A novel Trichinella spiralis serine proteinase disrupted gut epithelial barrier and mediated larval invasion through binding to RACK1 and activating MAPK/ERK1/2 pathway

BACKGROUND

Gut epithelium is the first natural barrier against Trichinella spiralis larval invasion, but the mechanism by which larval penetration of gut epithelium is not completely elucidated. Previous studies showed that proteases secreted by T. spiralis intestinal infective larvae (IIL) degraded tight junctions (TJs) proteins of gut epithelium and mediated larval invasion. A new T. spiralis serine proteinase (TsSPc) was identified in the IIL surface proteins and ES proteins, rTsSPc bound to the intestinal epithelial cell (IECs) and promoted larval invasion of IECs. The aim of this study was to characterize the interacted proteins of TsSPc and IECs, and to investigate the molecular mechanisms of TsSPc mediating larval invasion of gut mucosa.

METHODOLOGY/PRINCIPAL FINDING

IIFT results showed natural TsSPc was detected in infected murine intestine at 6, 12 hours post infection (hpi) and 3 dpi. The results of GST pull-down, mass spectrometry (MS) and Co-IP indicated that rTsSPc bound and interacted specifically with receptor for activated protein C kinase 1 (RACK1) in Caco-2 cells. rTsSPc did not directly hydrolyze the TJs proteins. qPCR and Western blot showed that rTsSPc up-regulated RACK1 expression, activated MAPK/ERK1/2 pathway, reduced the expression levels of gut TJs (occludin and claudin-1) and adherent protein E-cad, increased the paracellular permeability and damaged the integrity of intestinal epithelial barrier. Moreover, the RACK1 inhibitor HO and ERK1/2 pathway inhibitor PD98059 abolished the rTsSPc activating ERK1/2 pathway, they also inhibited and abrogated the rTsSPc down-regulating expression of occludin, claudin-1 and E-cad in Caco-2 monolayer and infected murine intestine, impeded larval invasion and improved intestinal epithelial integrity and barrier function, reduced intestinal worm burdens and alleviated intestinal inflammation.

CONCLUSIONS

rTsSPc bound to RACK1 receptor in gut epithelium, activated MAPK/ERK1/2 pathway, decreased the expression of gut epithelial TJs proteins and disrupted the epithelial integrity, consequently mediated T. spiralis larval invasion of gut epithelium. The results are valuable to understand T. spiralis invasion mechanism, and TsSPc might be regarded as a vaccine target against T. spiralis invasion and infection.

The protective immunity induced by Trichinella spiralis galectin against larval challenge and the potential of galactomannan as a novel adjuvant

Previous studies showed that recombinant Trichinella spiralis galectin (rTsgal) promoted larval invasion of gut epithelial cells, while anti-rTsgal antibodies inhibited the invasion. Galactomannan (GM) is a polysaccharide capable of regulating immune response. The aim of this study was to evaluate protective immunity induced by rTsgal immunization and the potential of GM as a novel adjuvant. The results showed that vaccination of mice with rTsgal+ISA201 and rTsgal+GM elicited a Th1/Th2 immune response. Mice immunized with rTsgal+ISA201 and rTsgal+GM exhibited significantly higher levels of serum anti-rTsgal antibodies, mucosal sIgA and cellular immune responses, but level of specific antibodies and cytokines of rTsgal+GM group was lower than the rTsgal+ISA201 group. Immunization of mice with rTsgal+ISA201 and rTsgal+GM showed a 50.5 and 40.16% reduction of intestinal adults, and 52.04 and 37.53% reduction of muscle larvae after challenge. Moreover, the numbers of goblet cells and expression level of mucin 2, Muc5ac and pro-inflammatory cytokines (TNF-α and IL-1β) in gut tissues of vaccinated mice were obviously decreased, while Th2 inducing cytokine (IL-4) expression was evidently increased. Galactomannan enhanced protective immunity, alleviated intestinal and muscle inflammation of infected mice. The results indicated that rTsgal+ISA201 vaccination induced a more prominent gut local as well as systemic immune response and protection compared to rTsgal+GM vaccination. The results suggested that Tsgal could be considered as a candidate vaccine target against Trichinella infection and galactomannan might be a potential novel candidate adjuvant of anti-Trichinella vaccines.

Trichinella spiralis galectin binding to toll-like receptor 4 induces intestinal inflammation and mediates larval invasion of gut mucosa

Previous studies showed that Trichinella spiralis galectin (Tsgal) facilitates larval invasion of intestinal epithelium cells (IECs). However, IEC proteins binding with Tsgal were not identified, and the mechanism by which Tsgal promotes larval invasion is not clear. Toll-like receptors (TLRs) are protein receptors responsible for recognition of pathogens. The aim of this study was to investigate whether recombinant Tsgal (rTsgal) binds to TLR-4, activates inflammatory pathway in gut epithelium and mediates T. spiralis invasion. Indirect immunofluorescence (IIF), GST pull-down and co-immunoprecipitation (Co-IP) assays confirmed specific binding between rTsgal and TLR-4 in Caco-2 cells. qPCR and Western blotting showed that binding of rTsgal with TLR-4 up-regulated the TLR-4 transcription and expression in Caco-2 cells, and activated p-NF-κB p65 and p-ERK1/2. Activation of inflammatory pathway TLR-4/MAPK-NF-κB by rTsgal up-regulated pro-inflammatory cytokines (IL-1β and IL-6) and down-regulated anti-inflammatory cytokine TGF-β in Caco-2 cells, and induced intestinal inflammation. TAK-242 (TLR-4 inhibitor) and PDTC (NF-κB inhibitor) significantly inhibited the activation of TLR-4 and MAPK-NF-κB pathway. Moreover, the two inhibitors also inhibited IL-1β and IL-6 expression, and increased TGF-β expression in Caco-2 cells. In T. spiralis infected mice, the two inhibitors also inhibited the activation of TLR-4/MAPK-NF-κB pathway, ameliorated intestinal inflammation, impeded larval invasion of gut mucosa and reduced intestinal adult burdens. The results showed that rTsgal binding to TLR-4 in gut epithelium activated MAPK-NF-κB signaling pathway, induced the expression of TLR-4 and pro-inflammatory cytokines, and mediated larval invasion. Tsgal might be regarded as a candidate molecular target of vaccine against T. spiralis enteral invasive stage.

Trichinella spiralis dipeptidyl peptidase 1 suppressed macrophage cytotoxicity by promoting M2 polarization via the STAT6/PPARγ pathway

Trichinella spiralis dipeptidyl peptidase 1 (TsDPP1), or cysteine cathepsin C, is a secretory protein that is highly expressed during the infective larvae and adult worm stages in the intestines. The aim of this study was to investigate the mechanism by which recombinant TsDPP1 (rTsDPP1) activates macrophages M2 polarization and decreases macrophage cytotoxicity to kill newborn larvae via ADCC. RAW264.7 macrophages and murine peritoneal macrophages were used in this study. The results of the immunofluorescence test (IFT) and confocal microscopy showed that rTsDPP1 specifically bound to macrophages, and the binding site was localized on the cell membrane. rTsDPP1 activated macrophage M2 polarization, as demonstrated by high expression levels of Arg1 (M2 marker) and M2-related genes (IL-10, TGF-β, CD206 and Arg1) and high numbers of CD206+ macrophages. Furthermore, the expression levels of p-STAT6, STAT6 and PPARγ were obviously increased in rTsDPP1-treated macrophages, which were evidently abrogated by using a STAT6 inhibitor (AS1517499) and PPARγ antagonist (GW9662). The results indicated that rTsDPP1 promoted macrophage M2 polarization through the STAT6/PPARγ pathway. Griess reaction results revealed that rTsDPP1 suppressed LPS-induced NO production in macrophages. qPCR and flow cytometry results showed that rTsDPP1 downregulated the expression of FcγR I (CD64) in macrophages. The ability of ADCC to kill newborn larvae was significantly decreased in rTsDPP1-treated macrophages, but AS1517499 and GW9662 restored its killing capacity. Our results demonstrated that rTsDPP1 induced macrophage M2 polarization, upregulated the expression of anti-inflammatory cytokines, and inhibited macrophage-mediated ADCC via activation of the STAT6/PPARγ pathway, which is beneficial to the parasitism and immune evasion of this nematode.

Molecular characterization of a novel serine proteinase from Trichinella spiralis and its participation in larval invasion of gut epithelium

BACKGROUND

A novel serine proteinase of Trichinells spiralis (TsSPc) has been identified in the excretion/secretion (ES) antigens, but its role in larval invasion is unclear. The aim of this study was to clone and express TsSPc, identify its biological and biochemical characteristics, and investigate its role on larval invasion of gut epithelium during T. spiralis infection.

METHODOLOGY/PRINCIPAL FINDINGS

TsSPc has a functional domain of serine proteinase, and its tertiary structure consists of three amino acid residues (His88, Asp139 and Ser229) forming a pocket like functional domain. Recombinant TsSPc (rTsSPc) was expressed and purified. The rTsSPc has good immunogenicity. On Western blot analysis, rTsSPc was recognized by infection serum and anti-rTsSPc serum, natural TsSPc in crude and ES antigens was identified by anti-rTsSPc serum. The results of qPCR, Western blot and indirect immunofluorescence test (IIFT) showed that TsSPc was expressed at diverse stage worms, and mainly localized at cuticle, stichosome and intrauterine embryos of this nematode. The rTsSPc had enzymatic activity of native serine protease, which hydrolyzed the substrate BAEE, casein and collagen I. After site directed mutation of enzymatic active sites of TsSPc, its antigenicity did not change but the enzyme activity was fully lost. rTsSPc specifically bound to intestinal epithelium cells (IECs) and the binding sites were mainly localized in cell membrane and cytoplasm. rTsSPc accelerated larval invasion of IECs, whereas anti-rTsSPc antibodies and TsSPc-specific dsRNA obviously hindered larval invasion.

CONCLUSIONS

TsSPc was a surface and secretory proteinase of the parasite, participated in larval invasion of gut epithelium, and may be considered as a candidate vaccine target molecule against Trichinella intrusion and infection.

[Infiltration and significance of M1 macrophage in breast cancer: an analysis of METABRIC database and clinical validation]

Objective: To investigate the differences of immune microenvironment between stage T1N3 and stage T3N0 breast cancer patients and explore the relationship between M1 macrophage infiltration and lymph node metastasis in breast cancer. Methods: Clinical information and RNA-sequencing (RNA-Seq) expression data of stage T1N3 (n=9) and stage T3N0 (n=11) breast cancer patients were extracted from Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) databases. Using CIBERSORT, the proportions of 22 types of immune cells were calculated, and then the differences of immune cell infiltration between stage T1N3 and T3N0 patients were compared. From 2011 to 2022, pathologic specimens were collected from breast cancer patients who underwent curative resection at the Cancer Hospital, Chinese Academy of Medical Sciences, including 77 at stage T1N3 and 58 at stage T3N0.The METABRIC database analysis results were verified by examining the density of M1 macrophages in tissues using dual-staining immunohistochemistry. Results: METABRIC data analysis showed M1 macrophage was the highest proportion, 15.85% in stage T1N3 breast cancer; M2 macrophage was the highest proportion, 13.07% in stage T3N0 breast cancer.M1 macrophage proportions were statistically different between patients with stage T1N3 and stage T3N0 (P=0.010). The dual-staining immunohistochemistry analysis of breast cancer tissues showed M1 macrophage density (median) of 62.0 and 38.0 cells/mm(2) for stage T1N3 and T3N0, respectively. The difference was statistically significant (P=0.002). Conclusion: The density of M1 macrophages is notably higher in stage T1N3 patients and is associated with lymph node metastasis.

A novel C-type lectin from Trichinella spiralis mediates larval invasion of host intestinal epithelial cells

The aim of this study was to investigate the characteristics of a novel type C lectin from Trichinella spiralis (TsCTL) and its role in larval invasion of intestinal epithelial cells (IECs). TsCTL has a carbohydrate recognition domain (CRD) of C-type lectin. The full-length TsCTL cDNA sequence was cloned and expressed in Escherichia coli BL21. The results of qPCR, Western blotting and immunofluorescence assays (IFAs) showed that TsCTL was a surface and secretory protein that was highly expressed at the T. spiralis intestinal infective larva (IIL) stages and primarily located at the cuticle, stichosome and embryos of the parasite. rTsCTL could specifically bind with IECs, and the binding site was localized in the IEC nucleus and cytoplasm. The IFA results showed that natural TsCTL was secreted and bound to the enteral epithelium at the intestinal stage of T. spiralis infection. The rTsCTL had a haemagglutinating effect on murine erythrocytes, while mannose was able to inhibit the rTsCTL agglutinating effect for mouse erythrocytes. rTsCTL accelerated larval intrusion into the IECs, whereas anti-rTsCTL antibodies and mannose significantly impeded larval intrusion in a dose-dependent manner. The results indicated that TsCTL specifically binds to IECs and promotes larval invasion of intestinal epithelium, and it might be a potential target of vaccines against T. spiralis enteral stages.

[The clinical effect and imaging features of accordion maneuver in promoting bone healing at the docking site after tibial transport under ultrasonic monitoring]

Objective: To explore the imaging features and clinical effect of accordion maneuver in promoting the bone healing at the docking site after tibial transport under ultrasonic monitoring. Methods: Retrospective analysis was conducted on the clinical data of 16 patients with tibial bone transport who were admitted to the Department of Orthopedics, the second Hospital of Shanxi Medical University from May 2018 to October 2019. All the patients were treated with accordion maneuver to promote bone healing at the docking site under ultrasound monitoring. There were 14 males and 2 females, aged (45.3±14.3) years (range: 6 to 61 years). Before tibial bone transport, the length of the tibial defect of 16 patients was (6.0±2.6) cm (range: 2.0 to 12.1 cm). The operation steps of accordion maneuver were as follows: pressurization for 2 weeks, suspension for 12 days, distraction for 2 weeks, retraction for 2 weeks, and then stop the operation to consolidate the bone mineralization. During accordion treatment, ultrasound was used to monitor the size of hematoma, Adler grade of blood flow signal and the changes of new callus in and around the docking site. X-ray was performed to monitor bone healing at the docking site. Pearson correlation coefficient was used to analyze the correlation between the size of hematoma, the resistance index of blood flow signal and the bone healing time of the docking site. Paley healing criterion was used to evaluate the bone healing and functional recovery of the patients. Results: During accordion maneuver, ultrasound examination showed that the Adler grade of blood flow signals around the docking site increased gradually before retraction and then decreased gradually, but the degree of callus mineralization continued to increase gradually. After 2 weeks of pressure on the docking site, hematoma was observed in 14 patients by ultrasound examination. X-ray showed that all docking sites had bony healing, with the healing time of (30.8±4.9) weeks (range: 23 to 40 weeks).The size of the hematoma was negatively correlated with the healing time of the docking site (r=-0.819,P<0.01). No hematoma was found in 2 patients, and after continuous observation for 20 weeks, there was still no obvious callus connection at the docking site. After bone cortical removal, ultrasound examination showed hematoma formed at the docking site. Accordion maneuver was continued, and the docking site healed at 30 and 32 weeks after surgery, respectively. There was a negative linear correlation between hematoma size at 2 weeks of compression and the blood flow resistance index at 2 weeks of retraction in 16 patients (r=-0.801, P<0.01). The patients were followed-up for (14.5±3.2) months (range: 10.6 to 20.2 months). At the last follow-up, 12 patients were evaluated as excellent and 4 were evaluated as good by Paley healing criteria. Conclusion: The distraction and compression stress applied in accordion maneuver can promote bone healing at the docking site, and ultrasound can monitor early signs of bone healing at the docking site to help determine the tendency of bone healing.

Influenza a virus and Streptococcus pneumonia coinfection potentially promotes bacterial colonization and enhances B lymphocyte depression and reduction

Influenza has frequently been epidemic in recent years. However, the mechanisms of severe pneumonia with postinfluenza Streptococcus pneumoniae (SP) secondary infection have not been fully understood. In this study, we explored the mechanisms of pneumonia in postinfluenza A virus (IAV) infection via a mouse model. Mice were intranasally inoculated with SP three days after IAV inoculation. We then collected samples at three time points to dynamically observe the pathological progression. In IAV infection alone, lymphocyte infiltration and widened alveolar intervals were observed. In the blood, levels of the CD19+, CD19+CD21+ and CD19+CD79β+B lymphocyte subpopulations were reduced, and IFN-γ and IL-10 were elevated. Slight atrophy was seen in the spleen, which was due to splenic B lymphocyteinitiated apoptosis through the mitochondrial pathway. When SP infection occurred after IAV infection, the pulmonary inflammation was significantly aggravated; a fair number of lymphocytes and neutrophils infiltrated simultaneously with exfoliated bronchial epithelial cells, vascular endothelial cells, widened alveolar septum and hemorrhaging. Increasing edema fluid and bacteria accumulated in the alveolar cavity. Decreased CD19+, CD19+CD21+ and CD19+CD79β+B lymphocyte subpopulations and increased interferon gamma (IFN-γ) or interleukin 10 (IL-10) were more prominent compared to those with viral infection alone. Spleen atrophy resulting from coinfection was more obvious because of massive splenic B lymphocyte apoptosis through the mitochondrial pathway compared to viral infection alone. This study shows that although inflammation caused by SP infection alone was temporary, preceding IAV infection provided favorable conditions for SP colonization and multiplication by destroying lung structure and suppressing humoral immunity. Synergistic IAV-SP coinfection is likely to facilitate more SP colonization and promote B lymphocyte-suppression and reduction. Eventually, the pneumonia worsened.

[Effects of thoracic epidural administration of lidocaine on hemodynamic and arousal responses of double lumen tracheal intubation during induction of anesthesia]

OBJECTIVE

To compare the effects of thoracic epidural administration of lidocaine on hemodynamic and arousal responses of double lumen tracheal intubation during induction of anesthesia.

METHODS

In the study, 40 patients with American Society of Anesthesiologists (ASA) physical statuses I-II, aged 19-66 years, scheduled for elective thoracic surgeries under general anesthesia requiring orotracheal intubation were allocated to either the double-lumen endobronchial intubation (T group) or double-lumen endobronchial intubation after epidural administration of lidocaine (E group). After an intravenous anesthetic induction, the orotracheal double-lumen intubation was performed using a Macintosh direct laryngoscopy (MDLS), respectively. Invasive blood pressure (BP), heart rate (HR) and bispectral index (BIS) were recorded before and after anesthetic induction, immediately after intubation and 5 minutes after intubation with 1-minute interval and the intubation time also noted. The rate pressure product (RPP) was calculated.

RESULTS

After anesthetic induction, BP and RPP in the two groups decreased significantly compared with their preinduction values. In comparison with their postinduction values, the orotracheal intubation in the two groups caused significant increases in BPs, HRs and RPP. In comparison with their preinduction values, BPs decreased significantly in E group, systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) increased significantly and lasted for 1 min in T group. The HRs of both groups after intubation were significantly higher than their baseline values , and increased in HR and lasted for 1 min and 4 min in E group and T group, respectively. SBP, DBP, MAP, HR and RPP after intubation in T group were significantly higher than those of E group during the observation period. The values of BIS were similar between both the groups. In T group, the incidences of SBP percent increased>30% of the baseline value and RPP more than 22 000 were significantly higher than in E group. None of the patients in group E had SBP more than 130% of the baseline value and RPP more than 22 000.

CONCLUSION

During double-lumen endobronchial intubation, epidural administration of lidocaine can provide less hemodynamic response and similar arousal response.

Correlation between the 677C>T polymorphism in the methylene tetrahydrofolate reductase gene and serum homocysteine levels in coronary heart disease

The aim of the current study was to explore the correlation between serum homocysteine (HCY) levels and the methylene tetrahydrofolate reductase (MTHFR) gene 677C/T polymorphism and coronary heart disease (CHD). We consecutively enrolled 208 patients with CHD confirmed by CTA or coronary angiography from our hospital. An additional 200 healthy volunteers were enrolled as the control group. Serum HCY levels, MTHFR C677T genotype, and other related indicators were evaluated for the two groups. Compared to those in the control group, the serum HCY levels in the CHD patients were significantly higher (P < 0.05). The proportion of individuals with the heterozygous MTHFR CT genotype and homozygous mutant TT genotype among CHD patients was significantly higher than that in the control group (P < 0.05). In the acute coronary syndrome (ACS) subgroup, the proportion of those with the CT and TT genotypes was significantly higher than that of the stable CHD subgroup (P < 0.05). In summary, serum HCY levels were elevated in CHD patients, and the frequency of the CT and TT genotypes were also significantly increased, especially among the ACS subgroup. Taken together, this suggests that serum HCY levels and MTHFR C677T genotypes are correlated with CHD.

Myocardial remodeling and bioelectric changes in tachycardia-induced heart failure in dogs

In this study, electrical and structural remodeling of ventricles was examined in tachycardia-induced heart failure (HF). We studied two groups of weight-matched adult male mongrel dogs: a sham-operated control group (n=5) and a pacing group (n=5) that underwent ventricular pacing at 230 bpm for 3 weeks. Clinical symptoms of congestive HF were observed in both groups. Their hemodynamic parameters were determined and the severity of the HF was evaluated by M-mode echocardiography. Changes in heart morphology were observed by scanning electron and light microscopy. Ventricular action potential duration (APD), as well as the 50 and 90% APD were measured in both groups. All dogs exhibited clinical symptoms of congestive HF after rapid right ventricular pacing for 3 weeks. These data indicate that rapid, right ventricular pacing produces a useful experimental model of low-output HF in dogs, characterized by biventricular pump dysfunction, biventricular cardiac dilation, and non-ischemic impairment of left ventricular contractility. Electrical and structural myocardial remodeling play an essential role in congestive HF progression, and should thus be prevented.

Industrial-scale spray layer-by-layer assembly for production of biomimetic photonic systems

Layer-by-layer assembly is a powerful and flexible thin film process that has successfully reproduced biomimetic photonic systems such as structural colour. While most of the seminal work has been carried out using slow and ultimately unscalable immersion assembly, recent developments using spray layer-by-layer assembly provide a platform for addressing challenges to scale-up and manufacturability. A series of manufacturing systems has been developed to increase production throughput by orders of magnitude, making commercialized structural colour possible. Inspired by biomimetic photonic structures we developed and demonstrated a heat management system that relies on constructive reflection of near infrared radiation to bring about dramatic reductions in heat content.

Calorimetric study of thermal denaturation of type I human placenta collagen

The thermal denaturations of type I human placenta collagen were studied in different aqueous solutions in the temperature range from 274 to 345 K by differential scanning calorimetry. The thermodynamic parameters of denaturational process were accurately. The average temperature of denaturation of the collagen Td is 47.1 degrees C, and the denaturational enthalpy delta Hd is 8.43 kJ per mole of residue in salt-free aqueous solution at pH 3.7. The linear relationship of delta Hd with Td has been obtained for the various collagens studied. The various factors concerning the stabilization of collagen structure of the Sigma collagen have been demonstrated. The dominant factors are hydrogen bonding and the participation of water molecules in the collagen structure. It is concluded from the thermodynamic evidence obtained that the water-carbonyl model is preferable to other models. By means of calculating the van't Hoff enthalpy of the collagen denaturation, the number and the size of cooperative blocks of the Sigma collagen have been evaluated. Its molecule contains five cooperative blocks, each having 600 residues or so. The type I human placenta collagen is a multi-domain protein.

[Measurement of fluidity of membrane lipids in lymphocytes from patients with pulmonary tuberculosis]

The degree of fluidity of cellular membranes was determined by fluorescence polarization analysis using fluorescent probe 1,6-Dipheny-1,3,5-hexatriene (DPH), when embedded in membrane lipid region of intact cells. Results have shown that lymphocytes isolated from patients have a more fluid lipid layer in their cellular membrane (eta = 2.69 +/- 0.77 poise chi +/- s) than lymphocytes isolated from normal health (eta = 3.11 +/- 0.95 poise chi +/- s)(P less than 0.05). Increase in degree of membrane microviscosity was closely correlated with the rise in cells number.