Tetrandrine ameliorated reperfusion injury of small bowel transplantation

Tetrandrine attenuates ischemia/reperfusion‑induced neuronal damage in the subacute phase

Ischemic stroke, the third leading cause of disability globally, imposes a notable economic burden. Tetrandrine (Tet), which has been widely used clinically, exhibits potential protective effects against stroke. However, there has been little pre‑clinical research to evaluate the therapeutic effects of Tet on stroke. The present study investigated the beneficial effect of Tet on ischemia‑reperfusion (I/R) injury and its underlying mechanism in rats. Rats were subjected to occlusion of the middle cerebral artery, then treated with Tet (30 mg/kg/day, intraperitoneal) in the subacute phase for 7 days. In order to detect the effects of Tet on the behavior of rats, modified neurological severity score and longa behavior, grasping capability and inclined plane tests were conducted on days 1, 3 and 7 following cerebral ischemia. In addition, neuronal apoptosis in the cortex and hippocampus following ischemia was assessed by Nissl staining and TUNEL assay. Finally, oxidative stress was evaluated by measurement of free radicals and immunofluorescence staining of LC3 was used to assess autophagy. Tet improved neurological function and decreased infarct volume in I/R injury rats. Tet also prevented neuronal apoptosis in the cortex and hippocampus region. In addition, Tet protected against oxidative damage following ischemia, which was reflected by decreased levels of nitric oxide and malondialdehyde and increased levels of glutathione (GSH) and GSH peroxidase. In addition, the expression levels of the autophagy marker LC3 decreased in the Tet treatment group. In conclusion, Tet attenuated I/R‑induced neuronal damage in the subacute phase by decreasing oxidative stress, apoptosis and autophagy.

Tetrandrine alleviates cerebral ischemia/reperfusion injury by suppressing NLRP3 inflammasome activation via Sirt-1

Background & Aims

Tetrandrine (Tet) has been reported to have anti-inflammatory effects and protect from the ischemic strokes. The NLRP3 inflammasome plays a key role in cerebral ischemia/reperfusion (I/R)-induced inflammatory lesions. However, the molecular mechanisms of Tet related to the progression of cerebral ischemia are still unclear. Therefore, the aim of this study was to investigate the possible effects of Tet on cerebral ischemia and the related mechanisms involved in NLRP3 inflammasome.

Methods

C57BL/6J mice used as a cerebral I/R injury model underwent middle cerebral artery occlusion (MCAO) for 2 h following reperfusion for 24 h. Tet (30 mg/kg/day, i.p.) was administered for seven days and 30 min before and after MCAO. Their brain tissues were evaluated for NLRP3 inflammasome and Sirtuin-1 (Sirt-1) expression. An intracerebroventricular injection of Sirt-1 siRNA was administered to assess the activation of the NLRP3 inflammasome.

Results

Tet significantly reduced the neurological deficits, infarction volume, and cerebral water content in MCAO mice. Moreover, it inhibited I/R-induced over expression of NLRP3, cleaved caspase-1, interleukin (IL)-1β, IL-18, and Sirt-1. Sirt-1 knockdown with siRNA greatly blocked the Tet-induced reduction of neurological severity score and infarct volume, and reversed the inhibition of NLRP3 inflammasome activation.

Conclusion

Our results demonstrate that Tet has benefits for cerebral I/R injury, which are partially related to the suppression of NLRP3 inflammasome activation via upregulating Sirt-1.

Influence of Growth Hormone and Glutamine on Intestinal Stem Cells: A Narrative Review

Growth hormone (GH) and glutamine (Gln) stimulate the growth of the intestinal mucosa. GH activates the proliferation of intestinal stem cells (ISCs), enhances the formation of crypt organoids, increases ISC stemness markers in the intestinal organoids, and drives the differentiation of ISCs into Paneth cells and enterocytes. Gln enhances the proliferation of ISCs and increases crypt organoid formation; however, it mainly acts on the post-proliferation activity of ISCs to maintain the stability of crypt organoids and the intestinal mucosa, as well as to stimulate the differentiation of ISCs into goblet cells and possibly Paneth cells and enteroendocrine cells. Since GH and Gln have differential effects on ISCs. Their use in combination may have synergistic effects on ISCs. In this review, we summarize the evidence of the actions of GH and/or Gln on crypt cells and ISCs in the literature. Overall, most studies demonstrated that GH and Gln in combination exerted synergistic effects to activate the proliferation of crypt cells and ISCs and enhance crypt organoid formation and mucosal growth. This treatment influenced the proliferation of ISCs to a similar degree as GH treatment alone and the differentiation of ISCs to a similar degree as Gln treatment alone.

Identifying the Growth Factors for Improving Neointestinal Regeneration in Rats through Transcriptome Analysis Using RNA-Seq Data

Using our novel surgical model of simultaneous intestinal adaptation "A" and neointestinal regeneration "N" conditions in individual rats to determine feasibility for research and clinical application, we further utilized next generation RNA sequencing (RNA-Seq) here in normal control tissue and both conditions ("A" and "N") across time to decipher transcriptome changes in neoregeneration and adaptation of intestinal tissue at weeks 1, 4, and 12. We also performed bioinformatics analyses to identify key growth factors for improving intestinal adaptation and neointestinal regeneration. Our analyses indicate several interesting phenomena. First, Gene Ontology and pathway analyses indicate that cell cycle and DNA replication processes are enhanced in week 1 "A"; however, in week 1 "N", many immune-related processes are involved. Second, we found some growth factors upregulated or downregulated especially in week 1 "N" versus "A". Third, based on each condition and time point versus normal control tissue, we found in week 1 "N" BMP2, BMP3, and NTF3 are significantly and specifically downregulated, indicating that the regenerative process may be inhibited in the absence of these growth factors. This study reveals complex growth factor regulation in small neointestinal regeneration and intestinal adaptation and provides potential applications in tissue engineering by introducing key growth factors identified here into the injury site.

Deferoxamine preconditioning activated hypoxia-inducible factor-1α and MyD88-dependent Toll-like receptor 4 signaling in intestinal stem cells

BACKGROUND/PURPOSE

Toll-like receptors (TLRs) are important regulators of innate immunity, and TLR4 pathway can regulate the survival, migration, and differentiation of stem cells, including intestinal stem cells (ISCs). Deferoxamine (DFO), a hypoxia-mimic compound, can activate the proliferation of ISCs. In this study, we investigated the response of TLR4 signaling to DFO-induced hypoxia in cultured ISCs in vitro.

METHODS

After DFO treatment, the crypt organoid number was counted, and the expression levels of Lgr5, Hsp70, HMGB1, HIF-1α, TLR4, MyD88, TRIF, and TRAM in ISCs were examined using QPCR and Western blotting. The chemical inhibitors of different signaling molecules were then used to determine their role in DFO-induced change in ISCs.

RESULTS

The expression levels of Lgr5, HIF-1α, TLR4, MyD88, and TRIF in ISCs increased after DFO treatment, with peak expression of these molecules 6h after DFO treatment. In addition, DFO-induced gene expression of Lgr5 and HIF-1α was partially reversed by pretreatment with the inhibitor of TLR4 or MyD88, but not TRIF inhibitor. Inhibition of HIF-1α also resulted in partial downregulation of DFO-induced elevation of Lgr5 and TLR4.

CONCLUSIONS

These results demonstrated that DFO treatment activated HIF-1α and the TLR4-MyD88 signaling pathway, which might mediate the activation of ISCs.

Distinct Effects of Growth Hormone and Glutamine on Activation of Intestinal Stem Cells

BACKGROUND

For patients with short bowel syndrome under parenteral nutrition support, growth hormone (GH) and glutamine (GLN) have been found to help the growth of intestinal mucosa. In this research, we studied the effects of GH and GLN on intestinal stem cells (ISCs).

METHODS

The in vitro and in vivo effects of GH and/or GLN on ISCs were evaluated by observing the ability of ISCs to form organoids in a Matrigel culture system. The expression levels of stemness and differentiation markers in ISCs and organoids were assessed using quantitative real-time polymerase chain reaction, immunofluorescence assay, and immunohistochemistry staining.

RESULTS

In vitro administration of GH activated the stemness of ISCs, whereas GLN enhanced the expression of chromogranin A and Muc2, which are differentiation markers in enteroendocrine and goblet cells, respectively. Administration of GH or GLN in mice showed that GH, but not GLN, upregulated the proliferative activity of ISCs with increased formation of crypt organoids. In addition, GH increased the expression of Lgr5 and GLN enhanced expression of Muc2 in the crypt fractions of the intestines in mice.

CONCLUSION

These results suggest that GH mainly enhances proliferative activities, whereas GLN promotes the differentiation potential of ISCs.

Spectroscopic studies on the interaction between tetrandrine and two serum albumins by chemometrics methods

The binding interactions of tetrandrine (TETD) with bovine serum albumin (BSA) and human serum albumin (HSA) have been investigated by spectroscopic methods. These experimental data were further analyzed using multivariate curve resolution-alternating least squares (MCR-ALS) method, and the concentration profiles and pure spectra for three species (BSA/HSA, TETD and TETD-BSA/HSA) existed in the interaction procedure, as well as, the apparent equilibrium constants Kapp were evaluated. The binding sites number n and the binding constants K were obtained at various temperatures. The binding distance between TETD and BSA/HSA was 1.455/1.451nm. The site markers competitive experiments indicated that TETD primarily bound to the tryptophan residue of BSA/HSA within site I. The thermodynamic parameters (ΔG, ΔH and ΔS) calculated on the basis of different temperatures revealed that the binding of TETD-BSA was mainly depended on the hydrophobic interaction strongly and electrostatic interaction, and yet the binding of TETD-HSA was strongly relied on the hydrophobic interaction. The results of synchronous fluorescence, 3D fluorescence and FT-IR spectra show that the conformation of proteins has altered in the presence of TETD. In addition, the effect of some common ions on the binding constants between TETD and proteins were also discussed.

Ischemic preconditioning increased the intestinal stem cell activities in the intestinal crypts in mice

BACKGROUND

Ischemic preconditioning (IPC) can protect against ischemia-reperfusion injury in the small intestine. Because intestinal stem cells (ISCs) control the recovery and growth of intestinal villi, this study investigated whether IPC had any effects on the activity of ISCs.

MATERIALS AND METHODS

The small intestines of mice were treated with IPC, laparotomy only (sham), or no surgery. The crypt fractions were isolated and the characteristics of ISCs among various groups were compared. The regenerative ability and the number of organoids grown from various crypt fractions were compared. The expression of hypoxia-inducible factor-1α (HIF-1α) and the related proteins of the Wnt-/β-catenin pathway in the crypt fractions were studied.

RESULTS

The IPC group had higher messenger RNA levels of various stem cell markers than the sham group at days 1 and 2 after surgery. The IPC group exhibited greater regenerative activity and more crypt organoids than the sham group (P < 0.05). The expression of HIF-1α, β-catenin, and phosphoglycogen synthase kinase 3β was increased in the IPC-treated crypt fractions in vivo and cultured crypt organoid cells with deferoxamine-mimicked hypoxia in vitro.

CONCLUSIONS

IPC significantly upregulated the activity of ISCs, possibly through the HIF-1α response and Wnt-/β-catenin signaling pathway.

Mucosal protective effect of PGI2 on canine small bowel auto-transplantation

PURPOSE

We designed this experimental study to assess the mucosal protective effects of continuous prostaglandin I2 (PGI2) infusion after canine small bowel autotransplantation.

MATERIALS AND METHODS

Six Mongrel dogs were randomly divided two groups: PGI2 (n = 3) and control (n = 3). The small bowel from jejunum to ileum was obtained, including the mesenteric vascular pedicle. After cold flushing ex vivo, the harvested segment was preserved in an icebox for 3 hours. Thereafter we reimplanted the harvested intestinal segment. While completing the anastomosis, PGI2 (50 μg) was slowly infused through the mesenteric artery in the PGI2 group versus the same volume of saline in the control group. At 1, 3 and 6 days after autotransplantation, we obtained blood samples, and at 6 days, small bowel segments. Endotoxin and interleukin 6 (IL-6) levels were measured and all histologic specimens stained with hematoxylin-eosin H-E were reviewed by a pathologist to grade mucosal damage as: mild (1 point), moderate (2 points), or severe (3 points) change.

RESULTS

Mean basal serum endotoxin levels were similar in both groups the PGI2 groups versus control group were 0.216 ± 0.018 versus 0.223 ± 0.040 EU/mL, respectively. However, on day 3 after the operation, the PGI2 group showed much decreased levels of serum endotoxin compared to control levels: 0.349 ± 0.196 versus 0.842 ± 0.446 EU/mL. The mean concentration of serum IL-6 on day 1 after operation among the PGI2 versus control group were 32.13 ± 7.13 pg/mL versus 36.96 ± 3.65 pg/mL. The histologic scores at 6 days after the operation were PGI2 group versus control group: 1.33 versus 1.66 (P = NS).

CONCLUSION

Continuous infusions of PGI2 through the mesenteric artery after the canine small bowel autotransplantation may protect the small bowel mucosal barrier.

Post-reperfusion syndrome during isolated intestinal transplantation: outcome and predictors

BACKGROUND

Post-reperfusion syndrome (PRS) during isolated intestinal transplantation (ITx) is characterized by decreased systemic blood pressure, systemic vascular resistance, and cardiac output and by a moderate increased pulmonary arterial pressure. We hypothesize that the more severe PRS causes a poorer long-term outcome. The primary aim of this study was to determine the independent clinical predictors of intra-operative PRS, as well as to investigate the link between the severity of PRS and the intra-operative profiles and to examine the post-operative complications and their relationship with transplant outcome.

METHODS

This observational study was conducted on 27 patients undergoing isolated ITx in a single adult liver and multivisceral transplantation center. PRS was considered when the mean arterial blood pressure was 30% lower than the pre-unclamping value and lasted for at least one min within 10 min after unclamping.

RESULTS AND CONCLUSIONS

The main results of this study can be summarized in two findings: in patients undergoing ITx, the duration of cold ischemia and the pre-operative glomerular filtration rate were independent predictors of PRS and the occurrence of intra-operative PRS was associated with significantly more frequent post-operative renal failure and early post-operative death.

The potential of tetrandrine as a protective agent for ischemic stroke

Stroke is one of the leading causes of mortality, with a high incidence of severe morbidity in survivors. The treatment to minimize tissue injury after stroke is still unsatisfactory and it is mandatory to develop effective treatment strategies for stroke. The pathophysiology of ischemic stroke is complex and involves many processes including energy failure, loss of ion homeostasis, increased intracellular calcium level, platelet aggregation, production of reactive oxygen species, disruption of blood brain barrier, and inflammation and leukocyte infiltration, etc. Tetrandrine, a bisbenzylisoquinoline alkaloid, has many pharmacologic effects including anti-inflammatory and cytoprotective effects. In addition, tetrandrine has been found to protect the liver, heart, small bowel and brain from ischemia/reperfusion injury. It is a calcium channel blocker, and can inhibit lipid peroxidation, reduce generation of reactive oxygen species, suppress the production of cytokines and inflammatory mediators, inhibit neutrophil recruitment and platelet aggregation, which are all devastating factors during ischemia/reperfusion injury of the brain. Because tetrandrine can counteract these important pathophysiological processes of ischemic stroke, it has the potential to be a protective agent for ischemic stroke.