribution of autonomic nerve dysfunction in diabetic wound healing it is crucial to explore the implication of neuropeptides. Here, we will discuss recent studies elucidating the role of specific neuropeptides in wound healing.

Mast Cells, Neuroinflammation and Pain in Fibromyalgia Syndrome

Fibromyalgia Syndrome (FMS) is a disorder of chronic, generalized muscular pain, accompanied by sleep disturbances, fatigue and cognitive dysfunction. There is no definitive pathogenesis except for altered central pain pathways. We previously reported increased serum levels of the neuropeptides substance P (SP) and its structural analogue hemokinin-1 (HK-1) together with the pro-inflammatory cytokines IL-6 and TNF in FMS patients as compared to sedentary controls. We hypothesize that thalamic mast cells contribute to inflammation and pain, by releasing neuro-sensitizing molecules that include histamine, IL-1β, IL-6 and TNF, as well as calcitonin-gene related peptide (CGRP), HK-1 and SP. These molecules could either stimulate thalamic nociceptive neurons directly, or via stimulation of microglia in the diencephalon. As a result, inhibiting mast cell stimulation could be used as a novel approach for reducing pain and the symptoms of FMS.

Mast Cells May Regulate The Anti-Inflammatory Activity of IL-37

Mast cells are unique immune cells involved in allergic reactions, but also in immunity and inflammation. Interleukin 37 (IL-37) has emerged as an important regulatory cytokine with ability to inhibit immune and inflammatory processes. IL-37 is made primarily by macrophages upon activation of toll-like receptors (TLR) leading to generation of mature IL-37 via the action of caspase 1. In this review, we advance the premise that mast cells could regulate the anti-inflammatory activity of the IL-37 via their secretion of heparin and tryptase. Extracellular IL-37 could either dimerize in the presence of heparin and lose biological activity, or be acted upon by proteases that can generate even more biologically active IL-37 forms. Molecules that could selectively inhibit the secretion of mast cell mediators may, therefore, be used together with IL-37 as novel therapeutic agents.

Mast Cells, Stress, Fear and Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a developmental condition characterized by impaired communication and obsessive behavior that affects 1 in 59 children. ASD is expected to affect 1 in about 40 children by 2020, but there is still no distinct pathogenesis or effective treatments. Prenatal stress has been associated with higher risk of developing ASD in the offspring. Moreover, children with ASD cannot handle anxiety and respond disproportionately even to otherwise benign triggers. Stress and environmental stimuli trigger the unique immune cells, mast cells, which could then trigger microglia leading to abnormal synaptic pruning and dysfunctional neuronal connectivity. This process could alter the "fear threshold" in the amygdala and lead to an exaggerated "fight-or-flight" reaction. The combination of corticotropin-releasing hormone (CRH), secreted under stress, together with environmental stimuli could be major contributors to the pathogenesis of ASD. Recognizing these associations and preventing stimulation of mast cells and/or microglia could greatly benefit ASD patients.

Profiles of immune cell infiltration and immune-related genes in the tumor microenvironment of colorectal cancer

PURPOSE

tumor-infiltrating immune cells are highly relevant to the progression and prognosis of colorectal cancer (CRC). The aim of this study is to explore the immune cells and immune-related gene expression in tumor microenvironment of CRC.

METHODS

CIBERSORT, a deconvolution algorithm, was used to analyze the infiltration of 22 immune cell types in the tumor microenvironment and immune-related gene expression in 404 CRC and 40 adjacent non-tumorous tissues.

RESULTS

a wide heterogeneity of immune cells among different paired tissues and in tumor stages was uncovered. M0 macrophages, M1 macrophages and CD4 memory activated T cells were infiltrated significantly more in CRC compared with normal tissues in both TCGA and GEO cohorts. CRC with T1-2 tumor stage showed increased CD4 memory activated T cells compared with T3-4 tumors. M0 macrophages were the highest in stage N1 tumors. Significant immune-related genes were identified to build prognostic models by Cox regression analysis. The concordance index of the prognostic model for TNM stage I-II was 0.69, and 0.71 for stage III-IV. The AUC values for 1-, 3-, and 5-year survivals were 0.674, 0.773, 0.812 for TNM stage I-II, respectively, and 0.764, 0.782, 0.803 for stage III-IV, respectively.

CONCLUSION

these results could assist clinicians in selecting targets for immunotherapies and individualize treatment strategies for patients with CRC.

Sex differences in the effects of early life stress exposure on mast cells in the developing rat brain

Early life stress leads to long lasting effects on behavior. Neuroimmune cells have been implicated as key mediators of experience-induced changes in brain and behavioral development, in that they are highly responsive to stress. Mast cells are one such type of neuroimmune cell, but little is known about their role in brain development or following early life stress. Here, we assessed the impact of three different early life stress exposure paradigms on mast cell dynamics in the developing brain of male and female rats, focusing on the hippocampus and hypothalamus, where most mast cells reside. We found that exposure to two weeks of chronic variable stress during gestation led to increased mast cell number and activation in the female offspring hypothalamus on the day of birth. Acute exposure to maternal separation stress on postnatal day (PN) 2 led to significant decreases in mast cells within the hypothalamus and hippocampus of females, but not males. In contrast, one week of exposure to brief daily maternal separation stress (e.g., handling), increased mast cell numbers in the female, but not male, hippocampus. We found significant sex differences in mast cell number and activation, including males having more mast cells than females in the hippocampus on the day of birth and males having significantly more degranulated mast cells on PN11. Thus, mast cells may be an unappreciated mediator of sex-specific brain development in response to early life perturbations.

Inhibition of Muscular Nociceptive Afferents via the Activation of Cutaneous Nociceptors in a Rat Model of Inflammatory Muscle Pain

Topical irritants such as capsaicin (CAP), peppermint oil (PO), and mustard oil (MO) are effective in relieving inflammatory muscle pain. We investigated the effects of topical irritants in a rat model of inflammatory muscle pain produced by injecting complete Freund's adjuvant (CFA) into the tibialis anterior muscle. CFA-induced mechanical hypersensitivity and the spontaneous activity of muscular nociceptive afferents, and decreased weight-bearing of the hindlimb were relieved by topical application of CAP, PO, or MO on the skin overlying the inflamed muscle. The effects of topical irritants were abolished when applied to the skin on the ipsilateral plantar region or on the contralateral leg, or when the relevant cutaneous nerve or dorsal root was transected. Our results demonstrated that topical irritants may alleviate inflammatory muscle pain via activating cutaneous nociceptors and subsequently inhibiting the abnormal activity of muscular nociceptive neurons.

Recent advances in our understanding of mast cell activation - or should it be mast cell mediator disorders?

INTRODUCTION

An increasing number of patients present with multiple symptoms affecting many organs including the brain due to multiple mediators released by mast cells. These unique tissue immune cells are critical for allergic reactions triggered by immunoglobulin E (IgE), but are also stimulated (not activated) by immune, drug, environmental, food, infectious, and stress triggers, leading to secretion of multiple mediators often without histamine and tryptase. The presentation, diagnosis, and management of the spectrum of mast cell disorders are very confusing. As a result, neuropsychiatric symptoms have been left out, and diagnostic criteria made stricter excluding most patients. Areas covered: A literature search was performed on papers published between January 1990 and November 2018 using MEDLINE. Terms used were activation, antihistamines, atopy, autism, brain fog, heparin, KIT mutation, IgE, inflammation, IL-6, IL-31, IL-37, luteolin, mast cells, mastocytosis, mediators, mycotoxins, release, secretion, tetramethoxyluteolin, and tryptase. Expert opinion: Conditions associated with elevated serum or urine levels of any mast cell mediator, in the absence of comorbidities that could explain elevated levels, should be considered 'Mast Cell Mediator Disorders (MCMD).' Emphasis should be placed on the identification of unique mast cell mediators, and development of drugs or supplements that inhibit their release.

The role of stress in the mosaic of autoimmunity: An overlooked association

Stress is defined as the pscyophysiological reaction in which the steady state is disturbed or threatened. Stress is not always perceived as a negative response. Stress results when environmental demands exceed an individuals' adaptive capacities. Autoimmune diseases are heterogeneous group of chronic diseases which occur secondary to loss of self antigen tolerance. The etiopathogenesis of autoimmune disease is uncertain. Genetic factors as well as environmental factors appear to interplay, leading to a cascade of events resulting in disease onset. Stress has been postulated to play a role in disease onset in the genetically susceptible patients. During the stress response, catecholamines and glucocorticoids are released from locus coeruleus and adrenal gland. These biomolecules exert control over various immune cells in the innate and adaptive arms of the immune system, thereby altering the cytokine profile released. The increase of IL-4 promotes T-helper 2 (T_h2) cell differentiation, while the decrease in IL-12 and the increased IL-10 production reduce the number of T-helper 1 (T_h1) cells. The relationship between stress and autoimmune diseases is intricate. Stress has been shown to be associated with disease onset, and disease exacerbations in rheumatoid arthritis, systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis, Graves' disease as well as other autoimmune conditions. In certain conditions such as psoriasis, stress has been implicated in delaying lesion clearance upon the application of standard treatment regimes. Finally, psychological therapy and cognitive behavioral therapy aimed to reduce stress levels was shown to be effective in influencing better outcomes in many autoimmune diseases. The purpose of this paper is to closer inspect the clinical evidence regarding the role of stress on influencing the various aspects of disease entities.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-Metabolic Disease or Disturbed Homeostasis due to Focal Inflammation in the Hypothalamus?

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disease characterized by debilitating fatigue, lasting for at least 6 months, with associated malaise, headaches, sleep disturbance, and cognitive impairment, which severely impacts quality of life. A significant percentage of ME/CFS patients remain undiagnosed, mainly due to the complexity of the disease and the lack of reliable objective biomarkers. ME/CFS patients display decreased metabolism and the severity of symptoms appears to be directly correlated to the degree of metabolic reduction that may be unique to each individual patient. However, the precise pathogenesis is still unknown, preventing the development of effective treatments. The ME/CFS phenotype has been associated with abnormalities in energy metabolism, which are apparently due to mitochondrial dysfunction in the absence of mitochondrial diseases, resulting in reduced oxidative metabolism. Such mitochondria may be further contributing to the ME/CFS symptomatology by extracellular secretion of mitochondrial DNA, which could act as an innate pathogen and create an autoinflammatory state in the hypothalamus. We propose that stimulation of hypothalamic mast cells by environmental, neuroimmune, pathogenic and stress triggers activates microglia, leading to focal inflammation in the brain and disturbed homeostasis. This process could be targeted for the development of novel effective treatments.

TNF stimulates IL-6, CXCL8 and VEGF secretion from human keratinocytes via activation of mTOR, inhibited by tetramethoxyluteolin

Psoriasis is an autoimmune skin disease characterized by keratinocyte hyperproliferation and chronic inflammation. The pathogenesis of psoriasis involves proinflammatory cytokines, such as tumor necrosis factor (TNF), but the mechanism of keratinocyte activation is not well understood. Here, we show that TNF (10 or 50 ng/mL) stimulates a significant (P < .0001) gene expression and secretion of proinflammatory IL-6, CXCL8 and VEGF from both cultured human HaCaT and normal epidermal human keratinocytes (NHEKs). This effect occurs via activation of the mammalian target of rapamycin (mTOR) signalling complex as shown by Western blot analysis and phospho-ELISAs. Pretreatment with the novel natural flavonoid tetramethoxyluteolin (10-100 μmol L^-1 ) significantly (P < .0001) inhibits gene expression and secretion (P < .0001) of all 3 mediators in a concentration-dependent manner. Moreover, tetramethoxyluteolin (50 μmol L^-1 ) appears to be a potent inhibitor of the phosphorylated mTOR substrates (pmTOR^Ser2448 , pp70S6K^Thr389 and p4EBP1^Thr37/46 ) as compared to known mTOR inhibitors in keratinocytes. The present findings indicate that TNF stimulates skin inflammation via mTOR signalling. Inhibition by tetramethoxyluteolin may be used in the treatment for psoriasis.

A holistic review on the autoimmune disease vitiligo with emphasis on the causal factors

Vitiligo is an idiopathic systemic autoimmune disease affecting skin, hair and oral mucosa. This genetic yet acquired disease characterized by melanin loss is a cause of morbidity across all races. Though thyroid disturbance has been recognized as a key trigger of this pathology, an array of other factors plays critical role in its manifestation. Multiple hormones (corticotropin-releasing hormone, adrenocorticotropic hormone, α-melanocyte-stimulating hormone, melatonin, calcitriol, testosterone, estrogen), genes (Human leukocyte antigen (HLA), Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), Forkhead box D3 (FOXD3), Cluster of differentiation 117 (CD117), Estrogen receptor (ESR) 1, Cyclooxygenase-2 (COX2), Vitiligo-associated protein 1 (VIT1)), and lifestyle choices (stress, diet, cosmetic products, and medications) have been suspected as drivers of this disorder. The pathological mechanisms have been understood in recent times, with the aid of genomic studies; however a universally-effective therapy is yet to be achieved. This review discusses these under-investigated facets of vitiligo onset and progression; hence, it is expected to enrich vitiligo research.

Neuroendocrinology of mast cells: Challenges and controversies

Mast cells (MC) are hemotopoietically derived tissue immune cells that are ubiquitous in the body, including neuroendocrine organs such as the hypothalamus, pineal, pituitary, ovaries, pancreas and uterus where their action is not well understood. Mast cells have historically been associated with allergies because of their rich content of histamine and tryptase, but more recently with regulation of immunity and inflammation due to their synthesis and release of numerous cytokines and chemokines. Mast cells are located perivascularly and express numerous receptors for diverse ligands such as allergens, pathogens, neurotransmitters, neuropeptides and hormones including acetylcholine, calcitonin gene-related peptide (CGRP), corticosteroids, corticotropin-releasing hormone (CRH), β-endorphin, epinephrine, 17β-oestradiol, gonadotrophins, hemokinin-A (HKA), leptin, melatonin, neurotensin (NT), parathyroid hormone (PTH), substance P (SP) and vasoactive intestinal peptide (VIP). Moreover, MC can synthesize and release most of their neurohormonal triggers, including adrenocorticotropin hormone (ACTH), CRH, endorphins, HKA, leptin, melatonin, NT, SP and VIP. Animal experiments have shown that diencephalic MC increase in number during courting in doves, while stimulation of brain and nasal MC leads to activation of the hypothalamic-pituitary-adrenal (HPA) axis. Recent evidence indicates that MC reactivity exhibits diurnal variations, and it is interesting that melatonin appears to regulate MC secretion. However, the way MC change their phenotype or secrete specific molecules selectively at different pathophysiological settings still remains unknown. Mast cells developed over 500 million years ago and may have served as the original prototype neuroimmunoendocrine cell and then evolved into a master regulator of such interactions, especially as most of the known diseases involve neuroinflammation that worsens with stress.

Neurotensin stimulates sortilin and mTOR in human microglia inhibitable by methoxyluteolin, a potential therapeutic target for autism

We had reported elevated serum levels of the peptide neurotensin (NT) in children with autism spectrum disorders (ASD). Here, we show that NT stimulates primary human microglia, the resident immune cells of the brain, and the immortalized cell line of human microglia-SV40. NT (10 nM) increases the gene expression and release (P < 0.001) of the proinflammatory cytokine IL-1β and chemokine (C-X-C motif) ligand 8 (CXCL8), chemokine (C-C motif) ligand 2 (CCL2), and CCL5 from human microglia. NT also stimulates proliferation (P < 0.05) of microglia-SV40. Microglia express only the receptor 3 (NTR3)/sortilin and not the NTR1 or NTR2. The use of siRNA to target sortilin reduces (P < 0.001) the NT-stimulated cytokine and chemokine gene expression and release from human microglia. Stimulation with NT (10 nM) increases the gene expression of sortilin (P < 0.0001) and causes the receptor to be translocated from the cytoplasm to the cell surface, and to be secreted extracellularly. Our findings also show increased levels of sortilin (P < 0.0001) in the serum from children with ASD (n = 36), compared with healthy controls (n = 20). NT stimulation of microglia-SV40 causes activation of the mammalian target of rapamycin (mTOR) signaling kinase, as shown by phosphorylation of its substrates and inhibition of these responses by drugs that prevent mTOR activation. NT-stimulated responses are inhibited by the flavonoid methoxyluteolin (0.1-1 μM). The data provide a link between sortilin and the pathological findings of microglia and inflammation of the brain in ASD. Thus, inhibition of this pathway using methoxyluteolin could provide an effective treatment of ASD.

Neuroendocrinology of the skin

The skin is considered the mirror of the soul and is affected by neurohormonal triggers, especially stress. Hair follicles, keratinocytes, mast cells, melanocytes, and sebocytes all express sex and stress hormones implicating them in a local "hypothalamic-pituitary-adrenal axis." In particular, the peptides corticotropin-releasing hormone (CRH) and neurotensin (NT) have synergistic action stimulating mast cells and are uniquely elevated in the serum of patients with skin diseases exacerbated by stress. Addressing the neurohormonal regulation of skin function could lead to new targets for effective treatment of inflammatory skin diseases.

Stress-related skin disorders

Emerging research has suggested that the skin is not only a target of organismal distress but also an active participant of the stress response through production of local "HPA axis" components, peripheral nerve endings, and resident skin cells, including keratinocytes, mast cells, and immune/immune accessory cells. There are also bidirectional communication pathways between the brain and the skin, which play significant roles in integrating these interactions. In this review, we summarize the intricate relations between stress and several skin conditions. We have tried to identify the underlying mechanisms that link stress to the common dermatoses according to the latest scientific findings.

Atopic diseases and inflammation of the brain in the pathogenesis of autism spectrum disorders

Autism spectrum disorders (ASDs) affect as many as 1 in 45 children and are characterized by deficits in sociability and communication, as well as stereotypic movements. Many children also show severe anxiety. The lack of distinct pathogenesis and reliable biomarkers hampers the development of effective treatments. As a result, most children with ASD are prescribed psychopharmacologic agents that do not address the core symptoms of ASD. Autoantibodies against brain epitopes in mothers of children with ASD and many such children strongly correlate with allergic symptoms and indicate an aberrant immune response, as well as disruption of the blood-brain barrier (BBB). Recent epidemiological studies have shown a strong statistical correlation between risk for ASD and either maternal or infantile atopic diseases, such as asthma, eczema, food allergies and food intolerance, all of which involve activation of mast cells (MCs). These unique tissue immune cells are located perivascularly in all tissues, including the thalamus and hypothalamus, which regulate emotions. MC-derived inflammatory and vasoactive mediators increase BBB permeability. Expression of the inflammatory molecules interleukin (IL-1β), IL-6, 1 L-17 and tumor necrosis factor (TNF) is increased in the brain, cerebrospinal fluid and serum of some patients with ASD, while NF-kB is activated in brain samples and stimulated peripheral blood immune cells of other patients; however, these molecules are not specific. Instead the peptide neurotensin is uniquely elevated in the serum of children with ASD, as is corticotropin-releasing hormone, secreted from the hypothalamus under stress. Both peptides trigger MC to release IL-6 and TNF, which in turn, stimulate microglia proliferation and activation, leading to disruption of neuronal connectivity. MC-derived IL-6 and TGFβ induce maturation of Th17 cells and MCs also secrete IL-17, which is increased in ASD. Serum IL-6 and TNF may define an ASD subgroup that benefits most from treatment with the natural flavonoid luteolin. Atopic diseases may create a phenotype susceptible to ASD and formulations targeting focal inflammation of the brain could have great promise in the treatment of ASD.

Circulating Proneurotensin Concentrations and Cardiovascular Disease Events in the Community: The Framingham Heart Study

OBJECTIVE

Neurotensin is a peptide whose receptor (sortilin receptor 1) is linked to cardiovascular disease (CVD) development. We hypothesized concentrations of proneurotensin (stable profragment of neurotensin) would predict incident cardiovascular events in community-based subjects.

APPROACH AND RESULTS

Blood samples from 3439 participants in the Framingham Heart Study (FHS) Offspring cohort (mean age 59.2 years, 47.1% male) were tested for proneurotensin. Primary outcome of interest was incident hard CVD (myocardial infarction, stroke, and cardiovascular death); interaction between proneurotensin concentration with sex, low-density lipoprotein concentrations, and sortilin receptor 1 single-nucleotide polymorphisms was sought. At baseline, those in the highest log-proneurotensin quartile were younger and heavier (P<0.001); across proneurotensin quartiles, more prevalent hard CVD (from 3% to 7%; P<0.001) and diabetes mellitus (from 6% to 14%; P<0.001) were present. In age- and sex-adjusted models, log-proneurotensin concentrations predicted incident hard CVD (hazard ratio [HR], 1.24 per SD change in log-proneurotensin; 95% confidence intervals [CIs], 1.11-1.39; P<0.001), a finding that remained on adjustment for standard CVD risk factors (HR, 1.13; 95% CI, 1.01-1.27; P=0.03). Elevated log-proneurotensin concentrations were associated with shorter time to first event (P=0.02). We found no effect modification by sex, low-density lipoprotein concentration, or sortilin receptor 1 single-nucleotide polymorphisms. Concentrations of proneurotensin were modestly associated with left ventricular mass and coronary artery calcium in these subjects.

CONCLUSIONS

Higher concentrations of proneurotensin are associated with a greater risk of incident cardiovascular events in the community. This association did not vary according to sex, baseline low-density lipoprotein, or sortilin receptor 1 genotype.

In Silico Modeling of Liver Metabolism in a Human Disease Reveals a Key Enzyme for Histidine and Histamine Homeostasis

Primary hyperoxaluria type I (PH1) is an autosomal-recessive inborn error of liver metabolism caused by alanine:glyoxylate aminotransferase (AGT) deficiency. In silico modeling of liver metabolism in PH1 recapitulated accumulation of known biomarkers as well as alteration of histidine and histamine levels, which we confirmed in vitro, in vivo, and in PH1 patients. AGT-deficient mice showed decreased vascular permeability, a readout of in vivo histamine activity. Histamine reduction is most likely caused by increased catabolism of the histamine precursor histidine, triggered by rerouting of alanine flux from AGT to the glutamic-pyruvate transaminase (GPT, also known as the alanine-transaminase ALT). Alanine administration reduces histamine levels in wild-type mice, while overexpression of GPT in PH1 mice increases plasma histidine, normalizes histamine levels, restores vascular permeability, and decreases urinary oxalate levels. Our work demonstrates that genome-scale metabolic models are clinically relevant and can link genotype to phenotype in metabolic disorders.

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In silico model of liver metabolism reveals global metabolic alterations in PH1

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Changes in amino acid metabolism in PH1 result in a reduction of histidine and histamine

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GPT overexpression normalizes histamine levels and reduces oxalate in PH1 mice

Genitourinary mast cells and survival

Mast cells (MCs) are ubiquitous in the body, but they have historically been associated with allergies, and most recently with regulation of immunity and inflammation. However, it remains a puzzle why so many MCs are located in the diencephalon, which regulates emotions and in the genitourinary tract, including the bladder, prostate, penis, vagina and uterus that hardly ever get allergic reactions. A number of papers have reported that MCs have estrogen, gonadotropin and corticotropin-releasing hormone (CRH) receptors. Moreover, animal experiments have shown that diencephalic MCs increase in number during courting in doves. We had reported that allergic stimulation of nasal MCs leads to hypothalamic-pituitary adrenal (HPA) activation. Interestingly, anecdotal information indicates that female patients with mastocytosis or mast cell activation syndrome may have increased libido. Preliminary evidence also suggests that MCs may have olfactory receptors. MCs may, therefore, have been retained phylogenetically not only to “smell danger”, but to promote survival and procreation.

Neuropeptides CRH, SP, HK-1, and Inflammatory Cytokines IL-6 and TNF Are Increased in Serum of Patients with Fibromyalgia Syndrome, Implicating Mast Cells

Fibromyalgia syndrome (FMS) is a chronic, idiopathic condition of widespread musculoskeletal pain affecting more women than men. Even though clinical studies have provided evidence of altered central pain pathways, the lack of definitive pathogenesis or reliable objective markers has hampered development of effective treatments. Here we report that the neuropeptides corticotropin-releasing hormone (CRH), substance P (SP), and SP-structurally-related hemokinin-1 (HK-1) were significantly (P = 0.026, P < 0.0001, and P = 0.002, respectively) elevated (0.82 ± 0.57 ng/ml, 0.39 ± 0.18 ng/ml, and 7.98 ± 3.12 ng/ml, respectively) in the serum of patients with FMS compared with healthy controls (0.49 ± 0.26 ng/ml, 0.12 ± 0.1 ng/ml, and 5.71 ± 1.08 ng/ml, respectively). Moreover, SP and HK-1 levels were positively correlated (Pearson r = 0.45, P = 0.002) in FMS. The serum concentrations of the inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor (TNF) were also significantly (P = 0.029 and P = 0.006, respectively) higher (2.97 ± 2.35 pg/ml and 0.92 ± 0.31 pg/ml, respectively) in the FMS group compared with healthy subjects (1.79 ± 0.62 pg/ml and 0.69 ± 0.16 pg/ml, respectively). In contrast, serum IL-31 and IL-33 levels were significantly lower (P = 0.0001 and P = 0.044, respectively) in the FMS patients (849.5 ± 1005 pg/ml and 923.2 ± 1284 pg/ml, respectively) in comparison with healthy controls (1281 ± 806.4 pg/ml and 3149 ± 4073 pg/ml, respectively). FMS serum levels of neurotensin were not different from controls. We had previously shown that CRH and SP stimulate IL-6 and TNF release from mast cells (MCs). Our current results indicate that neuropeptides could stimulate MCs to secrete inflammatory cytokines that contribute importantly to the symptoms of FMS. Treatment directed at preventing the secretion or antagonizing these elevated neuroimmune markers, both centrally and peripherally, may prove to be useful in the management of FMS.

Children with autism spectrum disorders, who improved with a luteolin-containing dietary formulation, show reduced serum levels of TNF and IL-6

Autism spectrum disorders (ASDs) have been associated with brain inflammation as indicated by microglia activation, as well as brain expression and increased plasma levels of interleukin-6 (IL-6) and tumor necrosis factor (TNF). Here we report that serum levels of IL-6 and TNF were elevated (61.95 ± 94.76 pg ml(-1) and 313.8 ± 444.3 pg ml(-1), respectively) in the same cohort of patients with elevated serum levels of corticotropin-releasing hormone (CRH) and neurotensin (NT), while IL-9, IL-31 and IL-33 were not different from controls. The elevated CRH and NT levels did not change after treatment with a luteolin-containing dietary formulation. However, the mean serum IL-6 and TNF levels decreased significantly (P=0.036 and P=0.015, respectively) at the end of the treatment period (26 weeks) as compared with levels at the beginning; these decreases were strongly associated with children whose behavior improved the most after luteolin formulation treatment. Our results indicate that there are distinct subgroups of children within the ASDs that may be identifiable through serum levels of IL-6 and TNF and that these cytokines may constitute distinct prognostic markers for at least the beneficial effect of luteolin formulation.

Fibromyalgia syndrome in need of effective treatments

Fibromyalgia syndrome (FMS) is a chronic, idiopathic condition of widespread musculoskeletal pain, affecting primarily women. It is clinically characterized by chronic, nonarticular pain and a heightened response to pressure along with sleep disturbances, fatigue, bowel and bladder abnormalities, and cognitive dysfunction. The diagnostic criteria have changed repeatedly, and there is neither a definitive pathogenesis nor reliable diagnostic or prognostic biomarkers. Clinical and laboratory studies have provided evidence of altered central pain pathways. Recent evidence suggests the involvement of neuroinflammation with stress peptides triggering the release of neurosenzitizing mediators. The management of FMS requires a multidimensional approach including patient education, behavioral therapy, exercise, and pain management. Here we review recent data on the pathogenesis and propose new directions for research and treatment.

Brain "fog," inflammation and obesity: key aspects of neuropsychiatric disorders improved by luteolin

Brain "fog" is a constellation of symptoms that include reduced cognition, inability to concentrate and multitask, as well as loss of short and long term memory. Brain "fog" characterizes patients with autism spectrum disorders (ASDs), celiac disease, chronic fatigue syndrome, fibromyalgia, mastocytosis, and postural tachycardia syndrome (POTS), as well as "minimal cognitive impairment," an early clinical presentation of Alzheimer's disease (AD), and other neuropsychiatric disorders. Brain "fog" may be due to inflammatory molecules, including adipocytokines and histamine released from mast cells (MCs) further stimulating microglia activation, and causing focal brain inflammation. Recent reviews have described the potential use of natural flavonoids for the treatment of neuropsychiatric and neurodegenerative diseases. The flavone luteolin has numerous useful actions that include: anti-oxidant, anti-inflammatory, microglia inhibition, neuroprotection, and memory increase. A liposomal luteolin formulation in olive fruit extract improved attention in children with ASDs and brain "fog" in mastocytosis patients. Methylated luteolin analogs with increased activity and better bioavailability could be developed into effective treatments for neuropsychiatric disorders and brain "fog."