Induction of arginase-1 in MDSC requires exposure to CD3/CD28 activated T cells

Tumor-induced myeloid derived suppressive cells (MDSC) have been reported to inhibit T cell responses. In our study MDSC inhibit T cell proliferation through arginase-1 dependent manner. However, surprisingly we observe that freshly isolated MDSC from the bone marrow of tumor bearing mice do not constitutively express arginase-1 until after exposure to T cell proliferation system. The aim of this study is to determine the mechanism by which arginase-1 is induced in MDSC following exposure to a proliferative T cell environment. We show that treatment of MDSC with culture supernatant isolated from T cells activated with CD3/CD28 antibodies successfully induced arginase-1 expression and this process is independent of IL-10 and IFNγ. This suggest that arginase-1 induction in MDSC can occur independently of cell-cell contact. Interestingly IL-2, Con A or PMA activated T-cell supernatant as well as supernatant from multiple cancer cell lines failed to induce arginase-1 in MDSC. We also show that M-MDSC express higher levels of arginase-1 than G-MDSC after co-culture with CD3/CD28 activated T cells as well as its supernatant. In addition, other bone marrow cells have shown potential to express arginase-1 following exposure to the same conditions. For example, we observe that healthy Ly6C+ monocytes but not mature granulocytes successfully express arginase-1. These data demonstrate that T cells activated through stimulation of TCR elicit the immunosuppressive function of MDSC through induction of arginase-1.

Dual role of SIRPα in macrophage activation: inhibiting M1 while promoting M2 polarization via selectively activating SHP-1 and SHP-2 signal

Macrophages polarization into proinflammatory M1 or alternative M2 states, which plays a central role in inflammation and host defense, is tightly controlled by multiple regulatory molecules. Here we examined the role of signal regulatory protein α (SIRPα), which negatively regulates leukocyte responses, in regulating macrophage polarization and function. Compared to WT macrophages, macrophage obtained from SIRPα deficient (SIRPα−/−) mice demonstrated an enhanced response to M1 induction but were refractory to M2 induction, as indicated by the increased expression of M1-related markers CD86, MHC-II, iNOS, IL-1β, IL-12 and TNF-α under M1-skewed LPS/IFNγ treatment but the defective expression of anti-inflammatory mediators CD206, Arg1, IL-10 and TGFβ during IL-4 induced M2 activation. Furthermore, ligating SIRPα by CD47 extracellular domain (mCD47-AP) suppressed M1 polarization but enhanced M2 polarization in WT macrophages, whereas had no effect on SIRPα−/− macrophage polarization. Interestingly, under M1 and M2 activation, macrophage SIRPα was found to be tyrosine-phosphorylated and selectively associated with SHP-1 and SHP-2, respectively. Mechanistic studies indicated that SIRPα deficiency promoted M1 but attenuated M2 polarization of macrophages by enhancing the PI3k/Akt2 signaling pathway. Overall, our findings demonstrated for the first time that SIRPα plays an important role in modulating macrophage polarization, inhibiting M1 while promoting M2 phenotypic polarization through selectively activating SHP-1 and SHP-2 signaling.

Peptide 11R-VIVIT stimulates osteoblastogenesis through regulating the expression of nuclear factor of activated T cells cytoplasmic 1

Osteoporosis is characterized by the imbalance of two relatively independent processes-osteoblastogenesis and osteoclastogenesis. Calcineurin (Cn)/nuclear factor of activated T cells (NFAT)(Cn/NFAT) signaling pathway is involved in these two processes in bone metabolism, but its potential as a target to treat osteoporosis needs to be defined. The aim of this study is to investigate the inhibition of polypeptide 11R-VIVIT onCn/NFAT signaling pathway. Rat calvaria (RC) cells were prepared from experimental model of osteoporosis in rat.11R-VIVIT wasused to treat cultured RC cells from wide type (WT) rat or from osteoporosis (OP) rat, we then measured the expressions of NFATc1, osteopontin (OPN), osteocalcin (OC), cytokines, NFκB subunit p65 by real time PCR, western blot or immunofluorescence. Then ALP expression and staining, and alizarin red S (ARS) staining were employed to study the osteoblastodifferentiation. 11R-VIVIT regulates the expression of NFATc1, and some other molecules in Cn/NFAT signaling pathway, such as OPN and OC, at transcriptional level and protein level. Further, it can regulate the expression of inflammatory cytokine like IL-1beta, IL-10 and TNF-alpha and NFκB activity. Further, 11R-VIVIT can accelerate osteoblastodifferentiation of RC cells demonstrated by ALP and ARS staining.11R-VIVIT can stimulate the bone formation by decreasing NFATc1 expression and regulating the expression of inflammation related molecules.

Patterns and correlates of major depression in Chinese adults: a cross-sectional study of 0.5 million men and women

BACKGROUND

Worldwide 350 million people suffer from major depression, with the majority of cases occurring in low- and middle-income countries. We examined the patterns, correlates and care-seeking behaviour of adults suffering from major depressive episode (MDE) in China.

METHOD

A nationwide study recruited 512 891 adults aged 30-79 years from 10 provinces across China during 2004-2008. The 12-month prevalence of MDE was assessed by the Modified Composite International Diagnostic Interview-short form. Logistic regression yielded adjusted odds ratios (ORs) of MDE associated with socio-economic, lifestyle and health-related factors and major stressful life events.

RESULTS

Overall, 0.7% of participants had MDE and a further 2.4% had major depressive symptoms. Stressful life events were strongly associated with MDE [adjusted OR 14.7, 95% confidence interval (CI) 13.7-15.7], with a dose-response relationship with the number of such events experienced. Family conflict had the highest OR for MDE (18.9, 95% CI 16.8-21.2) among the 10 stressful life events. The risk of MDE was also positively associated with rural residency (OR 1.5, 95% CI 1.4-1.7), low income (OR 2.3, 95% CI 2.1-2.4), living alone (OR 2.6, 95% CI 2.3-3.0), smoking (OR 1.4, 95% CI 1.3-1.6) and certain other mental disorders (e.g. anxiety, phobia). Similar, albeit weaker, associations were observed with depressive symptoms. Among those with MDE, about 15% sought medical help or took psychiatric medication, 15% reported having suicidal ideation and 6% reported attempting suicide.

CONCLUSIONS

Among Chinese adults, the patterns and correlates of MDE were generally consistent with those observed in the West. The low rates of seeking professional help and treatment highlight the great gap in mental health services in China.

The risk predictive values of UK-PBC and GLOBE scoring system in Chinese patients with primary biliary cholangitis: the additional effect of anti-gp210

BACKGROUND

Adequate risk stratification is critical for the management of the patients with primary biliary cholangitis (PBC). The UK-PBC and GLOBE scoring systems for prognosis of PBC have been proposed recently, but have not been validated in Asian population.

AIM

To validate the UK-PBC and GLOBE scoring systems in Chinese patients for prognosis of PBC. To clarify the role of anti-gp210 as a biomarker, and to investigate whether anti-gp210 could affect the prognostic values of UK-PBC and GLOBE scoring systems.

METHODS

We retrospectively analysed 276 patients with PBC evaluated between September 2004 and May 2016, including 133 anti-gp210+ and 143 anti-gp210- patients.

RESULTS

The 5-year adverse outcome-free survivals of anti-gp210+ vs. anti-gp210- patients were 70% and 85%, respectively (P = 0.005). Cirrhosis (P = 0.001), albumin level ≤40 g/L (P = 0.011) and platelet count ≤153 × 10⁹ (P < 0.001) had a superimposition effect on anti-gp210 antibody as a risk factor. Furthermore, long-term prognoses were evaluated using the UK-PBC and GLOBE scores. For UK-PBC scoring system, the area under receiver operating characteristic curve (AUROC) was 0.924 for all patients with PBC (n = 223), 0.940 for anti-gp210+ patients (n = 110) and 0.888 for anti-gp210- patients (n = 113). For GLOBE scoring system, the area under receiver operating characteristic curve was 0.901 for all patients with PBC (n = 223), 0.924 for anti-gp210+ patients (n = 110) and 0.848 for anti-gp210- patients (n = 113). UK-PBC score >0.0578 (P < 0.001, HR: 32.736, 95% CI: 11.368-94.267) and GLOBE score <0.850 (P < 0.001, HR: 18.763, 95% CI: 7.968-44.180) were associated with poorer outcomes in the whole cohort.

CONCLUSIONS

The UK-PBC and GLOBE scoring systems were good 5-year prognostic predictors in Chinese patients with PBC, especially in anti-gp210+ patients. As a biomarker, anti-gp210 antibody was associated with a more severe cholestatic manifestation and a worse long-term prognosis. The anti-gp210 antibody could be added to further optimise the UK-PBC and GLOBE scoring systems.

[Association between body mass index and both total and cause-specific mortality in China: findings from data through the China Kadoorie Biobank]

Objective: To evaluate the associations between body mass index (BMI) and both total and cause-specific mortality. Methods: After excluding participants with heart disease, stroke, cancer, chronic obstructive pulmonary disease, and diabetes at baseline study, 428 593 participants aged 30-79 in the China Kadoorie Biobank study were chosen for this study. Participants were categorized into 9 groups according to their BMI status. Cox regression analysis was used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) of mortality on BMI. Results: Among 3 085 054 person-years of the follow-up program between 2004 and 2013 (median 7.2 years), a total of 7 862 men and 6 315 women died. After adjusting for known or potential confounders, an increased risks of all-cause deaths were shown among participants with a BMI less than 18.5 (HR=1.40, 95%CI: 1.31-1.50), between 18.5-20.4 (HR=1.11, 95%CI: 1.05-1.17), and more than 35.0 (HR=2.05, 95%CI: 1.60-2.61), when compared to those with BMI between 20.5-22.4. Ranges of BMI with lower risk of cause-specific mortality were: 18.5-23.9 for ischemic heart disease, <26.0 for cerebro-vascular disease, 26.0-34.9 for cancers, and 24.0-25.9 for respiratory diseases. Conclusions: In this large prospective study, both underweight and obesity were associated with the increased total and certain cause-specific mortality, which were independent from other risk factors of death. Programs related to extensive follow-up, thorough analysis BMI and the risks of incidence on major chronic diseases all need to be developed, in order to better understand the impact of BMI on human health.

[Associations between airflow obstruction and total and cause-specific mortality in adults in China]

Objective: To examine the prospective associations between airflow obstruction and total and cause-specific mortality. Methods: The study was based on China Kadoorie Biobank, in which 199 099 men and 287 895 women aged 30-79 years at baseline survey were included after excluding those with heart disease, stroke and cancer. The Global Initiative on Obstructive Lung Disease (GOLD) guideline was used to classify airflow obstruction. Cox regression models were used to estimate adjusted HR and 95%CI. Results: During 3 494 079 person-years of follow-up between 2004 and 2013 (median 7.2 years), a total of 21 649 people died. Absolute mortality rates were 5.5, 9.9, 13.1, 32.4 and 63.3 deaths per 1 000 person-years for participants who had normal airflow, GOLD-1 to GOLD-4 airflow obstruction, respectively. After adjusting potential confounders, compared with participants with normal lung function, the HRs for death were 0.98 (95%CI: 0.88-1.09), 1.03 (95%CI: 0.97-1.09), 1.62 (95% CI: 1.53-1.73) and 2.83 (95% CI: 2.59-3.10) for those whose airflow obstruction were classified as GOLD-1 to GOLD-4, respectively. The airflow obstruction was also associated with increased risk for deaths due to ischemic heart disease, cerebrovascular disease and chronic obstructive pulmonary disease. Conclusion: Airflow obstruction is associated with total and certain cause-specific mortality, the higher the airflow obstruction degree is, the higher the death risk is.

Pyruvate kinase type M2 promotes tumour cell exosome release via phosphorylating synaptosome-associated protein 23

Tumour cells secrete exosomes that are involved in the remodelling of the tumour-stromal environment and promoting malignancy. The mechanisms governing tumour exosome release, however, remain incompletely understood. Here we show that tumour cell exosomes secretion is controlled by pyruvate kinase type M2 (PKM2), which is upregulated and phosphorylated in tumours. During exosome secretion, phosphorylated PKM2 serves as a protein kinase to phosphorylate synaptosome-associated protein 23 (SNAP-23), which in turn enables the formation of the SNARE complex to allow exosomes release. Direct phosphorylation assay and mass spectrometry confirm that PKM2 phosphorylates SNAP-23 at Ser95. Ectopic expression of non-phosphorylated SNAP-23 mutant (Ser95→Ala95) significantly reduces PKM2-mediated exosomes release whereas expression of selective phosphomimetic SNAP-23 mutants (Ser95→Glu95 but not Ser20→Glu20) rescues the impaired exosomes release induced by PKM2 knockdown. Our findings reveal a non-metabolic function of PKM2, an enzyme associated with tumour cell reliance on aerobic glycolysis, in promoting tumour cell exosome release.

The Effect of a Bi-annual Professional Application of APF Foam on Dental Caries Increment in Primary Teeth: 24-month Clinical Trial

The purpose of this study was to evaluate the effect of a bi-annual professional application of acidulated phosphate fluoride (APF) foam on caries increment in the primary dentition over a two-year period in the People’s Republic of China. In a double-blind, cluster-randomized, placebo-controlled trial, 392 children aged 3–4 years from 15 classes were randomly assigned to two groups on a school class basis. The experimental group (8 classes) received a bi-annual APF foam application, and the control group (7 classes) received the placebo. The mean increment of dmfs in the experimental group was 24.2% lower than that in the control group (p < 0.05). The significant caries reduction was observed on approximal surfaces in the experimental group compared with the control group (p < 0.01), but there were no differences on occlusal surfaces (p > 0.05). A bi-annual professional application of APF foam was effective in reducing the increment of dental caries in the primary teeth.

[Association and interaction between age at menarche and risk of diabetes in adult women]

Objective: To explore the associations between age at menarche and diabetes in adult women. Methods: We analyzed the baseline data of 32 364 female participants who were aged 30-79 years and had been enrolled into China Kadoorie Biobank (CKB) study from Tongxiang, Zhejiang province. Multiple logistic regression analysis were used to investigate the putative associations after adjusting for potential confounders. Variables of menarche age and others were added to the logistic regression model to evaluate the multiplicative interaction, respectively. Results: The mean age of female participants was (51.42 ± 9.63) years. And 3.73% and 24.17% of them reported their menarche age, ≤12 years, ≥17 years, respectively. The prevalence of diabetes among them was 5.75%. Compared with those with menarche age ≤12 years, the OR(95%CI) of 15-16, 13-14 and ≤12 years group were 1.13(1.00-1.27), 1.29(1.12-1.49) and 1.68(1.31-2.15) after adjusting for age, socioeconomic status, family history, health behaviors, menopause status, BMI and waist circumference. No significant differences were found in multiplicative interaction on diabetes between menarche age and smoking, alcohol consumption, physical activity, obesity, etc. (P>0.05). Conclusions: Menarche age is associated with higher risk of diabetes in female adults. The earlier menarche age is the higher risk of diabetes. There are no multiplicative interaction on diabetes between menarche age and other adults factors.

Cd47-Sirpα interaction and IL-10 constrain inflammation-induced macrophage phagocytosis of healthy self-cells

Rapid clearance of adoptively transferred Cd47-null (Cd47(-/-)) cells in congeneic WT mice suggests a critical self-recognition mechanism, in which CD47 is the ubiquitous marker of self, and its interaction with macrophage signal regulatory protein α (SIRPα) triggers inhibitory signaling through SIRPα cytoplasmic immunoreceptor tyrosine-based inhibition motifs and tyrosine phosphatase SHP-1/2. However, instead of displaying self-destruction phenotypes, Cd47(-/-) mice manifest no, or only mild, macrophage phagocytosis toward self-cells except under the nonobese diabetic background. Studying our recently established Sirpα-KO (Sirpα(-/-)) mice, as well as Cd47(-/-) mice, we reveal additional activation and inhibitory mechanisms besides the CD47-SIRPα axis dominantly controlling macrophage behavior. Sirpα(-/-) mice and Cd47(-/-) mice, although being normally healthy, develop severe anemia and splenomegaly under chronic colitis, peritonitis, cytokine treatments, and CFA-/LPS-induced inflammation, owing to splenic macrophages phagocytizing self-red blood cells. Ex vivo phagocytosis assays confirmed general inactivity of macrophages from Sirpα(-/-) or Cd47(-/-) mice toward healthy self-cells, whereas they aggressively attack toward bacteria, zymosan, apoptotic, and immune complex-bound cells; however, treating these macrophages with IL-17, LPS, IL-6, IL-1β, and TNFα, but not IFNγ, dramatically initiates potent phagocytosis toward self-cells, for which only the Cd47-Sirpα interaction restrains. Even for macrophages from WT mice, phagocytosis toward Cd47(-/-) cells does not occur without phagocytic activation. Mechanistic studies suggest a PKC-Syk-mediated signaling pathway, to which IL-10 conversely inhibits, is required for activating macrophage self-targeting, followed by phagocytosis independent of calreticulin Moreover, we identified spleen red pulp to be one specific tissue that provides stimuli constantly activating macrophage phagocytosis albeit lacking in Cd47(-/-) or Sirpα(-/-) mice.

Broad Infiltration of Macrophages Leads to a Proinflammatory State in Streptozotocin-Induced Hyperglycemic Mice

Chronic diseases are often associated with altered inflammatory response, leading to increased host vulnerability to new inflammatory challenges. Employing streptozotocin (STZ)-induced diabetes as a model, we further investigate mechanisms leading to enhanced neutrophil (polymorphonuclear leukocytes [PMN]) responses under hyperglycemia and compare them with those under chronic colitis. We show that, different from colitis under which the PMN response is significantly potentiated, the existence of a proinflammatory state associated with broad increases in macrophages in various organs plays a dominant role in promoting the PMN inflammatory response in diabetic mice. Studies of PMN infiltration during zymosan-induced peritonitis reveal that hyperglycemia enhances PMN recruitment not through inducing a high level of IL-17, which is the case in colitis, but through increasing F4/80⁺ macrophages in the peritoneal cavity, resulting in elevations of IL-6, IL-1β, TNF-α, and CXCL1 production. Insulin reversal of hyperglycemia, but not the neutralization of IL-17, reduces peritoneal macrophage numbers and ameliorates PMN infiltration during peritonitis. Significantly increased macrophages are also observed in the liver, kidneys, and intestines under hyperglycemia, and they are attributable to exacerbated nephropathy and colitis when inflammatory conditions are induced by doxorubicin and dextran sulfate sodium, respectively. Furthermore, analyses of monocyte production and macrophage proliferation in tissues suggest that significant monocytosis of inflammatory F4/80⁺Gr-1⁺ monocytes from the spleen and macrophage proliferation in situ synergistically contribute to the increased macrophage population under hyperglycemia. In conclusion, our results demonstrate that STZ-induced hyperglycemic mice develop a systemic proinflammatory state mediated by broad infiltration of macrophages.

[Major depressive disorder in relation with coronary heart disease and stroke in Chinese adults aged 30-79 years]

OBJECTIVE

To investigate the associations of major depressive disorder with coronary heart disease (CHD) and stroke in Chinese adults aged 30-79 years.

METHODS

In 2004-2008, China Kadoorie Biobank was conducted in 10 geographically defined regions (5 urban and 5 rural) of China. A total number of 512 891 participants aged 30-79 years were recruited in the baseline survey. A laptop-based electronic questionnaire was administrated face-to-face by trained health workers, collecting the general demographic and socio-economic status, dietary and other lifestyle behaviours (e.g. smoking, alcohol drinking, physical activity), medical history and family history of common chronic diseases. Major depressive episodes (MDE) in the past 12 months were assessed with the World Health Organization composite international diagnostic interview-short form (CIDI-SF). The physical measurements included the heights and weights, which were used to calculate the body mass indexes (BMI).Chi squared and t test were used to compare the differences in participants characteristics according to their major depressive disorder. Logistic models were employed to estimate the odds ratios (OR) and 95% CI of their major depressive disorder with prevalent coronary heart disease and stroke.

RESULTS

Among the 512 891 participants, 3 281 (0.6%) showed an MDE in the preceding 12 months, 15 472 (3.0%) reported prevalent CHD, and 8 884 (1.7%) reported prevalent stroke. Major depressive disorder was significantly associated with an increased risk of CHD and risk of stroke. Age- and gender-adjusted ORs (95% CI) were 1.80 (1.53-2.12) for CHD and 2.53 (2.09-3.05) for stroke. The associations were significant after further adjustment for potential confounders, such as other socio-demographic status, smoking, alcohol drinking, physical activity, and BMI, prevalent hypertension, diabetes as well as family history of cardiovascular diseases (OR=1.83, 95% CI=1.54-2.18 for CHD; OR=2.19, 95% CI=1.79-2.69 for stroke). Moreover, gender significantly interacted with MDE on prevalent stroke (P for multiplicative interaction=0.013). The men with an MDE in the past 12 months had the highest risk of stroke in the joint analyses of gender and depression disorder (OR=5.02, 95% CI=3.70-6.82).

CONCLUSION

The findings from this large cross-sectional study suggest that the presence of MDE is a risk factor for both CHD and stroke in Chinese adults aged 30-79 years, but further prospective studies are warranted to validate the results.

[Prevalence and risk factors of hypertension among residents of 30 years or above years old in Pengzhou city of Sichuan province]

OBJECTIVE

To investigate the prevalence and risk factors of hypertension among residents in Pengzhou city of Sichuan province.

METHODS

Among 20 townships in Pengzhou city of Sichuan Province, 14 townships were selected using a clustered sampling based on the economic level and distance. The registered residents in the selected townships aged 30-79 years were recruited for a comprehensive survey from 2004 to 2007. A total of 55 687 residents (21 315 males and 34 372 females) were selected based on a face to face questionnaire interview and physical examination; the patient group included 14 151 residents with hypertension and the control group had 41 536 residents without hypertension were selected. Multivariate logistic regression model was used to investigate the influence factors for hypertension. OR (95%CI) values were calculated. Different levels of risk exposure factors were transformed into the risk scores using a statistical model.

RESULTS

The prevalence rate of hypertension was 25.41% among residents aged 30 years or above in Pengzhou (14 151/55 687), 28.95% (6 170/21 315) for male residents and 23.22% (7 981/34 372) for female residents. Multivaraite logistic regression analysis showed that main risk factors for hypertension in male residents were age, low educational level, widower, low household income, no medical insurance, no fresh fruits intake, high body mass index (BMI), high waist to hip ratio, and low physical activity, which was less than 3 metabolic equivalent of task (MET) level, among which the highest three riskswere (not including the social demographic characteristics) BMI≥28 kg/m(2), waist to hip ratio ≥0.90, and not consuming fresh fruits. OR (95% CI) values for these three key factors were 3.74 (3.27-4.28), 1.34 (1.24-1.44), and 1.27 (1.14-1.41), respectively. The corresponding risk scores for these factors were 2.993, 1.102, and 1.237, respectively. Main risk factors for hypertension in female residents were age, working hours, no medical insurance, fewer number of family members, no fresh fruits intake, smoking, never drinking tea, no dairy products intake, high BMI, highwaist to hip ratio and low physical activity, among which the highest three risks were (not including the social demographic characteristics) BMI ≥28 kg/m(2), MET level, and waist to hip ratio ≥0.85. OR (95% CI) values for these three key factors were 3.30 (3.02-3.60), 1.35 (1.22-1.51), and 1.33 (1.23-1.44), respectively. The corresponding risk scores for these factors were 2.390, 1.263, and 1.051, respectively.

CONCLUSION

The prevalence rate of hypertension among the residents over 30 years of age in Pengzhou city was 25.41%. The main risk factors were age, not consuming fresh fruits, high BMI, high waist to hip ratio, and low MET level.

Reprogramming of myeloid compartments supporting tissue repair during DSS-induced colitis recovery

Myeloid-derived suppressor cells (MDSC) emerging during tumor growth or chronic inflammation play a critical role in regulating T cell function. However, mechanisms governing the generation of these cells remain unclear and need to be further defined. Using a DSS-induced colitis and recovery model, we characterized the dynamic changes within the myeloid compartments and the emerging of MDSC during active and resolution phases of inflammation. We show that the immature myeloid cell population expands and undergoes a functional reprogramming event in bone marrow (BM) and the spleen to form suppressive MDSC not at the active inflammation phase, but specifically at the resolution phase during colitis transition to recovery. In particular, two major functional changes occur when colitic mice were allowed to recover: 1) CD11b+Gr-1+myeloid cells in bone marrow and spleen acquire T cell suppressive functions, and 2) immature granulocytic myeloid cells increase the expression of chemokine receptor CXCR2, which enables their entry into circulation from BM. Additionally we determined enhanced activation of STAT3 and subsequent transcriptional enhancement of Arg1, iNOS, and gp91 in the MDSC isolated from resolution time points. We found that IL-17, the major cytokine associated with active colitis, remains elevated in the serum throughout the wound healing/resolution process. IL-17, together with the enhanced production of tissue repair cytokines, including IL-10, an activator of STAT3, produce a unique cytokine profile, resulting in a switch to induce reprograming and mobilization of the immature myeloid cells to suppress the inflammatory reaction in favor of tissue repair.

Signal regulatory protein α suppresses macrophage inflammatory responses via reducing PKM2 tyrosine phosphorylation

Signal regulatory protein α (SIRPα) plays an important part to restrain macrophage chemotaxis, secretion and phagocytosis. However, the signals involved in SIRPα-mediated control of macrophage inflammatory responses are poorly defined. Here we report that the inhibitory effect of SIRPα is mainly due to its suppression on macrophage aerobic glycolysis (Warburg effect). Upon ligation by CD47, SIRPα recruits/activates SHP-1 to dephosphorylate pyruvate kinase M2 (PKM2), a rate limiting enzyme of glycolysis. Compared to wild-type mice, SIRPα-deficiency mice (SIRPα−/−) develop a faster and severer macrophage-mediated insulitis induced by multiple low-dose streptozotocin. SIRPα−/− macrophages are M1-preferential and have higher level of phosphorylated PKM2 (p-PKM2) compared to their WT littermates. In addition, activation of macrophages to M1 phenotype, accompanying with reduction of SIRPα but increase of p-PKM2 and aerobic glycolysis level, can be abolished by SIRPα overexpression, as well as glycolysis inhibitors. Overexpression of SIRPα also strongly reduces the levels of macrophage aerobic glycolysis and p-PKM2. Finally, substrate-trapping and mutagenesis study clearly shows the binding of p-PKM2 with SIRPα-recruited SHP-1 complex and identifies PKM2 Tyr105 as a key site mediating SHP-1-PKM2 interaction. In summary, our findings identify SIRPα as a critical molecule that controls both metabolic switch and inflammatory responses in macrophages

Pyruvate kinase type M2 promotes tumor cell exocytosis via phosphorylating synaptosome-associated protein-23

Tumor cells secret large amount of microvesicles (MVs) which are involved in remodeling tumor-stromal interactions to promote malignancy. The regulatory mechanisms governing the active exocytosis in tumor cells, however, remain incompletely understood. We show here that tumor cell exocytosis is tightly controlled by aerobic glycolysis (Warburg effect) and pyruvate kinase type M2 (PKM2), which is commonly upregulated and phosphorylated in tumor cells, plays critical roles in promoting exocytosis. Upon stimulation by EGF, more phosphorylated PKM2 switches to dimer form and is recruited to exosomes where it associates with synaptosome-associated protein (SNAP)-23 (SNAP-23). The association of PKM2 and SNAP-23 in secreted exosomes is confirmed by cross immunoprecipitation and Western blot analysis. Dimerized PKM2 enhances the exosome release via phosphorylating SNAP-23. Direct phosphorylation assay and mass spectrometry identifies SNAP-23 phosphorylation at Ser95by PKM2. Ectopic expression of non-phosphorylated SNAP-23 mutant (Ser95→Ala95) significantly reduces PKM2-mediated exocytosis whereas phosphomimetic SNAP-23 mutants (Ser95→Ele95) partially rescue the impaired exocytosis in tumor cells with PKM2 knockdown. Our findings reveal a previously unrecognized non-metabolic function of PKM2 in promoting tumor cell exocytosis.

Controlling macrophage phagocytosis towards healthy self cells: Two layers of activating and inhibitory mechanisms

Rapid clearance of adoptively transferred CD47-null cells in mice suggests a critical self-recognition mechanism, in which CD47 is the ubiquitous marker of ‘self’, and its interaction with macrophage SIRPα triggers inhibitory signaling through SIRPα cytoplasmic ITIMs and tyrosine phosphatase SHP-1/2. However, instead of displaying self-destruction phenotype, the mice deficient of CD47 manifest no enhanced macrophage phagocytosis towards self, a phenomenon suggesting that additional mechanisms besides CD47-SIRPα command macrophage behavior. Studying our recently established SIRPα-knockout (SIRPα−/−) mice, as well as CD47−/− mice, we reveal that macrophage phagocytosis toward self is not only inhibited by CD47-SIRPα signaling but also requires an activation mechanism induced by unique inflammatory stimuli. SIRPα−/− mice and CD47−/− mice, though being healthy under normal condition, develop severe anemia and splenomegaly owing to splenic macrophages aggressively phagocytizing self RBC under chronic colitis, peritonitis, inflammatory cytokine treatments, or CFA and LPS-induced inflammation. Ex vivo phagocytosis assays demonstrate that macrophages from SIRPα−/− or CD47−/− mice, and even peritoneal macrophages from WT mice, are generally incompetent to attack self cells albeit their aggressiveness towards bacteria, fungi, apoptotic cells and immune complexes. However, treating all macrophages with IL-17, LPS, IL-6, IL-1β and TNFα, but not IFNg, dramatically initiates potent phagocytosis towards self cells providing an absence of the SIRPα-CD47 restraint. In addition, we identify that WT spleen red pulp is one specific environment that stimulates macrophage phagocytosis and that is lacking in deficient mice.

Dopamine D1 receptor agonist A-68930 inhibits NLRP3 inflammasome activation and protects rats from spinal cord injury-induced acute lung injury

STUDY DESIGN

Randomized experimental study.

OBJECTIVES

The study aimed to investigate the therapeutic efficacy and molecular mechanisms of A-68930 in a rat model of spinal cord injury (SCI)-induced acute lung injury (ALI).

SETTING

China.

METHODS

The influences of A-68930 on the pulmonary edema, histological changes, proinflammatory cytokines levels, myeloperoxidase (MPO) activity and NLRP3 inflammasome protein expression were estimated.

RESULTS

SCI significantly promoted NLRP3 inflammasome activation, increased proinflammatory cytokine productions and MPO activity, and induced pulmonary edema and tissue damage in the SCI group as compared with the control group. A-68930 administration significantly inhibited NLRP3 inflammasome activation and reduced inflammatory cytokines levels and MPO activity. Moreover, A-68930 administration attenuated pulmonary edema and histopathology.

CONCLUSION

Our experimental findings indicated that A-68930 exhibited a protective effect on SCI-induced ALI by the alleviations of inflammatory response with the inhibition NLRP3 inflammasome activation 72 h post injury. The present study indicated that A-68930 could be a potentially efficient therapeutic strategy for the treatment of SCI-induced ALI.

A Method for the Highly Selective, Colorimetric and Ratiometric Detection of Hg(2+) in a 100% Aqueous Solution

Mercury (Hg) and its derivatives pose a serious threat to the environment and human health. Thus, the development of methods for the selective and sensitive determination of Hg(2+) is very important to understand its distribution, and to implement more detailed toxicological studies. Herein, we developed a new method for the detection of Hg(2+) based on the tricyanoethylene derivative and mercaptoethanol. This method could selectively detect Hg(2+) in a 100% aqueous solution by the naked-eye within the range of 1 - 60 μM. Importantly, this method also could detect Hg(2+) quantitatively by ratiometic absorption spectroscopy in the range of 0.1 - 6 μM with a detection limit of 55 nM. We anticipate that this proposed method will be used widely to monitor Hg(2+) in the environment.

CD47 deficiency ameliorates autoimmune nephritis in Fas(lpr) mice by suppressing IgG autoantibody production

CD47, a self-recognition marker, plays an important role in both innate and adaptive immune responses. To explore the potential role of CD47 in activation of autoreactive T and B cells and the production of autoantibodies in autoimmune disease, especially systemic lupus erythematosus (SLE), we have generated CD47 knockout Fas(lpr) (CD47(-/-) -Fas(lpr) ) mice and examined histopathological changes in the kidneys, cumulative survival rates, proteinuria, extent of splenomegaly and autoantibodies, serum chemistry and immunological parameters. In comparison with Fas(lpr) mice, CD47(-/-) -Fas(lpr) mice exhibit a prolonged lifespan and delayed autoimmune nephritis, including glomerular cell proliferation, basement membrane thickening, acute tubular atrophy and vacuolization. CD47(-/-) -Fas(lpr) mice have lower levels of proteinuria, associated with reduced deposition of complement C3 and C1q, and IgG but not IgM in the glomeruli, compared to age-matched Fas(lpr) mice. Serum levels of antinuclear antibodies and anti-double-stranded DNA antibodies are significantly lower in CD47(-/-) -Fas(lpr) than in Fas(lpr) mice. CD47(-/-) -Fas(lpr) mice also display less pronounced splenomegaly than Fas(lpr) mice. The mechanistic studies further suggest that CD47 deficiency impairs the antigenic challenge-induced production of IgG but not IgM, and that this effect is associated with reduction of T follicular cells and impairment of germinal centre development in lymphoid tissues. In conclusion, our results demonstrate that CD47 deficiency ameliorates lupus nephritis in Fas(lpr) mice via suppression of IgG autoantibody production.

Loss of Cell Surface CD47 Clustering Formation and Binding Avidity to SIRPα Facilitate Apoptotic Cell Clearance by Macrophages

CD47, a self recognition marker expressed on tissue cells, interacts with immunoreceptor SIRPα expressed on the surface of macrophages to initiate inhibitory signaling that prevents macrophage phagocytosis of healthy host cells. Previous studies suggested that cells may lose surface CD47 during aging or apoptosis to enable phagocytic clearance. In the current study, we demonstrate that the level of cell surface CD47 is not decreased, but the distribution pattern of CD47 is altered, during apoptosis. On nonapoptotic cells, CD47 molecules are clustered in lipid rafts forming punctates on the surface, whereas on apoptotic cells, CD47 molecules are diffused on the cell surface following the disassembly of lipid rafts. We show that clustering of CD47 in lipid rafts provides a high binding avidity for cell surface CD47 to ligate macrophage SIRPα, which also presents as clusters, and elicits SIRPα-mediated inhibitory signaling that prevents phagocytosis. In contrast, dispersed CD47 on the apoptotic cell surface is associated with a significant reduction in the binding avidity to SIRPα and a failure to trigger SIRPα signal transduction. Disruption of plasma membrane lipid rafts with methyl-β-cyclodextrin diffuses CD47 clusters, leading to a decrease in the cell binding avidity to SIRPα and a concomitant increase in cells being engulfed by macrophages. Taken together, our study reveals that CD47 normally is clustered in lipid rafts on nonapoptotic cells but is diffused in the plasma membrane when apoptosis occurs; this transformation of CD47 greatly reduces the strength of CD47-SIRPα engagement, resulting in the phagocytosis of apoptotic cells.