Effects of simulated weightlessness on tight junction protein occludin and Zonula Occluden-1 expression levels in the intestinal mucosa of rats

Transcriptomic annotation of the Chungtien schizothoracin (Ptychobarbus chungtienensis) using Iso-seq and RNA-seq data

The Chungtien schizothoracin (Ptychobarbus chungtienensis), an endangered fish species endemic to the Zhongdian Plateau, remains underexplored in terms of transcriptomic sequencing. This investigation used tissues from five distinct organs (heart, liver, spleen, kidney, and brain) of the Chungtien schizothoracin for PacBio Iso-seq and RNA-seq analyses, yielding a repertoire of 16,598 full-length transcripts spanning lengths from 363 bp to 7,157 bp. Gene family clustering and phylogenetic analysis encompassed a comprehensive set of 13 fish species, all of which were cyprinids, including the zebrafish and the examined species Ptychobarbus chungtienensis. Moreover, the identification of long non-coding RNAs (lncRNAs) and coding sequences was accomplished across all five tissues. Comprehensive analyses of gene expression profiles and differentially expressed genes among the above five tissues were performed. In summary, the obtained full-length transcripts and detailed gene expression profiles of the Chungtien schizothoracin tissues furnish crucial expression data and genetic sequences, laying the groundwork for future investigations and fostering a holistic comprehension of the adaptive mechanisms inherent in the Chungtien schizothoracin under various conditions.

Impacts of microgravity on amino acid metabolism during spaceflight

Spaceflight exerts an extreme and unique influence on human physiology as astronauts are subjected to long-term or short-term exposure to microgravity. During spaceflight, a multitude of physiological changes, including the loss of skeletal muscle mass, bone resorption, oxidative stress, and impaired blood flow, occur, which can affect astronaut health and the likelihood of mission success. In vivo and in vitro metabolite studies suggest that amino acids are among the most affected nutrients and metabolites by microgravity (a weightless condition due to very weak gravitational forces). Moreover, exposure to microgravity alters gut microbial composition, immune function, musculoskeletal health, and consequently amino acid metabolism. Appropriate knowledge of daily protein consumption, with a focus on specific functional amino acids, may offer insight into potential combative and/or therapeutic effects of amino acid consumption in astronauts and space travelers. This will further aid in the successful development of long-term manned space mission and permanent space habitats.

Proteomic analysis of the effects of simulated microgravity in human gastric mucosal cells

Microgravity is an ecological factor that affects the environment of the body. In this study, quantitative isobaric labeling (tandem mass tag) method was used to study the changes in human gastric mucosal cells under simulated microgravity for the first time. Comparative proteomic analysis identified 394 (202 upregulated and 192 downregulated) and 542 (286 upregulated and 256 downregulated) proteins differentially regulated by simulated microgravity after 3 and 7 days, respectively. Then the identified proteins were subjected to Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses for further exploration. The results of the analysis showed that the ribosomes of gastric mucosal cells were significantly impacted after exposure to simulated microgravity for 3 days, and the cells appeared to be in a state of stress and inflammation. Exposure to simulated microgravity for 7 days significantly affected the mitochondria of the cells, oxidative stress became more evident, while inflammation and weakened connections were observed in the cells. The results of this study highlighted the temporal response trend of gastric mucosal cells to the stressor of microgravity at the two time points of 3 and 7 days. These findings will provide insights into the development of methods to protect the gastric mucosa during space flight.

The effects of microgravity on the digestive system and the new insights it brings to the life sciences

BACKGROUND

Weightlessness is a component of the complex space environment. It exerts adverse effects on the human body, and may pose unknown challenges to the implementation of space missions. The regular function of the digestive system is an important checkpoint for astronauts to conduct missions. Simulated microgravity can recreate the changes experienced by the human body in a weightless environment in space to a certain extent, providing technical support for the exploration of its mechanism and a practical method for other scientific research.

METHODS AND MATERIALS

In the present study, we reviewed and discussed the latest research on the effects of weightlessness or simulated microgravity on the digestive system, as well as the current challenges and future expectations for progress in medical science and further space exploration.

RESULTS

A series of studies have investigated the effects of weightlessness on the human digestive system. On one hand, weightlessness and the changing space environment may exert certain adverse effects on the human body. Studies based on cells or animals have demonstrated the complex effects on the human digestive system in response to weightlessness. On the other hand, a microgravity environment also facilitates the ideation of novel concepts for research in the domain of life science.

CONCLUSION

The effects of weightlessness on the digestive system are considerably complicated. The emergence of methods that help simulate a weightless environment provides a more convenient alternative for assessing the impact and the mechanism underlying the effect of weightlessness on the human body. In addition, the simulated microgravity environment facilitates the ideation of novel concepts for application in regenerative medicine and other fields of life science.

Myosin light chain kinase mediates intestinal barrier dysfunction following simulated microgravity based on proteomic strategy

Microgravity induces injury of intestinal barrier. However, the underlying mechanism remains unclear. The present study aimed to investigate the pathological change of intestinal mucosa induced by long term simulated microgravity and to explore its etiological mechanism using a proteomic approach. The well accepted tail-suspended rat model was used to simulate microgravity. The damage of rat small intestine was evaluated via histological and molecular test, and a label-free comparative proteomic strategy was used to determine the molecular mechanism. Simulated microgravity for 21 days damaged intestine barrier with decreased numbers of the goblet cells, large intercellular space, and down-regulated adhesion molecules, accompanied by increased intestinal permeability. Proteomic analysis identified 416 differentially expressed proteins and showed simulated microgravity dramatically down-regulated the adhesion molecules and deteriorated several pathways for metabolism, focal adhesion, and regulation of actin cytoskeleton. Western-blot analysis confirmed that myosin regulatory light chain (MLC) 12B was significantly down-regulated, while rho-associated protein kinase, myosin light chain kinase (MLCK), and phosphorylated MLC were dramatically up-regulated. Taken together, these data reveal that down-regulation of adhesion molecules and MLCK dependent up-regulation MLC phosphorylation mediate intestinal barrier dysfunction during simulated microgravity injury. Our results also indicate that regulation of epithelial MLCK is a potential target for the therapeutic treatment of microgravity injury.

Tolerable upper intake level of iron damages the intestine and alters the intestinal flora in weaned piglets

Iron is an indispensable element for animal growth but become toxic at high concentrations, while tolerable upper intake level of iron shows adverse effect in the intestine.

Progress in research of digestive system trauma and stress injury under microgravity environment

The last two decades have witnessed the rapid develop-ment of China's manned spaceflight industry. Studies have showed that the weightlessness environment has a series of adverse effects on the human body. Due to the complexity of the structure and function of the digestive system, the impact of weightlessness on the digestive system has certain particularity. How to ensure the steady state of the digestive system during astronaut's space mission and in the training under simulated weightlessness needs to be studied urgently. This review focuses on the progress in the research of digestive system trauma, stress injury, and repair under microgravity environment.

Amelioration of Intestinal Barrier Dysfunction by Berberine in the Treatment of Nonalcoholic Fatty Liver Disease in Rats

Objective:

To investigate the effect of berberine (BBR) on intestinal barrier function in nonalcoholic fat liver disease (NAFLD) in rats.

Materials and Methods:

Rats were divided into three groups: normal diet group (control group [CON group]), high-fat diet feeding group (HFD group), and HFD with BBR group. After 8 weeks of HFD feeding, rats in the BBR group were given BBR intragastrically at a dose of 150 mg/kg daily for 4 weeks. The same volume of normal saline was given to the CON and HFD groups. Liver index was detected, and Sudan black B staining was used to study fatty degeneration, also the expression level of occluding and intestinal flora was analyzed.

Results:

BBR administration significantly reduced HFD-induced increase in body weight (CON group: 379.83 ± 61.51 g, HFD group: 485.24 ± 50.15 g, and BBR group: 428.60 ± 37.37 g). It obviously alleviated the HFD-induced liver fatty degeneration and histopathological changes of intestinal mucosa according to liver index low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, and total cholesterol (P < 0.05). The triglyceride, alanine transaminase, and aspartate aminotransferase levels were greatly elevated after BBR treatment (P < 0.05); while endotoxin, intestinal fatty acid-binding protein, and tumor necrosis factor-α were significantly reduced (P < 0.05). Moreover, we found that BBR could obviously elevate the level of occludin and decrease the level of Faecalibacterium prausnitzii and upregulate the level of bacteroides.

Conclusion:

BBR provides significant protection in NAFLD through ameliorating intestinal barrier function.

SUMMARY

Berberine (BBR), an alkaloid that can be isolated from many plants, has been medically used for its wide range of antimicrobial and anti-inflammatory effects

This is a study of BBR on liver function and intestinal barrier function in nonalcoholic fat liver disease (NAFLD)

BBR treatment for NAFLD could significantly restore the liver function and provide significant protection in NAFLD through ameliorating intestinal barrier function.

Abbreviations used: BBR: Berberine, NAFLD: Nonalcoholic fat liver disease, ALT: Alanine transaminase, AST: Aspartate aminotransferase, TG: Triglyceride, I-FABP: Intestinal-fatty acid-binding protein, IBD: Inflammatory bowel disease.

The complete mitochondrial genome of the Gymnocypris chui (Cypriniformes: Cyprinidae)

The Gymnocypris chui, a new recorded species in Lange Lake, was grouped into genus Gymnocypris in Schizothoracinae, and had the rare quantity and limited resources on biology and genetics, especially in the mitochondrion. In this study, the complete mitochondrial sequence of G. chui was assembled and phylogenetic relationships with other species in Cyprinidae were analyzed. The whole mitochondrial sequence was 16,864 bp in length, which contained two control regions (D-loop regions), two rRNA genes (12S and 16S rRNA), 13 protein-coding genes and 22 tRNA genes. The D-loop region was separated by tRNAPro . The 12S rRNA and 16S rRNA located between tRNAPhe and tRNALeu and were separated by tRNAVal . The 13 mRNAs had three start codons, five termination codons and four overlap regions. The 22 tRNA scattered among the whole mitochondrion, and they were range from 66 (tRNACys ) to 76 (tRNALys andtRNALeu ) in length. To further explore the phylogenetic relationship of the G. chui, we constructed the phylogenetic tree and verified that the G. chui was a part of genus Gymnocypris and had closer relationship with Gymnocypris dobula and was independent from other species of Schizothoracinae, Barbinae and Labeoninae in Cyprinidae. This study provided the valuable evidence on phylogenetic relationship of the G. chui at the molecular level and essential resource for further research on this species.

Increased expression of nerve growth factor correlates with visceral hypersensitivity and impaired gut barrier function in diarrhoea-predominant irritable bowel syndrome: a preliminary explorative study

BACKGROUND

Neural-immune-endocrine network mechanism has attracted increased attention in diarrhoea-predominant irritable bowel syndrome (IBS-D). Pre-clinical evidence indicates that nerve growth factor (NGF) mediates visceral hypersensitivity and gut barrier dysfunction, via interactions with mast cells and sensory nerve fibres.

AIM

To explore the role of nerve growth factor, as well as mast cell-nerve growth factor-nerve interaction in IBS-D pathophysiology.

METHODS

In this cross-sectional study, IBS-D patients and healthy controls first underwent clinical and psychological assessments. Visceral sensitivity to rectal distension was tested. As gut barrier function markers, serum diamine oxidase and d-lactate were detected. Rectosigmoid biopsies were taken for the analyses of nerve growth factor expression, mast cell count and activation, and sensory nerve fibres expressing transient receptor potential vanilloid 1 and calcitonin gene-related peptide. Correlations between these parameters were examined in patients.

RESULTS

Thirty-eight IBS-D patients (28 males, 10 females; average age 30.2 years) and 20 healthy controls (12 males, 8 females; average age 26.8 years) participated in the study. The patients presented increased psychological symptoms, visceral hypersensitivity and impaired gut barrier function. NGF gene expression, mast cell count and sensory nerve fibres were significantly increased in the patients (P < 0.05). In correlation analysis, NGF expression was positively correlated with the disease severity, anxiety and serum diamine oxidase; visceral sensitivity thresholds were negatively associated with NGF expression (Bonferroni corrected P < 0.0029).

CONCLUSIONS

Elevated mucosal NGF may interact with mast cells and sensory nerve fibres, contributing to visceral hypersensitivity and impaired gut barrier function in IBS-D.

The gut microbiome and the brain

The human gut microbiome impacts human brain health in numerous ways: (1) Structural bacterial components such as lipopolysaccharides provide low-grade tonic stimulation of the innate immune system. Excessive stimulation due to bacterial dysbiosis, small intestinal bacterial overgrowth, or increased intestinal permeability may produce systemic and/or central nervous system inflammation. (2) Bacterial proteins may cross-react with human antigens to stimulate dysfunctional responses of the adaptive immune system. (3) Bacterial enzymes may produce neurotoxic metabolites such as D-lactic acid and ammonia. Even beneficial metabolites such as short-chain fatty acids may exert neurotoxicity. (4) Gut microbes can produce hormones and neurotransmitters that are identical to those produced by humans. Bacterial receptors for these hormones influence microbial growth and virulence. (5) Gut bacteria directly stimulate afferent neurons of the enteric nervous system to send signals to the brain via the vagus nerve. Through these varied mechanisms, gut microbes shape the architecture of sleep and stress reactivity of the hypothalamic-pituitary-adrenal axis. They influence memory, mood, and cognition and are clinically and therapeutically relevant to a range of disorders, including alcoholism, chronic fatigue syndrome, fibromyalgia, and restless legs syndrome. Their role in multiple sclerosis and the neurologic manifestations of celiac disease is being studied. Nutritional tools for altering the gut microbiome therapeutically include changes in diet, probiotics, and prebiotics.

Expression of glucocorticoid receptor-α in the epidermis of patients with psoriasis vulgaris

Expression of glucocorticoid receptor (GR)-α is observed in almost all tissues and cells of the body; thus, investigating the expression of the receptor in the epidermis of patients with psoriasis vulgaris. The aim of the present study was to investigate GR-α expression in the epidermis of psoriasis vulgaris patients The study population consisted of 26 patients with psoriasis vulgaris and 10 normal control cases. None of the patients had received any prior treatment with glucocorticoids. Epithelial tissue samples were detected using a streptavidin peroxidation-enzymatic method for biopsy. Non-lesional tissue samples from within a range of 3 cm of lesions formed the non-lesional group, and lesional tissue samples formed the lesional group. Pathological image analysis system (named CMIAS) was used to convert image signals into numeric values, according to the optical density per unit area. GR-α expression was observed within the nucleus in the normal control group; however, cytoplasmic expression was observed in the lesions of the psoriatic group. The optical density values were significantly lower in the psoriatic group when compared with the normal control group, indicating a statistically significant difference in GR-α expression between the two groups (P<0.001), and this decreasing correlation was unaffected by the administration of steroids for 6 months. Therefore, decreased expression of GR-α may play an important role in the degeneration of keratinocytes in patients with psoriasis vulgaris.

Effect of acute stress on immune cell counts and the expression of tight junction proteins in the duodenal mucosa of rats

Background/Aims

Duodenal immune alterations have been reported in a subset of patients with functional dyspepsia (FD). The aim of this study was to investigate the effect of acute stress on immune cell counts and the expression of tight junction proteins in the duodenal mucosa.

Methods

Twenty-one male rats were divided into the following three experimental groups: 1) the nonstressed, control group, 2) the 2-hour-stressed group, and 3) the 4-hour-stressed group. Eosinophils, mast cells and CD4⁺ and CD8⁺ T lymphocytes in the duodenal mucosa were counted. The protein and mRNA expressions of occludin and zonula occludens-1 (ZO-1) were examined.

Results

Eosinophils, mast cells and CD8⁺ T lymphocyte counts did not differ between the stressed and control groups. The number of CD4⁺ T lymphocytes and the protein and mRNA expressions of occludin and ZO-1 were significantly lower in the 4-hour-stressed group compared with the control group. The plasma adrenocorticotrophic hormone and cortisol levels of the 4-hour-stressed group were significantly higher than those of the control group.

Conclusions

Acute stress reduces the number of CD4⁺ T lymphocytes and the expression of tight junction proteins in the duodenal mucosa, which might be associated with the duodenal immune alterations found in a subset of FD patients.

Intestinal microbiota, probiotics and mental health: from Metchnikoff to modern advances: Part II - contemporary contextual research

In recent years there has been a renewed interest concerning the ways in which the gastrointestinal tract – its functional integrity and microbial residents – might influence human mood (e.g. depression) and behavioral disorders. Once a hotbed of scientific interest in the early 20th century, this area lay dormant for decades, in part due to its association with the controversial term ‘autointoxication’. Here we review contemporary findings related to intestinal permeability, small intestinal bacterial overgrowth, lipopolysaccharide endotoxin (LPS) exposure, D-lactic acid, propionic acid, and discuss their relevance to microbiota and mental health. In addition, we include the context of modern dietary habits as they relate to depression, anxiety and their potential interaction with intestinal microbiota.

Effect of simulated weightlessness on the healing of experimental gastric ulcer in rats

AIM: To investigate the effect of simulated weightlessness on the healing of acetic acid-induced experimental gastric ulcer in rats and to explore the potential mechanisms involved.

METHODS: Thirty-two SD rats were randomly and equally divided into four groups: 7 d tail suspension group, 7 d control group,14 d tail suspension, and 14 d control group. Gastric ulcer was induced in rats with acetic acid. Tail suspension was used to simulate the weightlessness condition 3 days after ulcer induction. The gastric ulcer area was measured with a vernier caliper. The ultrastructure of regenerative mucosa was observed by electronic microscopy. Epidermal growth factor (EGF) level in gastric juice was determined by radioimmunoassay (RIA). The staging of ulcer healing was performed.

RESULTS: Compared to the 7 d control group, the ulcer area significantly increased (6.0 mm² ± 1.7 mm² vs 2.2 mm² ± 0.7 mm², t = 5.661, P < 0.01) and the stage of ulcer significantly decreased (χ² = 12.771, P < 0.01) in the 7d suspension group. Compared to the 14 d control group, the ulcer area and EGF level increased (3.0 mm² ± 1.2 mm² vs 1.1 mm² ± 0.4 mm², t = 4.233, P < 0.01; 0.155 ng/mL ± 0.052 ng/mL vs 0.103 ng/mL ± 0.019 ng/mL, t = 2.635, P < 0.05) in the 14 d suspension group. Compared to the 7 d suspension group, the ulcer area, EGF level and stage of ulcer significantly decreased (3.0 mm² ± 1.2 mm² vs 6.0 mm² ± 1.7 mm², t = 3.805, P < 0.01; 0.155 ng/mL ± 0.052 ng/mL vs 0.434 ng/mL ± 0.137 ng/mL, t = 5.657, P < 0.01; χ² = 12.953, P < 0.01) in the 14 d suspension group. The ultrastructural restoration and histological maturity of healed ulcer in the 7 d and 14 d suspension groups were inferior to those in the 7 d and 14 d control groups.

CONCLUSION: Simulated weightlessness may depress the structure of regenerative gastric mucosa, delay the healing of ulcer, and increase EGF level in gastric juice.