Pyroptosis modulation by bacterial effector proteins

Pyroptosis is a proinflammatory form of programmed cell death featured with membrane pore formation that causes cellular swelling and allows the release of intracellular inflammatory mediators. This cell death process is elicited by the activation of the pore-forming proteins named gasdermins, and is intricately orchestrated by diverse regulatory factors in mammalian hosts to exert a prompt immune response against infections. However, growing evidence suggests that bacterial pathogens have evolved to regulate host pyroptosis for evading immune clearance and establishing progressive infection. In this review, we highlight current understandings of the functional role and regulatory network of pyroptosis in host antibacterial immunity. Thereafter, we further discuss the latest advances elucidating the mechanisms by which bacterial pathogens modulate pyroptosis through adopting their effector proteins to drive infections. A better understanding of regulatory mechanisms underlying pyroptosis at the interface of host-bacterial interactions will shed new light on the pathogenesis of infectious diseases and contribute to the development of promising therapeutic strategies against bacterial pathogens.

A Golgi-resident GPR108 cooperates with E3 ubiquitin ligase Smurf1 to suppress antiviral innate immunity

The regulation of antiviral immunity is crucial in maintaining host immune homeostasis, a process that involves dynamic modulations of host organelles. The Golgi apparatus is increasingly perceived as a host organelle functioning as a critical platform for innate immunity, but the detailed mechanism by which it regulates antiviral immunity remains elusive. Here, we identify the Golgi-localized G protein-coupled receptor 108 (GPR108) as a regulator of type Ι interferon responses by targeting interferon regulatory factor 3 (IRF3). Mechanistically, GPR108 enhances the ubiquitin ligase Smad ubiquitylation regulatory factor 1 (Smurf1)-mediated K63-linked polyubiquitination of phosphorylated IRF3 for nuclear dot 10 protein 52 (NDP52)-dependent autophagic degradation, leading to suppression of antiviral immune responses against DNA or RNA viruses. Taken together, our study provides insight into the crosstalk between the Golgi apparatus and antiviral immunity via a dynamic and spatiotemporal regulation of GPR108-Smurf1 axis, thereby indicating a potential target for treating viral infection.

A mycobacterial effector promotes ferroptosis-dependent pathogenicity and dissemination

Ferroptosis is a lipid peroxidation-driven and iron-dependent programmed cell death involved in multiple physical processes and various diseases. Emerging evidence suggests that several pathogens manipulate ferroptosis for their pathogenicity and dissemination, but the underlying molecular mechanisms remain elusive. Here, we identify that protein tyrosine phosphatase A (PtpA), an effector secreted by tuberculosis (TB)-causing pathogen Mycobacterium tuberculosis (Mtb), triggers ferroptosis to promote Mtb pathogenicity and dissemination. Mechanistically, PtpA, through its Cys11 site, interacts with host RanGDP to enter host cell nucleus. Then, the nuclear PtpA enhances asymmetric dimethylation of histone H3 arginine 2 (H3R2me2a) via targeting protein arginine methyltransferase 6 (PRMT6), thus inhibiting glutathione peroxidase 4 (GPX4) expression, eventually inducing ferroptosis to promote Mtb pathogenicity and dissemination. Taken together, our findings provide insights into molecular mechanisms of pathogen-induced ferroptosis, indicating a potential TB treatment via blocking Mtb PtpA-host PRMT6 interface to target GPX4-dependent ferroptosis.

TRIM27 maintains gut homeostasis by promoting intestinal stem cell self-renewal

Dysregulation of gut homeostasis is associated with irritable bowel syndrome (IBS), a chronic functional gastrointestinal disorder affecting approximately 11.2% of the global population. The poorly understood pathogenesis of IBS has impeded its treatment. Here, we report that the E3 ubiquitin ligase tripartite motif-containing 27 (TRIM27) is weakly expressed in IBS but highly expressed in inflammatory bowel disease (IBD), a frequent chronic organic gastrointestinal disorder. Accordingly, knockout of Trim27 in mice causes spontaneously occurring IBS-like symptoms, including increased visceral hyperalgesia and abnormal stool features, as observed in IBS patients. Mechanistically, TRIM27 stabilizes β-catenin and thus activates Wnt/β-catenin signaling to promote intestinal stem cell (ISC) self-renewal. Consistent with these findings, Trim27 deficiency disrupts organoid formation, which is rescued by reintroducing TRIM27 or β-catenin. Furthermore, Wnt/β-catenin signaling activator treatment ameliorates IBS symptoms by promoting ISC self-renewal. Taken together, these data indicate that TRIM27 is critical for maintaining gut homeostasis, suggesting that targeting the TRIM27/Wnt/β-catenin axis could be a potential treatment strategy for IBS. Our study also indicates that TRIM27 might serve as a potential biomarker for differentiating IBS from IBD.

A bacterial phospholipid phosphatase inhibits host pyroptosis by hijacking ubiquitin

The inflammasome-mediated cleavage of gasdermin D (GSDMD) causes pyroptosis and inflammatory cytokine release to control pathogen infection, but how pathogens evade this immune response remains largely unexplored. Here we identify the known protein phosphatase PtpB from Mycobacterium tuberculosis as a phospholipid phosphatase inhibiting the host inflammasome-pyroptosis pathway. Mechanistically, PtpB dephosphorylated phosphatidylinositol-4-monophosphate and phosphatidylinositol-(4,5)-bisphosphate in host cell membrane, thus disrupting the membrane localization of the cleaved GSDMD to inhibit cytokine release and pyroptosis of macrophages. Notably, this phosphatase activity requires PtpB binding to ubiquitin. Disrupting phospholipid phosphatase activity or the ubiquitin-interacting motif of PtpB enhanced host GSDMD-dependent immune responses and reduced intracellular pathogen survival. Thus, pathogens inhibit pyroptosis and counteract host immunity by altering host membrane composition.

HDAC6 contributes to human resistance against Mycobacterium tuberculosis infection via mediating innate immune responses

Tuberculosis (TB), which is caused by Mycobacterium tuberculosis (Mtb), remains a major cause of morbidity and mortality worldwide. Increasing lines of evidence indicate that certain individuals, which are termed resisters, are naturally resistant to TB infection. The resister phenotype has been linked to host efficient innate immune responses, but the underlying mechanisms and the key immune factors remain unclear. Here, we find that upon Mtb infection, monocyte-derived macrophages (MDMs) from TB resisters exhibited distinctly higher production of TNF-α, IL-1β and IL-6, higher ratio of bacteria in acidic vacuoles, and lower intracellular bacterial loads, as compared to that from the healthy controls, individuals with latent TB infection, and TB patients. Such enhanced anti-Mtb immune capacity of macrophages from resisters largely depends on histone deacetylase 6 (HDAC6), whose expression is specifically maintained in MDMs from TB resisters during Mtb infection. Furthermore, we demonstrate that HDAC6 is required for acidification of Mtb-containing phagosomes in macrophages, thus controlling the intracellular survival of Mtb. Taken together, these findings unravel an indispensable role of HDAC6 in human innate resistance against Mtb infection, suggesting that HDAC6 may serve as a marker for individual TB risk as well as a novel host-directed anti-TB therapeutic target.

M. tuberculosis PknG manipulates host autophagy flux to promote pathogen intracellular survival

The eukaryotic-type protein kinase G (PknG), one of the eleven eukaryotic type serine-threonine protein kinase (STPK) in Mycobacterium tuberculosis (Mtb), is involved in mycobacterial survival within macrophages, presumably by suppressing phagosome and autophagosome maturation, which makes PknG an attractive drug target. However, the exact mechanism by which PknG inhibits pathogen clearance during mycobacterial infection remains largely unknown. Here, we show that PknG promotes macroautophagy/autophagy induction but inhibits autophagosome maturation, causing an overall effect of blocked autophagy flux and enhanced pathogen intracellular survival. PknG prevents the activation of AKT (AKT serine/threonine kinase) via competitively binding to its pleckstrin homology (PH) domain, leading to autophagy induction. Remarkably, PknG could also inhibit autophagosome maturation to block autophagy flux via targeting host small GTPase RAB14. Specifically, PknG directly interacts with RAB14 to block RAB14-GTP hydrolysis. Furthermore, PknG phosphorylates TBC1D4/AS160 (TBC1 domain family member 4) to suppress its GTPase-activating protein (GAP) activity toward RAB14. In macrophages and in vivo, PknG promotes Mtb intracellular survival through blocking autophagy flux, which is dependent on RAB14. Taken together, our data unveil a dual-functional bacterial effector that tightly regulates host autophagy flux to benefit pathogen intracellular survival.Abbreviations: AKT: AKT serine/threonine kinase; ATG5: autophagy related 5; BMDMs: bone marrow-derived macrophages; DTT: dithiothreitol; FBS: fetal calf serum; GAP: GTPase-activating protein; MOI: multiplicity of infection; Mtb: Mycobacterium tuberculosis; MTOR: mechanistic target of rapamycin kinase; OADC: oleic acid-albumin-dextrose-catalase; PC, phosphatidylcholine; PH: pleckstrin homology; PI3K: phosphoinositide 3-kinase; PknG: protein kinase G; PtdIns(3,4,5)P₃: phosphatidylinositol(3,4,5)-trisphosphate; SQSTM1: sequestosome 1; STPK: serine-threonine protein kinase; TB: tuberculosis; TBC1D4: TBC1 domain family member 4; TPR: tetratricopeptide repeat; ULK1: unc-51 like autophagy activating kinase 1; WT: wild-type.

Mycobacterium tuberculosis protein kinase G acts as an unusual ubiquitinating enzyme to impair host immunity

Upon Mycobacterium tuberculosis (Mtb) infection, protein kinase G (PknG), a eukaryotic-type serine-threonine protein kinase (STPK), is secreted into host macrophages to promote intracellular survival of the pathogen. However, the mechanisms underlying this PknG-host interaction remain unclear. Here, we demonstrate that PknG serves both as a ubiquitin-activating enzyme (E1) and a ubiquitin ligase (E3) to trigger the ubiquitination and degradation of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TGF-β-activated kinase 1 (TAK1), thereby inhibiting the activation of NF-κB signaling and host innate responses. PknG promotes the attachment of ubiquitin (Ub) to the ubiquitin-conjugating enzyme (E2) UbcH7 via an isopeptide bond (UbcH7 K82-Ub), rather than the usual C86-Ub thiol-ester bond. PknG induces the discharge of Ub from UbcH7 by acting as an isopeptidase, before attaching Ub to its substrates. These results demonstrate that PknG acts as an unusual ubiquitinating enzyme to remove key components of the innate immunity system, thus providing a potential target for tuberculosis treatment.

Simulated microgravity suppresses MAPK pathway-mediated innate immune response to bacterial infection and induces gut microbiota dysbiosis

During spaceflight, astronauts are subjected to various physical stressors including microgravity, which could cause immune dysfunction and thus potentially predispose astronauts to infections and illness. However, the mechanisms by which microgravity affects innate immunity remain largely unclear. In this study, we conducted RNA-sequencing analysis to show that simulated microgravity (SMG) suppresses the production of inflammatory cytokines including tumor necrosis factor (TNF) and interleukin-6 (IL-6) as well as the activation of the innate immune signaling pathways including the p38 mitogen-activated protein kinase (MAPK) and the Erk1/2 MAPK pathways in the Enteropathogenic escherichia coli (EPEC)-infected macrophage cells. We then adopted hindlimb-unloading (HU) mice, a model mimicking the microgravity of a spaceflight environment, to demonstrate that microgravity suppresses proinflammatory cytokine-mediated intestinal immunity to Citrobacter rodentium infection and induces the disturbance of gut microbiota, both of which phenotypes could be largely corrected by the introduction of VSL#3, a high-concentration probiotic preparation of eight live freeze-dried bacterial species. Taken together, our study provides new insights into microgravity-mediated innate immune suppression and intestinal microbiota disturbance, and suggests that probiotic VSL#3 has great potential as a dietary supplement in protecting individuals from spaceflight mission-associated infections and gut microbiota dysbiosis.

New insights into the evasion of host innate immunity by Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is an extremely successful intracellular pathogen that causes tuberculosis (TB), which remains the leading infectious cause of human death. The early interactions between Mtb and the host innate immune system largely determine the establishment of TB infection and disease development. Upon infection, host cells detect Mtb through a set of innate immune receptors and launch a range of cellular innate immune events. However, these innate defense mechanisms are extensively modulated by Mtb to avoid host immune clearance. In this review, we describe the emerging role of cytosolic nucleic acid-sensing pathways at the host-Mtb interface and summarize recently revealed mechanisms by which Mtb circumvents host cellular innate immune strategies such as membrane trafficking and integrity, cell death and autophagy. In addition, we discuss the newly elucidated strategies by which Mtb manipulates the host molecular regulatory machinery of innate immunity, including the intranuclear regulatory machinery, the ubiquitin system, and cellular intrinsic immune components. A better understanding of innate immune evasion mechanisms adopted by Mtb will provide new insights into TB pathogenesis and contribute to the development of more effective TB vaccines and therapies.

[Etiology and clinical analysis of central nervous system infection caused by Coxsackievirus B5 in severe hand, foot and mouth disease in Qingdao City, 2013-2014]

Objective: To illuminate the gene characteristics and clinical characterization of Coxsackievirus B5 (CV-B5) strains isolated from patients with sevre hand, foot and mouth disease (HFMD) in Qingdao city. Methods: A total of 1 844 patients of HFMD were consecutively admitted to Qingdao Women and Children's Hospital from 2013 to 2014. Information of the study population described above was collected retrospectively. The samples were collected from at least 1 site (throat swab, cerebrospinal fluid), which viral nucleic acid extracted and the entire VP1 gene sequences of CV-B5 isolates were amplified and sequenced, then the homology and phylogeny analysis were conducted by MEGA7.0. The prototype Faulkner strain and other VP1 amino acid sequences were derived from the GenBank database. Results: A total of 8 CV-B5 positive cases were obtained, including 4 males and 4 females; 6 severe hospitalized cases and 2 outpatients. The age of 6 hospitalized patients ranged from 3 to 48 months, with a median of 26 months. For the six inpatients, fever, convulsions vomiting, diarrhea and rash were the main clinical manifestation, and all combined with viral encephalitis. Compared with the prototype strain Faulkner, in the VP1 region,the nucleotide and the amino acid homologies was 77.3%-78.8% and 95.5%-97.0% respectively. Five out of the six severe cases with substitution of serine (S) to asparagine (N) at amino acid site 95 in the VP1 region. The sequences of 8 CV-B5 strains were classified into genogroup D. Conclusion: Hand, foot and mouth disease associated with CV-B5 virus infection can result in nervous system involvement and the main complication was viral encephalitis. The CV-B5 strains associated with severe hand, foot and mouth disease had high nucleotide homology and present a certain regional aggregation.

Mycobacterium tuberculosis: An Adaptable Pathogen Associated With Multiple Human Diseases

Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), is an extremely successful pathogen that adapts to survive within the host. During the latency phase of infection, M. tuberculosis employs a range of effector proteins to be cloud the host immune system and shapes its lifestyle to reside in granulomas, sophisticated, and organized structures of immune cells that are established by the host in response to persistent infection. While normally being restrained in immunocompetent hosts, M. tuberculosis within granulomas can cause the recrudescence of TB when host immunity is compromised. Aside from causing TB, accumulating evidence suggests that M. tuberculosis is also associated with multiple other human diseases, such as pulmonary complications, autoimmune diseases, and metabolic syndromes. Furthermore, it has been recently appreciated that M. tuberculosis infection can also reciprocally interact with the human microbiome, which has a strong link to immune balance and health. In this review, we highlight the adaptive survival of M. tuberculosis within the host and provide an overview for regulatory mechanisms underlying interactions between M. tuberculosis infection and multiple important human diseases. A better understanding of how M. tuberculosis regulates the host immune system to cause TB and reciprocally regulates other human diseases is critical for developing rational treatments to better control TB and help alleviate its associated comorbidities.

Mycobacterium tuberculosis Mce2E suppresses the macrophage innate immune response and promotes epithelial cell proliferation

The intracellular pathogen Mycobacterium tuberculosis (Mtb) can survive in the host and cause disease by interfering with a variety of cellular functions. The mammalian cell entry 2 (mce2) operon of Mtb has been shown to contribute to tuberculosis pathogenicity. However, little is known about the regulatory roles of Mtb Mce2 family proteins towards host cellular functions. Here we show that the Mce2 family protein Mce2E suppressed the macrophage innate immune response and promoted epithelial cell proliferation. Mce2E inhibited activation of the extracellular signal-regulated kinase (ERK) and Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) signaling pathways in a non-canonical D motif (a MAPK-docking motif)-dependent manner, leading to reduced expression of TNF and IL-6 in macrophages. Furthermore, Mce2E promoted proliferation of human lung epithelium-derived lung adenoma A549 cells by inhibiting K48-linked polyubiquitination of eEF1A1 in a β strand region-dependent manner. In summary, Mce2E is a novel multifunctional Mtb virulence factor that regulates host cellular functions in a niche-dependent manner. Our data suggest a potential novel target for TB therapy.

The mycobacterial phosphatase PtpA regulates the expression of host genes and promotes cell proliferation

Mycobacterium tuberculosis PtpA is a secreted effector protein that dephosphorylates several proteins in the host cell cytoplasm, such as p-JNK, p-p38, and p-VPS33B, leading to suppression of host innate immunity. Here we show that, in addition, PtpA enters the nucleus of host cells and regulates the expression of host genes, some of which are known to be involved in host innate immunity or in cell proliferation and migration (such as GADD45A). PtpA can bind directly to the promoter region of GADD45A in vitro. Both phosphatase activity and DNA-binding ability of PtpA are important in suppressing host innate immune responses. Furthermore, PtpA-expressing Mycobacterium bovis BCG promotes proliferation and migration of human lung adenoma A549 cells in vitro and in a mouse xenograft model. Further research is needed to test whether mycobacteria, via PtpA, might affect cell proliferation or migration in humans.

Mycobacterium tuberculosis secretes a protein, PtpA, that dephosphorylates proteins in the host cell cytoplasm, weakening immune responses. Here, the authors show that PtpA also enters the nucleus, affects the expression of several host genes, and promotes proliferation and migration of a cancer cell line.

Computational design of a specific heavy chain/κ light chain interface for expressing fully IgG bispecific antibodies

The use of bispecific antibodies (BsAbs) to treat human diseases is on the rise. Increasingly complex and powerful therapeutic mechanisms made possible by BsAbs are spurring innovation of novel BsAb formats and methods for their production. The long-lived in vivo pharmacokinetics, optimal biophysical properties and potential effector functions of natural IgG monoclonal (and monospecific) antibodies has resulted in a push to generate fully IgG BsAb formats with the same quaternary structure as monoclonal IgGs. The production of fully IgG BsAbs is challenging because of the highly heterogeneous pairing of heavy chains (HCs) and light chains (LCs) when produced in mammalian cells with two IgG HCs and two LCs. A solution to the HC heterodimerization aspect of IgG BsAb production was first discovered two decades ago; however, addressing the LC mispairing issue has remained intractable until recently. Here, we use computational and rational engineering to develop novel designs to the HC/LC pairing issue, and particularly for κ LCs. Crystal structures of these designs highlight the interactions that provide HC/LC specificity. We produce and characterize multiple fully IgG BsAbs using these novel designs. We demonstrate the importance of specificity engineering in both the variable and constant domains to achieve robust HC/LC specificity within all the BsAbs. These solutions facilitate the production of fully IgG BsAbs for clinical use.

Shape memory polymer foams prepared from a heparin-inspired polyurethane/urea

Shape memory foams have been prepared using a heparin-inspired polyurea/urethane that displays excellent resistance to platelet adherence.

[Composition of potassium channels in normal rat coronary smooth muscle cells and activation effects of docosahexaenoic acid]

OBJECTIVE

To investigate the composition of potassium channels in normal rat coronary smooth muscle cells (CASMCs) and the activation effects of docosahexaenoic acid (DHA).

METHODS

CASMCs were isolated by enzyme digestion.Effects of different types of potassium channel blockers and/or DHA on potassium channels currents were studied by whole-cell patch clamp technique.

RESULTS

Potassium currents were significantly increased with 5 μmol/L DHA perfusion (P<0.05). The current density was increased from (52.80±6.68) pA/pF to (110.09±13.39) pA/pF (P<0.05) after DHA perfusion when the stimulation voltage was 100 mV.Compared with baseline, potassium currents were significantly decreased by various inhibitor perfusion (tetraethylammonium: (49.63±5.75) pA/pF vs. (13.96±2.18) pA/pF; ibritoxin: (50.67±7.89) pA/pF vs. (26.53±4.68) pA/pF; TRAM-34: (52.60±7.02) pA/pF vs. (46.05±7.60) pA/pF; apamin: (51.97±3.83) pA/pF vs. (44.89±5.04) pA/pF; 4-aminopyridine: (51.19±3.44) pA/pF vs. (29.92±2.81) pA/pF; glyburide: (49.67±1.77) pA/pF vs. (49.61±1.87) pA/pF, all P<0.05). In presence of different inhibitors, potassium channel current densities were increased after DHA perfusion except tetraethylammonium (tetraethylammonium: ( 12.79±1.89) pA/pF; ibritoxin: (67.08±5.54) pA/pF; TRAM-34: (117.91±21.79) pA/pF; apamin: (108.33±7.06) pA/pF; 4-aminopyridine: (127.73±20.56) pA/pF; glyburide: (121.53±13.83) pA/pF, all P<0.05 compared with baseline).

CONCLUSIONS

Large-conductance calcium-activated potassium channel and voltage-gated potassium channel are the major constituents of potassium channels in CASMCs.DHA can activate potassium channels in CASMCs, mainly the large conductance calcium-activated potassium channel, thus dilate coronary arteries.

[Docosahexaenoic acids activate large conductance calcium-activated potassium channels via phospholipase C- inositol triphosphate- calcium pathway in normal rat coronary smooth muscle cells]

OBJECTIVE

To investigate the mechanisms of docosahexaenoic acids (DHA) on activating large conductance calcium-activated potassium channels (BK channels) in normal rat coronary smooth muscle cells.

METHODS

Normal coronary smooth muscle cells were isolated by enzyme digestion from Sprague-Dawley rats. BK currents were recorded by patch clamp in whole cell and single channel configurations, respectively. The effects of DHA on cytosolic calcium concentrations were examined by recording the changes of fluorescence intensity ratios.

RESULTS

DHA (1 μmol/L) could activate BK channels. Open probabilities (NP0) of BK channels at test potential 60 mV, and calcium concentrations in external solution at 0, 0.01, 0.1, 1, 3, 10, 50 and 100 μmol/L were 0.002 7±0.000 4, 0.006 0±0.001 4, 0.097 2±0.010 6, 0.137 9±0.032 9, 0.468 7±0.163 7, 2.097 1±0.310 4 and 3.120 4±0.242 7, respectively (P<0.05, n=4). Before DHA perfusion, the fluorescence intensity ratio was 0.51±0.01, and the ratios were 0.53±0.02 and 0.55±0.01 after 0.001 and 0.01 μmol/L DHA perfusion, respectively (P>0.05, n≥5). The ratios were 0.64±0.01, 0.65±0.01, 0.70±0.01, 0.69±0.01, 0.68±0.01 and 0.67±0.02 after 0.1, 0.3, 1, 3, 5 and 10 μmol/L DHA perfusion, respectively, and EC50 was (0.04±0.02) μmol/L(P<0.05, n≥4). They were all higher than that before DHA perfusion. After incubating with phospholipase C (PLC) blocker U73122 and inositol triphosphate (IP3) blocker 2-APB, the ratios were 0.52±0.01 and 0.49±0.02 on the setting of 0.1 μmol/L DHA, respectively. Compared with control group(0.64±0.01), the ratios decreased after incubating with blockers (P<0.05, n≥4).

CONCLUSIONS

Docosahexaenoic acids can activate large conductance calcium-activated potassium channels by the pathway of PLC-IP3-Ca(2+) to increase cytosolic calcium concentration in normal coronary smooth muscle cells, dilate the coronary vessels and bestow protective effects on cardiovascular system.

Percutaneous sclerotherapy of massive macrocystic lymphatic malformations of the face and neck using fibrin glue with OK-432 and bleomycin

Picibanil (OK-432) and bleomycin have been used as alternative sclerosing agents for lymphatic malformations. This study evaluated the clinical curative effect of sclerotherapy using fibrin glue combined with OK-432 and bleomycin for the treatment of macrocystic lymphatic malformations of the face and neck. Fifteen paediatric patients (6 males; 9 females, aged 13 months to 14 years) who had received percutaneous sclerotherapy for massive macrocystic lymphatic malformations of the face and neck were retrospectively reviewed. Affected regions included the neck, parotid region and parapharynx, mouth floor, face and cheek, and orbital regions. All patients showed preoperative symptoms of space-occupying lesions between 4 cm × 5 cm and 12 cm × 16 cm in size. Fibrin glue with OK-432 and bleomycin was injected under general anaesthesia. All patients received preoperative and follow-up CT scans. Outcomes were assessed by three surgeons. All patients exhibited mid-facial swelling for 3-4 weeks after surgery, but no major complications. Follow-up periods ranged from 8 to 16 months. Eight lesions were completely involuted, five were mostly involuted, and two were partially involuted. Percutaneous sclerotherapy using fibrin glue with OK-432 and bleomycin provided a simple, safe, and reliable alternative treatment for massive macrocystic lymphatic malformations of the face and neck.

Effect of total flavonoid fraction of Astragalus complanatus R. Brown on angiotensin II-induced portal-vein contraction in hypertensive rats

The objective of the present study was to examine further the underlying mechanism of the antihypertensive effect of the total flavonoid (TF), extracted from the seed of Astragalus complanatus R.Brown. Renovascular hypertension rats (RHR) were established by the two-kidney one clip (2K1C) method. The effect of TF on the contraction of portal vein was studied in an isolated preparation. The response of portal vein to angiotensin II (Ang II) was expressed as a percentage of the 100 mmol/l KCl induced maximum contraction. We took the dose-response curve of portal vein to Ang II (from 10(-9) to 10(-6) mmol/l) as the control and then observed the change of curve after TF and Valsartan (Ang II receptor blocker) administration. Ang II induced a concentration-dependent increase of the contraction amplitude (maximal increase, 46.53+/-5.15% of 100 mmol/l KCl induced contraction at Ang II 10(-6) mmol/l in RHR). The Ang II-induced portal vein contraction was prevented by TF with a concentration related manner (maximal inhibition amplitude from 46.53+/-5.15% to 22.525+/-4.67% of 100 mmol/l KCl contraction at 10(-6)mmol/l Ang II and 3.12 x 10(-1) mg/l TF in RHR). The effect of TF on Ang II-induced portal vein contraction was similar to Valsartan. These results showed that the antihypertensive action of TF was attributed to the dilation of vessels and is related to the blockade of the Ang II receptor.

The use of transgenic animals in the study of diabetic kidney disease

Diabetic nephropathy is one of the most common diseases leading to fibrosis and end-stage renal disease (ESRD) world wide. Under normal conditions, a delicate equilibrium exists between synthesis, composition, and removal of extracellular matrix (ECM). If this is disturbed, ECM accumulation and fibrosis may result. The fragile balance between synthesis and removal of ECM is crucial for the prognosis of glomerular as well as interstitial pathological processes. Some features may favor ECM accumulation and progression to ESRD (dialysis and transplantation), whereas other elements may favor ECM removal and resolution (recovery). Pathogenetic mechanisms and the cellular sources of ECM in the glomerular basement membrane as well as in the tubulointerstitial space are still under investigation. Among several growth factors, transforming growth factor beta1 (TGF-beta1) plays a major role. We consider the use of living animals necessary for our understanding of the complex biological processes that occur during the development of ESRD. The present review will discuss the glomerular as well as interstitial accumulation of ECM and the use of transgenic animals in studying the pathogenetic mechanisms with special emphasis on diabetic kidney disease and TGF-beta1.

Archaeoglobus fulgidus RNase HII in DNA replication: enzymological functions and activity regulation via metal cofactors

RNA primer removal during DNA replication is dependent on ribonucleotide- and structure-specific RNase H and FEN-1 nuclease activities. A specific RNase H involved in this reaction has long been sought. RNase HII is the only open reading frame in Archaeoglobus fulgidus genome, while multiple RNases H exist in eukaryotic cells. Data presented here show that RNase HII from A. fulgidus (aRNase HII) specifically recognizes RNA-DNA junctions and generates products suited for the FEN-1 nuclease, indicating its role in DNA replication. Biochemical characterization of aRNase HII activity in the presence of various divalent metal ions reveals a broad metal tolerance with a preference for Mg(2+) and Mn(2+). Combined mutagenesis, biochemical competitions, and metal-dependent activity assays further clarify the functions of the identified amino acid residues in substrate binding or catalysis, respectively. These experiments also reveal that Asp129 form a second-metal binding site, and thus contribute to activity attenuation.

Structural biochemistry of a type 2 RNase H: RNA primer recognition and removal during DNA replication

DNA replication and cellular survival requires efficient removal of RNA primers during lagging strand DNA synthesis. In eukaryotes, RNA primer removal is initiated by type 2 RNase H, which specifically cleaves the RNA portion of an RNA-DNA/DNA hybrid duplex. This conserved type 2 RNase H family of replicative enzymes shares little sequence similarity with the well-characterized prokaryotic type 1 RNase H enzymes, yet both possess similar enzymatic properties. Crystal structures and structure-based mutational analysis of RNase HII from Archaeoglobus fulgidus, both with and without a bound metal ion, identify the active site for type 2 RNase H enzymes that provides the general nuclease activity necessary for catalysis. The two-domain architecture of type 2 RNase H creates a positively charged binding groove and links the unique C-terminal helix-loop-helix cap domain to the active site catalytic domain. This architectural arrangement apparently couples directional A-form duplex binding, by a hydrogen-bonding Arg-Lys phosphate ruler motif, to substrate-discrimination, by a tyrosine finger motif, thereby providing substrate-specific catalytic activity. Combined kinetic and mutational analyses of structurally implicated substrate binding residues validate this binding mode. These structural and mutational results together suggest a molecular mechanism for type 2 RNase H enzymes for the specific recognition and cleavage of RNA in the RNA-DNA junction within hybrid duplexes, which reconciles the broad substrate binding affinity with the catalytic specificity observed in biochemical assays. In combination with a recent independent structural analysis, these results furthermore identify testable molecular hypotheses for the activity and function of the type 2 RNase H family of enzymes, including structural complementarity, substrate-mediated conformational changes and coordination with subsequent FEN-1 activity.

TGF-beta1-induced glomerular disorder is associated with impaired concentrating ability mimicking primary glomerular disease with renal failure in man

Transforming growth factor-beta1 (TGF-beta1) may play a major role in the pathogenesis of glomerulopathy and end-stage renal disease (ESRD). The aim of this study was to explore the functional consequences of localized overproduction of TGF-beta1 in relation to glomerular ultrastructure and the composition of the extracellular matrix (ECM) in the inner medulla. We used a transgenic mouse with overexpression of TGF-beta1 targeted to the juxtaglomerular apparatus (JGA) by the Ren-1c promoter. The kidney function was evaluated using urine production and metabolite excretion over a 24-hour period, glomerular filtration rate (GFR), and concentrating ability. The glomerular structure was analyzed in terms of volume, ie, the volume of the mesangium per glomerulus (Vv[mes/glom]) and the volume of the matrix per glomerulus (Vv[matrix/glom]), ECM per glomerulus, the area of the filtration surface, and the thickness of the peripheral basement membrane (PBM). Immunohistochemistry or in situ hybridization was used to examine the expression of aquaporin 2 (AQP2), plasminogen activator inhibitor-1 (PAI-1), and the composition of the ECM in the inner medulla. The mice exhibited polyuria, reduced concentrating ability, decreased GFR, and albuminuria paralleled by increased glomerular volume, with increased volume of ECM, decreased filtration surface, and thickening of the PBM being detectable between 1 and 2 months of age. The deposition of glomerular ECM was accompanied by increased levels of PAI-1. As estimated by excretion of Clara cell protein-1 (CC16) and lysozyme, tubular damage occurred only in older mice. Collagen Type I was deposited in the inner medulla in the presence of normal AQP2-expression in the collecting ducts. This study reached the following conclusions: (a) TGF-beta1 reduces the GFR and the glomerular filtration surface, (b) TGF-beta1 induces albuminuria in association with widening of the PBM, (c) expansion of the mesangial volume seems to precede the widening of the PBM, (d) TGF-beta1-induced accumulation of glomerular ECM is partly explained by increased PAI-1 expression, (e) Decreased concentrating ability and polyuria caused by accumulation of ECM in the inner medulla may be an early marker of glomerular diseases associated with increased expression of TGF-beta1 in man.

[Effect of cGMP on calcium-activated potassium channels in primary cultured porcine coronary artery smooth muscle cells]

Guanosine 3',5'-cyclic monophosphate (cGMP) is capable of relaxing vascular smooth muscle through activating calcium-activated potassium channels (KCa channel) in the vascular smooth muscle cell membrane. But regarding the mechanism it is still under debate. In the present work the mechanism of the effect of cGMP on KCa channel in primary cultured porcine coronary artery smooth muscle cells using patch clamp technique was investigated. Experimental results showed that (1) different concentrations of 8-bromo-cGMP (0.25 mmol/L, 0.50 mmol/L, 1.00 mmol/L), serving as a membrane permeable analogue, could activate KCa channels, and (2) 1.00 mmol/L 8-bromo-cGMP could not activate such kind of channels in inside-out patch under the same condition. These results suggested that the activating effect of cGMP on KCa channels was indirect, being mediated by some intracellular process.

[Protective effect of puerarin on acute cerebral ischemia in rats]

Acute incomplete brain ischemia in rats was induced by bilateral carotid artery occlusion(BCAO). BCAO results in severe suppression of EEG and increase of brain water content. Left middle cerebral artery occlusion(MCAO) in rats by electrical coagulation results in increase of brain water content of ipsilateral hemisphere and contralateral hemiparesis. The typical ischemic neuropathological damage emerges in both BCAO and MCAO models. Intraperitoneal injection of puerarin significantly helps improve all these brain ischemic disturbances.

Angiotensin II controls p21ras activity via pp60c-src

Angiotensin II is the major effector peptide of the renin-angiotensin system, and it exerts its physiologic functions via a G protein-coupled cell surface receptor called AT1. We found that in rat aortic smooth muscle cells, angiotensin II stimulated the formation of Ras-GTP, Ras-Raf-1 complex formation, and the tyrosine phosphorylation of two important Ras GTPase-activating proteins (GAPs), p120 Ras-GAP and p190 Rho-GAP. Electroporation of anti-pp60c-src antibody into cultured, adherent smooth muscle cells blocked the angiotensin II stimulation of Ras-GAP and Rho-GAP tyrosine phosphorylation. In contrast electroporation of antibodies against c-Yes or c-Fyn had no effect. Anti-pp60c-src antibody also blocked angiotensin II-stimulated Ras activation and Ras-Raf-1 complex formation. These data strongly suggest that a G protein-coupled receptor such as the AT1 receptor can activate the Ras protein cascade via the tyrosine kinase pp60c-src.

[Effect of puerarin on cerebral blood flow in dogs]

The hemodynamics of left intra- and extracranial arteries was determined by a pulsatile Doppler flowmeter and a transcranial Doppler system simultaneously in anesthetized dogs. Low doses of puerarin (50mg/kg, iv) did not alter the cerebral perfusion pressure, but reduced the flow velocities of both middle cerebral artery and anterior cerebral artery. The globle cerebral blood flow was enhanced due to dilatation of the intracranial arteries.