The effectiveness of dexmedetomidine for preventing acute kidney injury after surgery: a systematic review and meta-analysis.

Background: Postoperative acute kidney injury (AKI) is a serious and distressing complication connected to various adverse outcomes following the surgical operation. Controversy remains regarding the dexmedetomidine's preventive impact on postoperative AKI. Therefore, this investigation aims to explore the efficiency and safety of dexmedetomidine in preventing AKI after surgical operation. Methods: We systematically searched electronic databases such as PubMed, Embase, Web of Science, and the Cochrane Library to detect eligible randomized controlled studies that used dexmedetomidine for the prevention of AKI following operation up to April 30, 2023. The main outcome evaluated was AKI incidence. The evidence quality was assessed employing the Grading of Recommendations Assessment, Development, and Evaluation. Results: The meta-analysis included 25 trials, including 3,997 individuals. Of these, 2,028 were in the dexmedetomidine group, and 1,969 were in the control group. The result showed that patients administered dexmedetomidine significantly decreased the AKI incidence following surgical operation in contrast to the control group (risk ratio, 0.60; 95% confidence intervals, 0.45-0.78; p < 0.05; I 2 = 46%). In addition, dexmedetomidine decreased the period of hospitalization in both the intensive care unit (ICU) and the hospital while also reducing postoperative delirium (POD) occurrence. However, dexmedetomidine elevated the incidence of bradycardia but did not have a significant impact on other indicators. Conclusion: Our meta-analysis indicates that the dexmedetomidine treatment reduces the postoperative AKI and POD risk while also shortening the time of hospitalization in the ICU and hospital. However, it is connected to an increased bradycardia risk.

Thinning by cluster breaking: Active matter and shear flows share thinning mechanisms.

Among many unexpected phenomena of active matter is the recently observed superfluid-like thinning (viscosity drop) behavior of bacteria suspensions. Understanding this peculiar self-propelled thinning by active matter is of theoretical and practical importance. Here, we find that, although distinct in driving mechanisms, active matter and shear flows exhibit similar thinning behaviors upon the increase of self-propulsion and shear forces, respectively. Our structural characterizations reveal that they actually share the same cluster-breaking mechanism of thinning. How fast and how shattered the cluster is broken determines the (dis)continuity of the thinning. This explains why adding active particles to Newtonian fluids can cause thinning, in which rotation of active particles play a key role in breaking clusters. Our work proposes a mechanism of self-propelled thinning and further establishes the underlying connections between active matter and shear flows.

Hidden blood loss and the influential factors after minimally invasive treatment of posterior pelvic ring injury with sacroiliac screw.

BACKGROUND: To analyze the perioperative bleeding and hidden blood loss (HBL) of sacroiliac screw minimally invasive treatment of pelvic posterior ring injury and explore the influential factors of HBL after operation for providing reference for clinical treatment. METHOD: A retrospective analysis was conducted on data from 369 patients with posterior pelvic ring injuries treated with sacroiliac screws internal fixation at our hospital from January 2015 to January 2022. The research was registered in the Chinese Clinical Trial Registry in July 2022 (ChiCTR2200061866). The total blood loss (TBL) and HBL of patients were counted, and the factors such as gender, age, and surgical duration were statistically analyzed. The influential factors of HBL were analyzed by multiple linear regression. RESULTS: The TBL was 417.96 ± 98.05 ml, of which the visible blood loss (VBL) was 37.00 ± 9.0 ml and the HBL was 380.96 ± 68.8 ml. The HBL accounted for 91.14 ± 7.36% of the TBL. Gender, surgical duration, fixed position, and fixed depth had significant effects on the HBL (P < 0.05). CONCLUSIONS: The HBL was the main cause of anemia after minimally invasive treatment of posterior pelvic ring injury with a sacroiliac screw. Gender, surgical duration, fixed position, and fixed depth were closely related to the occurrence of HBL. In clinical treatment, we should consider these influential factors and take effective measures to reduce the impact of HBL on patients.

Celastrol induced the autophagy of spermatogonia cells contributed to tripterygium glycosides-related testicular injury.

Tripterygium glycosides (TG) is extracted from the roots of Chinese herbal medicine named Tripterygium wilfordii Hook F (TwHF). TG tablets are the representative TwHF-based agents with anti-inflammatory and immunomodulatory activities for treating rheumatoid arthritis. Although the curative effect of TG is remarkable, the clinical application is limited by a variety of organ toxicity. One of the most serious side-effects induced by TG is damage of the male reproductive system and the toxic mechanism is still not fully elucidated. TG-induced testicular injury was observed in male mice by treated with different concentrations of TG. The results showed that TG induced a significant decrease in testicular index. Pathological observation showed that spermatogenic cells were obviously shed, arranged loosely, and the spermatogenic epithelium was thin compared with control mice. In addition, the toxic effect of TG on mouse spermatogonia GC-1 cells was investigated. The results displayed that TG induced significant cytotoxicity in mouse GC-1 cells. To explore the potential toxic components that triggered testicular injury, the effects of 8 main components of TG on the viability of GC-1 cells were detected. The results showed that celastrol was the most toxic component of TG to GC-1 cells. Western blot analysis showed that LC3-II and the ratio of LC3-II/LC3-I were significantly increased and the expression level of p62 were decreased in both TG and celastrol treated cells, which indicated the significant activation of autophagy in spermatogonia cells. Therefore, autophagy plays an important role in the testicular injury induced by TG, and inhibition of autophagy is expected to reduce the testicular toxicity of TG.

Exploring the effective compounds and potential mechanisms of Shengxian Decoction against coronary heart disease by UPLC-Q-TOF/MS and network pharmacology analysis.

As a well-known classical Chinese medicine prescription, Shengxian Decoction (SXD) has been applied for a century to treat cardiovascular diseases, especially coronary heart disease (CHD), but the potentially effective compounds and underlying mechanisms remain unclear. With ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF/MS) and network pharmacology analysis, the potential effective compounds of SXD and their pharmacological mechanisms against CHD were identified and revealed. 57 effective compounds with favorable pharmacokinetic characteristics and biological activities were screened through UPLC-Q-TOF/MS analysis, database and literature mining, interacting with 96 CHD-related targets to support potential synergistic therapeutic actions. Systematic analysis of the PPI network and microarray data further revealed six core targets, including TNF, IL-1ß, IL-6, TP53, VEGFA and PTGS2, which were mainly involved in fluid shear stress and atherosclerosis, lipid and atherosclerosis, PI3K-Akt signaling pathway et al. Moreover, the proposed contribution indexes of effective compounds indicated these compounds, including isoferulic acid, quercetin, calycosin, ferulic acid, kaempferol, calycosin 7-O-glycoside, formononetin, astragaloside IV and saikosaponin D, as the core compounds of SXD. The molecular docking results confirmed that those core compound-target pairs exhibited strong binding energy. Furthermore, we validated that SXD significantly alleviated myocardial tissue injury in CHD rats and reversed H/R-induced decreases in H9c2 cell viability by attenuating the production of TNF, IL-6 and IL-1ß, and reducing cardiomyocyte apoptosis via down-regulating the TP53, caspase3 and cytochrome C mRNA expression levels as well as caspase3, caspase9 and cytochrome C protein expression levels according to RT-qPCR and Western blot results. Our findings explained the pharmacological mechanisms underlying the effectiveness of SXD in the treatment of CHD, and laid a foundation for future basic and clinical research of SXD.

The pathological mechanisms and potential therapeutic drugs for myocardial ischemia reperfusion injury.

BACKGROUND: Cardiovascular disease is the main cause of death and disability, with myocardial ischemia being the predominant type that poses a significant threat to humans. Reperfusion, an essential therapeutic approach, promptly reinstates blood circulation to the ischemic myocardium and stands as the most efficacious clinical method for myocardial preservation. Nevertheless, the restoration of blood flow associated with this process can potentially induce myocardial ischemia-reperfusion injury (MIRI), thereby diminishing the effectiveness of reperfusion and impacting patient prognosis. Therefore, it is of great significance to prevent and treat MIRI. PURPOSE: MIRI is an important factor affecting the prognosis of patients, and there is no specific in-clinic treatment plan. In this review, we have endeavored to summarize its pathological mechanisms and therapeutic drugs to provide more powerful evidence for clinical application. METHODS: A comprehensive literature review was conducted using PubMed, Web of Science, Embase, Medline and Google Scholar with a core focus on the pathological mechanisms and potential therapeutic drugs of MIRI. RESULTS: Accumulated evidence revealed that oxidative stress, calcium overload, mitochondrial dysfunction, energy metabolism disorder, ferroptosis, inflammatory reaction, endoplasmic reticulum stress, pyroptosis and autophagy regulation have been shown to participate in the process, and that the occurrence and development of MIRI are related to plenty of signaling pathways. Currently, a range of chemical drugs, natural products, and traditional Chinese medicine (TCM) preparations have demonstrated the ability to mitigate MIRI by targeting various mechanisms. CONCLUSIONS: At present, most of the research focuses on animal and cell experiments, and the regulatory mechanisms of each signaling pathway are still unclear. The translation of experimental findings into clinical practice remains incomplete, necessitating further exploration through large-scale, multi-center randomized controlled trials. Given the absence of a specific drug for MIRI, the identification of therapeutic agents to reduce myocardial ischemia is of utmost significance. For the future, it is imperative to enhance our understanding of the pathological mechanism underlying MIRI, continuously investigate and develop novel pharmaceutical agents, expedite the clinical translation of these drugs, and foster innovative approaches that integrate TCM with Western medicine. These efforts will facilitate the emergence of fresh perspectives for the clinical management of MIRI.

Heparan sulfate selectively inhibits the collagenase activity of cathepsin K.

Cathepsin K (CtsK) is a cysteine protease with potent collagenase activity. CtsK is highly expressed by bone-resorbing osteoclasts and plays an essential role in resorption of bone matrix. Although CtsK is known to bind heparan sulfate (HS), the structural details of the interaction, and how HS regulates the biological functions of CtsK, remains largely unknown. In this report, we discovered that HS is a multifaceted regulator of the structure and function of CtsK. Structurally, HS forms a highly stable complex with CtsK and induces its dimerization. Co-crystal structures of CtsK with bound HS oligosaccharides reveal the location of the HS binding site and suggest how HS may support dimerization. Functionally, HS plays a dual role in regulating the enzymatic activity of CtsK. While it preserves the peptidase activity of CtsK by stabilizing its active conformation, it inhibits the collagenase activity of CtsK in a sulfation level-dependent manner. These opposing effects can be explained by our finding that the HS binding site is remote from the active site, which allows HS to specifically inhibit the collagenase activity without affecting the peptidase activity. At last, we show that structurally defined HS oligosaccharides effectively block osteoclast resorption of bone in vitro without inhibiting osteoclast differentiation, which suggests that HS-based oligosaccharide might be explored as a new class of selective CtsK inhibitor for many diseases involving exaggerated bone resorption.

[Real-time traking and virtual reality technology-assisted trauma orthopaedic surgery robot for femoral neck fractures].

OBJECTIVE: To investigate the effectiveness of real-time tracking and virtual reality technology（RTVI） used to assist the intraoperative alignment of the trauma orthopaedic surgery robot for the treatment of femoral neck fractures and its impact on the treatment outcome. METHODS: A retrospective analysis was conducted on 60 patients with femoral neck fractures treated with trauma orthopedic robotic surgery from September 2020 to September 2022. Patients were divided into two groups according to whether RTVI technology was used during surgery to assist robotic surgery. There were 28 patients in the RTVI group （12 males and 16 females）, with an average age of （46.2±9.3） years old ranging from 28 to 60 years old. There were 32 patients in the simple Tianji surgical robot group, including 15 males and 17 females, aged （48.2±7.8） years old ranging from 32 to 58. The number of registered fluoroscopy, operation time, total number of intraoperative fluoroscopy, intraoperative blood loss, and hospitalization time of the two groups of patients were observed and recorded. All patients received regular follow-up after surgery, and hip X-rays were routinely reviewed to record Garden alignment index, fracture healing time, postoperative complications, and Harris score. RESULTS: All 60 patients were followed up. The RTVI group was followed up for 9 to 16 months with an average of （13.0±1.2） months, and the Tianji surgical robot group alone was followed up for 10 to 14 months with an average of （12.0±1.3） months. During the follow-up period, the femoral neck fractures of both groups of patients healed well, and no complications such as internal fixation loosening and incision infection occurred. The number of registered fluoroscopy, operation time, and number of intraoperative fluoroscopy of patients in the RTVI group were significantly better than those in the simple Tianji surgical robot group（P<0.01）. There was no statistically significant difference in intraoperative blood loss, hospital stay, Garden alignment index, fracture healing time, and hip Harris score between two groups（P>0.05）. CONCLUSION: Although RTVI technology assisted by the surgical robot for femoral neck fracture surgery has little impact on its postoperative outcome, it can effectively reduce the operating time, the number of intraoperative X-ray projections, and the risk of intraoperative radiation exposure to patients. It also shortened the learning curve of the operator and better reflected the precision and efficiency of the trauma orthopaedic surgery robot.

Controlling Molecular Photoisomerization in Photonic Cavities through Polariton Funneling.

Strong coupling between photonic modes and molecular electronic excitations, creating hybrid light-matter states called polaritons, is an attractive avenue for controlling chemical reactions. Nevertheless, experimental demonstrations of polariton-modified chemical reactions remain sparse. Here, we demonstrate modified photoisomerization kinetics of merocyanine and diarylethene by coupling the reactant's optical transition with photonic microcavity modes. We leverage broadband Fourier-plane optical microscopy to noninvasively and rapidly monitor photoisomerization within microcavities, enabling systematic investigation of chemical kinetics for different cavity-exciton detunings and photoexcitation conditions. We demonstrate three distinct effects of cavity coupling: first, a renormalization of the photonic density of states, akin to a Purcell effect, leads to enhanced absorption and isomerization rates at certain wavelengths, notably red-shifting the onset of photoisomerization. This effect is present under both strong and weak light-matter couplings. Second, kinetic competition between polariton localization into reactive molecular states and cavity losses leads to a suppression of the photoisomerization yield. Finally, our key result is that in reaction mixtures with multiple reactant isomers, exhibiting partially overlapping optical transitions and distinct isomerization pathways, the cavity resonance can be tuned to funnel photoexcitations into specific reactant isomers. Thus, upon decoherence, polaritons localize into a chosen isomer, selectively triggering the latter's photoisomerization despite initially being delocalized across all isomers. This result suggests that careful tuning of the cavity resonance is a promising avenue to steer chemical reactions and enhance product selectivity in reaction mixtures.

The identification of metabolites from gut microbiota in coronary heart disease via network pharmacology.

Although the gut microbial metabolites exhibit potential effects on coronary heart disease (CHD), the underlying mechanism remains unclear. In this study, the active gut microbial metabolites acting on CHD and their potential mechanisms of action were explored through a network pharmacological approach. We collected a total of 208 metabolites from the gutMgene database and 726 overlapping targets from the similarity ensemble approach (SEA) and SwissTargetPrediction (STP) database, and ultimately identified 610 targets relevant to CHD. In conjunction with the gutMGene database, we identified 12 key targets. The targets of exogenous substances were removed, and 10 core targets involved in CHD were eventually retained. The microbiota-metabolites-targets-signalling pathways network analysis revealed that C-type lectin receptor signalling pathway, Lachnospiraceae, Escherichia, mitogen-activated protein kinase 1, prostaglandin-endoperoxidase synthase 2, phenylacetylglutamine and alcoholic acid are notable components of CHD and play important roles in the development of CHD. The results of molecular docking experiments demonstrated that AKT1-glycocholic acid and PTGS2-phenylacetylglutamine complexes may act on C-type lectin receptor signalling pathways. In this study, the key substances and potential mechanisms of gut microbial metabolites were analysed via network pharmacological methods, and a scientific basis and comprehensive idea were provided for the effects of gut microbial metabolites on CHD.

Low-frequency vibrational density of states of ordinary and ultra-stable glasses.

A remarkable feature of disordered solids distinct from crystals is the violation of the Debye scaling law of the low-frequency vibrational density of states. Because the low-frequency vibration is responsible for many properties of solids, it is crucial to elucidate it for disordered solids. Numerous recent studies have suggested power-law scalings of the low-frequency vibrational density of states, but the scaling exponent is currently under intensive debate. Here, by classifying disordered solids into stable and unstable ones, we find two distinct and robust scaling exponents for non-phononic modes at low frequencies. Using the competition of these two scalings, we clarify the variation of the scaling exponent and hence reconcile the debate. Via the study of both ordinary and ultra-stable glasses, our work reveals a comprehensive picture of the low-frequency vibration of disordered solids and sheds light on the low-frequency vibrational features of ultra-stable glasses on approaching the ideal glass.

The effective combination therapies with irinotecan for colorectal cancer.

Colorectal cancer is the third most common type of cancer worldwide and has become one of the major human disease burdens. In clinical practice, the treatment of colorectal cancer has been closely related to the use of irinotecan. Irinotecan combines with many other anticancer drugs and has a broader range of drug combinations. Combination therapy is one of the most important means of improving anti-tumor efficacy and overcoming drug resistance. Reasonable combination therapy can lead to better patient treatment options, and inappropriate combination therapy will increase patient risk. For the colorectal therapeutic field, the significance of combination therapy is to improve the efficacy, reduce the adverse effects, and improve the ease of treatment. Therefore, we explored the clinical advantages of its combination therapy based on mechanism or metabolism and reviewed the rationale basis and its limitations in conducting exploratory clinical trials on irinotecan combination therapy, including the results of clinical trials on the combination potentiation of cytotoxic drugs, targeted agents, and herbal medicine. We hope that these can evoke more efforts to conduct irinotecan in the laboratory for further studies and evaluations, as well as the possibility of more in-depth development in future clinical trials.

A study integrated metabolomics and network pharmacology to investigate the effects of Shicao in alleviating acute liver injury.

ETHNOPHARMACOLOGICAL RELEVANCE: Shicao is the aerial part of Achillea alpina L., a common herb found mainly in Europe, Asia, and North America. Traditional Chinese medicine has a history of thousands of years and is widely used to treat various diseases. AIM OF STUDY: To explore the hepatoprotective effects of Shicao on CCl4-induced acute liver injury. METHODS: A rat model of acute liver injury was established and liver function indices were assessed to evaluate the protective effect of Shicao on the liver. Untargeted metabolomics of the serum and liver tissues was conducted using UPLC-Q-TOF/MS to identify differential metabolites related to acute liver injury. A network of metabolite-reaction-enzyme-gene constituents was constructed using network pharmacology. Hub targets and key components of the effect of Shicao on acute liver injury were screened from the network. RESULTS: Compared to the model group, Shicao improved the degree of liver damage through the assessment of the liver index, ALT and AST levels, and hepatic pathology slices, demonstrating its hepatoprotective effect against acute liver injury in rats. 10 and 38 differential metabolites involved in acute liver injury were identified in serum and liver tissues, respectively. Most of these were regulated or restored following treatment with Shicao, which mainly consisted of bile acids, lipids, and nucleotides such as taurocholic acid, LysoPC (17:0), and adenosine diphosphate ribose. Through the network of metabolite-reaction-enzyme-gene-constituents, 10 key components and 5 hub genes, along with 7 crucial differential metabolites, were mainly involved in glycerophospholipid metabolism, purine metabolism, biosynthesis of unsaturated fatty acids, and primary bile acid biosynthesis, which may play important roles in the prevention of acute liver injury by Shicao. CONCLUSION: This study revealed that Shicao had protective effects against CCl4-induced liver injury in rats. It was speculated that the ingredients of Shicao might be closely related to the hub targets, thereby regulating the levels of key metabolites, affecting inflammatory response and oxidative stress and attenuate the liver injury consequently. This study provides a basis for further investigation of its therapeutic potential and the mechanism of action.

Cuproptosis-Related lncRNAs Modulate the Prognosis of MIBC by Regulating the Expression Pattern of Immunosuppressive Molecules Within the Tumor Microenvironment.

Background: Cuproptosis-related gene and long non-coding RNA (lncRNA) modulation of cancer regulation is well-established. This investigation aimed to elucidate the prognostic implications of cuproptosis-associated lncRNAs in muscle-invasive bladder cancer (MIBC). Methods: Employing the Cancer Genome Atlas (TCGA) and IMvigor210 cohorts, bioinformatics and statistical analyses probed the prognostic relevance of cuproptosis-related lncRNAs. Results: Co-expression analysis revealed tight associations between lncRNA expression and cuproptosis-linked genes, with 13 cuproptosis-related lncRNAs found to correlate with MIBC prognosis. Lasso regression identified a six-lncRNA prognostic signature, enabling patient stratification into high- and low-risk categories. Tissue validation substantiated differential expression of FAM13A-AS1, GHRLOS, LINC00456, OPA1-AS1, RAP2C-AS1, and UBE2Q1-AS1 between MIBC tumor and normal tissues. Comparative analyses of tumor microenvironments and immune profiles between risk groups disclosed elevated immunosuppressive molecule expression, including programmed cell death-1 (PD-L1) and T-cell immunoglobulin-3 (TIM-3), in high-risk individuals. Conclusion: These findings suggest that cuproptosis-related lncRNAs may modulate the expression of immunosuppressive molecules, thereby influencing MIBC tumorigenesis and progression. Further exploration is warranted to unveil novel therapeutic targets for MIBC based on the expression patterns of cuproptosis-related lncRNAs and their impact on immune responses in the tumor microenvironment.

Topical Application of Cell-Penetrating Peptide Modified Anti-VEGF Drug Alleviated Choroidal Neovascularization in Mice.

Background: Age-related macular degeneration (AMD) stands as the foremost cause of irreversible central vision impairment, marked by choroidal neovascularization (CNV). The prevailing clinical approach to AMD treatment relies on intravitreal injections of anti-vascular endothelial growth factor (VEGF) drugs. However, this method is encumbered by diverse complications, prompting exploration of non-invasive alternatives such as ocular administration via eye drops for anti-VEGF therapy. Methods: Two complexes, 5-FITC-CPP-Ranibizumab (5-FCR) and 5-FITC-CPP-Conbercept (5-FCC), were synthesized by incorporating the anti-VEGF drugs Ranibizumab (RBZ) or Conbercept (CBC) with cell-penetrating peptide (CPP). Circular dichroism spectrum (CD) facilitated complexes characterization. Eye drops was utilized to address laser-induced CNV in mice. Fluorescein fundus angiography (FFA) observe the CNV lesion, while FITC-dextran and IB4 dual fluorescent staining, along with hematoxylin-eosin (HE) staining, assessed in lesion size. Tissue immunofluorescence examined CD31 and VEGF expression in choroidal/retinal pigment epithelial (RPE) tissues. Biocompatibility and biosafety of 5-FCR and 5-FCC was evaluated through histological examination of various organs or cell experiments. Results: Both 5-FCR and 5-FCC exhibited favorable biocompatibility and safety profiles. VEGF-induced migration of Human umbilical vein endothelial cells (HUVECs) significantly decreased post-5-FCR/5-FCC treatment. Additionally, both complexes suppressed VEGF-induced tube formation in HUVECs. FFA results revealed a significant improvement in retinal exudation in mice. Histological examination unveiled the lesion areas in the 5-FCR and 5-FCC groups showed a significant reduction compared to the control group. Similar outcomes were observed in histological sections of the RPE-choroid-sclera flat mounts. Conclusion: In this study, utilizing the properties of CPP and two anti-VEGF drugs, we successfully synthesized two complexes, 5-FCR and 5-FCC, through a straightforward approach. Effectively delivering the anti-VEGF drugs to the target area in a non-invasive manner, suppressing the progression of laser-induced CNV. This offers a novel approach for the treatment of wet AMD.

Neuroprotection by tetramethylpyrazine and its synthesized analogues for central nervous system diseases: a review.

BACKGROUND: Due to the global increase in aging populations and changes in modern lifestyles, the prevalence of neurodegenerative diseases, cerebrovascular disorders, neuropsychiatrcic conditions, and related ailments is rising, placing an increasing burden on the global public health system. MATERIALS AND METHODS: All studies on tetramethylpyrazine (TMP) and its derivatives were obtained from reputable sources such as PubMed, Elsevier, Library Genesis, and Google Scholar. Comprehensive data on TMP and its derivatives was meticulously compiled. RESULTS: This comprehensive analysis explains the neuroprotective effects demonstrated by TMP and its derivatives in diseases of the central nervous system. These compounds exert their influence on various targets and signaling pathways, playing crucial roles in the development of various central nervous system diseases. Their multifaceted mechanisms include inhibiting oxidative damage, inflammation, cell apoptosis, calcium overload, glutamate excitotoxicity, and acetylcholinesterase activity. CONCLUSION: This review provides a brief summary of the most recent advancements in research on TMP and its derivatives in the context of central nervous system diseases. It involves synthesizing analogs of TMP and evaluating their effectiveness in models of central nervous system diseases. The ultimate goal is to facilitate the practical application of TMP and its derivatives in the future treatment of central nervous system diseases.

Heparan sulfate selectively inhibits the collagenase activity of cathepsin K.

Cathepsin K (CtsK) is a cysteine protease with potent collagenase activity. CtsK is highly expressed by bone-resorbing osteoclasts and plays an essential role in bone remodeling. Although CtsK is known to bind heparan sulfate (HS), the structural details of the interaction, and how HS ultimately regulates the biological functions of CtsK, remains largely unknown. In this report, we determined that CtsK preferably binds to larger HS oligosaccharides, such as dodecasaccharides (12mer), and that the12mer can induce monomeric CtsK to form a stable dimer in solution. Interestingly, while HS has no effect on the peptidase activity of CtsK, it greatly inhibits the collagenase activity of CtsK in a manner dependent on sulfation level. By forming a complex with CtsK, HS was able to preserve the full peptidase activity of CtsK for prolonged periods, likely by stabilizing its active conformation. Crystal structures of Ctsk with a bound 12mer, alone and in the presence of the endogenous inhibitor cystatin-C reveal the location of HS binding is remote from the active site. Mutagenesis based on these complex structures identified 6 basic residues of Ctsk that play essential roles in mediating HS-binding. At last, we show that HS 12mers can effectively block osteoclast resorption of bone in vitro. Combined, we have shown that HS can function as a multifaceted regulator of CtsK and that HS-based oligosaccharide might be explored as a new class of selective CtsK inhibitor in many diseases that involve exaggerated bone resorption.

Targeting the heparan sulfate-binding site of RAGE with monoclonal antibodies.

Heparan sulfate (HS) plays its biological functions by interacting with hundreds of secreted extracellular and transmembrane proteins. Interaction with HS has been shown to be required for the normal function of many HS-binding proteins. Receptor for advanced glycation end-product (RAGE) is such a protein, whose activation requires HS-induced oligomerization. Using RAGE as an exemplary protein, we show here the workflow of a simple method of developing and characterizing mAbs that targets the HS-binding site. We found that HS-binding site of RAGE is quite immunogenic as 18 out of 94 anti-RAGE mAbs target various epitopes within the HS-binding site. Sequence analysis found that a common feature of anti-HS-binding site mAbs is the presence of abundant acidic residues (range between 6 to 11) in the complementarity determining region, suggesting electrostatic interaction plays an important role in promoting antigen-antibody interaction. Interestingly, mAbs targeting different epitopes within the HS-binding site blocks HS-RAGE interaction to different degrees, and the inhibitory effect is highly consistent among mAbs that target the same epitope. Functional assay revealed that anti-HS-binding site mAbs show different potency in inhibiting osteoclastogenesis, and the inhibitory potency does not have a simple correlation with the affinity and the epitope. Our study demonstrates that developing HS-binding site targeting mAbs should be applicable to most HS-binding proteins. By targeting this unique functional site, these mAbs might find therapeutic applications in treating various human diseases.