REV-ERBα negatively regulates NLRP6 transcription and reduces the severity of Salmonella infection in mice.

Non-typhoidal Salmonella infection is among the most frequent foodborne diseases threatening human health worldwide. The host circadian clock orchestrates daily rhythms to adapt to environmental changes, including coordinating immune function in response to potential infections. However, the molecular mechanisms underlying the interplay between the circadian clock and the immune system in modulating infection processes are incompletely understood. Here, we demonstrate that NLRP6, a novel nucleotide-oligomerization domain (NOD)-like receptor (NLR) family member highly expressed in the intestine, is closely associated with the differential day-night response to Salmonella infection. The core clock component REV-ERBα negatively regulates NLRP6 transcription, leading to the rhythmic expression of NLRP6 and the secretion of IL-18 in intestinal epithelial cells, playing a crucial role in mediating the differential day-night response to Salmonella infection. Activating REV-ERBα with agonist SR9009 in wild-type mice attenuated the severity of infection by decreasing the NLRP6 level in intestinal epithelial cells. Our findings provide new insights into the association between the host circadian clock and the immune response to enteric infections by revealing the regulation of Salmonella infection via the inhibitory effect of REV-ERBα on NLRP6 transcription. Targeting REV-ERBα to modulate NLRP6 activation may be a potential therapeutic strategy for bacterial infections.

Quercetin Limits Tumor Immune Escape through PDK1/CD47 Axis in Melanoma.

Quercetin (3,3[Formula: see text],4[Formula: see text],5,7-pentahydroxyflavone) is a bioactive plant-derived flavonoid, abundant in fruits and vegetables, that can effectively inhibit the growth of many types of tumors without toxicity. Nevertheless, the effect of quercetin on melanoma immunology has yet to be determined. This study aimed to investigate the role and mechanism of the antitumor immunity action of quercetin in melanoma through both in vivo and in vitro methods. Our research revealed that quercetin has the ability to boost antitumor immunity by modulating the tumor immune microenvironment through increasing the percentages of M1 macrophages, CD8[Formula: see text] T lymphocytes, and CD4[Formula: see text] T lymphocytes and promoting the secretion of IL-2 and IFN-[Formula: see text] from CD8[Formula: see text] T cells, consequently suppressing the growth of melanoma. Furthermore, we revealed that quercetin can inhibit cell proliferation and migration of B16 cells in a dose-dependent manner. In addition, down-regulating PDK1 can inhibit the mRNA and protein expression levels of CD47. In the rescue experiment, we overexpressed PDK1 and found that the protein and mRNA expression levels of CD47 increased correspondingly, while the addition of quercetin reversed this effect. Moreover, quercetin could stimulate the proliferation and enhance the function of CD8[Formula: see text] T cells. Therefore, our results identified a novel mechanism through which CD47 is regulated by quercetin to promote phagocytosis, and elucidated the regulation of quercetin on macrophages and CD8[Formula: see text] T cells in the tumor immune microenvironment. The use of quercetin as a therapeutic drug holds potential benefits for immunotherapy, enhancing the efficacy of existing treatments for melanoma.

NLRP6 induces RIP1 kinase-dependent necroptosis via TAK1-mediated p38MAPK/MK2 phosphorylation in S. typhimurium infection.

Programmed cell death (PCD) is tightly orchestrated by molecularly defined executors and signaling pathways. NLRP6, a member of cytoplasmic pattern recognition receptors, has a multifaceted role in host resistance to bacterial infection. However, whether and how NLRP6 may contribute to regulate host PCD during Gram-negative bacterial infection remain to be illuminated. Here, we report that NLRP6 promotes RIP1 kinase-mediated necroptosis, a form of lytic PCD, in both an in vitro and in vivo model of Salmonella typhimurium infection. By downregulating TAK1-mediated p38MAPK/MK2 phosphorylation, NLRP6 decreased RIP1 phosphorylation at residue S321 and subsequently increased RIP1 kinase-dependent MLKL phosphorylation. Suppression of p38MAPK/MK2 cascade not only reduced the number of dead cells caused by NLRP6 but also decreased the systemic dissemination of S. typhimurium resulting from NLRP6. Taken together, our findings provide new insights into the role and regulatory mechanism of NLRP6-associated antimicrobial responses by revealing a function for NLRP6 in regulating necroptosis.

Intra- and Interimage Reliability of Inter-Rectus Distance Measurements Determined via Ultrasound Imaging by the Same or Different Testers in Women in the Early Postpartum Period.

OBJECTIVES: No consensus regarding the optimal position and location for the measurement of the inter-rectus distance (IRD) via ultrasound (US) has been reached. By investigating the intra- and interimage reliability of IRD measurements taken in different positions and at different locations within and between testers, this study provides a theoretical basis for the current situation. METHODS: The IRD was measured via US in 46 women at 42-60 days after delivery at the superior margin of the umbilicus and 3 cm above, 5 cm above and 3 cm below the umbilicus while the women were in the supine, crunch and standing positions. In the interimage test, every participant was tested 2 times by Physician X and 1 time by Physician Y; in the intraimage test, the images collected by Physician X during the first test were saved in the machines, and two measurements were performed by Physician X and one measurement was performed by Physician Y. Paired t tests and intraclass correlation coefficients (ICCs) were calculated. RESULTS: Only the first IRD measurements by tester X and tester Y at 3 cm below the umbilicus in the crunch position were significantly different (9.56 ± 6.00 versus 11.00 ± 5.55) (P < .05). All the ICCs were greater than .75, and the intratester ICCs were greater than or equal to the corresponding intertester ICCs. The ICCs at 3 cm below the umbilicus were the smallest in the supine and crunch positions and the largest in the standing position due to the increased frequency of IRD values of 0. The ICCs for the crunch position were greatest according to the intraimage test but smallest according to the interimage test. The interimage ICCs between the two testers in the supine position at the superior margin, 3 cm above, 5 cm above, and 3 cm below the umbilicus were .972, .974, .975, and .956, respectively. CONCLUSIONS: Ultrasound imaging (USI) is a reliable method for measuring the IRD in women in the early postpartum period. The dynamic measurement of the IRD at or above the umbilicus in the supine position by different testers in real time showed the highest reliability.

Cordycepin enhances anti-tumor immunity in colon cancer by inhibiting phagocytosis immune checkpoint CD47 expression.

Cordycepin, also known as 3'-deoxyadenosine, is an extract from Cordyceps militaris, which has been reported as an anti-inflammation and anti-tumor substance without toxicity. However, the pharmacological mechanism of Cordycepin on tumor immunity under its anti-tumor effect has not yet been elucidated. Herein, we investigated Cordycepin's anti-tumor effect on colon cancer both in vitro and in vivo. Our results show that Cordycepin can inhibit growth, migration, and promoted apoptosis of CT26 cells in a dose-dependent manner. Cordycepin suppressed the growth of colon cancer in mouse subcutaneous tumor model by modulating tumor immune microenvironment where CD4+ T, CD8+ T, M1 type macrophages, NK cells were up-regulated. Further investigations revealed that Cordycepin inhibited phagocytosis immune checkpoint CD47 protein expression by reducing BNIP3 expression. In addition, Cordycepin also inhibited the expression of TSP1 in tumor cells and Jurkat cells, which may reduce the binding of TSP1 to CD47, thereby reducing T cell apoptosis and allowing more T cells to infiltrate into tumors. And in vitro co-culture experiments proved that Cordycepin could enhance the phagocytosis of CT26 cells by macrophages. These results explained the underlying mechanism of the anti-tumor immunity of Cordycepin. In conclusion, our results identify a novel mechanism by which Cordycepin inhibits phagocytosis immune checkpoint CD47 in tumor cells to promote tumor cells phagocytosis of macrophages. Cordycepin may be able to serve as a more effective immunotherapeutic drug against colon cancer.

Salmonella pSLT-encoded effector SpvB promotes RIPK3-dependent necroptosis in intestinal epithelial cells.

Salmonella is one of the most important worldwide zoonotic pathogens. After invading a host orally, the bacteria break through the intestinal epithelial barrier for further invasion. Intestinal epithelial cells (IECs) play a crucial role in maintaining the integrity of the intestinal epithelial barrier. Necroptosis is considered one of the virulence strategies utilized by invasive Salmonella. Our previous work has shown that SpvB, an effector encoded by S. Typhimurium virulence plasmid (pSLT), promotes bacterial translocation via the paracellular route. However, it is still unknown whether SpvB could promote bacterial invasion through disrupting the integrity of IECs. Here, we demonstrated that SpvB promoted necroptosis of IECs and contributed to the destruction of the intestinal barrier during Salmonella infection. We found that SpvB enhanced the protein level of receptor-interacting protein kinase 3 (RIPK3) through inhibiting K48-linked poly-ubiquitylation of RIPK3 and the degradation of the protein in an autophagy-dependent manner. The abundant accumulation of RIPK3 upregulated the phosphorylation of MLKL, which contributed to necroptosis. The damage to IECs ultimately led to the disruption of the intestinal barrier and aggravated infection. In vivo, SpvB promoted the pathogenesis of Salmonella, favoring intestinal injury and colonic necroptosis. Our findings reveal a novel function of Salmonella effector SpvB, which could facilitate salmonellosis by promoting necroptosis, and broaden our understanding of the molecular mechanisms of bacterial invasion.

A detrimental role of NLRP6 in host iron metabolism during Salmonella infection.

Maintaining host iron homeostasis is an essential component of nutritional immunity responsible for sequestrating iron from pathogens and controlling infection. Nucleotide-oligomerization domain-like receptors (NLRs) contribute to cytoplasmic sensing and antimicrobial response orchestration. However, it remains unknown whether and how NLRs may regulate host iron metabolism, an important component of nutritional immunity. Here, we demonstrated that NLRP6, a member of the NLR family, has an unconventional role in regulating host iron metabolism that perturbs host resistance to bacterial infection. NLRP6 deficiency is advantageous for maintaining cellular iron homeostasis in both macrophages and enterocytes through increasing the unique iron exporter ferroportin-mediated iron efflux in a nuclear factor erythroid-derived 2-related factor 2 (NRF2)-dependent manner. Additional studies uncovered a novel mechanism underlying NRF2 regulation and operating through NLRP6/AKT interaction and that causes a decrease in AKT phosphorylation, which in turn reduces NRF2 nuclear translocation. In the absence of NLRP6, increased AKT activation promotes NRF2/KEAP1 dissociation via increasing mTOR-mediated p62 phosphorylation and downregulates KEAP1 transcription by promoting FOXO3A phosphorylation. Together, our observations provide new insights into the mechanism of nutritional immunity by revealing a novel function of NLRP6 in regulating iron metabolism, and suggest NLRP6 as a therapeutic target for limiting bacterial iron acquisition.

Salmonella Effector SpvB Inhibits NF-κB Activity via KEAP1-Mediated Downregulation of IKKß.

Bacterial pathogens have a broad arsenal of genes that are tightly regulated and coordinated to facilitate adaptation to alter host inflammatory response and prolong intracellular bacterial survival. Salmonella enterica serovar Typhimurium utilizes a type III secretion system (T3SS) to deliver effector molecules into host cells and regulate signal transduction pathways such as NF-κB, thereby resulting in salmonellosis. SpvB, a pSLT-encoded cytotoxic protein secreted by Salmonella pathogenicity island-2 T3SS, is associated with enhanced Salmonella survival and intracellular replication. In this report, we characterized the effects of SpvB on NF-κB signaling pathway. We showed that SpvB has a potent and specific ability to prevent NF-κB activation by targeting IκB kinase ß (IKKß). Previous studies from our laboratory showed that SpvB decreases Nrf2 through its C-terminal domain. Here we further demonstrated that KEAP1, a cytoplasmic protein that interacts with Nrf2 and mediates its proteasomal degradation, is involved in SpvB-induced downregulation of IKKß expression and phosphorylation. Reduction of KEAP1 by small-interfering RNA prevented the suppression of IKKß and its phosphorylation mediated by SpvB. These findings revealed a novel mechanism by which Salmonella modulates NF-κB activity to ultimately facilitate intracellular bacterial survival and proliferation and delay host immune response to establish infection.

Salmonella effector SpvB aggravates dysregulation of systemic iron metabolism via modulating the hepcidin-ferroportin axis.

Iron withholding, an essential component of nutritional immunity, plays a fundamental role in host resistance to Salmonella infection. Our previous study showed that SpvB, an important pSLT-encoded cytotoxic effector, facilitated Salmonella pathogenesis within macrophages via perturbing cellular iron metabolism. However, the underlying mechanisms of SpvB in Salmonella-relevant disorders of systemic iron metabolism have not yet been identified. Here, we demonstrated that SpvB facilitated Salmonella to scavenge iron from the host by modulating the hepcidin-ferroportin axis, a key regulator of systemic iron metabolism. We observed that SpvB enhanced hepatic hepcidin synthesis in a STAT3-dependent manner, but not the BMP/SMAD pathway. This subsequently resulted in a reduction of the unique cellular iron exporter ferroportin, which facilitated hypoferremia and hepatic iron accumulation and ultimately countered the limitation of iron availability, thereby improving the chances of Salmonella survival and replication. Moreover, SpvB promoted the production of proinflammatory molecules associated with the infiltration of inflammatory cells via highly upregulating TREM-1 signaling. Our data supported a role of TREM-1 in SpvB-related dysregulation of host iron metabolism and suggested that targeting TREM-1 might provide a potential therapeutic strategy to prevent or alleviate Salmonella pathogenesis.

The application of enhanced recovery after surgery for upper gastrointestinal surgery: Meta-analysis.

BACKGROUND: Although enhanced recovery after surgery (ERAS) has made great progress in the field of surgery, the guidelines point to the lack of high-quality evidence in upper gastrointestinal surgery. METHODS: Randomized controlled trials in four electronic databases that involved ERAS protocols for upper gastrointestinal surgery were searched through December 12, 2018. The primary endpoints were lung infection, urinary tract infection, surgical site infection, postoperative anastomotic leakage and ileus. The secondary endpoints were postoperative length of stay, the time from end of surgery to first flatus and defecation, and readmission rates. Subgroup analysis was performed based on the type of surgery. RESULTS: A total of 17 studies were included. The results of the meta-analysis indicate that there was a decrease in rates of lung infection (RR = 0.50, 95%CI: 0.33 to 0.75), postoperative length of stay (MD = -2.53, 95%CI: - 3.42 to - 1.65), time until first postoperative flatus (MD = -0.64, 95%CI: - 0.84 to - 0.45) and time until first postoperative defecation (MD = -1.10, 95%CI: - 1.74 to - 0.47) in patients who received ERAS, compared to conventional care. However, other outcomes were not significant difference. There was no significant difference between ERAS and conventional care in rates of urinary tract infection (P = 0.10), surgical site infection (P = 0.42), postoperative anastomotic leakage (P = 0.45), readmissions (P = 0.31) and ileus (P = 0.25). CONCLUSIONS: ERAS protocols can reduce the risk of postoperative lung infection and accelerating patient recovery time. Nevertheless, we should also consider further research ERAS should be performed undergoing gastrectomy and esophagectomy.

Salmonella Effector SpvB Disrupts Intestinal Epithelial Barrier Integrity for Bacterial Translocation.

Salmonella are common enteric bacterial pathogens that infect both humans and animals. Intestinal epithelial barrier, formed by a single layer of epithelial cells and apical junctional complex (AJC), plays a crucial role in host defense against enteric pathogens to prevent bacterial translocation. However, the underlying mechanisms of intestinal epithelial barrier dysfunction caused by Salmonella are poorly understood. It is found that a locus termed Salmonella plasmid virulence (spv) gene exists extensively in clinically important Salmonella serovars. SpvB is a key effector encoded within this locus, and closely related to Salmonella pathogenicity such as interfering with autophagy and iron homeostasis. To investigate the interaction between SpvB and intestinal epithelial barrier and elucidate the underlying molecular mechanism, we used the typical foodborne disease agent Salmonella enterica serovar Typhimurium (Salmonella typhimurium) carrying spvB or not to construct infection models in vivo and in vitro. C57BL/6 mice were orally challenged with S. typhimurium wild-type strain SL1344 or spvB-deficient mutant strain SL1344-ΔspvB. Caco-2 cell monolayer model, as a widely used model to mimic the human intestinal epithelium in vitro, was infected with SL1344, SL1344-ΔspvB, or spvB complementary strain SL1344-c-ΔspvB, respectively. The results showed that SpvB enhanced bacterial pathogenicity during S. typhimurium infection in vivo, and contributed to intestinal epithelial barrier dysfunction in both infection systems. This SpvB-mediated barrier dysfunction was attributed to the cellular redistribution of Claudin-1, Occludin, and E-cadherin junctional proteins. Moreover, by using pharmacological inhibitors, we found that F-actin rearrangement and suppression of protein kinase C (PKC) signaling pathway were involved in SpvB-mediated barrier dysfunction. In conclusion, the study reveals the contribution of Salmonella effector SpvB to the dysfunction of intestinal epithelial barrier integrity, which facilitates bacterial translocation via the paracellular route to promote Salmonella systemic dissemination. Our findings broaden the understanding of host-pathogen interactions in salmonellosis, and provide new strategies for the therapy in limiting bacterial dissemination during infection.

Salmonella effector SpvB interferes with intracellular iron homeostasis via regulation of transcription factor NRF2.

Iron is a necessary nutrient for humans and nearly all bacterial species. During Salmonella infection, macrophages limit the availability of iron to intracellular pathogens in one of the central components of nutritional immunity. However, Salmonella also have mechanisms to interfere with the antimicrobial effect of host iron withdrawal and meet their own nutrient requirements by scavenging iron from the host. Here, we provide what is, to our knowledge, the first report that SpvB, a pSLT-encoded cytotoxic protein whose function is associated with the intracellular stage of salmonellosis, perturbs macrophage iron metabolism, thereby facilitating Salmonella survival and intracellular replication. In investigating the underlying mechanism, we observed that the Salmonella effector SpvB down-regulated nuclear factor erythroid-derived 2-related factor 2 (NRF2), and its C-terminal domain was necessary and sufficient for NRF2 degradation via the proteasome pathway. Decreased NRF2 expression in the nucleus resulted in a decrease in its transcriptional target ferroportin, encoding the sole macrophage iron exporter, thus ultimately decreasing iron efflux and increasing the intracellular iron content. Additionally, SpvB contributes to the pathogenesis of Salmonella including severe serum hypoferremia, increased splenic and hepatic bacterial burden, and inflammatory injury in vivo. Together, our observations uncovered a novel contribution of SpvB to Salmonella pathology via interference with host intracellular iron metabolism.-Yang, S., Deng, Q., Sun, L., Dong, K., Li, Y., Wu, S., Huang, R. Salmonella effector SpvB interferes with intracellular iron homeostasis via regulation of transcription factor NRF2.

Enhanced Recovery After Surgery for Breast Reconstruction: Pooled Meta-Analysis of 10 Observational Studies Involving 1,838 Patients.

Purpose: This study aims to explore the effectiveness and safety of the enhanced recovery after surgery (ERAS) protocol vs. traditional perioperative care programs for breast reconstruction. Methods: Three electronic databases (PubMed, EMBASE, and Cochrane Library) were searched for observational studies comparing an ERAS program with a traditional perioperative care program from database inception to 5 May 2018. Two reviewers independently screened the literature according to the inclusion and exclusion criteria, extracted the data, and evaluated study quality using the Newcastle-Ottawa Scale. Subgroup and sensitivity analyses were performed. The outcomes included the length of hospital stay (LOS), complication rates, pain control, costs, emergency department visits, hospital readmission, and unplanned reoperation. Results: Ten studies were included in the meta-analysis. Compared with a conventional program, ERAS was associated with significantly decreased LOS, morphine administration (including postoperative patient-controlled analgesia usage rate and duration; intravenous morphine administration on postoperative day [POD] 0, 1, 2, and 4; total intravenous morphine administration on POD 0-3; oral morphine consumption on POD 0-4; and total postoperative oral morphine consumption), and pain scores (postoperative pain score on POD 0 and total pain score on POD 0-3). The other variables did not differ significantly. Conclusion: Our results suggest that ERAS protocols can decrease LOS and morphine equivalent dosing; therefore, further larger, and better-quality studies that report on bleeding amount and patient satisfaction are needed to validate our findings.

Scoliotic Imaging With a Novel Double-Sweep 2.5-Dimensional Extended Field-of-View Ultrasound.

Extended field-of-view ultrasound (US EFOV) imaging is a technique used extensively in the clinical field to attain interpretable panorama of anatomy; 2.5-D US EFOV has recently been proposed for spine imaging. In the original 2.5-D US EFOV, it makes use of a six degrees-of-freedom positional sensor attached to the US probe to record the corresponding position of each B-scan. By combining the positional information and the B-scan images, the 2.5-D EFOV can reconstruct a panorama on a curved image plane when the scanning trajectory of the US probe is curved. In this paper, an improved method based on the Bezier interpolation is proposed to better reconstruct 2.5-D US EFOV imaging, producing the panoramas with smoother texture and higher quality. To make it more applicable for scoliosis patients, we designed a novel method called double-sweep 2.5-D EFOV to better image the spinal tissues and easily compute the Cobb angle. In vitro and in vivo experiments demonstrated that the 2.5-D EFOV images obtained by the proposed method can present anatomical structures of the scanning region accurately.

Impact of enhanced recovery after surgery on postoperative recovery after joint arthroplasty: results from a systematic review and meta-analysis.

STUDY DESIGN: Systematic review with meta-analysis. OBJECTIVES: To evaluate the effects of enhanced recovery after surgery (ERAS) on the postoperative recovery of patients who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA). METHODS: The PubMed, Embase, Cochrane and ISI Web of Science databases were searched to identify literature including randomised controlled trials (RCTs), cohort studies and case-control studies through 2 May 2018. The analysed outcomes were mortality rate, transfusion rate, range of motion (ROM), 30-day readmission rate, postoperative complication rate and in-hospital length of stay (LOS). RESULTS: A total of 25 studies involving 16 699 patients met the inclusion criteria and were included in the meta-analysis. Compared with conventional care, ERAS was associated with a significant decrease in mortality rate (relative risk (RR) 0.48, 95% CI 0.27 to 0.85), transfusion rate (RR 0.43, 95% CI 0.37 to 0.51), complication rate (RR 0.74, 95% CI 0.62 to 0.87) and LOS (mean difference (MD) -2.03, 95% CI -2.64 to -1.42) among all included trials. However, no significant difference was found in ROM (MD 7.53, 95% CI -2.16 to 17.23) and 30-day readmission rate (RR 0.86, 95% CI 0.56 to 1.30). There was no significant difference in complications of TKA (RR 0.84, 95% CI 0.34 to 2.06) and transfusion rate in RCTs (RR 0.66, 95% CI 0.15 to 2.88) between the ERAS group and the control group. CONCLUSIONS: This meta-analysis showed that ERAS significantly reduced the mortality rate, transfusion rate, incidence of complications and LOS of patients undergoing TKA or THA. However, ERAS did not show a significant impact on ROM and 30-day readmission rate. Complications after hip replacement are less than those of knee replacement, and the young patients recover better. LEVEL OF EVIDENCE: Level 1.

spv locus aggravates Salmonella infection of zebrafish adult by inducing Th1/Th2 shift to Th2 polarization.

Salmonella enterica serovar typhimurium (S. typhimurium) are facultative intracellular enteric pathogens causing disease with a broad range of hosts. It was known that Th1-type cytokines such as IFN-γ, IL-12, and TNF-α etc. could induce protective immunity against intracellular pathogens, while Th2-type cytokines such as IL-4, IL-10, and IL-13 etc. are proved to help pathogens survive inside hosts and cause severe infection. One of the critical virulence factor attributes to the pathogenesis of S. typhimurium is Salmonella plasmid virulence genes (spv). Until now, the interaction between spv locus and the predictable generation of Th1 or Th2 immune responses to Salmonella has not been identified. In this study, zebrafish adults were employed to explore the effect of spv locus on Salmonella pathogenesis as well as host adaptive immune responses especially shift of Th1/Th2 balance. The pathological changes of intestines and livers in zebrafish were observed by hematoxylin-eosin (HE) staining and electron microscopy. Levels of the transcription factors of Th1 (Tbx21) and Th2 (GATA3) were measured by real-time quantitative PCR (RT-qPCR). Expression of cytokines were determined by using RT-qPCR and ELISA, respectively. Results showed that spv operon aggravates damage of zebrafish. Furthermore, it demonstrated that spv locus could inhibit the transcription of tbx21 gene and suppress the expression of cytokines IFN-γ, IL-12 and TNF-α. On the contrary, the transcription of gata3 gene could be promoted and the expression of cytokines IL-4, IL-10 and IL-13 were enhanced by spv locus. Taken together, our data revealed that spv locus could aggravate Salmonella infection of zebrafish adult by inducing an imbalance of Th1/Th2 immune response and resulting in a detrimental Th2 bias of host.

Synthesis and biological evaluation of 4,4-dimethyl lithocholic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B.

Protein tyrosine phosphatase 1B (PTP1B) is a major negative regulator of both insulin and leptin signals. For years, inhibiting of PTP1B has been considered to be a potential therapeutics for treating Type 2 diabetes and obesity. Recently, we recognized lithocholic acid (LCA) as a natural inhibitor against PTP1B (IC(50)=12.74 µM) by a vertical screen for the first time. Further SAR research was carried out by synthesizing and evaluating a series of compounds bearing two methyls at C-4 position and a fused heterocycle to ring A. Among them, compound 14b achieved a PTP1B inhibitory activity about eightfold than LCA and a 14-fold selectivity over the homogenous enzyme TCPTP.