The Gut Microbiota and the Emergence of Autoimmunity: Relevance to Major Psychiatric Disorders.

BACKGROUND: Autoimmune phenotypes are prevalent in major psychiatric disorders. Disequilibria of cellular processes occurring in the gastrointestinal (GI) tract likely contribute to immune dysfunction in psychiatric disorders. As the venue of a complex community of resident microbes, the gut in a homeostatic state equates with a functional digestive system, cellular barrier stability and properly regulated recognition of self and non-self antigens. When gut processes become disrupted as a result of environmental or genetic factors, autoimmunity may ensue. METHODS: Here, we review the issues pertinent to autoimmunity and the microbiome in psychiatric disorders and show that many of the reported immune risk factors for the development of these brain disorders are in fact related and consistent with dysfunctions occurring in the gut. We review the few human microbiome studies that have been done in people with psychiatric disorders and supplement this information with mechanistic data gleaned from experimental rodent studies. RESULTS: These investigations demonstrate changes in behavior and brain biochemistry directly attributable to alterations in the gut microbiome. We present a model by which autoantigens are produced by extrinsicallyderived food and microbial factors bound to intrinsic components of the gut including receptors present in the enteric nervous system. CONCLUSION: This new focus on examining activities outside of the CNS for relevance to the etiology and pathophysiology of psychiatric disorders may require new modalities or a re-evaluation of pharmaceutical targets found in peripheral systems.

Is there a final common path in malignancies?

UNLABELLED: We found that malignant cells and tumors contain very little low molecular weight (MW) peptides and amino acids compared to normal cells and tissues. However, the low molecular weight (MW) peptides that inhibit mitosis, cell growth and cause differentiation were recovered from cell growth medium or ascites. We therefore hypothesize that out transport and, or diffusion of the low MW compounds is possibly central to carcinogenesis, since the controlling low MW signals are lost from the cell. Without inhibitors mitosis should not or would not stop. HYPOTHESIS: Loss of low MW peptides and amino acids may be a common trait in carcinogenesis. It would entail that normal cell regulation such as growth, mitosis inhibition and differentiation would probably be lost, especially as we recover the missing compounds (chalones) from the incubation fluid or ascites. The chalones and deprimerones seem to induce differentiation of cells when inhibiting mitosis, and when lost from the cells may explain the de-differentiation typical of malignant cells. Such a mechanism would make room for membrane damaging mechanical, inflammatory and chemical as well as viral aetiologies in carcinogenesis. Faster than normal growth also increases the probability of geneic malfunction.

Gluten- and casein-free dietary intervention for autism spectrum conditions.

Dietary intervention as a tool for maintaining and improving physical health and wellbeing is a widely researched and discussed topic. Speculation that diet may similarly affect mental health and wellbeing particularly in cases of psychiatric and behavioral symptomatology opens up various avenues for potentially improving quality of life. We examine evidence suggestive that a gluten-free (GF), casein-free (CF), or gluten- and casein-free diet (GFCF) can ameliorate core and peripheral symptoms and improve developmental outcome in some cases of autism spectrum conditions. Although not wholly affirmative, the majority of published studies indicate statistically significant positive changes to symptom presentation following dietary intervention. In particular, changes to areas of communication, attention, and hyperactivity are detailed, despite the presence of various methodological shortcomings. Specific characteristics of best- and non-responders to intervention have not been fully elucidated; neither has the precise mode of action for any universal effect outside of known individual cases of food-related co-morbidity. With the publication of controlled medium- and long-term group studies of a gluten- and casein-free diet alongside more consolidated biological findings potentially linked to intervention, the appearance of a possible diet-related autism phenotype seems to be emerging supportive of a positive dietary effect in some cases. Further debate on whether such dietary intervention should form part of best practice guidelines for autism spectrum conditions (ASCs) and onward representative of an autism dietary-sensitive enteropathy is warranted.

Peptides' role in autism with emphasis on exorphins.

PROBLEM: The nature of the peptides found increased in urine from autism needs verification of their structure, especially those that show opioid activity. METHODS: The peptides were separated on reverse phase C-18 HPLC in Trifluoroacetic acid-acetonitril gradients. Peaks eluting where synthetic opioids appear, and peaks that are common to most autistic children were analyzed by mass spectrometry and fragmentation pattern on a quadropole mass-spectrometer. RESULTS: We could demonstrate exorphins in the urine from autistic children, and their length varied from one patient to the next. CONCLUSION: Exorphins are found in urine of autistic children and may account for their symptoms.

Altered amino acid excretion in children with autism.

Autism is a complex and life-long behavioural disorder of unknown aetiology. Recent reports have indicated the involvement of digestive tract dysfunction and possible complications from inadequate nutrition. In this study, 34 autistic children (12 untreated and 22 receiving therapeutic treatments related to digestive function and nutritional uptake) and 29 control subjects (all 5-15 years of age) were investigated to determine whether there were any anomalies in the urinary excretion of amino acids, glucose, sucrose, arabinose and tartaric acid using GC/FID and GC/MS analysis techniques. Significantly lower relative urinary levels of essential amino acids were revealed for both the untreated (mean +/- SEM, 32.53 +/- 3.09%) and treated (31.98 +/- 2.87%) autistic children compared with the controls (37.87 +/- 1.50%). There were no significant differences in measured excretions of sugars or tartaric acid. It was concluded that the untreated autistic children had evidence of altered metabolic homeostasis.

Chalones: from aqueous extracts to oligopeptides.

The term "chalone" was coined about 40 years ago to describe endogenous growth-inhibiting factors with a tissue-specific and reversible effect. A large number of "chalones" were reported in the 1970's and early 80's. The term was, however, used rather indiscriminately and attempts at purification of the active component(s) were without success. As a result, most laboratories lost interest. Then, in the early 1980's, two different research teams demonstrated that the active growth-inhibiting constituents were N-substituted oligopeptides. In the following years, similar oligopeptides were characterized in extracts of liver, the large bowel, melanocytes, lymphocytes, and neuroblastoma, in addition to the two first ones from monomyelopoietic cells and epidermis, respectively. All peptides have a bell-shaped dose response pattern and optimal effect at very low concentrations. Several of them inhibit growth even in tumors derived from the respective organs. Preliminary studies have revealed that two of the oligopeptides alter the expression of growth- and differentiation-related genes. Quite recently, some papers are again using the term "chalone" and a short review therefore seems appropriate.

Pyroglutamyl-histidyl-glycine, the endogenous colon mitosis inhibitor, regulates cyclic AMP level in non-tumorigenic colonic epithelial cells.

BACKGROUND: We have proposed that the mitosis inhibiting peptide, pyroGlu-His-Gly (pEHG), a colon-specific negative feedback regulator of cell proliferation, works through a G protein-coupled receptor (GPCR), as do many other pyroglutamyl-peptides. MATERIALS AND METHODS: Non-tumorigenic YAMC (colon mucosa of Immorto mice), IMCE (Immorto-Min mouse hybrid) and human hepatoma (HepG2) cell lines were exposed to pEHG. cAMP concentrations were measured with a protein binding assay, mRNA levels with real-time PCR and Ca2+ concentration with an inverted fluorescence microscope on Fura-2/AM-loaded cells. RESULTS: pEHG (1 nM) increased the intracellular concentration of cAMP after 5-10 min in YAMC cells, but not in HepG2 cells. No effect was seen on cytosolic Ca2+, or in the expression of the proliferation and differentiation regulatory genes c-fos, egr-1 or fosB in YAMC or IMCE cells. CONCLUSION: pEHG stimulates the second messenger cAMP, but has no effect on intracellular Ca2+ or the gene expression of c-fos, egr-1 or fosB.

The colon mitosis inhibitor pyroglutamyl-histidyl-glycine inhibits growth of non-tumorigenic colonic epithelial cells.

BACKGROUND: The colon mitosis inhibiting peptide pyroglutamyl-histidyl-glycine (pEHG) increases the expression of c-fos, fosB and egr-1 genes in the colon carcinoma cell line HT-29. However, the effect on non-tumorigenic colonic cells has not been investigated. MATERIALS AND METHODS: After exposure of the cell lines YAMC (from colon mucosa of Immorto mice) and IMCE (fromn Immorto-Min mouse hybrid) to pEHG, DNA-synthesis was analysed by H3-thymidine incorporation, apoptosis and necrosis by fluorescence microscopy, and cell cycle distribution by flow cytometry. RESULTS: pEHG inhibited DNA-synthesis with a maximal effect at 10(-8)-10(-9) M, but stimulated at 10(-4) M. It blocked cell flow through the cell cycle at GC/M after 8 h of treatment, but had no effect on apoptosis or necrosis at any concentration. A low concentration of ascorbic acid stabilised the cells, maybe as a free radical scavanger. CONCLUSION: pEHG inhibits flux at the G2/M transition, but has no effect on cell death.

The effects of a growth-inhibiting tripeptide, acetylGlu-Ser-GlyNH2 (Ac-ESG), on gene expression and cell cycle progression of two lymphoma cell lines.

BACKGROUND: We recently isolated and characterized a tripeptide, acetylGlu-Ser-GlyNH2 (Ac-ESG), which inhibits proliferation of lymphoid cells. In this paper we describe the effects of Ac-ESG on growth-related gene expression and cell cycle progression in two lymphoma cell lines, Ramos and Molt, representing B and T lymphocytes, respectively. MATERIALS AND METHODS: RNA was extracted from Molt and Ramos cells with or without the tripeptide treatment. Gene expression was examined by semi-quantitative RT-PCR and Northern blot hybridization, and cell cycle progression was detected by flow cytometry. RESULTS: In the Molt cells, p53 gene expression was increased following treatment while c-myc was decreased after treatment shorter than 24 hours; N-ras expression was significantly reduced at picomolar concentration for 24-hour treatment; cyclinD1 and cdk4 expression did not show any change; DNA flow cytometry demonstrated that Molt cells were arrested or delayed predominantly in G2-M. Untreated Ramos cells had higher gene expression levels of c-myc, N-Ras and cdk4 than Molt cells, but lower p53 expression. These cells were not sensitive to Ac-ESG. CONCLUSION: The tripeptide Ac-ESG alters the expression of several growth-related genes in the Molt cell line and brings about an arrest or delay of cells in G2-M.

The colon mitosis-inhibitor pyroglutamyl-histidyl-glycine alters expression of immediate-early cancer-related genes in HT-29 cells.

BACKGROUND: The intestinal mitosis-inhibiting peptide pyroglu-His-GlyOH (pEHG), inhibits normal intestinal epithelial cells and the human colon adenocarcinoma cell line HT-29 and increases the expression of c-fos (1). In this study, we investigated the mechanisms of the growth-inhibiting effects of pEHG. MATERIALS AND METHODS: cDNA expression array was hybridized with cDNA from HT-29 cells exposed to pEHG or control. The results were confirmed with Northern blot or real-time PCR. RESULTS: pEHG(1 nM) provoked a significant increase in the expression of the early growth response protein 1 (egr-1) after an incubation of 20 minutes, while c-fos was confirmed up-regulated by the same treatment. We further studied the expression of fosB, c-jun and junB, in the AP-1 complex. fosB was up-regulated 20-fold, but only minor effects on jun variants were observed. CONCLUSION: pEHG stimulates the gene expression of some immediate-early transcription factors involved in cell proliferation.

Early oncogene mRNA expression in HT-29 cells treated with the endogenous colon mitosis inhibitor pyroglutamyl-histidyl-glycine.

BACKGROUND: The tripeptide pyroGlu-His-GlyOH (pEHG), isolated from intestinal extracts (1), suppresses growth of human colonic epithelial cells and human colorectal adenocarcinoma cells (HT-29) both in vitro and in vivo. The present study represents the first attempt to relate alterations in relevant gene expression to the effect on cell growth. MATERIALS AND METHODS: Northern blot with RNA, extracted from HT-29 cells exposed to pEHG, was hybridised with c-fos and c-myc probes. RESULTS: c-fos gene expression was doubled in HT-29 cells after 20 minutes of incubation with pEHG and decreased to half the initial value after 2 hours. The increase at 20 minutes was concentration-dependent at a peptide concentration range from 10(-6)-10(-12) M. The expression of the oncogene c-myc showed only marginal alternations at the concentrations and times tested. CONCLUSION: The colon mitosis-inhibiting peptide pEHG increases gene expression of c-fos, but not that of c-myc.

Endogenous tetrapeptide from neuroblastoma and new-born pig brain inhibits neuroblastoma cell growth in vitro.

Neuroblastoma, the most frequent malignant tumour in neonates and young children, has an unusual clinical behaviour, age being the most important single factor. This could indicate that some growth-regulating mechanism in lost, or changed, during the first years of life. In search for possible growth-modifying factors, we identified a tetrapeptide, acetyl-Asp-Gln-Tyr-GlyNH2, in extracts of neuroblastoma tissue, in neuroblastoma cell cultures and in new-born pig brain tissue. The purified native peptide as well as a synthetic peptide with the same structure decreases in vitro growth of neuroblastoma cells at a restricted, low (picomolar) range. The structure of the peptide as well as its dose-response characteristics, indicates that it belongs to a group of endogenous growth-modifying oligopeptides that previously have been isolated from other organs and tissues. A possible role for the new peptide in clinical medicine is discussed.