Meat proteins in a high-fat diet have a substantial impact on intestinal barriers through mucus layer and tight junction protein suppression in C57BL/6J mice.

Protein diets are well known for body maintenance and weight loss. However, it remains unclear whether and how different protein sources affect the intestinal epithelial integrity through tight junctions, mucus secretions and host immunity in diet-induced obesity. To evaluate possible effects, soybean, chicken and pork proteins either with low fat (12% kcal) or high fat (60% kcal) were administered to C57BL/6J mice for 12 weeks. Muc2 expression, tight junction proteins, goblet cells, and inflammatory cytokines in the colon and serum were measured. The intake of a high-fat pork protein diet decreased the number of goblet cells and inhibited Muc2 expression in the colon, which impaired the mucus barrier. Immunohistochemistry indicated decreased crypt depth and downregulation of tight junction proteins in high-fat diet fed mice, signifying losses of epithelial barriers. In addition, a pork protein diet reduces the key zonula occludens-1 and E-cadherin proteins. A high-fat meat protein diet induces colonic inflammatory injury by upregulating several key cytokines and increasing IL-1ß, TNF-α, IL-6 and IFN-γ concentrations in serum. The intake of high-fat meat protein diets resulted in the impairment of the colon barrier through mucus suppression, downregulation of tight junctions, and gut inflammation in mice.

Serum affects keratinization and tight junctions in three-dimensional cultures of the mouse keratinocyte cell line COCA through retinoic acid receptor-mediated signaling.

Vitamin A, which is found in serum, is known to affect keratinocyte proliferation, epidermal differentiation, and keratinization. In mice, stratified epithelia in the oral cavity, esophagus, and forestomach are keratinized; however, these epithelia are not keratinized in humans. Several studies have reported that three-dimensional (3D) cultures of human keratinocytes in serum-containing medium could form keratinized epithelia. Here, we evaluated the effects of serum on the morphology, expression, and localization of differentiation markers and tight junction proteins, and paracellular permeability in 3D cultures of mouse keratinocytes. We found that only 0.1% calcium-depleted serum inhibited keratinization and induced a change in the expression of differentiation marker proteins from loricrin to keratin 4; the inhibition of retinoic acid receptor-mediated signaling reversed these changes. Furthermore, the serum reduced claudin-1 protein expression and prevented its localization at occludin-positive spots on the surface of 3D cultures. On the other hand, the serum increased the protein expression of claudin-4, occludin, zonula occludens-1, and E-cadherin. These changes may contribute to the reduction of the transepithelial electrical resistance by approximately half. In conclusion, mouse keratinocytes derived from the epidermis formed non-keratinized structures in 3D cultures in response to vitamin A in serum. The results suggest that retinoic acid receptor-mediated signaling may be inhibited in the mouse epithelia in the oral cavity, esophagus, and forestomach as well as the epidermis, leading to the keratinization of these epithelia.

Fingolimod reduces circulating tight-junction protein levels and in vitro peripheral blood mononuclear cells migration in multiple sclerosis patients.

There are no data on the effects of fingolimod, an immunomodulatory drug used in treatment of multiple sclerosis (MS), on circulating tight-junction (TJ) protein levels as well as on peripheral blood mononuclear cells (PBMC) migration. Serum TJ protein [occludin (OCLN), claudin-5 (CLN-5) and zonula occludens-1 (ZO-1)] levels, sphingosine-1 phosphate 1 (S1P1) receptor expression on circulating leukocyte populations as well as in vitro PBMC migration were longitudinally assessed in 20 MS patients under 12-months fingolimod treatment and correlated with clinical and magnetic resonance imaging (MRI) parameters. After 12 months of treatment, a significant reduction of mean relapse rate as well as number of active lesions at MRI was found. TJ protein levels significantly decreased and were associated with reduction of S1P1 expression as well as of PBMC in vitro migratory activity. A significant correlation of CLN-5/OCLN ratio with new T2 MRI lesions and a significant inverse correlation of CLN-5/ZO-1 ratio with disability scores were found. These findings support possible in vivo effects of fingolimod on the blood-brain barrier (BBB) functional activity as well as on peripheral cell trafficking that could result in avoiding passage of circulating autoreactive cells into brain parenchyma. Circulating TJ protein levels and respective ratios could be further studied as a novel candidate biomarker of BBB functional status to be monitored in course of fingolimod as well as of other immunomodulatory treatments in MS.

The current state of biomarkers of mild traumatic brain injury.

Mild traumatic brain injury (mTBI) is a common occurrence, with over 3 million cases reported every year in the United States. While research into the underlying pathophysiology is ongoing, there is an urgent need for better clinical guidelines that allow more consistent diagnosis of mTBI and ensure safe return-to-play timelines for athletes, nonathletes, and military personnel. The development of a suite of biomarkers that indicate the pathogenicity of mTBI could lead to clinically useful tools for establishing both diagnosis and prognosis. Here, we review the current evidence for mTBI biomarkers derived from investigations of the multifactorial pathology of mTBI. While the current literature lacks the scope and size for clarification of these biomarkers' clinical utility, early studies have identified some promising candidates.

Circulating tight junction proteins mirror blood-brain barrier integrity in leukaemia central nervous system metastasis.

The aim of this study was to evaluate the clinical significance of circulating tight junction (TJ) proteins as biomarkers reflecting of leukaemia central nervous system (CNS) metastasis. TJs [claudin5 (CLDN5), occludin (OCLN) and ZO-1] concentrations were measured in serum and cerebrospinal fluid (CSF) samples obtained from 45 leukaemia patients. Serum ZO-1 was significantly higher (p < 0.05), but CSF ZO-1 levels were not significantly higher in the CNS leukaemia (CNSL) compared to the non-CNSL. The CNSL patients also had a lower CLDN5/ZO1 ratio in both serum and CSF than in non-CNSL patients (p < 0.05). The TJ index was negatively associated with WBCCSF , ALBCSF and BBB values in leukaemia patients. Among all of the parameters studied, CLDN5CSF had the highest specificity in discriminating between CNSL and non-CNSL patients. Therefore, analysing serum and CSF levels of CLDN5, OCLN and the CLDN5/ZO1 ratio is valuable in evaluating the potential of leukaemia CNS metastasis. Copyright © 2016 John Wiley & Sons, Ltd.

The Role of Circulating Tight Junction Proteins in Evaluating Blood Brain Barrier Disruption following Intracranial Hemorrhage.

Brain injury after intracranial hemorrhage (ICH) results in significant morbidity and mortality. Blood brain barrier (BBB) disruption is a hallmark of ICH-induced brain injury; however, data mirroring BBB disruption in human ICH are scarce. The aim of this study was to assess the significance of circulating biomarkers in evaluating BBB disruption after ICH. Twenty-two patients with ICH were recruited in this study. Concentrations of the tight junction proteins (TJs) Claudin-5 (CLDN5), Occludin (OCLN), and zonula occludens 1 (ZO-1) and vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) were measured by using enzyme-linked immunosorbent assay in serum and cerebrospinal fluid (CSF) samples obtained from patients with ICH. The white blood cell (WBC) count in blood and CSF, albumin (ALB) levels in the CSF (ALBCSF), and the BBB ratio were significantly higher in the ICH than in controls (p < 0.05). Significantly higher levels of CLDN5, OCLN, ZO-1, MMP-9, and VEGF in CSF were observed in the ICH group; these biomarkers were also positively associated with BBB ratio (p < 0.05). Our data revealed that circulating TJs could be considered the potential biomarkers reflecting the integrity of the BBB in ICH.