The transcription factor Zeb1 controls homeostasis and function of type 1 conventional dendritic cells

Type 1 conventional dendritic cells (cDC1) are the most efficient cross-presenting cells that induce protective cytotoxic T cell response. However, the regulation of their homeostasis and function is incompletely understood. Here we observe a selective reduction of splenic cDC1 accompanied by excessive cell death in mice with Zeb1 deficiency in dendritic cells, rendering the mice more resistant to Listeria infection. Additionally, cDC1 from other sources of Zeb1-deficient mice display impaired cross-presentation of exogenous antigens, compromising antitumor CD8+ T cell responses. Mechanistically, Zeb1 represses the expression of microRNA-96/182 that target Cybb mRNA of NADPH oxidase Nox2, and consequently facilitates reactive-oxygen-species-dependent rupture of phagosomal membrane to allow antigen export to the cytosol. Cybb re-expression in Zeb1-deficient cDC1 fully restores the defective cross-presentation while microRNA-96/182 overexpression in Zeb1-sufficient cDC1 inhibits cross-presentation. Therefore, our results identify a Zeb1-microRNA-96/182-Cybb pathway that controls cross-presentation in cDC1 and uncover an essential role of Zeb1 in cDC1 homeostasis.

Transcription factor TCF-1 regulates the functions, but not the development, of lymphoid tissue inducer subsets in different tissues

Lymphoid tissue inducer (LTi) cells, a subset of innate lymphoid cells (ILCs), play an essential role in the formation of secondary lymphoid tissues. However, the regulation of the development and functions of this ILC subset is still elusive. In this study, we report that the transcription factor T cell factor 1 (TCF-1), just as GATA3, is indispensable for the development of non-LTi ILC subsets. While LTi cells are still present in TCF-1-deficient mice, the organogenesis of Peyer's patches (PPs), but not of lymph nodes, is impaired in these mice. LTi cells from different tissues have distinct gene expression patterns, and TCF-1 regulates the expression of lymphotoxin specifically in PP LTi cells. Mechanistically, TCF-1 may directly and/or indirectly regulate Lta, including through promoting the expression of GATA3. Thus, the TCF-1-GATA3 axis, which plays an important role during T cell development, also critically regulates the development of non-LTi cells and tissue-specific functions of LTi cells.

The glycolysis/HIF-1α axis defines the inflammatory role of IL-4-primed macrophages

T helper type 2 (Th2) cytokine-activated M2 macrophages contribute to inflammation resolution and wound healing. This study shows that IL-4-primed macrophages exhibit a stronger response to lipopolysaccharide stimulation while maintaining M2 signature gene expression. Metabolic divergence between canonical M2 and non-canonical proinflammatory-prone M2 (M2_INF) macrophages occurs after the IL-4Rα/Stat6 axis. Glycolysis supports Hif-1α stabilization and proinflammatory phenotype of M2_INF macrophages. Inhibiting glycolysis blunts Hif-1α accumulation and M2_INF phenotype. Wdr5-dependent H3K4me3 mediates the long-lasting effect of IL-4, with Wdr5 knockdown inhibiting M2_INF macrophages. Our results also show that the induction of M2_INF macrophages by IL-4 intraperitoneal injection and transferring of M2_INF macrophages confer a survival advantage against bacterial infection in vivo. In conclusion, our findings highlight the previously neglected non-canonical role of M2_INF macrophages and broaden our understanding of IL-4-mediated physiological changes. These results have immediate implications for how Th2-skewed infections could redirect disease progression in response to pathogen infection.

B cell residency but not T cell-independent IgA switching in the gut requires innate lymphoid cells

Immunoglobulin A (IgA)-producing plasma cells derived from conventional B cells in the gut play an important role in maintaining the homeostasis of gut flora. Both T cell-dependent and T cell-independent IgA class switching occurs in the lymphoid structures in the gut, whose formation depends on lymphoid tissue inducers (LTis), a subset of innate lymphoid cells (ILCs). However, our knowledge on the functions of non-LTi helper-like ILCs, the innate counter parts of CD4 T helper cells, in promoting IgA production is still limited. By cell adoptive transfer and utilizing a unique mouse strain, we demonstrated that the generation of IgA-producing plasma cells from B cells in the gut occurred efficiently in the absence of both T cells and helper-like ILCs and without engaging TGF-β signaling. Nevertheless, B cell recruitment and/or retention in the gut required functional NKp46-CCR6+ LTis. Therefore, while CCR6+ LTis contribute to the accumulation of B cells in the gut through inducing lymphoid structure formation, helper-like ILCs are not essential for the T cell-independent generation of IgA-producing plasma cells.

Thinking differently about ILCs-Not just tissue resident and not just the same as CD4+ T-cell effectors

Innate lymphoid cells (ILCs) resemble adaptive T lymphocytes based on transcription factor expression, cytokine production, and their presumptive roles in immunity, but are activated for effector function through cytokine signaling and not antigen-specific receptors. The prevailing view is that ILCs adapt to specific microenvironments during development and operate as tissue-resident cells in co-operation with antigen-specific T cells to provide host protection and contribute to tissue maintenance. In particular, conventional models equate the activity of different ILC subsets with CD4⁺ effector T-cell types based on corresponding transcription factor expression and a potential for comparable cytokine production. Based on recent data from our laboratory, we suggest that these views on tissue residence and parallel functioning to CD4⁺ T cells are too restrictive. Our findings show that ILC2s can be mobilized from the gut under inflammatory conditions and contribute to distal immunity in the lungs during infection, whereas gut-resident ILC3s operate in a quite distinct manner from Th17 CD4⁺ effector cells in responding to commensal microbes, with important implications for control of metabolic homeostasis. In this review, we discuss the recent advances leading to these revised views of ILC inter-organ trafficking and the distinct and complementary function of ILCs with respect to adaptive T cells in establishing and maintaining a physiologic host environment.

[Present treatment situation of hepatocellular carcinoma with extrahepatic metastasis]

With the development of diagnostic and screening technologies, the incidence of hepatocellular carcinoma (HCC) with extrahepatic metastasis is increasing. It is a kind of refractory disease with extremely poor prognosis. Currently, there is no standard therapy. The existing guidelines only recommend targeted therapy, systemic chemotherapy or best supportive care for HCC patients with extrahepatic metastasis, but have not mentioned surgical therapy.Several studies have shown that the majority of HCC patients with extrahepatic metastasis died of progressive intrahepatic tumor leading to hepatic failure, but not extrahepatic metastases; and primary tumor resection may have a favorable impact on the prognosis of these patients with resectable primary tumors.Furthermore, the role of resection of metastatic tumors for HCC patients with extrahepatic metastasis remains unclear so far.Majority of experts think that resection of lung metastases has survival benefit when the hepatic lesion is resected or controlled, whereas resection of lymph nodes, bone metastases, adrenal gland lesions, or brain metastases does not prolong survival, which may be recommended when the goal is to relieve symptoms or improve quality of life.Therefore, surgical treatment is important for HCC patients with extrahepatic metastasis, and surgical therapy combined with personalized systemic treatment shows survival benefit for selected patients.

B cell recruitment to the intestine critically depends on GATA3- and RORgt-mediated development of NKp46 negative innate lymphoid cells

The isolated lymphoid follicles (ILFs) enrich for B cells, most of which are conventional B cells, however, how they are recruited into and remain in intestine is not fully understood. Here, we show that in the small intestine lamina propria (siLP) of the Gata3f/f-VavCre mouse strain, in which no T cells and very few innate lymphoid cells (ILCs) are present, B cells were also largely absent, despite B cells were normal in number in the spleen of these mice. Mixed bone marrow chimera experiments showed that Gata3-deficient B cells were able to migrate to the siLP. Normal intestinal B cells were found in Tcra−/− mice excluding the possibility of T cell contribution to B cell recruitment. Bone marrow reconstitution of various donors into Gata3f/f-VavCre mice indicated that ILCs were involved in B cell migrating into small intestine LP. Further immunofluorescent analyses using RorcGFP/GFPand Gata3f/f-Rorc-Cre mice implicated that deficiency in NKp46 negative ILC3s, presumably the lymphoid tissue inducers, was responsible for impaired B cell recruitment. In summary, our findings suggest that NKp46 negative ILC3-mediated formation of tertiary lymphoid structures such as ILFs is required for B cell recruitment and/or retention in the small intestine.

T-bet expression is fine-tuned for balancing IFN-γ-producing Th1 and Tfh cell differentiation and IgG2a(c) production

T follicular helper (Tfh) cells and cytokine IFN-γ are involved in Ig class switching in B cells to produce IgG2a(c). Tfh cells mainly produce IL-21 as their signature cytokine, and several studies have also shown that some Tfh cells are capable of expressing Th1 signature cytokine IFN-γ without expressing the Th1 master transcription factor T-bet. In Toxoplasma gondii peptide AS15/Complete Freund’s Adjuvant (CFA)-induced immune response, we found antigen AS15-specific IgG2a(c) were abolished in CD4-Cre-mediated T-bet-deficient mice. By using T-bet-fate-mapping mouse strains, we reported that transient expression of T-bet epigenetically imprints the Ifng locus for cytokine production in a subset of Tfh cells; In germinal centers, multi-color tissue imaging revealed that the ex-T-bet Tfh cells express IFN-γ in situ; IFN-γ-expressing Tfh cells are absent in T-bet-deficient mice. More interestingly, we noticed that IFN-γ-expressing Tfh cells were fully present in mice with T-bet deletion at late stages of T cell differentiation, and antigen AS15-specific IgG2a(c) were even further up-regulated in such “T-bet late knockout” mice. Taken together, our findings demonstrate that IFN-γ expressed by T cells plays a dominant role in antibody IgG2a(c) production; T-bet expression is fine-tuned as spatiotemporal manner for balancing Th1 and Tfh cell differentiation in vivo and regulating the strength of antibody production.

Transient T-bet expression functionally specifies a distinct T follicular helper subset

The mechanisms underlying the differentiation of T follicular helper (Tfh) cell subsets are poorly understood. Here, Fang et al. show that the NKG2D^high Tfh cells in germinal centers with a history of T-bet expression represent the IFN-γ–producing Tfh subset.

T follicular helper (Tfh) cells express transcription factor BCL-6 and cytokine IL-21. Mature Tfh cells are also capable of producing IFN-γ without expressing the Th1 transcription factor T-bet. Whether this IFN-γ–producing Tfh population represents a unique Tfh subset with a distinct differentiation pathway is poorly understood. By using T-bet fate–mapping mouse strains, we discovered that almost all the IFN-γ–producing Tfh cells have previously expressed T-bet and express high levels of NKG2D. DNase I hypersensitivity analysis indicated that the Ifng gene locus is partially accessible in this “ex–T-bet” population with a history of T-bet expression. Furthermore, multicolor tissue imaging revealed that the ex–T-bet Tfh cells found in germinal centers express IFN-γ in situ. Finally, we found that IFN-γ–expressing Tfh cells are absent in T-bet–deficient mice, but fully present in mice with T-bet deletion at late stages of T cell differentiation. Together, our findings demonstrate that transient expression of T-bet epigenetically imprints the Ifng locus for cytokine production in this Th1-like Tfh cell subset.

Lactobacillus acidophilus and Clostridium butyricum ameliorate colitis in murine by strengthening the gut barrier function and decreasing inflammatory factors

Ulcerative colitis is a type of chronic inflammation present in the intestines for which the aetiology is not yet clear. The current therapies for ulcerative colitis cannot be considered to be long-term management strategies due to their significant side effects. Therefore, it is essential to identify an alternative therapeutic strategy for ulcerative colitis. The present study focused on the evaluation of the anti-inflammatory activities of Lactobacillus acidophilus CGMCC 7282 and Clostridium butyricum CGMCC 7281. The roles of both single and combination of L. acidophilus CGMCC 7282 and C. butyricum CGMCC 7281 in ulcerative colitis were investigated in 2,4,6-trinitrobenzenesulfonic acid-induced acute colitis (Th1-type colitis) in Sprague-Dawley rats and oxazolone-induced chronic colitis (Th2-type colitis) in BALB/c mice. The in vivo studies showed that the administration of L. acidophilus CGMCC 7282, C. butyricum CGMCC 7281 and L. acidophilus CGMCC 7282 plus C. butyricum CGMCC 7281 could reduce the Th1-type colitis as well as the Th2-type colitis, and the combination of the two strains exhibited the most notable effects, as indicated by the reduced mortality rates, the suppressed disease activity indices, the improved body weights, the reduced colon weight/colon length and colon weight/body weight ratios, and the improved gross anatomic characteristics and histological features (ameliorations of neutrophil infiltration and ulceration in the colon). It was found that the alterations of the gut microbiome, the barrier function changing and the selected inflammation-related cytokines are observed in the ulcerative colitis rats/mice treated with L. acidophilus CGMCC 7282 and C. butyricum CGMCC 7281. The combination of L. acidophilus CGMCC 7282 plus C. butyricum CGMCC 7281 also exerted a stronger anti-inflammatory effect than either of the single strains alone in vitro. These findings provide evidence that the administration of L. acidophilus CGMCC 7282 plus C. butyricum CGMCC 7281 may be a promising therapy for ulcerative colitis.

S1P-dependent interorgan trafficking of group 2 innate lymphoid cells supports host defense

Innate lymphoid cells (ILCs) are innate counterparts of adaptive T lymphocytes, contributing to host defense, tissue repair, metabolic homeostasis, and inflammatory diseases. ILCs have been considered to be tissue-resident cells, but whether ILCs move between tissue sites during infection has been unclear. We show here that interleukin-25- or helminth-induced inflammatory ILC2s are circulating cells that arise from resting ILC2s residing in intestinal lamina propria. They migrate to diverse tissues based on sphingosine 1-phosphate (S1P)-mediated chemotaxis that promotes lymphatic entry, blood circulation, and accumulation in peripheral sites, including the lung, where they contribute to anti-helminth defense and tissue repair. This ILC2 expansion and migration is a behavioral parallel to the antigen-driven proliferation and migration of adaptive lymphocytes to effector sites and indicates that ILCs complement adaptive immunity by providing both local and distant tissue protection during infection.

Innate and adaptive lymphocytes sequentially shape the gut microbiota and lipid metabolism

The mammalian gut is colonized by numerous microorganisms collectively termed the microbiota, which have a mutually beneficial relationship with their host. Normally, the gut microbiota matures during ontogeny to a state of balanced commensalism marked by the absence of adverse inflammation. Subsets of innate lymphoid cells (ILCs) and conventional T cells are considered to have redundant functions in containment and clearance of microbial pathogens, but how these two major lymphoid-cell populations each contribute to shaping the mature commensal microbiome and help to maintain tissue homeostasis has not been determined. Here we identify, using advanced multiplex quantitative imaging methods, an extensive and persistent phosphorylated-STAT3 signature in group 3 ILCs and intestinal epithelial cells that is induced by interleukin (IL)-23 and IL-22 in mice that lack CD4+ T cells. By contrast, in immune-competent mice, phosphorylated-STAT3 activation is induced only transiently by microbial colonization at weaning. This early signature is extinguished as CD4+ T cell immunity develops in response to the expanding commensal burden. Physiologically, the persistent IL-22 production from group 3 ILCs that occurs in the absence of adaptive CD4+ T-cell activity results in impaired host lipid metabolism by decreasing lipid transporter expression in the small bowel. These findings provide new insights into how innate and adaptive lymphocytes operate sequentially and in distinct ways during normal development to establish steady-state commensalism and tissue metabolic homeostasis.

Inflammatory ILC2: An IL-25-activated circulating ILC population with a protective role during helminthic infection

Innate lymphoid cells (ILCs) play important roles in host defense, tissue repair, metabolic homeostasis and inflammatory diseases. While ILCs are generally considered to mediate these functions in a tissue-resident manner, whether ILCs can move between sites when infection demands has not been carefully explored. We have reported the existence of an ILC population, inflammatory ILC2 (iILC2) cells, which are not present in the steady state but appear in high numbers in lung, liver, mesenteric lymph nodes and spleen upon IL-25 or Nippostongylus brasiliensis infection. iILC2 cells develop into natural ILC2-like cells and contribute to the expulsion of N. brasiliensis worms. They can also acquire IL-17-producing ability and provide protection against Candida albicans, indicating their multipotentiality or plasticity. Our recent data reveals that iILC2 cells are circulating cells, exchanging to a much greater extent between parabiotic mice than other ILC populations. iILC2 cells that appear after IL-25 administration or helminthic infection in peripheral, non-gut tissues such as the lung arise from distant resting ILC2 cells residing in the intestinal lamina propria. IL-25 induces rapid proliferation of these intestinal ILC2 cells and a change in their sensitivity to S1P-mediated chemotaxis, leading to lymphatic entry, blood circulation, and accumulation in many non-gut sites. These gut-derived cells are critical for anti-helminth immunity and tissue repair in the bowel and lung. Thus, inflammatory ILC2 cells are a circulating ILC population that is derived from the intestine but plays important roles in peripheral tissue host defense.

This work was supported by the Intramural Research Program of NIAID, NIH and by the USDA.

Sequential activity of innate and adaptive lymphocytes supports non-inflammatory gut microbial commensalism

The mammalian gut is colonized by trillions of microorganisms termed the “microbiota”, which have a mutually beneficial relationship with their host. In normal individuals, the gut microbiota matures after birth to a state of balanced commensalism that is marked by the absence of adverse inflammation. Both innate lymphoid cells (ILCs) and antigen-specific conventional T cells contribute to containment and clearance of microbial pathogens. But how these two major lymphoid cell populations help shape the mature commensal (non-pathogenic) microbiome and maintain tissue homeostasis has not been determined. Using advanced multiplex quantitative imaging methods, here we show that in the absence of adaptive lymphocytes, IL-23 induced by specific commensal bacteria such as Segmented Filamentous Bacteria (SFB) persistently activates RORgt+ group 3 innate lymphoid cells (ILC3s) in the ileum to produce IL-22, which induces STAT3 activation in virtually all epithelial cells, contributing to production of molecules such as anti-microbial peptides that protect the tissue from microbial damage. The distinct roles of ILCs in handling gut microbes play out in normal mice during development. The pSTAT3 signature is absent after birth, which is followed by microbial colonization and strong ILC3 activation and an extensive epithelial pSTAT3 signature upon weaning. This innate immune activity is subsequently extinguished as adaptive CD4+ T cell immunity develops in response to the expanding commensal burden. Our findings provide new insights into how innate and adaptive lymphocytes sequentially operate during normal development to establish steady state commensalism.

Group 3 innate lymphoid cells continuously require the transcription factor GATA-3 after commitment

We have previously reported that the transcription factor GATA-3 is critical for the development of all interleukin 7 receptor α-chain (IL-7Rα)-expressing innate lymphoid cells (ILCs) from their progenitor. After ILC lineage commitment, GATA-3 is essential for the maintenance and function of group 2 ILCs (ILC2 cells). Moreover, GATA-3 also maintains low expression in other mature ILCs, such as ILC3 cells, but its function is still elusive. We found that GATA-3 regulated the homeostasis of ILC3 cells by controlling IL-7Rα expression. In addition, GATA-3 served an indispensable function for the further development of the NKp46+ ILC3 subset. GATA-3 bound directly to the Rorc locus in ILC3 cells, repressed RORγt expression, and, thus, regulated the balance between the transcription factors T-bet and RORγt during NKp46+ ILC3 development. Whole transcriptome comparison of CCR6+ lymphoid tissue-inducer (LTi) ILC3 and NKp46+ ILC3 subsets from Gata3 sufficient and deficient mice showed that, among NKp46+ ILC3 cells, GATA-3 not only positively regulated genes specific to the NKp46+ ILC3 subset, but also negatively regulated genes specific to LTi ILC3 cells. Furthermore, GATA-3 also bound to the Il22 promoter locus and was required for IL-22 production in both ILC3 subsets. Mice deficient for Gata3 in ILC3 cells succumbed to Citrobacter rodentium infection due to defective IL-22 production. In conclusion, despite its low expression, GATA-3 was required for the homeostasis, development and function of ILC3 subsets.

Group 3 innate lymphoid cells continuously require the transcription factor GATA-3 after commitment

The transcription factor GATA-3 is indispensable for the development of all innate lymphoid cells (ILCs) that express the interleukin 7 receptor α-chain (IL-7Rα). However, the function of low GATA-3 expression in committed group 3 ILCs (ILC3 cells) has not been identified. We found that GATA-3 regulated the homeostasis of ILC3 cells by controlling IL-7Rα expression. In addition, GATA-3 served a critical function in the development of the NKp46(+) ILC3 subset by regulating the balance between the transcription factors T-bet and RORγt. Among NKp46(+) ILC3 cells, although GATA-3 positively regulated genes specific to the NKp46(+) ILC3 subset, it negatively regulated genes specific to lymphoid tissue-inducer (LTi) or LTi-like ILC3 cells. Furthermore, GATA-3 was required for IL-22 production in both ILC3 subsets. Thus, despite its low expression, GATA-3 was critical for the homeostasis, development and function of ILC3 subsets.

Penetration depth scaling for impact into wet granular packings

We present experimental measurements of penetration depths for the impact of spheres into wetted granular media. We observe that the penetration depth in the liquid saturated case scales with projectile density, size, and drop height in a fashion consistent with the scaling observed in the dry case, but with smaller penetrations. Neither viscous drag nor density effects can explain the enhancement to the stopping force. The penetration depth exhibits a complicated dependence on liquid fraction, accompanied by a change in the drop-height dependence, that must be the consequence of accompanying changes in the conformation of the liquid phase in the interstices.

β-arrestin1 is critical for the full activation of NLRP3 and NLRC4 inflammasomes

Inflammasomes are multiprotein complexes that trigger the activation of caspase-1 and the maturation of IL-1β, which are critical for inflammation and control of pathogen infection. Although the function of inflammasomes in immune response and disease development is well studied, the molecular mechanism by which inflammasomes are activated and assembled remains largely unknown. In this study, we found that β-arrestin1, a key regulator of the G protein-coupled receptor signaling pathway, was required for nucleotide-binding domain and leucine-rich repeat containing (NLR) family pyrin domain-containing 3 (NLRP3) and NLR family CARD domain-containing protein 4 (NLRC4) inflammasome-mediated IL-1β production and caspase-1 activation, but it had no effect on absent in melanoma 2 (AIM2) inflammasome activation. Moreover, apoptosis-associated speck-like protein containing a CARD (ASC) pyroptosome, which is ASC aggregation mediating caspase-1 activation, was also impaired in β-arrestin1-deficient macrophages upon NLRP3 or NLRC4, but not AIM2 inflammasome activation. Mechanistic study revealed that β-arrestin1 specifically interacted with NLRP3 and NLRC4 and promoted their self-oligomerization. In vivo, in a monosodium urate crystal (MSU)-induced NLRP3-dependent peritonitis model, MSU-induced IL-1β production and neutrophil flux were significantly reduced in β-arrestin1 knockout mice. Additionally, β-arrestin1 deficiency rescued the weight loss of mice upon log-phase Salmonella typhimurium infection, with less IL-1β production. Taken together, our results indicate that β-arrestin1 plays a critical role in the assembly and activation of two major canonical inflammasomes, and it may provide a new therapeutic target for inflammatory diseases.

Negative regulation of Nmi on virus-triggered type I IFN production by targeting IRF7

Viral infection causes host cells to produce type I IFNs, which play a critical role in viral clearance. IFN regulatory factor (IRF) 7 is the master regulator of type I IFN-dependent immune responses. In this article, we report that N-Myc and STATs interactor (Nmi), a Sendai virus-inducible protein, interacted with IRF7 and inhibited virus-triggered type I IFN production. The overexpression of Nmi inhibited the Sendai virus-triggered induction of type I IFNs, whereas the knockdown of Nmi promoted IFN production. Furthermore, the enhanced production of IFNs resulting from Nmi knockdown was sufficient to protect cells from infection by vesicular stomatitis virus. In addition, Nmi was found to promote the K48-linked ubiquitination of IRF7 and the proteasome-dependent degradation of this protein. Finally, an impairment of antiviral responses is also detectable in Nmi-transgenic mice. These findings suggest that Nmi is a negative regulator of the virus-triggered induction of type I IFNs that targets IRF7.

Cellular localization of NLRP3 inflammasome

Inflammasome is a large protein complex activated upon cellular stress or microbial infection, which triggers maturation of pro-inflammatory cytokines interleukin-1β and interleukin-18 through caspase-1 activation. Nod-like receptor family protein 3 (NLRP3) is the most characterized inflammasome activated by various stimuli. However, the mechanism of its activation is unclear and its exact cellular localization is still unknown. We examined the potential co-localization of NLRP3 inflammasome with mitochondria and seven other organelles under adenosine triphosphate, nigericin or monosodium urate stimulation in mouse peritoneal macrophages using confocal microscopy approach. Our results revealed that the activated endogenous apoptosis-associated speck-like protein containing a CARD (ASC) pyroptosome forms in the cytoplasm and co-localizes with NLRP3 and caspase-1, but not with any of the organelles screened. This study indicates that the ASC pyroptosome universally localizes within the cytoplasm rather than with any specific organelles.

Nitric oxide suppresses NLRP3 inflammasome activation and protects against LPS-induced septic shock

Inflammasomes are multi-protein complexes that trigger the activation of caspase-1 and the maturation of interleukin-1β (IL-1β), yet the regulation of these complexes remains poorly characterized. Here we show that nitric oxide (NO) inhibited the NLRP3-mediated ASC pyroptosome formation, caspase-1 activation and IL-1β secretion in myeloid cells from both mice and humans. Meanwhile, endogenous NO derived from iNOS (inducible form of NO synthase) also negatively regulated NLRP3 inflammasome activation. Depletion of iNOS resulted in increased accumulation of dysfunctional mitochondria in response to LPS and ATP, which was responsible for the increased IL-1β production and caspase-1 activation. iNOS deficiency or pharmacological inhibition of NO production enhanced NLRP3-dependent cytokine production in vivo, thus increasing mortality from LPS-induced sepsis in mice, which was prevented by NLRP3 deficiency. Our results thus identify NO as a critical negative regulator of the NLRP3 inflammasome via the stabilization of mitochondria. This study has important implications for the design of new strategies to control NLRP3-related diseases.

Mafa expression enhances glucose-responsive insulin secretion in neonatal rat beta cells

AIM/HYPOTHESIS

Neonatal beta cells lack glucose-stimulated insulin secretion and are thus functionally immature. We hypothesised that this lack of glucose responsiveness results from a generalised low expression of genes characteristic of mature functional beta cells. Important glucose-responsive transcription factors, Mafa and Pdx1, regulate genes involved in insulin synthesis and secretion, and have been implicated in late beta cell development. The aim of this study was to assess whether Mafa and/or Pdx1 regulates the postnatal functional maturation of beta cells.

METHODS

By quantitative PCR we evaluated expression of these and other beta cell genes over the first month compared with adult. After infection with adenovirus expressing MAFA, Pdx1 or green fluorescent protein (Gfp), P2 rat islets were evaluated by RT-PCR and insulin secretion with static incubation and reverse haemolytic plaque assay (RHPA).

RESULTS

At P2 most beta cell genes were expressed at about 10% of adult, but by P7 Pdx1 and Neurod1 no longer differ from adult; by contrast, Mafa expression remained significantly lower than adult through P21. Overexpression of Pdx1 increased Mafa, Neurod1, glucokinase (Gck) mRNA and insulin content but failed to enhance glucose responsiveness. Similar overexpression of MAFA resulted in increased Neurod1, Nkx6-1, Gck and Glp1r mRNAs and no change in insulin content but, importantly, acquisition of glucose-responsive insulin secretion. Both the percentage of secreting beta cells and the amount of insulin secreted per beta cell increased, approaching that of adult beta cells.

CONCLUSIONS/INTERPRETATION

In the process of functional maturation acquiring glucose-responsive insulin secretion, neonatal beta cells undergo a coordinated gene expression programme in which Mafa plays a crucial role.

ECM1 controls T(H)2 cell egress from lymph nodes through re-expression of S1P(1)

Type 2 helper T cells (T(H)2) are critically involved in allergies and asthma. Here we demonstrate that extracellular matrix protein-1 (ECM1) is highly and selectively expressed in T(H)2 cells. ECM1 deficiency caused impaired T(H)2 responses and reduced allergic airway inflammation in vivo. Functional analysis demonstrated that although the T(H)2 polarization of ECM1-deficient cells was unimpaired, these cells had a defect in migration and were retained in peripheral lymphoid organs. This was associated with reduced expression of KLF2 and S1P(1). We also found that ECM1 could directly bind the interleukin-2 (IL-2) receptor to inhibit IL-2 signaling and activate S1P(1) expression. Our data identify a previously unknown function of ECM1 in regulating T(H)2 cell migration through control of KLF2 and S1P(1) expression.

Tripartite-motif protein 30 negatively regulates NLRP3 inflammasome activation by modulating reactive oxygen species production

The NLR family, pyrin domain-containing 3 (NLRP3) inflammasome is critical for caspase-1 activation and the proteolytic processing of pro-IL-1β. However, the mechanism that regulates NLRP3 inflammasome activation remains unclear. In this paper, we demonstrate that tripartite-motif protein 30 (TRIM30) negatively regulates NLRP3 inflammasome activation. After stimulation with ATP, an agonist of the NLRP3 inflammasome, knockdown of TRIM30 enhanced caspase-1 activation and increased production of IL-1β in both J774 cells and bone marrow-derived macrophages. Similarly with ATP, knockdown of TRIM30 increased caspase-1 activation and IL-1β production triggered by other NLRP3 inflammasome agonists, including nigericin, monosodium urate, and silica. Production of reactive oxygen species was increased in TRIM30 knockdown cells, and its increase was required for enhanced NLRP3 inflammasome activation, because antioxidant treatment blocked excess IL-1β production. Conversely, overexpression of TRIM30 attenuated reactive oxygen species production and NLRP3 inflammasome activation. Finally, in a crystal-induced NLRP3 inflammasome-dependent peritonitis model, monosodium urate-induced neutrophil flux and IL-1β production was reduced significantly in TRIM30 transgenic mice as compared with that in their nontransgenic littermates. Taken together, our results indicate that TRIM30 is a negative regulator of NLRP3 inflammasome activation and provide insights into the role of TRIM30 in maintaining inflammatory responses.

In vivo disruption of TGF-beta signaling by Smad7 in airway epithelium alleviates allergic asthma but aggravates lung carcinogenesis in mouse

Background

TGF-β has been postulated to play an important role in the maintenance of epithelial homeostasis and the development of epithelium-derived cancers. However, most of previous studies are mainly focused on the function of TGF-β in immune cells to the development of allergic asthma and how TGF-β signaling in airway epithelium itself in allergic inflammation is largely unknown. Furthermore, the in vivo TGF-β function specifically in the airway epithelium during lung cancer development has been largely elusive.

Methodology/Principal Findings

To evaluate the in vivo contribution of TGF-β signaling in lung epithelium to the development of allergic disease and lung cancer, we generated a transgenic mouse model with Smad7, an intracellular inhibitor of TGF-β signaling, constitutively expressed in mouse airway Clara cells using a mouse CC10 promoter. The mice were subjected to the development of OVA-induced allergic asthma and urethane-induced lung cancer. The Smad7 transgenic animals significantly protected from OVA-induced asthma, with reduced airway inflammation, airway mucus production, extracellular matrix deposition, and production of OVA-specific IgE. Further analysis of cytokine profiles in lung homogenates revealed that the Th2 cytokines including IL-4, IL-5 and IL-13, as well as other cytokines including IL-17, IL-1, IL-6, IP10, G-CSF, and GM-CSF were significantly reduced in the transgenic mice upon OVA induction. In contrast, the Smad7 transgenic animals had an increased incidence of lung carcinogenesis when subjected to urethane treatment.

Conclusion/Significance

These studies, therefore, demonstrate for the first time the in vivo function of TGF-β signaling specifically in airway epithelium during the development of allergic asthma and lung cancer.

Trichosanthin functions as Th2-type adjuvant in induction of allergic airway inflammation

It is important to understand the pathogenesis of asthma induced by natural allergens, which could exclude the interference of artificial adjuvant and provide insights of natural immune response in the disease. In the present study, we show that Trichosanthin (TCS) could induce airway inflammation even without the help of alum. Furthermore, TCS appeared capable of replacing alum to promote OVA-specific airway inflammation. TCS induced accumulation of IL-4-producing eosinophils in peritoneum at an early stage and the adjuvant function of TCS was eliminated by blockage of IL-4 at this stage. Finally, the eosinophils triggered by TCS from WT mice, but not from IL-4-deficient mice were shown to function as adjuvant for the induction of OVA-specific Th2 responses. Our data indicate that TCS is not only an allergen, but also a Th2-type adjuvant modulating the switching of immune responses to a Th2 pathway. This chain of events results from IL-4 production by eosinophils at an early stage of TCS-priming. In conclusion, TCS may be useful as a Th2 adjuvant, and innate immune cells, such as eosinophils, may be a good target to study the initiation of Th2 response.

TIMP-1 mediates the inhibitory effect of interleukin-6 on the proliferation of a hepatocarcinoma cell line in a STAT3-dependent manner

The tissue inhibitor of metalloproteinases (TIMP)-1 is a multifunctional protein which is not only an inhibitor of matrix metalloproteinases (MMPs) but also to have a possible "cytokine-like" action. Here, we first compared mRNA expression of TIMP-1 and MMP-9 in BEL-7402 (a hepatocellular carcinoma cell line), L-02 (a normal liver cell line) and QSG-7701 (a cell line derived from peripheral tissue of liver carcinoma) using real-time quantitative RT-PCR. By evaluating the variation of the MMP-9/TIMP-1 ratio as an index of reciprocal changes of the expression of the two genes, we observed that the MMP-9/TIMP-1 ratio was about 13- and 5-fold higher in BEL-7402 than in L-02 and QSG-7701, respectively. Significantly, overexpression of TIMP-1 decreased the MMP-9/TIMP-1 ratio in BEL-7402 and then inhibited the cell growth to 60% and reduced the migration to about 30%. Meanwhile, our data showed that interleukin-6 (IL-6) (100 ng/mL) could also inhibited the cell growth of BEL-7402. Further studies indicated that TIMP-1 mediated the inhibitory effect of IL-6 on BEL-7402 cell proliferation in a STAT3-dependent manner, which could further accelerate the expression of the cyclin-dependent kinase inhibitor p21. A dominant negative STAT3 mutant totally abolished IL-6-induced TIMP-1 expression and its biological functions. The present results demonstrate that TIMP-1 may be one of the mediators that regulate the inhibitory effect of IL-6 on BEL-7402 proliferation in which STAT3 signal transduction and p21 up-regulation also play important roles.

Learning-based Method for P53 Immunohistochemically Stained Cell Image Segmentation

In this study, a learning-based color image conversion method is proposed for cell image segmentation. Firstly, we demonstrate that minimum distance-based pixel classification, such as clustering, for color image segmentation in the color space is equivalent to thresholding grayscale images. Motivated by this result, we develop the so called C-G-T procedure for color image segmentation, where color image (C) is first converted into grayscale (G) and thresholding (T) is then performed on the gray image to segment objects out of background. The transform for image conversion is learned from the global pixel distribution in the color space, while the threshold is learned from local pixel distribution of the gray image. The combination of global and local learning makes the C-G- T procedure adaptive and computational efficient. Extensive experiments are performed to verify the effectiveness of our method.

Effects of the silanized mica surface on protein crystallization

A freshly cleaved mica surface silanized by 3-aminopropyl triethoxysilane is flat over a large area, displays a controlled degree of hydrophobicity and contains positive charges. In this paper, mica sheets silanized by this method have been used as crystallization surfaces for lysozyme, trichosanthin and three other proteins of unknown structure. Crystallization experiments have been carried out by the hanging-drop vapour-diffusion technique and the results indicate that the silanized mica surface can ameliorate the protein crystallization process considerably compared with a silanized glass cover slip control. For lysozyme on the silanized mica surface, the induction time required for crystal growth decreases markedly. For trichosanthin, the crystal size is obviously larger and the number of crystals grown is much lower. For the three proteins of unknown structure, the diffraction ability of the crystals is improved considerably.

S-Nitroglutathione, a product of the reaction between peroxynitrite and glutathione that generates nitric oxide

Peroxynitrite (ONOO-) has been shown in studies on vascular relaxation and guanylate cyclase activation to react with glutathione (GSH), generating an intermediate product that promotes a time-dependent production of nitric oxide (NO). In this study, reactions of ONOO- with GSH produced a new substance, which was characterized by liquid chromatography, ultraviolet spectroscopy, and electrospray tandem mass spectrometry. The mass spectrometric data provided evidence that the product of this reaction was S-nitroglutathione (GSNO2) and that S-nitrosoglutathione (GSNO) was not a detectable product of this reaction. Further evidence was obtained by comparison of the spectral and chromatographic properties with synthetic standards prepared by reaction of GSH with nitrosonium or nitronium borofluorates. Both the synthetic and ONOO-/GSH-derived GSNO2 generated a protonated ion, GSNO2H+, at m/z 353, which was unusually resistant to decomposition under collision activation, and no fragmentation was observed at collision energy of 25 eV. In contrast, an ion at m/z 337 (GSNOH+), generated from the synthetic GSNO, readily fragmented with the abundant loss of NO at 9 eV. Reactions of ONOO- with GSH resulted in the generation of NO, which was detected by the head space/NO-chemiluminescence analyzer method. The generation of NO was inhibited by the presence of glucose and/or CO2 in the buffers employed. Synthetic GSNO2 spontaneously generated NO in a manner that was not significantly altered by glucose or CO2. Thus, ONOO- reacts with GSH to form GSNO2, and GSNO2 decomposes in a manner that generates NO.

Dose-dependent selective suppression of light (NFL) and medium (NFM) but not heavy (NFH) molecular weight neurofilament mRNA levels in acute aluminum neurotoxicity

We inoculated 5- to 6-week old New Zealand white rabbits intracisternally with either 100, 250, 500, 750, or 1000 micrograms of AlCl3 or 0.9% NaCl and correlated the extent of cervical motor neuron neurofilamentous inclusion formation at 48 h postinoculation with alterations in neurofilament (NF) mRNA levels. RNA was isolated from cervical spinal cord by the guanidine isothiocyanate method and individual RNA samples were normalized for poly(A+) content. Northern blot analysis was performed with cDNA probes for light (NFL), medium (NFM), and heavy (NFH) neurofilament subunit protein or with oligonucleotide probes for alpha-tubulin or actin. No significant alteration in the levels of alpha-tubulin, actin, or NFH mRNA were observed, regardless of the aluminum dose. In contrast, dose-dependent reductions in NFL and NFM mRNA levels occurred in direct proportion to the extent of neurofilamentous inclusion formation. While inoculums of NaCl or 100 or 250 micrograms AlCl3 induced neither inclusion formation or alterations in mRNA levels, both inclusion formation and reductions in the levels of NFL and NFM mRNA occurred thereafter, becoming maximal with inoculums of 1000 micrograms AlCl3. These experiments indicate that intracisternally administered AlCl3 acutely suppresses NFL and NFM mRNA levels without affecting those of NFH. This pattern is in distinct contrast to the uniform reductions of all NF mRNA transcript levels during neurogenesis or following axotomy, indicating a specific effect of aluminum upon steady-state levels of NF mRNA that correlates with the induction of neurofilamentous aggregates.

Salivary estradiol and progesterone during the normal ovulatory menstrual cycle in Chinese women

Salivary and serum levels of estradiol and progesterone were measured by radioimmunoassay in 10 Chinese women during their normal menstrual cycles. Changes in salivary estradiol and progesterone levels followed a similar pattern to that in the serum. Significant correlation was found between salivary and serum levels of estradiol and progesterone (p less than 0.001). Measurements of these salivary steroids may be used to assess follicular dynamics. Moreover, salivary sampling is simple, convenient and stress free.