IL‐34‐ and M‐CSF‐induced macrophages switch memory T cells into Th17 cells via membrane IL‐1α

Macrophages orchestrate the immune response via the polarization of CD4⁺ T helper (Th) cells. Different subsets of macrophages with distinct phenotypes, and sometimes opposite functions, have been described. M‐CSF and IL‐34 induce the differentiation of monocytes into IL‐10^high IL‐12^low immunoregulatory macrophages, which are similar to tumor‐associated macrophages (TAMs) in ovarian cancer. In this study, we evaluated the capacity of human macrophages induced in the presence of M‐CSF (M‐CSF macrophages) or IL‐34 (IL‐34 macrophages) and ovarian cancer TAMs to modulate the phenotype of human CD4⁺ T cells. Taken together, our results show that M‐CSF‐, IL‐34 macrophages, and TAMs switch non‐Th17 committed memory CD4⁺ T cells into conventional CCR4⁺ CCR6⁺ CD161⁺ Th17 cells, expressing or not IFN‐gamma. Contrary, the pro‐inflammatory GM‐CSF macrophages promote Th1 cells. The polarization of memory T cells into Th17 cells is mediated via membrane IL‐1α (mIL‐1α), which is constitutively expressed by M‐CSF‐, IL‐34 macrophages, and TAMs. This study elucidates a new mechanism that allows macrophages to maintain locally restrained and smoldering inflammation, which is required in angiogenesis and metastasis.     

IFN‐λ‐mediated IL‐12 production in macrophages induces IFN‐γ production in human NK cells

With increasing interest in alternative options to interferon‐alpha‐based treatments, IFN‐λ has shown therapeutic promise in a variety of diseases. Although the antiviral activity of IFN‐λ has been extensively studied, there is limited knowledge regarding the immunological functions of IFN‐λ and how these differ from those of other classes of IFNs. In this study, we investigated the effects of IFN‐λ on primary human NK cells, both in a direct and indirect capacity. We demonstrate that in contrast to interferon‐alpha, IFN‐λ is unable to directly stimulate NK cells, due to the absence of IFN‐λ receptor chain 1 (IFN‐λR1) on NK cells. However, IFN‐λ, in combination with TLR4 challenge, is able to induce the production of select members of the IL‐12 family of cytokines in monocyte‐derived macrophages. We further show that through macrophage‐mediated IL‐12 production, IFN‐λ is able to indirectly affect NK cells and ultimately induce IFN‐γ production.     

TGF‐β interactions with IL‐1 family members trigger IL‐4‐independent IL‐9 production by mouse CD4+ T cells

TGF‐β and IL‐4 were recently shown to selectively upregulate IL‐9 production by naïve CD4⁺ T cells. We report here that TGF‐β interactions with IL‐1α, IL‐1β, IL‐18, and IL‐33 have equivalent IL‐9‐stimulating activities that function even in IL‐4‐deficient animals. This was observed after in vitro antigenic stimulation of immunized or unprimed mice and after polyclonal T‐cell activation. Based on intracellular IL‐9 staining, all IL‐9‐producing cells were CD4⁺ and 80–90% had proliferated, as indicated by reduced CFSE staining. In contrast to IL‐9, IL‐13 and IL‐17 were strongly stimulated by IL‐1 and either inhibited (IL‐13) or were unaffected (IL‐17) by addition of TGF‐β. IL‐9 and IL‐17 production also differed in their dependence on IL‐2 and regulation by IL‐1/IL‐23. As IL‐9 levels were much lower in Th2 and Th17 cultures, our results identify TGF‐β/IL‐1 and TGF‐β/IL‐4 as the main control points of IL‐9 synthesis.     

TSLP production by dendritic cells is modulated by IL‐1β and components of the endoplasmic reticulum stress response

Thymic stromal lymphopoietin (TSLP) produced by epithelial cells acts on dendritic cells (DCs) to drive differentiation of T_H2‐cells, and is therefore important in allergic disease pathogenesis. However, DCs themselves make significant amounts of TSLP in response to microbial products, but little is known about the key downstream signals that induce and modulate this TSLP secretion from human DCs. We show that human monocyte derived DC (mDC) secretion of TSLP in response to Candida albicans and β‐glucans requires dectin‐1, Syk, NF‐κB, and p38 MAPK signaling. In addition, TSLP production by mDCs is greatly enhanced by IL‐1β, but not TNF‐α, in contrast to epithelial cells. Furthermore, TSLP secretion is significantly increased by signals emanating from the endoplasmic reticulum (ER) stress response, specifically the unfolded protein response sensors, inositol‐requiring transmembrane kinase/endonuclease 1 and protein kinase R‐like ER kinase, which are activated by dectin‐1 stimulation. Thus, TSLP production by mDCs requires the integration of signals from dectin‐1, the IL‐1 receptor, and ER stress signaling pathways. Autocrine TSLP production is likely to play a role in mDC‐controlled immune responses at sites removed from epithelial cell production of the cytokine, such as lymphoid tissue.     

IL‐13Rα1 is a surface marker for M2 macrophages influencing their differentiation and function

In this study, we examined the role IL‐13 receptor alpha 1 (IL‐13Rα1) plays in macrophage differentiation and function. The findings indicate that IL‐13Rα1 is expressed on the M2 but not on the M1 subset of macrophages and specifically heterodimerizes with the IL‐4Rα chain to form a type II receptor, which controls the differentiation and function of these cells. Indeed, BM cells from IL‐13Rα1^+/+ and IL‐13Rα1^?/? mice yield equivalent numbers of macrophages when cultured under M2 polarizing conditions. However, IL‐13Rα1^?/? BM cells yield a much higher number of macrophages than IL‐13Rα1^+/+ BM cells when the differentiation is carried out under M1‐polarizing conditions. Further analyses indicated that macrophages that express IL‐13Rα1 also display surface markers associated with an M2 phenotype. In addition, the IL‐13Rα1⁺ macrophages were highly efficient in phagocytizing zymosan bioparticles both in vitro and in vivo, and supported differentiation of naïve T cells to a Th2 phenotype. Finally, when stimulated by IL‐13, a cytokine that uses the heteroreceptor, the cells were able to phosphorylate STAT6 efficiently. These previously unrecognized findings indicate that IL‐13Rα1 serves as a marker for M2 macrophages and the resulting heteroreceptor influences both their differentiation and function.     

EAE mediated by a non‐IFN‐γ/non‐IL‐17 pathway

Previous studies have shown that EAE can be elicited by the adoptive transfer of either IFN‐γ‐producing (Th1) or IL‐17‐producing (Th17) myelin‐specific CD4⁺ T‐cell lines. Paradoxically, mice deficient in either IFN‐γ or IL‐17 remain susceptible to EAE following immunization with myelin antigens in CFA. These observations raise questions about the redundancy of IFN‐γ and IL‐17 in autoimmune demyelinating disease mediated by a diverse, polyclonal population of autoreactive T cells. In this study, we show that an atypical form of EAE, induced in C57BL/6 mice by the adoptive transfer of IFN‐γ‐deficient effector T cells, required IL‐17 signaling for the development of brainstem infiltrates. In contrast, classical EAE, characterized by predominant spinal cord inflammation, occurred in the combined absence of IFN‐γ and IL‐17 signaling, but was dependent on GM‐CSF and CXCR2. Our findings contribute to a growing body of data, indicating that individual cytokines vary in their importance across different models of CNS autoimmunity.     

Protein tyrosine phosphatase PTPN22 regulates IL‐1β dependent Th17 responses by modulating dectin‐1 signaling in mice

A single nucleotide polymorphism within the PTPN22 gene is a strong genetic risk factor predisposing to the development of multiple autoimmune diseases. PTPN22 regulates Syk and Src family kinases downstream of immuno‐receptors. Fungal β‐glucan receptor dectin‐1 signals via Syk, and dectin‐1 stimulation induces arthritis in mouse models. We investigated whether PTPN22 regulates dectin‐1 dependent immune responses. Bone marrow derived dendritic cells (BMDCs) generated from C57BL/6 wild type (WT) and Ptpn22^?/? mutant mice, were pulsed with OVA_323‐339 and the dectin‐1 agonist curdlan and co‐cultured in vitro with OT‐II T‐cells or adoptively transferred into OT‐II mice, and T‐cell responses were determined by immunoassay. Dectin‐1 activated Ptpn22^?/? BMDCs enhanced T‐cell secretion of IL‐17 in vitro and in vivo in an IL‐1β dependent manner. Immunoblotting revealed that compared to WT, dectin‐1 activated Ptpn22^?/? BMDCs displayed enhanced Syk and Erk phosphorylation. Dectin‐1 activation of BMDCs expressing Ptpn22^R619W (the mouse orthologue of human PTPN22^R620W) also resulted in increased IL‐1β secretion and T‐cell dependent IL‐17 responses, indicating that in the context of dectin‐1 Ptpn22^R619W operates as a loss‐of‐function variant. These findings highlight PTPN22 as a novel regulator of dectin‐1 signals, providing a link between genetically conferred perturbations of innate receptor signaling and the risk of autoimmune disease.     

Interleukin‐17A participates in podocyte injury by inducing IL‐1β secretion through ROS‐NLRP3 inflammasome‐caspase‐1 pathway

Studies show that the Th17/IL ‐17A axis plays an important role in the pathogenesis of kidney diseases. Previously, we also showed that IL ‐17A may play a role in the pathogenesis of primary nephrotic syndrome; however, the underlying mechanism(s) is unclear. The aim of this study was to explore the molecular mechanism of IL ‐17A‐inducing podocyte injury in vitro. In this study, the NLRP 3 inflammasome activation and the morphology of podocytes were detected by Western blot and immunofluorescence. The results showed that podocytes persistently expressed IL ‐17A receptor and that NLRP 3 inflammasome in these cells was activated upon exposure to IL ‐17A. Also, activity of caspase‐1 and secretion of IL ‐1β increased in the presence of IL ‐17A. In addition, IL ‐17A disrupted podocyte morphology by decreasing expression of podocin and increasing expression of desmin. Blockade of intracellular ROS or inhibition of caspase‐1 prevented activation of the NLRP 3 inflammasome, thereby restoring podocyte morphology. Taken together, the results suggest that IL ‐17A induces podocyte injury by activating the NLRP 3 inflammasome and IL ‐1β secretion and contributes to disruption of the kidney's filtration system.     

IL‐17‐producing γδ T cells

IL‐17 is produced not only by CD4⁺ αβ T cells, but also CD8⁺ αβ T cells, NKT cells, and γδ T cells, plus some non‐T cells, including macrophages and neutrophils. The ability of IL‐17 to deploy neutrophils to sites of inflammation imparts this cytokine with a key role in diseases of several types. Surprisingly, γδ T cells are responsible for much of the IL‐17 produced in several disease models, particularly early on.     

The Role of TLR4, TNF‐α and IL‐1β in Type 2 Diabetes Mellitus Development within a North Indian Population

This study investigated the role of IL‐1β‐511 (rs16944), TLR4‐896 (rs4986790) and TNF‐α‐308 (rs1800629) polymorphisms in type 2 diabetes mellitus (T2DM) among an endogamous Northern Indian population. Four hundred fourteen participants (204 T2DM patients and 210 nondiabetic controls) were genotyped for IL‐1β‐511, TLR4‐896 and TNF‐α‐308 loci. The C allele of IL‐1β‐511 was shown to increase T2DM susceptibility by 75% (OR: 1.75 [CI 1.32–2.33]). Having two parents affected by T2DM increased susceptibility by 5.7 times (OR: 5.693 [CI 1.431–22.648]). In this study, we have demonstrated a conclusive association with IL‐1β‐511 locus and IL‐1β‐511‐TLR4‐896 diplotype (CC‐AA) and T2DM, which warrants further comprehensive analyses in larger cohorts.     

Galectin‐3 is an amplifier of the interleukin‐1β‐mediated inflammatory response in corneal keratinocytes

Interleukin‐1β (IL‐1β) is a potent mediator of innate immunity commonly up‐regulated in a broad spectrum of inflammatory diseases. When bound to its cell surface receptor, IL‐1β initiates a signalling cascade that cooperatively induces the expression of canonical IL‐1 target genes such as IL‐8 and IL‐6. Here, we present galectin‐3 as a novel regulator of IL‐1β responses in corneal keratinocytes. Using the SNAP‐tag system and digitonin semi‐permeabilization, we show that recombinant exogenous galectin‐3 binds to the plasma membrane of keratinocytes and is internalized into cytoplasmic compartments. We find that exogenous galectin‐3, but not a dominant negative inhibitor of galectin‐3 polymerization lacking the N‐terminal domain, exacerbates the response to IL‐1β by stimulating the secretion of inflammatory cytokines. The activity of galectin‐3 could be reduced by a novel d ‐galactopyranoside derivative targeting the conserved galactoside‐binding site of galectins and did not involve interaction with IL‐1 receptor 1 or the induction of endogenous IL‐1β. Consistent with these observations, we demonstrate that small interfering RNA‐mediated suppression of endogenous galectin‐3 expression is sufficient to impair the IL‐1β‐induced secretion of IL‐8 and IL‐6 in a p38 mitogen‐activated protein kinase‐independent manner. Collectively, our findings provide a novel role for galectin‐3 as an amplifier of IL‐1β responses during epithelial inflammation through an as yet unidentified mechanism.     

The Cag pathogenicity island and interaction between TLR2/NOD2 and NLRP3 regulate IL‐1β production in Helicobacter pylori infected dendritic cells

Helicobacter pylori colonization of the stomach affects about half of the world population and is associated with the development of gastritis, ulcers, and cancer. Polymorphisms in the IL1B gene are linked to an increased risk of H. pylori associated cancer, but the bacterial and host factors that regulate interleukin (IL)‐1β production in response to H. pylori infection remain unknown. Using murine BM‐derived DCs, we show that the bacterial virulence factors cytotoxin‐associated genes pathogenicity island and CagL, but not vacuolating cytotoxin A or CagA, regulate the induction of pro‐IL‐1β and the production of mature IL‐1β in response to H. pylori infection. We further show that the host receptors, Toll‐like receptor 2 (TLR2) and nucleotide‐binding oligomerization domain 2 (NOD2), but not NOD1, are required for induction of pro‐IL‐1β and NOD‐like receptor pyrin domain containing 3 (NLRP3) in H. pylori infected DCs. In contrast, NLRP3 and the adaptor ASC were essential for the activation of caspase‐1, processing of pro‐IL‐1β into IL‐1β, and IL‐1β secretion. Finally, we show that mice deficient in caspase‐1, IL‐1β, and IL‐1 receptor, but not NLRP3, are impaired in the clearance of CagA‐positive H. pylori from the stomach when compared with WT mice. These studies identify bacterial cag pathogenicity island and the cooperative interaction among host innate receptors TLR2, NOD2, and NLRP3 as important regulators of IL‐1β production in H. pylori infected DCs.     

Submandibular gland morphogenesis: Stage‐specific expression of TGF‐α/EGF,IGF, TGF‐β, TNF,and IL‐6 signal transduction in normal embryonic mice and the phenotypic effects of TGF‐β2, TGF‐β3, and EGF‐r null mutations

Branching morphogenesis of the mouse submandibular gland (SMG) is dependent on cell‐cell conversations between and within epithelium and mesenchyme. Such conversations are typically mediated in other branching organs (lung, mammary glands, etc.) by hormones, growth factors, cytokines, and the like in such a way as to translate endocrine, autocrine, and paracrine signals into specific gene responses regulating cell division, apoptosis, and histodifferentiation. We report here the protein expression in embryonic SMGs of four signal transduction pathways: TGF‐α/EGF/EGF‐R; IGF‐II/IGF‐IR/IGF‐IIR; TGF‐βs and cognate receptors; TNF, IL‐6, and cognate receptors. Their in vivo spatiotemporal expression is correlated with specific stages of progressive SMG development and particular patterns of cell proliferation, apoptosis, and mucin expression. Functional necessity regarding several of these pathways was assessed in mice with relevant null mutations (TGF‐β2, TGF‐β₃, EGF‐R). Among many observations, the following seem of particular importance: (1) TGF‐α and EGF‐R, but not EGF, are found in the Initial and Pseudoglandular Stages of SMG development; (2) ductal and presumptive acini lumena formation was associated with apoptosis and TNF/TNF‐R1 signalling; (3) TGF‐β2 and TGF‐β3 null mice have normal SMG phenotypes, suggesting the presence of other pathways of mitostasis; (4) EGF‐R null mice displayed an abnormal SMG phenotype consisting of decreased branching. These and other findings provide insight into the design of future functional studies. Anat Rec 256:252–268, 1999. © 1999 Wiley‐Liss, Inc.     

Secreted IL‐1α promotes T‐cell activation and expansion of CD11b+Gr1+ cells in carbon tetrachloride‐induced liver injury in mice

Interleukin‐1α is mainly expressed on the cell membrane, but can also be secreted during inflammation. The roles of secreted and membrane IL‐1α in acute liver inflammation are still not known. Here, we examined the functions of secreted and membrane IL‐1α in a mouse model of carbon tetrachloride‐induced acute liver injury. We show that secreted IL‐1α aggravates liver damage and membrane IL‐1α slightly protects mice from liver injury. Further studies showed that secreted IL‐1α promotes T‐cell activation. It also increased the expansion of CD11b⁺Gr1⁺ myeloid cells, which may serve as a negative regulator of acute liver inflammation. Moreover, secreted IL‐1α induced IL‐6 production from hepatocytes. IL‐6 neutralization reduced the proliferation of CD11b⁺Gr1⁺ myeloid cells in vivo. CCL2 and CXCL5 expression was increased by secreted IL‐1α in vitro and in vivo. Antagonists of the chemokine receptors for CCL2 and CXCL5 significantly reduced the migration of CD11b⁺Gr1⁺ myeloid cells. These results demonstrate that secreted and membrane IL‐1α play different roles in acute liver injury. Secreted IL‐1α could promote T‐cell activation and the recruitment and expansion of CD11b⁺Gr1⁺ myeloid cells through induction of CCL2, CXCL5, and IL‐6. The controlled release of IL‐1α could be a critical regulator during acute liver inflammation.     

The stimulatory effect of α‐melanotropin on progesterone release from rat granulosa cells is inhibited by interleukin‐1β and by tumour necrosis factor‐α

Aim: Several studies have shown that a variety of peptides and cytokines are involved in ovarian regulatory mechanisms; however, their exact function is still unclear. In this work we study whether the administration of peptide α‐melanotropin and the cytokines interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) on their own modify the release of progesterone in cultured granulosa cells (GC) from pro‐oestrous rats. We also investigate an interaction between these cytokines and α‐melanotropin in the modulation of progesterone secretion. Methods: Granulosa cells were collected from the ovaries of female Wistar rats and cultured for up to 24 h in the presence of different concentrations of α‐melanotropin, cytokines or a combination of both. Progesterone concentration was measured by radioimmunoassay. Results: The addition of α‐melanotropin in a dose of 0.01 and 0.1 mm had no effect on progesterone release, whereas a dose of 1 mm significantly increased progesterone release (P < 0.01) compared with the control culture. Progesterone release was not modified when different concentrations of interleukin‐1β or TNF‐α were added to the cell cultures. However, when interleukin‐1β or TNF‐α were added simultaneously with 1 μm α‐melanotropin, a significant reduction (P < 0.01 for interleukin‐1β and P < 0.05 for TNF‐α) of the steroid release was found with respect to the α‐melanotropin‐treated group. Conclusions: These results lead us to suggest that, although α‐melanotropin stimulates progesterone release in pre‐ovulatory GC, this effect is blocked by the presence of interleukin‐1β or TNF‐α.