Neutrophils require SHP1 to regulate IL-1β production and prevent inflammatory skin disease

Combined Serum ALBUMIN with Neutrophil-to-Lymphocyte Ratio Predicts the Prognosis of Biliary Tract Cancer after Curative Resection

BACKGROUND

The mainstay treatment of biliary tract cancer is complete tumor resection. Prior to surgery, risk stratification may help to predict and plan treatment approaches. In this study, we investigated the possibility of combining serum albumin concentrations and neutrophil-to-lymphocyte ratios (NLR) to create a score as ANS to predict the prognoses of biliary tract cancer before surgery.

METHODS

This study retrospectively collected serum albumin concentration, neutrophil, and lymphocyte data measured in biliary tract cancer patients slated to receive complete tumor resections within two weeks before surgery. From January 2013 to December 2019, 268 biliary tract cancer patients who had received tumor resections at our hospital were categorized into 3 ANS groups: ANS = 0 (high albumin and low NLR), ANS = 1 (low albumin or high NLR), and ANS = 2 (low albumin and high NLR).

RESULTS

Five-year survival rates were 70.1%, 47.6%, and 30.8% in the ANS = 0, 1, and 2 groups, respectively. The median overall survival time for the ANS = 0 group could not be determined by the end of the study, while those for ANS = 1 and ANS = 2 groups were 54.90 months and 16.62 months, respectively. The results of our multivariate analysis revealed that ANS could be used as an independent predictor of overall and recurrent-free survival. A high ANS was also correlated with other poor prognostic factors.

CONCLUSIONS

The ANS devised for this study can be used to predict postoperative survival in patients with BTC and to guide treatment strategies.

CD47 halts Ptpn6-deficient neutrophils from provoking lethal inflammation

Mice with SHP1 proteins, which have a single amino acid substitution from tyrosine-208 residue to asparagine (hereafter Ptpn6^spin mice), develop an autoinflammatory disease with inflamed footpads. Genetic crosses to study CD47 function in Ptpn6^spin mice bred Ptpn6^spin × Cd47^-/- mice that were not born at the expected Mendelian ratio. Ptpn6^spin bone marrow cells, when transferred into lethally irradiated Cd47-deficient mice, caused marked weight loss and subsequent death. At a cellular level, Ptpn6-deficient neutrophils promoted weight loss and death of the lethally irradiated Cd47^-/- recipients. We posited that leakage of gut microbiota promotes morbidity and mortality in Cd47^-/- mice receiving Ptpn6^spin cells. Colonic cell death and gut leakage were substantially increased in the diseased Cd47^-/- mice. Last, IL-1 blockade using anakinra rescued the morbidity and mortality observed in the diseased Cd47^-/- mice. These data together demonstrate a protective role for CD47 in tempering pathogenic neutrophils in the Ptpn6^spin mice.

Elevated neutrophil-to-lymphocyte ratio and predominance of intrahepatic cholangiocarcinoma prediction of poor hepatectomy outcomes in patients with combined hepatocellular-cholangiocarcinoma

Objectives

Although elevated neutrophil-to-lymphocyte ratio (NLR) has been associated with survival in some liver cancers, its prognostic relevance has not been studied in the context of combined hepatocellular cholangiocarcinoma CHCC-CC, a rare primary liver cancer. We investigated whether elevated NLR and a predominance of cholangiocarcinoma might predict poor prognosis in patients with resectable CHCC-CC.

Methods

We retrospectively reviewed the clinicopathologic data of forty-two patients with CHCC-CC receiving hepatectomies at our hospital. We used Kaplan-Meier and Cox regression to analyze survival.

Results

Two-year disease-free survival and five-year overall survival rates were 43.2% and 32.9%, respectively. Univariate analyses showed that patients with NLR ≥3 had significantly worse 2-year DFS and 5-year OS rates. Univariant Kaplan-Meier survival analysis also associated these rates with a predominance in intrahepatic cholangiocarcinoma, AJCC tumor stage, pathological T stage and lymph-vascular invasion. However, our multivariate analysis found NLR ≥3 to be the only independent predictor of disease recurrence and poorer survival.

Conclusions

Neutrophil-to-lymphocyte ratio was the most important independent predictor of poorer survival in patients with resectable CHCC-CC. Predominance of intrahepatic cholangiocarcinoma, advanced AJCC tumor stage and pathological T stage, and lymph-vascular invasion also may affect poor prognosis in patients receiving complete tumor resections.

Topical application of zwitterionic chitosan suppresses neutrophil-mediated acute skin inflammation

Zwitterionic chitosan (ZWC), a water-soluble succinylated chitosan derivative, has anti-inflammatory activities with therapeutic effects on sepsis and colitis. However, it remains unknown whether ZWC has any influence on skin inflammation. Here, we investigated the role of ZWC in the tape-stripping-induced acute skin inflammation model. Topical application of ZWC to the wounded area significantly reduced skin lesion compared with PBS controls. Since tape-stripping-induced skin inflammation is mediated by neutrophils, we examined if ZWC has any suppressive effects on neutrophil's function. ZWC treatment downregulated the skin recruitment of neutrophils, subsequently reducing inflammatory responses by keratinocytes. ZWC also suppressed LPS-induced inflammatory responses of neutrophils in vitro, indicating the direct effect of ZWC on neutrophils. Moreover, such anti-inflammatory effects of ZWC extended to other immune cells such as basophils in the spleen. Overall, our results support that ZWC may be used as a therapeutic material to control acute skin inflammation.

Ptpn6 inhibits caspase-8- and Ripk3/Mlkl-dependent inflammation

Ptpn6 is a cytoplasmic phosphatase that functions to prevent autoimmune and interleukin-1 (IL-1) receptor-dependent, caspase-1-independent inflammatory disease. Conditional deletion of Ptpn6 in neutrophils (Ptpn6^∆PMN) is sufficient to initiate IL-1 receptor-dependent cutaneous inflammatory disease, but the source of IL-1 and the mechanisms behind IL-1 release remain unclear. Here, we investigate the mechanisms controlling IL-1α/β release from neutrophils by inhibiting caspase-8-dependent apoptosis and Ripk1-Ripk3-Mlkl-regulated necroptosis. Loss of Ripk1 accelerated disease onset, whereas combined deletion of caspase-8 and either Ripk3 or Mlkl strongly protected Ptpn6^∆PMN mice. Ptpn6^∆PMN neutrophils displayed increased p38 mitogen-activated protein kinase-dependent Ripk1-independent IL-1 and tumor necrosis factor production, and were prone to cell death. Together, these data emphasize dual functions for Ptpn6 in the negative regulation of p38 mitogen-activated protein kinase activation to control tumor necrosis factor and IL-1α/β expression, and in maintaining Ripk1 function to prevent caspase-8- and Ripk3-Mlkl-dependent cell death and concomitant IL-1α/β release.

β-glucan-dependent shuttling of conidia from neutrophils to macrophages occurs during fungal infection establishment

The initial host response to fungal pathogen invasion is critical to infection establishment and outcome. However, the diversity of leukocyte–pathogen interactions is only recently being appreciated. We describe a new form of interleukocyte conidial exchange called “shuttling.” In Talaromyces marneffei and Aspergillus fumigatus zebrafish in vivo infections, live imaging demonstrated conidia initially phagocytosed by neutrophils were transferred to macrophages. Shuttling is unidirectional, not a chance event, and involves alterations of phagocyte mobility, intercellular tethering, and phagosome transfer. Shuttling kinetics were fungal-species–specific, implicating a fungal determinant. β-glucan serves as a fungal-derived signal sufficient for shuttling. Murine phagocytes also shuttled in vitro. The impact of shuttling for microbiological outcomes of in vivo infections is difficult to specifically assess experimentally, but for these two pathogens, shuttling augments initial conidial redistribution away from fungicidal neutrophils into the favorable macrophage intracellular niche. Shuttling is a frequent host–pathogen interaction contributing to fungal infection establishment patterns.

Imaging of the behaviour of white blood cells in living zebrafish embryos infected with fungi reveals “shuttling,” a specific and previously undescribed form of microorganism exchange between neutrophils and macrophages.

Protein Tyrosine Phosphatases as Potential Regulators of STAT3 Signaling

The signal transducer and activator of transcription 3 (STAT3) protein is a major transcription factor involved in many cellular processes, such as cell growth and proliferation, differentiation, migration, and cell death or cell apoptosis. It is activated in response to a variety of extracellular stimuli including cytokines and growth factors. The aberrant activation of STAT3 contributes to several human diseases, particularly cancer. Consequently, STAT3-mediated signaling continues to be extensively studied in order to identify potential targets for the development of new and more effective clinical therapeutics. STAT3 activation can be regulated, either positively or negatively, by different posttranslational mechanisms including serine or tyrosine phosphorylation/dephosphorylation, acetylation, or demethylation. One of the major mechanisms that negatively regulates STAT3 activation is dephosphorylation of the tyrosine residue essential for its activation by protein tyrosine phosphatases (PTPs). There are seven PTPs that have been shown to dephosphorylate STAT3 and, thereby, regulate STAT3 signaling: PTP receptor-type D (PTPRD), PTP receptor-type T (PTPRT), PTP receptor-type K (PTPRK), Src homology region 2 (SH-2) domain-containing phosphatase 1(SHP1), SH-2 domain-containing phosphatase 2 (SHP2), MEG2/PTP non-receptor type 9 (PTPN9), and T-cell PTP (TC-PTP)/PTP non-receptor type 2 (PTPN2). These regulators have great potential as targets for the development of more effective therapies against human disease, including cancer.

Cutting Edge: Blockade of Inhibitor of Apoptosis Proteins Sensitizes Neutrophils to TNF- but Not Lipopolysaccharide-Mediated Cell Death and IL-1β Secretion

The mammalian inhibitor of apoptosis proteins (IAPs) are key regulators of cell death and inflammation. A major function of IAPs is to block the formation of a cell death-inducing complex, termed the ripoptosome, which can trigger caspase-8-dependent apoptosis or caspase-independent necroptosis. Recent studies report that upon TLR4 or TNF receptor 1 (TNFR1) signaling in macrophages, the ripoptosome can also induce NLRP3 inflammasome formation and IL-1β maturation. Whether neutrophils have the capacity to assemble a ripoptosome to induce cell death and inflammasome activation during TLR4 and TNFR1 signaling is unclear. In this study, we demonstrate that murine neutrophils can signal via TNFR1-driven ripoptosome assembly to induce both cell death and IL-1β maturation. However, unlike macrophages, neutrophils suppress TLR4-dependent cell death and NLRP3 inflammasome activation during IAP inhibition via deficiencies in the CD14/TRIF arm of TLR4 signaling.

Elevated neutrophil-to-lymphocyte ratio is an independent poor prognostic factor in patients with intrahepatic cholangiocarcinoma

We investigated whether elevated neutrophil-to-lymphocyte ratio (NLR) was associated with poor anti-tumor immunity and prognosis in patients with intrahepatic cholangiocarcinoma (ICC). Clinicopathologic data of 102 patients with ICC who underwent hepatectomy was retrospectively analyzed. The Kaplan-Meier method and Cox regression model were used to analyze the survival and prognosis. The percentage of overall lymphocytes, T cells and CD8+ T cells in the high NLR group was lower than that in the low NLR group. The percentage of PD-1+CD4+ and PD-1+CD8+ T cells was higher and the percentage of IFN-γ+CD4+ and IFN-γ+CD8+ T cells was lower in the high NLR group than that in the low NLR group (p = 0.045, p = 0.008; p = 0.012, p = 0.006). Density of tumor-infiltrating CD3+ T cells in the high NLR group was lower than that in the low NLR group (p < 0.001). Elevated NLR was an independent predictor for poor overall survival (OS; p = 0.035) and recurrence-free survival (RFS; p = 0.008). These results indicate that elevated NLR is associated with poor anti-tumor immunity and could be a poor biomarker for prognosis in patients with ICC.

C-reactive protein/albumin and neutrophil/lymphocyte ratios and their combination predict overall survival in patients with gastric cancer

Multiple studies have reported the prognostic association of certain inflammatory factors with various types of cancer. The present study assessed the prognostic value of the C-reactive protein (CRP)/albumin (Alb) ratio and the neutrophil/lymphocyte ratio (NLR), separately and in combination, in gastric cancer (GC). A total of 337 cases pathologically diagnosed with gastric adenocarcinoma were retrospectively evaluated. The clinicopathological and prognostic relevance of the CRP/Alb ratio and NLR and their combination were analyzed. The optimal cut-off values of the CRP/Alb ratio and NLR were 0.38 and 3.14, respectively. High CRP/Alb ratio (≥0.38) and NLR (≥3.14) values were associated with increased tumor invasion, more distant metastasis and a more advanced tumor-node-metastasis stage (all P<0.05). In addition, a high NLR value was also associated with increased tumor size (P=0.02). The CRP/Alb ratio (≥0.38/<0.38) and NLR (≥3.14/<3.14) were independent prognostic factors for overall survival time (OS) in GC by multivariate analysis (P=0.005 and P=0.001). Using the CRP/Alb ratio and NLR classification, patients were stratified into three subgroups with different OS time (P<0.001), which were identified as independent prognostic variables in multivariate analysis (P<0.001). The present study demonstrated that the CRP/Alb ratio and NLR were independent prognostic factors for OS in patients with GC. The combination of these indexes was associated with significant prognostic value and may further stratify prognosis.

Defining a therapeutic window for kinase inhibitors in leukemia to avoid neutropenia

Neutropenia represents one of the major dose-limiting toxicities of many current cancer therapies. To circumvent the off-target effects of cytotoxic chemotherapeutics, kinase inhibitors are increasingly being used as an adjunct therapy to target leukemia. In this study, we conducted a screen of leukemic cell lines in parallel with primary neutrophils to identify kinase inhibitors with the capacity to induce apoptosis of myeloid and lymphoid cell lines whilst sparing primary mouse and human neutrophils. We have utilized a high-throughput live cell imaging platform to demonstrate that cytotoxic drugs have limited effects on neutrophil viability but are toxic to hematopoietic progenitor cells, with the exception of the topoisomerase I inhibitor SN-38. The parallel screening of kinase inhibitors revealed that mouse and human neutrophil viability is dependent on cyclin-dependent kinase (CDK) activity but surprisingly only partially dependent on PI3 kinase and JAK/STAT signaling, revealing dominant pathways contributing to neutrophil viability. Mcl-1 haploinsufficiency sensitized neutrophils to CDK inhibition, demonstrating that Mcl-1 is a direct target for CDK inhibitors. This study reveals a therapeutic window for the kinase inhibitors BEZ235, BMS-3, AZD7762, and (R)-BI-2536 to induce apoptosis of leukemia cell lines whilst maintaining immunocompetence and hemostasis.

Shp1 function in myeloid cells

The motheaten mouse was first described in 1975 as a model of systemic inflammation and autoimmunity, as a result of immune system dysregulation. The phenotype was later ascribed to mutations in the cytoplasmic tyrosine phosphatase Shp1. This phosphatase is expressed widely throughout the hematopoietic system and has been shown to impact a multitude of cell signaling pathways. The determination of which cell types contribute to the different aspects of the phenotype caused by global Shp1 loss or mutation and which pathways within these cell types are regulated by Shp1 is important to further our understanding of immune system regulation. In this review, we focus on the role of Shp1 in myeloid cells and how its dysregulation affects immune function, which can impact human disease.

Tyrosine Kinase SYK Licenses MyD88 Adaptor Protein to Instigate IL-1α-Mediated Inflammatory Disease

Mice carrying a hypomorphic point mutation in the Ptpn6 gene (Ptpn6^spin mice) develop an inflammatory skin disease that resembles neutrophilic dermatosis in humans. Here, we demonstrated that interleukin-1α (IL-1α) signaling through IL-1R and MyD88 in both stromal and immune cells drive inflammation in Ptpn6^spin mice. We further identified SYK as a critical kinase that phosphorylates MyD88, promoted MyD88-dependent signaling and mediates dermatosis in Ptpn6^spin mice. Our studies further demonstrated that SHP1 encoded by Ptpn6 binds and suppresses SYK activation to inhibit MyD88 phosphorylation. Downstream of SHP1 and SYK-dependent counterregulation of MyD88 tyrosine phosphorylation, we have demonstrated that the scaffolding function of receptor interacting protein kinase 1 (RIPK1) and tumor growth factor-β activated kinase 1 (TAK1)-mediating signaling were required to spur inflammatory disease. Overall, these studies identify SHP1 and SYK crosstalk as a critical regulator of MyD88 post-translational modifications and IL-1-driven inflammation.

Neutrophils Directly Recognize Group B Streptococci and Contribute to Interleukin-1β Production during Infection

Previous studies have shown that the pro-inflammatory cytokine IL-1β has a crucial role in host defenses against group B streptococcus (GBS), a frequent human pathogen, by recruiting neutrophils to infection sites. We examined here the cell types and mechanisms involved in IL-1β production during infection. Using a GBS-induced peritonitis model in mice, we first found that a large proportion of exudate cells contain intracellular IL-1β by immunofluorescence. Of the IL-1β positive cells, 82 and 7% were neutrophils and macrophages, respectively, suggesting that the former cell type might significantly contribute to IL-1β production. Accordingly, depletion of neutrophils with anti-Ly6G antibodies resulted in a significant reduction in the levels of IL-1β, but not of TNF-α or IL-6. We next found that neutrophils are capable of releasing mature IL-1β and TNF-α directly in response to in vitro stimulation with GBS. The production of pro-IL-1β and TNF-α in these cells required the Toll-like receptor (TLR) adaptor MyD88 and the chaperone protein UNC93B1, which is involved in mobilization of a subfamily of TLRs to the endosomes. Moreover, pro-IL-1β processing and IL-1β release was triggered by GBS hemolysin and required components of the canonical inflammasome, including caspase-1, ASC and NLRP3. Collectively our findings indicate that neutrophils make a significant contribution to IL-1β production during GBS infection, thereby amplifying their own recruitment. These cells directly recognize GBS by means of endosomal TLRs and cytosolic sensors, leading to activation of the caspase-1 inflammasome.

A differential gene expression study: Ptpn6 (SHP-1)-insufficiency leads to neutrophilic dermatosis-like disease (NDLD) in mice

BACKGROUND

Irradiated syngeneic wild-type mice developed the same neutrophilic dermatosis-like disease (NDLD) after adoptive transfer of bone marrow cells from Ptpn6(meb2/meb2) mutant mice.

OBJECTIVE

To analyze differentially expressed genes in the bone marrow of mice with NDLD to gain insight into the role of Ptpn6 in myelopoietic bone marrow pathology, and the mechanisms by which Ptpn6 insufficiency in the hematopoietic cells can lead to the development of skin lesions.

METHODS

As Ptpn6 is involved in a myriad of signaling pathways, we used a global approach with microarray technology for the first time to characterize changes in the bone marrow and skin of motheaten-type mice.

RESULTS

A total number of 1,511 probe sets in the bone marrow showed at least two-fold changes with FDR <0.05, of which 256 probe sets had over four-fold changes. A group of 63 genes in the bone marrow of NDLD mice had more than a 4-fold change with FDR <0.0001. From 503 genes encoding proteins with ITIM motif that binds to Ptpn6, 109 were up-regulated and 83 were down-regulated. We found that genes encoding hematopoietic receptors, neutrophil chemoattractants, Toll-like receptors (Tlr1, Tlr2 and Tlr4) and C-type lectin innate immunity receptors (Clec4e, Clec4d, Clec4n, Clec4a2 and Clec4a3) were significantly up-regulated in both NDLD bone marrow and skin. The Il1b gene was also significantly overexpressed in skin samples, confirming the importance of the IL-1/TLR pathway in the development of early skin inflammation in NDLD mice.

CONCLUSION

Our results suggest that innate immunity genes play a major role in development of neutrophilic dermatosis-like disease in mice.

Protein Tyrosine Phosphatase SHP-1 Modulates T Cell Responses by Controlling Cbl-b Degradation

Previously, we demonstrated that CD28 and CTLA-4 signaling control Casitas-B-lineage lymphoma (Cbl)-b protein expression, which is critical for T cell activation and tolerance induction. However, the molecular mechanism(s) of this regulation remains to be elucidated. In this study, we found that Cbl-b fails to undergo tyrosine phosphorylation upon CD3 stimulation because SHP-1 is recruited to and dephosphorylates Cbl-b, whereas CD28 costimulation abrogates this interaction. In support of this finding, T cells lacking SHP-1 display heightened tyrosine phosphorylation and ubiquitination of Cbl-b upon TCR stimulation, which correlates with decreased levels of Cbl-b protein. The aberrant Th2 phenotype observed in T cell-specific Shp1(-/-) mice is reminiscent of heightened Th2 response in Cblb(-/-) mice. Indeed, overexpressing Cbl-b in T cell-specific Shp1(-/-) T cells not only inhibits heightened Th2 differentiation in vitro, but also Th2 responses and allergic airway inflammation in vivo. Therefore, SHP-1 regulates Cbl-b-mediated T cell responses by controlling its tyrosine phosphorylation and ubiquitination.

Loss of NADPH oxidase-derived superoxide skews macrophage phenotypes to delay type 1 diabetes

Macrophages are early islet-infiltrating cells seen in type 1 diabetes (T1D). While proinflammatory M1 macrophages induce T1D, M2 macrophages have been shown to delay this autoimmune disease in nonobese diabetic (NOD) mice, but the environmental cues that govern macrophage polarization and differentiation remain unresolved. We previously demonstrated the importance of reactive oxygen species (ROS) in T1D, as NOD mice deficient in NADPH oxidase (NOX)-derived superoxide (Ncf1(m1J)) were protected against T1D partly because of blunted Toll-like receptor-dependent macrophage responses. We provide evidence that NOX-derived ROS contribute to macrophage differentiation in T1D. During spontaneous diabetes progression, T1D-resistant NOD.Ncf1(m1J) islet-resident macrophages displayed a dampened M1 and increased M2 phenotype. The transfer of diabetogenic T cells into NOX-deficient NOD.Rag.Ncf1(m1J) recipients resulted in decreased TNF-α(+) and IL-1β(+) islet-infiltrating M1 macrophages and a concomitant enhancement in arginase-1(+) M2 macrophages. Mechanistic analysis of superoxide-deficient bone marrow-derived macrophages revealed a marked diminution in a proinflammatory M1 phenotype due to decreased P-STAT1 (Y701) and interferon regulatory factor 5 compared with NOD mice. We have therefore defined a novel mechanistic link between NOX-derived ROS and macrophage phenotypes, and implicated superoxide as an important factor in macrophage differentiation. Thus, targeting macrophage redox status may represent a promising therapy in halting human T1D.

HSP90 inhibition suppresses lipopolysaccharide-induced lung inflammation in vivo

Inflammation is an important component of cancer diathesis and treatment-refractory inflammation is a feature of many chronic degenerative lung diseases. HSP90 is a 90kDa protein which functions as an ATP-dependent molecular chaperone that regulates the signalling conformation and expression of multiple protein client proteins especially oncogenic mediators. HSP90 inhibitors are in clinical development as cancer therapies but the myeleosuppressive and neutropenic effect of first generation geldanamycin-class inhibitors has confounded studies on the effects on HSP90 inhibitors on inflammation. To address this we assessed the ability of Ganetespib, a non-geldanamycin HSP90 blocker, to suppress lipopolysaccharide (LPS)-induced cellular infiltrates, proteases and inflammatory mediator and transcriptional profiles. Ganetespib (10-100 mg/kg, i.v.) did not directly cause myelosuppression, as assessed by video micrography and basal blood cell count, but it strongly and dose-dependently suppressed LPS-induced neutrophil mobilization into blood and neutrophil- and mononuclear cell-rich steroid-refractory lung inflammation. Ganetespib also suppressed B cell and NK cell accumulation, inflammatory cytokine and chemokine induction and MMP9 levels. These data identify non-myelosuppresssive HSP90 inhibitors as potential therapies for inflammatory diseases refractory to conventional therapy, in particular those of the lung.

Inflammasome-independent regulation of IL-1-family cytokines

Induction, production, and release of proinflammatory cytokines are essential steps to establish an effective host defense. Cytokines of the interleukin-1 (IL-1) family induce inflammation and regulate T lymphocyte responses while also displaying homeostatic and metabolic activities. With the exception of the IL-1 receptor antagonist, all IL-1 family cytokines lack a signal peptide and require proteolytic processing into an active molecule. One such unique protease is caspase-1, which is activated by protein platforms called the inflammasomes. However, increasing evidence suggests that inflammasomes and caspase-1 are not the only mechanism for processing IL-1 cytokines. IL-1 cytokines are often released as precursors and require extracellular processing for activity. Here we review the inflammasome-independent enzymatic processes that are able to activate IL-1 cytokines, paying special attention to neutrophil-derived serine proteases, which subsequently induce inflammation and modulate host defense. The inflammasome-independent processing of IL-1 cytokines has important consequences for understanding inflammatory diseases, and it impacts the design of IL-1-based modulatory therapies.

Fas regulates neutrophil lifespan during viral and bacterial infection

The regulation of neutrophil lifespan is critical for a circumscribed immune response. Neutrophils are sensitive to Fas/CD95 death receptor signaling in vitro, but it is unknown if Fas regulates neutrophil lifespan in vivo. We hypothesized that FasL-expressing CD8(+) T cells, which kill antigen-stimulated T cells during chronic viral infection, can also induce neutrophil death in tissues during infection. With the use of LysM-Cre Fas(fl/fl) mice, which lack Fas expression in macrophages and neutrophils, we show that Fas regulates neutrophil lifespan during lymphocytic choriomeningitis virus (LCMV) infection in the lung, peripheral blood, and spleen. Fas also contributed to the regulation of neutrophil numbers in the colon of Citrobacter rodentium-infected mice. To examine the effects of infection on Fas activation in neutrophils, we primed neutrophils with TLR ligands or IL-18, resulting in ablation of Fas death receptor signaling. These data provide the first in vivo genetic evidence that neutrophil lifespan is controlled by death receptor signaling and provide a mechanism to account for neutrophil resistance to Fas stimulation during infection.

The SHP-1 expression is associated with cytokines and psychopathological status in unmedicated first episode schizophrenia patients

BACKGROUND

Recent lines of research have boosted awareness of the immunological facets of schizophrenia. However, associations with protein tyrosine phosphatase regulators have never been reported. The aim of our study was to investigate the expression and promoter status methylation of phosphatase SHP-1, a key negative regulator of the inflammatory process, in Peripheral blood mononuclear cells (PBMCs) of Schizophrenic patients.

METHODS

We enrolled fifty-four (28 men and 26 women) unmedicated first episode subjects (SC) who met DSM-IV and thirty-eight (22 men and 16 women) healthy controls (HC). The SC psychopathological status was assessed using the Positive and Negative Syndrome Scale. We evaluated SHP-1 expression by Quantitative Real-time PCR (qPCR) and Western blotting (WB) methods and promoter status methylation through PCR bisulfate. IKK/NFkB signaling was detected by WB, and medium and plasma levels of pro-inflammatory cytokines (IL-1β, IL-2, and TNF-α) by the ELISA method. SHP-1 was silenced by treating cells with specific siRNA.

RESULTS

We found a significantly lower level of SHP-1 gene expression in PBMCs from SC vs. HC, consistently with which the promoter region analyzed presented significant hypermethylation. Silencing of SHP-1 expression induced higher activation of IKK/NF-kB signaling and pro-inflammatory cytokine production in ex vivo PBMCs from both SC and HC. Linear regression among patients generated a model in which SHP-1 expression explained 30% of the clinical negative symptom variance (adjusted R(2)=0.30, ANOVA p<0.001).

CONCLUSIONS

Our findings are the first to suggest that impairment of SHP-1 expression is involved in the physiopathology of schizophrenia, opening fruitful new avenues for ameliorating treatment at least of negative symptoms.

Comparative studies of Toll-like receptor signalling using zebrafish

Zebrafish model systems for infectious disease are increasingly used for the functional analysis of molecular pattern recognition processes. These studies benefit from the high conservation level of all innate immune factors in vertebrates. Zebrafish studies are strategically well positioned for this because of the ease of comparisons with studies in other fish species of which the immune system also has been intensively studied, but that are currently still less amendable to detailed genetic or microscopic studies. In this paper we focus on Toll-like receptor (TLR) signalling factors, which currently are the best characterized in mammalian systems. We review the knowledge on TLR signalling in the context of recent advances in zebrafish studies and discuss possibilities for future approaches that can complement studies in cell cultures and rodent models. A focus in these comparisons is the role of negative control mechanisms in immune responses that appear very important in a whole organism to keep adverse systemic responses in check. We also pay much attention to comparisons with studies in common carp that is highly related to zebrafish and that because of its large body mass can complement immune studies in zebrafish.

The TLR and IL-1 signalling network at a glance

Toll-like receptors (TLRs) and the receptors for interleukin (IL)-1, IL-18 and IL-33 are required for defence against microbial pathogens but, if hyper-activated or not switched off efficiently, can cause tissue damage and inflammatory and autoimmune diseases. Understanding how the checks and balances in the system are integrated to fight infection without the network operating out of control will be crucial for the development of improved drugs to treat these diseases in the future. In this Cell Science at a Glance article and the accompanying poster, I provide a brief overview of how one of these intricate networks is controlled by the interplay of protein phosphorylation and protein ubiquitylation events, and the mechanisms in myeloid cells that restrict and terminate its activation to prevent inflammatory and autoimmune diseases. Finally, I suggest a few protein kinases that have been neglected as drug targets, but whose therapeutic potential should be explored in the light of recent advances in our understanding of their roles in the innate immune system.

Interleukin-1β in innate inflammation, autophagy and immunity

Although IL-1β is the master inflammatory cytokine in the IL-1 family, after more than ten years of continuous breeding, mice deficient in IL-1β exhibit no spontaneous disease. Therefore, one concludes that IL-1β is not needed for homeostasis. However, IL-1β-deficient mice are protected against local and systemic inflammation due to live infections, autoimmune processes, tumor metastasis and even chemical carcinogenesis. Based on a large number of preclinical studies, blocking IL-1β activity in humans with a broad spectrum of inflammatory conditions has reduced disease severity and for many, has lifted the burden of disease. Rare and common diseases are controlled by blocking IL-1β. Immunologically, IL-1β is a natural adjuvant for responses to antigen. Alone, IL-1β is not a growth factor for lymphocytes; rather in antigen activated immunocompetent cells, blocking IL-1 reduces IL-17 production. IL-1β markedly increases in the expansion of naive and memory CD4T cells in response to challenge with their cognate antigen. The response occurs when only specific CD4T cells respond to IL-1β and not to IL-6 or CD-28. A role for autophagy in production of IL-1β has emerged with deletion of the autophagy gene ATG16L1. Macrophages from ATG16L1-deficient mice produce higher levels of IL-1β after stimulation with TLR4 ligands via a mechanism of caspase-1 activation. The implications for increased IL-1β release in persons with defective autophagy may have clinical importance for disease.

Overexpression of membrane-bound fas ligand (CD95L) exacerbates autoimmune disease and renal pathology in pristane-induced lupus

Loss-of-function mutations in the Fas death receptor or its ligand result in a lymphoproliferative syndrome and exacerbate clinical disease in most lupus-prone strains of mice. One exception is mice injected with 2,6,10,14-tetramethylpentadecane (TMPD), a hydrocarbon oil commonly known as pristane, which induces systemic lupus erythematosus-like disease. Although Fas/Fas ligand (FasL) interactions have been strongly implicated in the activation-induced cell death of both lymphocytes and other APCs, FasL can also trigger the production of proinflammatory cytokines. FasL is a transmembrane protein with a matrix metalloproteinase cleavage site in the ectodomain. Matrix metalloproteinase cleavage inactivates membrane-bound FasL and releases a soluble form reported to have both antagonist and agonist activity. To better understand the impact of FasL cleavage on both the proapoptotic and proinflammatory activity of FasL, its cleavage site was deleted through targeted mutation to produce the deleted cleavage site (ΔCS) mouse line. ΔCS mice express higher levels of membrane-bound FasL than do wild-type mice and fail to release soluble FasL. To determine to what extent FasL promotes inflammation in lupus mice, TMPD-injected FasL-deficient and ΔCS BALB/c mice were compared with control TMPD-injected BALB/c mice. We found that FasL deficiency significantly reduced the early inflammatory exudate induced by TMPD injection. In contrast, ΔCS mice developed a markedly exacerbated disease profile associated with a higher frequency of splenic neutrophils and macrophages, a profound change in anti-nuclear Ab specificity, and markedly increased proteinuria and kidney pathology compared with controls. These results demonstrate that FasL promotes inflammation in TMPD-induced autoimmunity, and its cleavage limits FasL proinflammatory activity.

Distinct roles for neutrophils and dendritic cells in inflammation and autoimmunity in motheaten mice

The motheaten mouse has long served as a paradigm for complex autoimmune and inflammatory disease. Null mutations in Ptpn6, which encodes the nonreceptor protein-tyrosine phosphatase Shp1, cause the motheaten phenotype. However, Shp1 regulates multiple signaling pathways in different hematopoietic cell types, so the cellular and molecular mechanism of autoimmunity and inflammation in the motheaten mouse has remained unclear. By using floxed Ptpn6 mice, we dissected the contribution of innate immune cells to the motheaten phenotype. Ptpn6 deletion in neutrophils resulted in cutaneous inflammation, but not autoimmunity, providing an animal model of human neutrophilic dermatoses. By contrast, dendritic cell deletion caused severe autoimmunity, without inflammation. Genetic and biochemical analysis showed that inflammation was caused by enhanced neutrophil integrin signaling through Src-family and Syk kinases, whereas autoimmunity resulted from exaggerated MyD88-dependent signaling in dendritic cells. Our data demonstrate that disruption of distinct Shp1-regulated pathways in different cell types combine to cause motheaten disease.

Bcl-2 overexpression ameliorates immune complex-mediated arthritis by altering FcγRIIb expression and monocyte homeostasis

RA is a chronic autoimmune disease characterized by accumulation of inflammatory cells within synovial joints. RA is associated with a failure of apoptosis of infiltrating leukocytes, thought to be a result of overexpression of prosurvival Bcl-2 proteins. Overexpression of Bcl-2 in hematopoietic cells can result in spontaneous autoimmunity. We therefore hypothesized that increased Bcl-2 in the hematopoietic compartment would reduce apoptosis and thereby, exacerbate inflammatory arthritis. Paradoxically, we found that overexpression of Bcl-2 in mice (vav-bcl-2) markedly reduced pathology in antibody-dependent models of RA (CIA and K/BxN serum transfer arthritis). No such protection was observed in a model of CD4(+) T cell-dependent, B cell-independent arthritis (mBSA/IL-1-induced arthritis). In CIA, vav-bcl-2 Tg mice had lower antibody production to CII, which might explain reduced disease. However, Bcl-2 overexpression also reduced passive K/BxN serum transfer arthritis. Overexpression of Bcl-2 caused a monocytosis, with preferential expansion of Ly6C(lo) monocytes and increased expression of the inhibitory receptor for IgG, FcγRIIb, on leukocytes. Skewing of the myeloid cell population, increases in FcγRIIb, and reduced arthritis were independent of the hypergammaglobulinemia found in vav-bcl-2 Tg mice. These data reveal selective effects of the Bcl-2-regulated apoptotic pathway on monocyte differentiation and the expression of FcRs critical for regulation of antibody/immune complex-mediated disease.

Deficiency in hematopoietic phosphatase ptpn6/Shp1 hyperactivates the innate immune system and impairs control of bacterial infections in zebrafish embryos

Deficiency in Src homology region 2 domain-containing phosphatase 1/protein tyrosine phosphatase nonreceptor type 6 (SHP1/PTPN6) is linked with chronic inflammatory diseases and hematological malignancies in humans. In this study, we exploited the embryonic and larval stages of zebrafish (Danio rerio) as an animal model to study ptpn6 function in the sole context of innate immunity. We show that ptpn6 knockdown induces a spontaneous inflammation-associated phenotype at the late larval stage. Surprisingly, glucocorticoid treatment did not suppress inflammation under ptpn6 knockdown conditions but further enhanced leukocyte infiltration and proinflammatory gene expression. Experiments in a germ-free environment showed that the late larval phenotype was microbe independent. When ptpn6 knockdown embryos were challenged with Salmonella typhimurium or Mycobacterium marinum at earlier stages of development, the innate immune system was hyperactivated to a contraproductive level that impaired the control of these pathogenic bacteria. Transcriptome analysis demonstrated that Kyoto Encyclopedia of Genes and Genomes pathways related to pathogen recognition and cytokine signaling were significantly enriched under these conditions, suggesting that ptpn6 functions as a negative regulator that imposes a tight control over the level of innate immune response activation during infection. In contrast to the hyperinduction of proinflammatory cytokine genes under ptpn6 knockdown conditions, anti-inflammatory il10 expression was not hyperinduced. These results support that ptpn6 has a crucial regulatory function in preventing host-detrimental effects of inflammation and is essential for a successful defense mechanism against invading microbes.

Increased promoter methylation of the immune regulatory gene SHP-1 in leukocytes of multiple sclerosis subjects

The protein tyrosine phosphatase, SHP-1, is a negative regulator of proinflammatory signaling and autoimmune disease. We have previously reported reduced SHP-1 expression in peripheral blood leukocytes of subjects with multiple sclerosis (MS). Recent evidence indicates that virus-induced DNA methylation of the SHP-1 promoter is responsible for aberrant silencing of SHP-1 expression and function in hematopoietic cells that might relate to inflammatory diseases. In the present study, bisulfite sequencing of the SHP-1 promoter demonstrated that over a third of MS subjects had abnormally high promoter methylation. As SHP-1 is deficient in MS leukocytes and SHP-1-regulated proinflammatory genes are correspondingly upregulated, we propose that increased SHP-1 promoter methylation may relate in part to decreased SHP-1 expression and increased leukocyte-mediated inflammation in MS.

Local response to microneedle-based influenza immunization in the skin

Microneedle patches (MN) provide a novel method of vaccine delivery to the skin with the objective of targeting the large network of resident antigen-presenting cells to induce an efficient immune response. Our previous reports demonstrated that cutaneous delivery of inactivated influenza virus-coated MN to mice protects against lethal infection. Protection is correlated with sustained levels of anti-influenza virus serum antibodies, hemagglutination inhibition titers, and robust cellular responses that are often stronger than those generated by intramuscular vaccination. Here we dissect the early events occurring in murine skin after microneedle delivery of inactivated influenza virus. We demonstrate correlation of immunization against influenza virus with a local increase of cytokines important for recruitment of neutrophils, monocytes and dendritic cells at the site of immunization. We also observed prolonged antigen deposition, and migration of matured dendritic cells bearing influenza virus antigen from the skin.

The immunological mechanisms by which MN vaccination confers protective immunity are not well understood. The present study provides a first analysis of the early immune events after microneedle-based vaccination.

Towards a four-dimensional view of neutrophils

Neutrophils are constitutively produced throughout adult life and are essential for host responses to many types of pathogen. Neutropenia has long been associated with poor prognosis in the clinic, yet we have an incomplete understanding of their life cycle, not only during homeostasis but also during infection and chronic inflammation. Here, we review recent advances that provide insight into the genetic and biochemical regulators of neutrophil production, function, and survival.

Fas-mediated neutrophil apoptosis is accelerated by Bid, Bak, and Bax and inhibited by Bcl-2 and Mcl-1

During immune responses, neutrophils must integrate survival and death signals from multiple sources to regulate their lifespan. Signals that activate either the Bcl-2- or death receptor-regulated apoptosis pathways can provide powerful stimuli for neutrophils to undergo cell death, but whether they act cooperatively in parallel or directly cross-talk in neutrophils is not known. Previous studies suggested that Bcl-2 family proteins are not required for Fas-induced cell death in neutrophils, but did not examine whether they could modulate its rapid onset. By monitoring the rate of change in neutrophil viability associated with activation of the Fas-triggered death receptor pathway using real-time cell imaging, we show that the Bcl-2-related proteins Bid, Bax, and Bak accelerate neutrophil apoptosis but are not essential for cell death. Increased Bcl-2 or Mcl-1 expression prevents efficient induction of apoptosis by Fas stimulation indicating that the Bcl-2-regulated apoptosis pathway can directly interfere with Fas-triggered apoptosis. Fas has been shown to initiate NFκB activation and gene transcription in cell lines, however gene transcription is not altered in Fas-activated Bid(-/-) neutrophils, indicating that apoptosis occurs independently of gene transcription in neutrophils. The specification of kinetics of neutrophil apoptosis by Bid impacts on the magnitude of neutrophil IL-1β production, implicating a functional role for the Bcl-2-regulated pathway in controlling neutrophil responses to FasL. These data demonstrate that the intrinsic apoptosis pathway directly controls the kinetics of Fas-triggered apoptosis in neutrophils.