IL-32, a novel cytokine with a possible role in disease

Human cathelicidin LL-37 and its derivative IG-19 regulate interleukin-32-induced inflammation

Human cathelicidin LL-37 protects against infections and endotoxin-induced inflammation. In a recent study we have shown that IG-19, an LL-37-derived peptide, protects in a murine model of arthritis. Cytokine interleukin-32 (IL-32) is elevated and directly associated with the disease severity of inflammatory arthritis. Therefore, in this study we examined the effects of LL-37 and IG-19 on IL-32-induced responses in human peripheral blood-derived mononuclear cells (PBMC) and macrophages. We showed that CD14(+) monocytes are the primary cells that produce pro-inflammatory tumour necrosis factor-α (TNF-α) following stimulation of PBMC with IL-32. We demonstrated that LL-37 and IG-19 significantly suppress IL-32-induced production of pro-inflammatory cytokines, e.g. TNF-α and IL-1β, without altering chemokine production. In contrast, LL-37 and IG-19 enhance the production of the anti-inflammatory cytokine IL-1RA. Further mechanistic studies revealed that LL-37 and IG-19 suppress IL-32-mediated phosphorylation of Fyn (Y420) Src kinase. In contrast, IL-32-mediated phosphorylation of AKT-1 (T308) and MKP-1 (S359) is not suppressed by the peptides. LL-37 and IG-19 alone induce the phosphorylation of MKP-1 (S359), which is a known negative regulator of inflammation. Furthermore, the peptides induce the activity of p44/42 mitogen-activated protein kinase, which is known to phosphorylate MKP-1 (S359). This is the first study to demonstrate the regulation of IL-32-induced inflammation by LL-37 and its derivative peptide IG-19. The mechanistic results from this study suggest that regulation of immune-mediated inflammation by these peptides may be controlled by the dual phosphatase MKP-1. We speculate that LL-37 and its derivatives may contribute to the control of immune-mediated inflammatory diseases.

Soluble interleukin-6 receptor is elevated during influenza A virus infection and mediates the IL-6 and IL-32 inflammatory cytokine burst

Influenza A virus (IAV) infection is a major worldwide public health problem. However, the factors involved in mediating the inflammatory response to this infection and their relationships remain poorly understood. Here, we show that IAV infection stimulates the expression of the soluble IL-6 receptor (sIL-6R), a multifunctional protein involved in IL-6 signaling. Interestingly, sIL-6R expression upregulated the levels of its own ligand, IL-6 and those of the pro-inflammatory cytokine IL-32. shRNA-mediated knockdown of sIL-6R suppressed IL-6 and IL-32, indicating that this regulation is dependent on sIL-6R during IAV infection. Furthermore, our results demonstrate that IL-32 participates in a negative feedback loop that inhibits sIL-6R while upregulating IL-6 expression during IAV infection. Therefore, we show that sIL-6R is a critical cellular factor involved in the acute inflammatory response to viral infection.

IL-32γ induces chemotaxis of activated T cells via dendritic cell-derived CCL5

Interleukin (IL)-32 has been associated with a variety of inflammatory diseases including rheumatoid arthritis, vasculitis and Crohn's disease. We have previously reported that IL-32γ, the IL-32 isoform with the highest biological activity, could act as an immune modulator through regulation of dendritic cell (DC) functions in immune responses. Cell locomotion is crucial for induction of an effective immune response. In this study, we investigated the effect and underlying mechanisms of IL-32γ on recruitment of T cells. IL-32γ upregulated the expression of several chemokines including CCL2, CCL4, and CCL5 in the DCs. In particular, IL-32γ significantly increased CCL5 expression in a dose-dependent manner. Treatment with JNK and NF-κB inhibitors suppressed IL-32γ-induced CCL5 expression in DCs, indicating that IL-32γ induced CCL5 production through the JNK and NF-κB pathways. Furthermore, supernatants from IL-32γ-treated DCs showed chemotactic activities controlling migration of activated CD4(+) and CD8(+) T cells, and these activities were suppressed by addition of neutralizing anti-CCL5 antibody. These results show that IL-32γ effectively promotes migration of activated T cells via CCL5 production in DCs. The chemotactic potential of IL-32γ may explain the pro-inflammatory effects of IL-32 and the pathologic role of IL-32 in immune disorders such as rheumatoid arthritis.

Elevated interleukin-32 expression is associated with Helicobacter pylori-related gastritis

Background

Interleukin-32 (IL-32) is a recently discovered proinflammatory cytokine involved in inflammatory diseases. We investigated the expression of IL-32 and its regulation mechanism in the inflammatory response of patients with Helicobacter pylori (H. pylori) infection.

Design and Methods

IL-32 mRNA and protein expression in gastric tissues was detected by quantitative real-time PCR and immunohistochemistry. The regulation of IL-32 in human gastric epithelia cell line AGS was investigated by different cytokine stimulation and different H. pylori strain infection.

Results

Gastric IL-32 mRNA and protein expression were elevated in patients with H. pylori infection and positively correlated with gastritis. In H. pylori-infected patients, the mRNA level of IL-32 was also correlated with that of proinflammatory cytokines IL-1β and TNF-α. In vitro IL-1β and TNF-α could upregulate IL-32 mRNA and protein level in AGS cells, which was dependent on NF-κB signal pathway. The regulation of IL-32 expression in response to H. pylori-infection could be weakened by using neutralizing antibodies to block IL-1β and TNF-α. Moreover, H. pylori-infected AGS cells also induced IL-32 mRNA and protein expression, which was dependent on CagA.

Conclusions

IL-32 level is elevated in patients with H. pylori infection and its expression is regulated by proinflammatory stimuli, suggesting that IL-32 may play a role in the pathogenesis of H. pylori-related gastritis.

Interleukin-32 isoforms: expression, interaction with interferon-regulated genes and clinical significance in chronically HIV-1-infected patients

Given the growing evidence for a role of interleukin-32 (IL-32) in the immune response to HIV-1 infection and its interplay with type I and III interferons (IFNs), we studied the gene expression of IL-32 isoforms (α and nonα) in untreated chronically HIV-1-infected patients and in gender- and age-matched healthy individuals. To further characterize both the anti-HIV properties of IL-32 and the cytokine's relationship with host antiviral innate immune responses, we evaluated whether IL-32 can induce ex vivo the expression of antiviral IFN-induced genes (ISGs), namely myxovirus resistance A (MxA), and apolipoprotein B mRNA-editing enzyme catalytic (APOBEC)3G and APOBEC3F. We also investigated whether in vivo IL-32 (α and nonα) mRNA levels were correlated with those of MxA and APOBEC3G/3F. Results indicated that IL-32 (α and nonα) mRNA levels were significantly higher in HIV-1-infected patients than in healthy individuals. Furthermore, IL-32 (α and nonα) mRNA levels correlated negatively with HIV RNA levels, but not with the CD4(+) T-cell count. Our ex vivo studies disclosed that ISGs mRNA levels were increased after IL-32γ treatment of peripheral blood mononuclear cells. Interestingly, significant positive correlations were found between transcript levels of both IL-32α and IL-32nonα and those of MxA and APOBEC3G/3F in untreated chronically HIV-1-infected patients. Overall, our results demonstrated that IL-32 isoforms are highly expressed during chronic HIV-1 infection and that IL-32 could have a central role in the antiviral immune response against HIV-1.

IL-32 promotes angiogenesis

IL-32 is a multifaceted cytokine with a role in infections, autoimmune diseases, and cancer, and it exerts diverse functions, including aggravation of inflammation and inhibition of virus propagation. We previously identified IL-32 as a critical regulator of endothelial cell (EC) functions, and we now reveal that IL-32 also possesses angiogenic properties. The hyperproliferative ECs of human pulmonary arterial hypertension and glioblastoma multiforme exhibited a markedly increased abundance of IL-32, and, significantly, the cytokine colocalized with integrin αVβ3. Vascular endothelial growth factor (VEGF) receptor blockade, which resulted in EC hyperproliferation, increased IL-32 three-fold. Small interfering RNA-mediated silencing of IL-32 negated the 58% proliferation of ECs that occurred within 24 h in scrambled-transfected controls. Reduction of IL-32 neither affected apoptosis (insignificant changes in Bak-1, Bcl-2, Bcl-xL, lactate dehydrogenase, annexin V, and propidium iodide) nor VEGF or TGF-β levels, but siIL-32-transfected adult and neonatal ECs produced up to 61% less NO, IL-8, and matrix metalloproteinase-9, and up to 3-fold more activin A and endostatin. In coculture-based angiogenesis assays, IL-32γ dose-dependently increased tube formation up to 3-fold; an αVβ3 inhibitor prevented this activity and reduced IL-32γ-induced IL-8 by 85%. In matrigel plugs loaded with IL-32γ, VEGF, or vehicle and injected into live mice, we observed the anticipated VEGF-induced increase in neocapillarization (8-fold versus vehicle), but unexpectedly, IL-32γ was equally angiogenic. A second signal such as IFN-γ was required to render cells responsive to exogenous IL-32γ; importantly, this was confirmed using a completely synthetic preparation of IL-32γ. In summary, we add angiogenic properties that are mediated by integrin αVβ3 but VEGF-independent to the portfolio of IL-32, implicating a role for this versatile cytokine in pulmonary arterial hypertension and neoplastic diseases.

Interleukin-32δ interacts with IL-32β and inhibits IL-32β-mediated IL-10 production

There is growing evidence for multifunctional properties of IL-32. We previously demonstrated that IL-32β upregulates IL-10 production through the association with PKCδ. In this study, we examined the effects of other IL-32 isoforms on IL-10 production. We found that IL-32δ decreased IL-10 production and investigated the inhibitory mechanism of IL-32δ. We showed that IL-32δ suppressed IL-32β binding to PKCδ by interacting with IL-32β. The inhibitory effect of IL-32δ on IL-32β association with PKCδ was further verified by immuno-fluorescence staining. The co-localization of IL-32β and PKCδ around the nuclear membrane was disrupted by IL-32δ. Our data therefore indicate that IL-32δ plays an inhibitory role against IL-32β function, which also suggests that IL-32 may be regulated by its own isoform.

IL-32-PAR2 axis is an innate immunity sensor providing alternative signaling for LPS-TRIF axis

Interleukin (IL)-32 is known to exert adujvant effects on innate immune response, however, receptors and downstream signaling pathways remain to be clarified. Here we found that IL-32γ upregulated serine protease activity of proteinase-3 (PR3), in turn triggering protease-activated receptor 2 (PAR2) signaling. Interestingly, silencing of PR3 or PAR2 using siRNA markedly diminished IL-32γ-induced TNFα and IFN-β mRNA expression. IL-32γ-PAR2 axis utilized TRIF and Ras-Raf-1 pathways. On stimulation with lipopolysaccharide (LPS), differential activation of protein kinase C isoforms modulated the balance between LPS-TLR4-TRIF and IL-32-PAR2-TRIF axes, because LPS was a strong inducer of IL-32γ. IL-32-PAR2-TRIF axis might serve not only as an extracellular sensor of bacterial and autologous proteases, but also as a modulator of innate and adaptive immunity during infection.

IL-32γ Inhibits Acetaminophen-Induced Acute Hepatotoxicity through Inactivation of NF-κB and Stat1 Signals

Although several studies have shown physiological functions of interleukin (IL)-32, the role of IL-32 in liver has not yet been reported. This study was initiated to examine the effects of IL-32γ on APAP-induced acute hepatic failure in IL-32γ transgenic mice. IL-32Γ overexpressing and non-transgenic mice received 500 mg/kg Acetoaminophen (APAP) intraperitoneally. Serum alanine transaminase and aspartate transaminase were significantly lower in the APAP treated IL-32γ overexpressing mice compared with those APAP-treated non-transgenic. IL-32γ markedly reduced a restricted area of the necrosis and inflammation. APAP-induced reduced glutathione depletion, induction of nitric oxide and lipid peroxidation, and cytochrome P4502E1 expression was significantly lowered in the IL-32γ overexpressing mice. Elevation of Kupffer cells and natural killer cells by APAP were reduced in the IL-32γ overexpressing mice. The expression of IL-1α, IL-1rα, macrophage inflammatory protein-2, C-C motif chemokine ligand 5 and tissue inhibitor of metalloproteinase-1 was increased by APAP in non-transgenic mice, and were lowered in the IL-32γ overexpressing mice. Moreover, APAP-induced nuclear transcription factor-kappa B (NF-κB) and signal transducers and activators of transcription 1 (STAT1) activities were greatly lowered in the IL-32γ overexpressing mice. The results indicate that IL-32γ could effectively inhibit drug-induced hepatic failure, and reduce the number of cytotoxic immune cells and pro-inflammatory cytokine production through reduced activities of NF-κB and STAT1. This might be attributable to lowering APAP-induced liver toxicity in IL-32γ overexpressing mice.

Role of interleukin-32 in chronic rhinosinusitis

PURPOSE OF REVIEW

IL-32 is a recently described proinflammatory cytokine and has been reported to be involved in inflammatory diseases. The purpose of this review is to discuss the role of IL-32 in chronic rhinosinusitis (CRS).

RECENT FINDINGS

Two groups have recently reported data regarding the expression of IL-32 in CRS. IL-32 was induced by IFN-γ, TNF-α, dsRNA, and incubation with Th1 cells in primary nasal epithelial cells. IL-32 may be elevated in epithelial cells from patients with CRS without nasal polyps. IL-32 was significantly elevated in whole sinonasal tissue samples of nasal polyps compared with control tissue. IL-32 mRNA expression positively correlated with mRNA for CD3 and macrophage mannose receptor in nasal polyp tissue. Immunohistochemical studies demonstrated localization of IL-32 in epithelium, CD3(+) and CD68(+) cells, suggesting that epithelial cells, T cells, and macrophages are the major IL-32-producing cells in CRS. Activation of these cell types may trigger IL-32-related inflammation in CRS.

SUMMARY

Elevated levels of IL-32 may play a role in the pathogenesis of CRS through its role as a proinflammatory cytokine and as an endogenous enhancer of pathogen-dependent cytokine production.

TLR-mediated induction of proinflammatory cytokine IL-32 in corneal epithelium

PURPOSE

IL-32, a newly discovered cytokine, has been associated with a variety of inflammatory diseases. The role of innate immunity in regulation of IL-32 expression has not been elucidated. This study was to explore TLR-mediated induction of IL-32 and the inflammatory effects of IL-32 in corneal epithelium.

METHODS

Human corneal tissues and primary human corneal epithelial cells (HCECs) were treated with a variety of viral or bacterial components, as well as IL-32 without or with different TLR pathway inhibitors. The mRNA expression was determined by reverse transcription and real time PCR, and the protein levels were measured by ELISA and immunostaining.

RESULTS

IL-32 mRNA and protein were largely induced by specific microbial components, including polyinosinic-polycytidylic acid (polyI:C) and flagellin, the ligands to TLR3 and TLR5 respectively, in human corneal epithelium ex vivo and in vitro cultures. The polyI:C-induced IL-32 production was blocked by TLR3 antibody or TRIF inhibitory peptide, while flagellin-stimulated IL-32 was blocked by TLR5 antibody or MyD88 inhibitory peptide. Interestingly, IκB-α inhibitor (BAY11-7082) or nuclear factor kappa B (NF-κB) inhibitor (quinazoline) blocked NF-κB p65 protein nuclear translocation, and also suppressed IL-32 production induced by polyI:C or flagellin. When HCECs were treated with IL-32, we observed its stimulatory affects on inflammatory cytokines, TNF-α, IL-1ß and IL-8, at both mRNA and protein levels.

CONCLUSION

These findings demonstrate that IL-32 is induced by microbial ligands through TLR-mediated innate signaling pathways, suggesting an important role of corneal epithelium in inflammatory disease.

The expression of interleukin-32 is activated by human cytomegalovirus infection and down regulated by hcmv-miR-UL112-1

BACKGROUND

Interleukin-32 (IL-32) is an important factor in innate and adaptive immune responses, which activates the p38MAPK, NF-kappa B and AP-1 signaling pathways. Recent reports have highlighted that IL-32 is regulated during viral infection in humans.

METHODS

Enzyme-linked immunosorbent assays (ELISA) were carried out to detect IL-32 levels in serum samples. Detailed kinetics of the transcription of IL-32 mRNA and expression of IL-32 protein during human cytomegalovirus (HCMV) infection were determined by semi-quantitative RT-PCR and western blot, respectively. The expression levels of hcmv-miR-UL112-1 were detected using TaqMan® miRNA assays during a time course of 96 hours. The effects of hcmv-miR-UL112-1 on IL-32 expression were demonstrated by luciferase assay and western blot, respectively.

RESULTS

Serum levels of IL-32 in HCMV-IgM positive patients (indicating an active HCMV infection) were significantly higher than those in HCMV-IgM negative controls. HCMV infection activated cellular IL-32 transcription mainly in the immediately early (IE) phase and elevated IL-32 protein levels between 6 and 72 hours post infection (hpi) in the human embryonic lung fibroblast cell line, MRC-5. The expression of hcmv-miR-UL112-1 was detected at 24 hpi and increased gradually as the HCMV-infection process was prolonged. In addition, it was demonstrated that hcmv-miR-UL112-1 targets a sequence in the IL-32 3'-UTR. The protein level of IL-32 in HEK293 cells could be functionally down-regulated by transfected hcmv-miR-UL112-1.

CONCLUSIONS

IL-32 expression was induced by active HCMV infection and could be functionally down-regulated by ectopically expressed hcmv-miR-UL112-1. Our data may indicate a new strategy of immune evasion by HCMV through post-transcriptional regulation.

IL-32 and IL-17 interact and have the potential to aggravate osteoclastogenesis in rheumatoid arthritis

Introduction

Interleukin (IL)-32 and IL-17 play critical roles in pro-inflammatory responses and are highly expressed in the synovium of patients with rheumatoid arthritis (RA). We investigated the relations between these two cytokines (IL-17 and IL-32) for their ability to induce each other and to stimulate osteoclasts in RA fibroblast-like synoviocytes (FLSs) and T cells.

Methods

FLSs were isolated through surgical synovectomy obtained from patients with RA or osteoarthritis (OA). Real-time PCR were performed to evaluate the expression of IL-32, IL-17 and osteoclast-related genes. Immunohistochemical staining and tartrate-resistant acid phosphatase (TRAP) staining were performed to determine the distribution of inflammatory cytokines and the presence of osteoclastogenesis.

Results

IL-17 induced the expression of IL-32 in the FLSs from RA patients, as assessed by microarray. IL-32 production was increased by IL-17. IL-32 in the FLSs from RA patients induced the production of IL-17 in CD4⁺ T cells. IL-32 and IL-17 were colocalized near TRAP-positive areas in joint specimens. IL-17 and IL-32 synergistically induced the differentiation of osteoclasts, as demonstrated by the expression of osteoclast-related genes. IL-32 and IL-17 also could induce resorption by osteoclasts in a RANKL-dependent manner.

Conclusions

IL-17 affected the expression of IL-32 in FLSs of RA patients and IL-32 induced the production of IL-17 in CD4+ T cells. Both IL-17 and IL-32 cytokines can reciprocally influence each other's production and amplify the function of osteoclastogenesis in the in RA synovium. Separately, IL-17 and IL-32 each stimulated osteoclastogenesis without RANKL. Together, the two cytokines synergistically amplified the differentiation of osteoclasts, independent of RANKL stimulation.

Real-imaging cDNA-AFLP transcript profiling of pancreatic cancer patients: Egr-1 as a potential key regulator of muscle cachexia

Background

Cancer cachexia is a progressive wasting syndrome and the most prevalent characteristic of cancer in patients with advanced pancreatic adenocarcinoma. We hypothesize that genes expressed in wasted skeletal muscle of pancreatic cancer patients may determine the initiation and severity of cachexia syndrome.

Experimental design

We studied gene expression in skeletal muscle biopsies from pancreatic cancer patients with and without cachexia utilizing Real-Imaging cDNA-AFLP-based transcript profiling for genome-wide expression analysis.

Results

Our approach yielded 183 cachexia-associated genes. Ontology analysis revealed characteristic changes for a number of genes involved in muscle contraction, actin cytoskeleton rearrangement, protein degradation, tissue hypoxia, immediate early response and acute-phase response.

Conclusions

We demonstrate that Real-Imaging cDNA-AFLP analysis is a robust method for high-throughput gene expression studies of cancer cachexia syndrome in patients with pancreatic cancer. According to quantitative RT-PCR validation, the expression levels of genes encoding the acute-phase proteins α-antitrypsin and fibrinogen α and the immediate early response genes Egr-1 and IER-5 were significantly elevated in the skeletal muscle of wasted patients. By immunohistochemical and Western immunoblotting analysis it was shown, that Egr-1 expression is significantly increased in patients with cachexia and cancer. This provides new evidence that chronic activation of systemic inflammatory response might be a common and unifying factor of muscle cachexia.

IL-32 aggravates synovial inflammation and bone destruction and increases synovial natural killer cells in experimental arthritis models

This study was performed to investigate the effects of IL-32 on joint inflammation, bone destruction, and synovial cytokine expressions, and on synovial natural killer (NK) cell expressions in collagen-induced arthritis (CIA). CIA was induced by type II collagen in DBA1 mice, and phosphate-buffered saline (PBS group) or IL-32 (IL-32 group) were injected into both knee joints at day 28 and 32, then mice were killed at day 35. Severity of synovial inflammation and bone destruction was determined by histological scoring method, and synovial cytokine expressions such as IL-1β, TNF-α, IL-17, IL-18, IFN-γ, IL-21, and IL-23 were measured by real-time RT-PCR and western blot. Synovial NK cell expressions were determined by real-time RT-PCR, western blot and immunohistochemistry, and chemokines and chemokine receptors expressions that are associated with NK cell migration were determined by real-time RT-PCR. Scores of synovial inflammation and bone destruction, synovial expressions of IL-1β, TNF-α, IL-18, and IFN-γ were significantly increased in IL-32 group compared with PBS group. Synovial expressions of NK cell, and chemokines (CCL2 and CXCL9) and chemokine receptors (CCR2 and CCR5) that are associated with NK cell migration were significantly increased in IL-32 group compared with PBS group. IL-32 aggravated joint inflammation and bone destruction and increased synovial expressions of inflammatory cytokine and NK cells in CIA. These results suggest that IL-32 play a role in joint inflammation and bone destruction, and IL-32 might be a new target for treatment of rheumatoid arthritis.

Expression levels of novel cytokine IL-32 in periodontitis and its role in the suppression of IL-8 production by human gingival fibroblasts stimulated with Porphyromonas gingivalis

Background

IL-32 was recently found to be elevated in the tissue of rheumatoid arthritis and inflammatory bowel disease. Periodontitis is a chronic inflammatory disease caused by polymicrobial infections that result in soft tissue destruction and alveolar bone loss. Although IL-32 is also thought to be associated with periodontal disease, its expression and possible role in periodontal tissue remain unclear. Therefore, this study investigated the expression patterns of IL-32 in healthy and periodontally diseased gingival tissue. The expression of IL-32 in cultured human gingival fibroblasts (HGF) as well as effects of autocrine IL-32 on IL-8 production from HGF were also examined.

Methods

Periodontal tissue was collected from both healthy volunteers and periodontitis patients, and immunofluorescent staining was performed in order to determine the production of IL-32. Using real-time PCR and ELISA, mRNA expression and protein production of IL-32 in HGF, stimulated by Porphyromonas gingivalis (Pg), were also investigated.

Results

Contrary to our expectation, the production of IL-32 in the periodontitis patients was significantly lower than in the healthy volunteers. According to immunofluorescent microscopy, positive staining for IL-32 was detected in prickle and basal cell layers in the epithelium as well as fibroblastic cells in connective tissue. Addition of fixed Pgin vitro was found to suppress the otherwise constitutive expression of IL-32 mRNA and protein in HGF. However, recombinant IL-32 in vitro inhibited the expression of IL-8 mRNA by HGF stimulated with Pg. Interestingly, anti-IL-32 neutralizing antibody upregulated the IL-8 mRNA expression in non-stimulated HGF, indicating that constitutive expression of IL-32 in HGF suppressed IL-8 mRNA expression in the absence of bacterial stimulation.

Conclusion

These results indicate that IL-32 is constitutively produced by HGF which can be suppressed by Pg and may play a role in the downregulation of inflammatory responses, such as IL-8 production, in periodontal tissue.

Interleukin-32 enhances cytotoxic effect of natural killer cells to cancer cells via activation of death receptor 3

Studies have demonstrated that the anti-tumour effect of natural killer (NK) cells is successful for patients with several cancers. Although interleukin-32 (IL-32) is endogenously expressed in NK cells, cytolytic function of NK cells against cancer cells has not been fully demonstrated. In the present study, we found that the growth of cancer cells was suppressed when colon cancer cells or prostate cancer cells were co-cultured with NK-92 cells, an NK cell line. We also found that the expression of tumour necrosis factor receptor 2 and death receptor 3 (DR3) was increased in PC3 cells, and the expression of FAS and DR3 was increased in SW620 cells by co-culture with NK-92 cells. However, cancer cell growth inhibition and IL-32 expression were abolished when cancer cells were co-cultured with NK cells transfected with small interfering (si) RNA of IL-32. DR3 expression was also diminished by co-culture with IL-32-specific siRNA-transfected NK-92 cells. Expression of APO3L, a ligand of DR3, was elevated in NK cells that were co-cultured with cancer cells. It was also found that expression of apoptosis-related proteins such as cleaved caspase-3 and bax was increased in cancer cells co-cultured with NK-92 cells, but their expression was abolished by co-culture with IL-32 siRNA-transfected NK-92 cells. Moreover, knockdown of DR3 in co-culture of NK-92 cells with cancer cells by siRNA or antibodies of DR3 and APO3L reversed the growth inhibitory effect of NK-92 cells. In conclusion, our study showed that IL-32 enhanced the cytotoxic effect of NK-92 cells on the cancer cells through activation of DR3 and caspase-3.

Differential expression of interleukin-32 in chronic rhinosinusitis with and without nasal polyps

BACKGROUND

  Chronic rhinosinusitis (CRS) is a heterogeneous disease characterized by local inflammation of the upper airways and sinuses and is frequently divided into polypoid CRS (CRSwNP) and nonpolypoid CRS (CRSsNP). However, the mechanism of inflammation in CRS has still not been fully elucidated. The aim of the study was to investigate the role of interleukin-32 (IL-32), a recently discovered proinflammatory cytokine, in CRS.

METHODS

  We collected nasal epithelial cells and nasal tissue from patients with CRS and control subjects. We assayed mRNA for IL-32 by real-time PCR and measured IL-32 protein using ELISA, Western blot, and immunohistochemistry.

RESULTS

  The expression of mRNA for IL-32 was elevated in epithelial cells from uncinate tissue from patients with CRSsNP compared with patients with CRSwNP (P < 0.05), control subjects (P=0.06), and epithelial cells from nasal polyp (NP) tissue (P < 0.05). Production of IL-32 was induced by IFN-γ, TNF, and dsRNA in primary airway epithelial cells. In whole-tissue extracts, the expression of IL-32 protein was significantly elevated in patients with CRSwNP compared with patients with CRSsNP and control subjects. Immunohistochemistry data showed that IL-32 was detected in mucosal epithelial cells and inflammatory cells in the lamina propria. Levels of IL-32 were correlated with the levels of CD3 and macrophage mannose receptor in NP tissue. Immunofluorescence data showed IL-32 co-localization with CD3-positive T cells and CD68-positive macrophages in NPs.

CONCLUSION

  Overproduction of IL-32 may be involved in the pathogenesis of CRS, although the role of IL-32 in the inflammation in CRSsNP and CRSwNP may be different.

Interleukin 32 (IL-32) contains a typical α-helix bundle structure that resembles focal adhesion targeting region of focal adhesion kinase-1

IL-32 can be expressed in several isoforms. The amino acid sequences of the major IL-32 isoforms were used to predict the secondary and tertiary protein structure by I-TASSER software. The secondary protein structure revealed coils and α-helixes, but no β sheets. Furthermore, IL-32 contains an RGD motif, which potentially activates procaspase-3 intracellular and or binds to integrins. Mutation of the RGD motif did not result in inhibition of the IL-32β- or IL-32γ-induced cytotoxicity mediated through caspase-3. Although IL-32α interacted with the extracellular part of αVβ3 and αVβ6 integrins, only the αVβ3 binding was inhibited by small RGD peptides. Additionally, IL-32β was able to bind to αVβ3 integrins, whereas this binding was not inhibited by small RGD peptides. In addition to the IL-32/integrin interactions, we observed that IL-32 is also able to interact with intracellular proteins that are involved in integrin and focal adhesion signaling. Modeling of IL-32 revealed a distinct α-helix protein resembling the focal adhesion targeting region of focal adhesion kinase (FAK). Inhibition of FAK resulted in modulation of the IL-32β- or IL-32γ-induced cytotoxicity. Interestingly, IL-32α binds to paxillin without the RGD motif being involved. Finally, FAK inhibited IL-32α/paxillin binding, whereas FAK also could interact with IL-32α, demonstrating that IL-32 is a member of the focal adhesion protein complex. This study demonstrates for the first time that IL-32 binds to the extracellular domain of integrins and to intracellular proteins like paxillin and FAK, suggesting a dual role for IL-32 in integrin signaling.

A cytokine-centric view of the pathogenesis and treatment of autoimmune arthritis

Cytokines are immune mediators that play an important role in the pathogenesis of rheumatoid arthritis (RA), an autoimmune disease that targets the synovial joints. The cytokine environment in the peripheral lymphoid tissues and the target organ (the joint) has a strong influence on the outcome of the initial events that trigger autoimmune inflammation. In susceptible individuals, these events drive inflammation and tissue damage in the joints. However, in resistant individuals, the inflammatory events are controlled effectively with minimal or no overt signs of arthritis. Animal models of human RA have permitted comprehensive investigations into the role of cytokines in the initiation, progression, and recovery phases of autoimmune arthritis. The discovery of interleukin-17 (IL-17) and its association with inflammation and autoimmune pathology has reshaped our viewpoint regarding the pathogenesis of arthritis, which previously was based on a simplistic T helper 1 (Th1)-Th2 paradigm. This review discusses the role of the newer cytokines, particularly those associated with the IL-17/IL-23 axis in arthritis. Also presented herein is the emerging information on IL-32, IL-33, and IL-35. Ongoing studies examining the role of the newer cytokines in the disease process would improve understanding of RA as well as the development of novel cytokine inhibitors that might be more efficacious than the currently available options.

IL-32 expression in the airway epithelial cells of patients with Mycobacterium avium complex lung disease

Lung disease due to Mycobacterium avium complex (MAC) organisms is increasing. A greater understanding of the host immune response to MAC organisms will provide a foundation to develop novel therapies for these recalcitrant infections. IL-32 is a newly described pro-inflammatory cytokine that enhances host immunity against various microbial pathogens. Cytokines that induce IL-32 such as interferon-gamma, IL-18, IL-12 and tumor necrosis factor-alpha are of considerable importance to mycobacterial immunity. We performed immunohistochemistry and morphometric analysis to quantify IL-32 expression in the lungs of 11 patients with MAC lung disease and 10 controls with normal lung tissues. After normalizing for basement membrane length, there was a profound increase in IL-32 expression in the airway epithelial cells of the MAC-infected lungs compared with controls. Following normalization for alveolar surface area, there was a trend toward increased IL-32 expression in type II alveolar cells and alveolar macrophages in the lungs of MAC patients. Human airway epithelial cells (BEAS-2B) infected with M. avium produced IL-32 by a nuclear factor-kappa B-dependent mechanism. In both BEAS-2B cells and human monocyte-derived macrophages, exogenous IL-32γ significantly reduced the growth of intracellular M. avium. This finding was corroborated by an increase in the number of intracellular M. avium recovered from THP-1 monocytes silenced for endogenous IL-32 expression. The anti-mycobacterial effect of IL-32 may be due, in part, to increased apoptosis of infected cells. These findings indicate that IL-32 facilitates host defense against MAC organisms but may also contribute to the airway inflammation associated with MAC pulmonary disease.

Association between IL-32 genotypes and outcome in infection-associated acute lung injury

INTRODUCTION

Our purpose was to investigate variation within the IL-32 promoter and gene, and susceptibility to and outcomes from infection associated acute lung injury (ALI).

METHODS

Retrospective case-control study involving healthy individuals (controls) and patients (cases) with infection-associated ALI. Two hundred fifty-eight healthy normal controls and 251 patients with infection-associated ALI were used for comparison. The IL-32 promoter/gene was sequenced in 52 healthy Caucasian individuals to identify single nucleotide polymorphisms (SNPs). Allelic discrimination was performed on 11 SNPs to determine differences between cases and controls and outcomes in patients with infection associated ALI.

RESULTS

Logistic and normal regression models were used to evaluate the associations with SNPs in cases and controls, and outcomes in patients with infection associated ALI. rs12934561, an intronic SNP, was found to be associated with risk for ALI in the case-control study and with more severe clinical course, as shown by increased time on the ventilator and the presence of fluid unresponsive hypotension. Further, it was found that rs12934561 has gender-specific effects and strongly interacts with other SNPs.

CONCLUSIONS

A common IL-32 genotype, rs12934561, is associated with the risk of ALI as well as the need for prolonged mechanical ventilatory support. This finding suggests that IL-32 is not only involved in the initiating inflammatory and cellular events that result in ALI, but also participates in determining the severity of pulmonary dysfunction associated with ALI.

Inflammatory cytokines IL-32 and IL-17 have common signaling intermediates despite differential dependence on TNF-receptor 1

Cytokines IL-32 and IL-17 are emerging as critical players in the pathophysiology of immune-mediated chronic inflammatory diseases. It has been speculated that the molecular mechanisms governing IL-32- and IL-17-mediated cellular responses are differentially dependent on the TNF pathway. In this study, kinome analysis demonstrated that following stimulation with cytokine IL-32, but not IL-17, there was increased phosphorylation of a peptide target corresponding to TNF-R1. Consistent with this observation, blocking TNF-R1 resulted in a suppression of IL-32-induced downstream responses, indicating that IL-32-mediated activity may be dependent on TNF-R1. In contrast, blocking TNF-R1 did not affect IL-17-induced downstream responses. Kinome analysis also implicated p300 (transcriptional coactivator) and death-associated protein kinase-1 (DAPK-1) as signaling intermediates for both IL-32 and IL-17. Phosphorylation of p300 and DAPK-1 upon stimulation with either IL-32 or IL-17 was confirmed by immunoblots. The presence of common targets was supported by results demonstrating similar downstream responses induced in the presence of IL-32 and IL-17, such as transcriptional responses and the direct activation of NF-κB. Furthermore, knockdown of p300 and DAPK-1 altered downstream responses induced by IL-32 and IL-17, and impacted certain cellular responses induced by TNF-α and IL-1β. We hypothesize that p300 and DAPK-1 represent nodes where the inflammatory networks of IL-32 and IL-17 overlap, and that these proteins would affect both TNF-R1-dependent and -independent pathways. Therefore, p300 and DAPK-1 are viable potential therapeutic targets for chronic inflammatory diseases.

The immunosuppressive role of IL-32 in lymphatic tissue during HIV-1 infection

One pathological hallmark of HIV-1 infection is chronic activation of the immune system, driven, in part, by increased expression of proinflammatory cytokines. The host attempts to counterbalance this prolonged immune activation through compensatory mediators of immune suppression. We recently identified a gene encoding the proinflammatory cytokine IL-32 in microarray studies of HIV-1 infection in lymphatic tissue (LT) and show in this study that increased expression of IL-32 in both gut and LT of HIV-1-infected individuals may have a heretofore unappreciated role as a mediator of immune suppression. We show that: 1) IL-32 expression is increased in CD4(+) T cells, B cells, macrophages, dendritic cells, and epithelial cells in vivo; 2) IL-32 induces the expression of immunosuppressive molecules IDO and Ig-like transcript 4 in immune cells in vitro; and 3) in vivo, IL-32-associated IDO/Ig-like transcript 4 expression in LT macrophages and gut epithelial cells decreases immune activation but also may impair host defenses, supporting productive viral replication, thereby accounting for the correlation between IL-32 levels and HIV-1 replication in LT. Thus, during HIV-1 infection, we propose that IL-32 moderates chronic immune activation to avert associated immunopathology but at the same time dampens the antiviral immune response and thus paradoxically supports HIV-1 replication and viral persistence.

Elevated serum level of interleukin-32α in the patients with myasthenia gravis

A new cytokine, interleukin-32 (IL-32), has been implicated in the pro-inflammatory immune responses in several autoimmune disorders, such as rheumatoid arthritis and inflammatory bowel diseases. Myasthenia gravis (MG) is a well-characterized autoimmune disease directed at the postsynaptic acetylcholine receptor (AChR) or end plate of the neuromuscular junction. IL-32 is a cytokine that induces tumor necrosis factor (TNF)-α, IL-6, IL-1β, and chemokine. IL-6, TNF-α, and IL-2 are related to the pathogenesis and immunoregulation of MG. The gene expression of IL-32 is increased in human natural killer (NK) cells and T lymphocytes when stimulated by IL-2 or mitogen. NK cells influence the development of experimental autoimmune MG (EAMG) and possibly MG. The aim of this study was to examine whether IL-32α levels are increased in patients with MG and to investigate the relationship between IL-32α levels and disease activity in human MG. Serum IL-32α levels were significantly higher in the MG patients (p = 0.03): 460.07 ± 192.30 pg/mL in MG patients and 248.45 ± 188.42 pg/mL in the healthy control group. Although there was no significant statistical difference, serum IL-32α levels of patients with both anti-AChR binding and blocking antibodies trended to be higher than those without either antibodies (521.56 ± 212.92 pg/mL vs. 339.52 ± 182.78 pg/mL, p = 0.16). IL-32α serum levels tended to decrease with clinical improvement in generalized MG. This study suggests the possibility that IL-32 might contribute to MG pathogenesis or immunoregulation.

Interleukin-32 expression induced by hepatitis B virus protein X is mediated through activation of NF-κB

HBV replicates noncytopathically in hepatocytes, but HBV or proteins encoded by HBV genome could induce cytokines, chemokines expression by hepatocytes. Moreover, liver damage in patients with HBV infection is immune-mediated and cytokines play important roles in immune-mediated liver damage after HBV infection. Interleukin-32 (IL-32) is a proinflammatory cytokine and plays a critical role in inflammation. However, the role of HBV in IL-32 expression remains unclear. In the present study, we demonstrate that hepatitis B virus protein X (HBx) increases IL-32 expression through the promoter of IL-32 at positions from -746 to +25 and in a dose-dependent manner. Furthermore, we demonstrate that increase of NF-κB subunits p65 and p50 in Huh7 cells also augments IL-32 expression, and the NF-κB inhibitor blocks the effect of HBx on IL-32 induction. These results indicate that NF-κB activation is required for HBx-induced IL-32 expression. In conclusion, IL-32 is induced by HBx in Huh7 cells. Our results suggest that IL-32 might play an important role in inflammatory response after HBV infection.

IL-32γ inhibits cancer cell growth through inactivation of NF-κB and STAT3 signals

Several studies have shown physiological functions of interleukin (IL)-32, a novel cytokine. However, the role of IL-32 in cancer development has not been reported. In this study, we showed that IL-32γ inhibited tumor growth in IL-32γ-overexpressing transgenic mice inoculated with melanoma as well as colon tumor growth in xenograft nude mice inoculated with IL-32γ-transfected colon cancer cells (SW620). The inhibitory effect of IL-32γ on tumor growth was associated with the inhibition of constitutive activated nuclear transcription factor-κB (NF-κB) and of signal transducer and activator of transcription 3 (STAT3). The expression of antiapoptotic, cell proliferation and tumor-promoting genes (bcl-2, X-chromosome inhibitor of apoptosis protein (IAP), cellular IAP and cellular FADD-like IL-1β-converting enzyme-inhibitory protein, cyclin D), cyclin-dependent kinase 4, cycolooxygenase-2 and inducible nitric oxide synthase was decreased, whereas the expression of apoptotic target genes (caspase-3 and -9, bax) increased. In tumor, spleen and blood, the number of cytotoxic CD8⁺ T cells and CD57⁺ natural killer cells and the levels of IL-10 increased, but that of tumor necrosis factor-α (TNF-α), IL-1β and IL-6 decreased. We also found that forced overexpression of IL-32γ inhibited colon cancer cell (SW620 and HCT116) growth accompanied with the inhibition of activated NF-κB and STAT3 in vitro. In addition, when IL-32γ was knocked down by small interfering RNA (siRNA) or neutralized with an anti-IL-32γ antibody, IL-32γ-induced colon cancer cell growth inhibition, the IL-32γ-induced decrease of TNF-α, IL-1 and IL-6 production, and the increase of IL-10 production were abolished. However, siRNA of NF-κB and STAT3 augmented IL-32γ-induced colon cancer cell growth inhibition. These findings indicate significant pathophysiological roles of IL-32γ in cancer development.

Native IL-32 is released from intestinal epithelial cells via a non-classical secretory pathway as a membrane-associated protein

Although IL-32 has been shown to be induced under various pathological conditions, a detailed understanding of native IL-32 intracellular distribution and mechanism of release from cells has not been reported. We examined the expression of IL-32 in the intestinal epithelial cell line HT-29 following TNFα and IFNγ co-stimulation. The subcellular localization of induced IL-32 was associated with the membrane of lipid droplet-like structures and vacuolar structures that co-localized with markers of endosomes and lysosomes. Prolonged co-stimulation resulted in cell death and appearance of IL-32 in the culture medium. IL-32 released from co-stimulated HT-29 cells was found in a detergent-sensitive particulate fraction, and in a step density gradient the IL-32 particulate was buoyant, suggesting association with a membrane-bound vesicle. Upon Triton X-114 partitioning, most of the IL-32 partitioned to the detergent phase, suggesting hydrophobic characteristics. When IL-32-containing vesicles were subjected to protease K treatment, a protease resistant ∼12kDa fragment was generated from ∼24kDa IL-32. We propose that under these conditions, native IL-32 is released via a non-classical secretory route perhaps involving multi-vesicular bodies and exosomes. Demonstration of membrane association for both intracellular and released IL-32 suggests this unique cytokine may have a complex biosynthetic pathway and mechanism of action.

Activation of the interleukin-32 pro-inflammatory pathway in response to human papillomavirus infection and over-expression of interleukin-32 controls the expression of the human papillomavirus oncogene

High-risk variants of human papillomavirus (HPV) induce cervical cancer by persistent infection, and are regarded as the principal aetiological factor in this malignancy. The pro-inflammatory cytokine interleukin-32 (IL-32) is present at substantial levels in cervical cancer tissues and in HPV-positive cervical cancer cells. In this study, we identified the mechanism by which the high-risk HPV-16 E7 oncogene induces IL-32 expression in cervical cancer cells. We used antisense transfection, over-expression, or knock-down of IL-32 to assess the effects of the HPV-16 E7 oncogene on IL-32 expression in cervical cancer cells. Cyclo-oxygenase 2 (COX-2) inhibitor treatment was conducted, and the expression levels, as well as the promoter activities, of IL-32 and COX-2 were evaluated in human HPV-positive cervical cancer cell lines. E7 antisense treatment reduced the expression levels and promoter activities of COX-2, which is constitutively expressed in HPV-infected cells. Constitutively expressed IL-32 was also inhibited by E7 antisense treatment. Moreover, IL-32 expression was blocked by the application of the selective COX-2 inhibitor, NS398, whereas COX-2 over-expression resulted in increased IL-32 levels. These results show that the high-risk variant of HPV induces IL-32 expression via E7-mediated COX-2 stimulation. However, E7 and COX-2 were down-regulated in the IL-32γ over-expressing cells and recovered by IL-32 small interfering RNA, indicating that E7 and COX-2 were feedback-inhibited by IL-32γ in cervical cancer cells.

Chungsim-Yeunja-Tang decreases the inflammatory response in peripheral blood mononuclear cells from patients with cerebral infarction through an NF-κB dependent mechanism

Background

Chungsim-Yeunja-Tang (CYT) has been used as a medicine for cerebral infarction (CI) patients in Korea. The objective of this study was to determine precisely the effect of CYT on CI patients using peripheral blood mononuclear cells (PBMCs).

Methods

For a clinical study, 47 CI patients were identified who had taken CYT (0.01 g/kg) 3 times a day after meals for 2 weeks by oral administration. For ex vivo experiments, peripheral blood mononuclear cells (PBMCs) were isolated from CI patients. We analyzed the effect of CYT and its main components on lipopolysaccharide (LPS)-induced cytokine production and mechanism on PBMCs of CI patients by using ELISA, western blot analysis, transcription factor enzyme-linked immunoassay, and caspase assay.

Results

Clinical signs of CI significantly disappeared about 2 weeks after oral administration of CYT to CI patients (P < 0.05). CYT and quercetin, an active compound of CYT, significantly inhibited LPS-induced interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α production and expression in PBMCs. CYT and quercetin also inhibited LPS-induced nuclear translocation and DNA binding activities of nuclear factor-κB and degradation of IκBα. In addition, CYT and quercetin inhibited LPS-induced IL-32 expression and caspase-1 activation.

Conclusion

These results suggest a mechanism that might explain the beneficial effect of CYT in treating CI patients. Taken together, our findings indicate that inhibition of IL-32 expression and caspase-1 activation may be a novel biomarker and potential therapeutic target in CI.

Down-regulation of p38 mitogen-activated protein kinase activation and proinflammatory cytokine production by mitogen-activated protein kinase inhibitors in inflammatory bowel disease

Crohn's disease and ulcerative colitis are inflammatory bowel diseases (IBD) characterized by chronic relapsing mucosal inflammation. Tumour necrosis factor (TNF)-α, a known agonist of the mitogen-activated protein kinase (MAPK) pathway, is a key cytokine in this process. We aimed first to determine whether p38 MAPK is activated in IBD inflamed mucosa, and then studied the effect of four different p38α inhibitory compounds on MAPK phosphorylation and secretion of proinflammatory cytokines by IBD lamina propria mononuclear cells (LPMCs) and organ culture biopsies. In vivo phospho-p38α and p38α expression was evaluated by immunoblotting on intestinal biopsies from inflamed areas of patients affected by Crohn's disease and ulcerative colitis, and from normal mucosa of sex- and age-matched control subjects. Both mucosal biopsies and isolated LPMCs were incubated with four different p38α selective inhibitory drugs. TNF-α, interleukin (IL)-1β and IL-6 were measured in the organ and cell culture supernatants by enzyme-linked immunosorbent assay. We found higher levels of phospho-p38α in the inflamed mucosa of IBD patients in comparison to controls. All the p38α inhibitory drugs inhibited p38α phosphorylation and secretion of TNF-α, IL-1β and IL-6 from IBD LPMCs and biopsies. Activated p38α MAPK is up-regulated in the inflamed mucosa of patients with IBD. Additionally, all the p38α selective inhibitory drugs significantly down-regulated the activation of the MAPK pathway and the secretion of proinflammatory cytokines.

Butyrate stimulates IL-32α expression in human intestinal epithelial cell lines

AIM: To investigate the effects of butyrate on interleukin (IL)-32α expression in epithelial cell lines.

METHODS: The human intestinal epithelial cell lines HT-29, SW480, and T84 were used. Intracellular IL-32α was determined by Western blotting analyses. IL-32α mRNA expression was analyzed by real-time polymerase chain reaction.

RESULTS: Acetate and propionate had no effects on IL-32α mRNA expression. Butyrate significantly enhanced IL-32α expression in all cell lines. Butyrate also up-regulated IL-1β-induced IL-32α mRNA expression. Butyrate did not modulate the activation of phosphatidylinositol 3-kinase (PI3K), a mediator of IL-32α expression. Like butyrate, trichostatin A, a histone deacetylase inhibitor, also enhanced IL-1β-induced IL-32α mRNA expression.

CONCLUSION: Butyrate stimulated IL-32α expression in epithelial cell lines. An epigenetic mechanism, such as histone hyperacetylation, might be involved in the action of butyrate on IL-32α expression.

IL-32 is a host protective cytokine against Mycobacterium tuberculosis in differentiated THP-1 human macrophages

Macrophages provide a first line of defense against Mycobacterium tuberculosis. However, in instances where macrophage activation for killing is suboptimal, M. tuberculosis is capable of surviving intracellularly. IL-32 is a recently described cytokine induced by M. tuberculosis in a variety of cell types including human monocytes and macrophages. In this study, we investigated the biological significance of IL-32 in an in vitro model of M. tuberculosis infection in differentiated THP-1 human macrophages in which IL-32 expression was silenced using stable expression of short hairpin RNA (shRNA). Inhibition of endogenous IL-32 production in THP-1 cells that express one of three distinct shRNA-IL-32 constructs significantly decreased M. tuberculosis induction of TNF-alpha by approximately 60%, IL-1beta by 30-60%, and IL-8 by 40-50% and concomitantly increased the number of cell-associated M. tuberculosis bacteria compared with THP-1 cells stably expressing a scrambled shRNA. In THP-1 cells infected with M. tuberculosis and stimulated with rIL-32, a greater level of apoptosis was observed compared with that with M. tuberculosis infection alone. Obversely, there was significant abrogation of apoptosis induced by M. tuberculosis and a concomitant decrease in caspase-3 activation in cells depleted of endogenous IL-32. rIL-32gamma significantly reduced the number of viable intracellular M. tuberculosis bacteria, which was modestly but significantly abrogated with a caspase-3 inhibitor. We conclude that IL-32 plays a host defense role against M. tuberculosis in differentiated THP-1 human macrophages.

Analysis of FOXP3+ regulatory T cells that display apparent viral antigen specificity during chronic hepatitis C virus infection

We reported previously that a proportion of natural CD25(+) cells isolated from the PBMC of HCV patients can further upregulate CD25 expression in response to HCV peptide stimulation in vitro, and proposed that virus-specific regulatory T cells (Treg) were primed and expanded during the disease. Here we describe epigenetic analysis of the FOXP3 locus in HCV-responsive natural CD25(+) cells and show that these cells are not activated conventional T cells expressing FOXP3, but hard-wired Treg with a stable FOXP3 phenotype and function. Of approximately 46,000 genes analyzed in genome wide transcription profiling, about 1% were differentially expressed between HCV-responsive Treg, HCV-non-responsive natural CD25(+) cells and conventional T cells. Expression profiles, including cell death, activation, proliferation and transcriptional regulation, suggest a survival advantage of HCV-responsive Treg over the other cell populations. Since no Treg-specific activation marker is known, we tested 97 NS3-derived peptides for their ability to elicit CD25 response (assuming it is a surrogate marker), accompanied by high resolution HLA typing of the patients. Some reactive peptides overlapped with previously described effector T cell epitopes. Our data offers new insights into HCV immune evasion and tolerance, and highlights the non-self specific nature of Treg during infection.

Suppressing IL-32 in monocytes impairs the induction of the proinflammatory cytokines TNFalpha and IL-1beta

Targeting major proinflammatory cytokines such as IL-1beta and TNFalpha is of great interest in patients with chronic inflammatory diseases, including rheumatoid arthritis, colitis, and psoriasis. The cytokine Interleukin (IL)-32 induces proinflammatory cytokines such as TNFalpha, IL-1beta, IL-6, and chemokines. We previously used an IL-32 ligand-affinity column to purify proteinase 3, which is abundantly expressed in neutrophil and monocytic leukocytes but not in other cell types, and found that IL-32 is mainly produced by monocytic leukocytes. This evidence suggested that silencing endogenous IL-32 by short hairpin RNA (shRNA) in monocytic cells might reveal the precise function of endogenous IL-32. Indeed, lipopolysaccharide (LPS)- or phorbol myristate acetate (PMA)-induced proinflammatory cytokine production was significantly inhibited in shRNA/IL-32 stable clones as compared to control clones. Furthermore, macrophages in PMA-differentiated shRNA/IL-32 stable clones displayed remarkably impaired LPS- and IL-1beta-induced proinflammatory cytokine production. These data suggest that IL-32 is not only involved in host defense against pathogens, but also might play a role in chronic inflammatory diseases. IL-32 production leads to major proinflammatory cytokine production during the initial immune response.

Gene expression profiling in neutrophils from children with polyarticular juvenile idiopathic arthritis

OBJECTIVE

We have previously reported a defect in neutrophil activation in children with polyarticular juvenile idiopathic arthritis (JIA). The current study was undertaken to determine whether gene expression abnormalities persist in JIA in remission and to use systems biology analysis to elucidate pathologic pathways in polyarticular JIA.

METHODS

We performed gene expression profiling on neutrophils from children with polyarticular JIA. Children were grouped according to disease status. We studied 14 children with active disease who were taking medication, 8 children with clinical remission of disease who were taking medication (CRM status), and 6 children with clinical remission of disease who were not taking medication (CR status). We also studied 13 healthy children whose age ranges overlapped those of the patients.

RESULTS

Neutrophil abnormalities persisted in children with polyarticular JIA even after disease remission was achieved. Children with active disease and those with CRM status showed no differences in expression of specific genes, although they could be separated on cluster analysis. A comparison of children with CR status and healthy control children revealed networks of pro- and antiinflammatory genes that suggested that remission is a state of homeostasis and balance rather than a return to normal immune function. Furthermore, gene overexpression in patients with CR status supports the hypothesis that neutrophils play a role in regulating adaptive immunity in this disease.

CONCLUSION

Neutrophil gene profiling in polyarticular JIA suggests important roles for neutrophils in disease pathogenesis. These findings suggest the presence of complex interactions between innate and adaptive immunity, that are not easily modeled in conventional, linear, reductionist systems.

Differential expression of immunoregulatory genes in monocytes in response to Porphyromonas gingivalis and Escherichia coli lipopolysaccharide

Porphyromonas gingivalis lipopolysaccharide (LPS) (strain W50) interacts with Toll-like receptor 2 (TLR-2) leading to cytokine expression and inflammation, and thereby plays a key role in the pathogenesis of periodontal disease. The aims of this study were to investigate gene expression of key regulatory mediators of innate immune responses in a human monocytic cell line (THP-1) to P. gingivalis LPS and to compare these results with those obtained using the TLR-4 ligand, Escherichia coli LPS. Custom-made Taqman low-density arrays were used for expression profiling of 45 different cytokine-related genes. Both types of LPS highly up-regulated interleukin (IL)-1alpha and IL-1beta, IL-18 receptor (IL-18R), IL-18R accessory protein and IL-1 family (IL-1F)9. Expression levels of IL-1F6, IL-1F7 and caspase-1 were unaltered by either LPS. Genes for tumour necrosis factor-alpha, IL-6, leukaemia inhibitory factor and IL-32 were also highly induced by both LPS. For a subset of genes, including CXC chemokine ligand 5 (CXCL5), expression was induced only by E. coli LPS or was up-regulated more highly by E. coli compared with P. gingivalis LPS in THP-1 monocytes. A similar expression pattern was also observed in dendritic cells. Analysis of signalling pathways which lead to CXCL5 expression indicated that the mechanisms underpinning the differential responses did not involve the recruitment of different adaptor proteins by TLR-2 and TLR-4, and therefore occur downstream of the receptor-adaptor complex. We conclude that differences in signalling pathways activated by TLR-2 and TLR-4 ligands lead to differential innate immune responses which may be important in polymicrobial diseases such as periodontal disease.

The biological and clinical importance of the 'new generation' cytokines in rheumatic diseases

A better understanding of cytokine biology over the last two decades has allowed the successful development of cytokine inhibitors against tumour necrosis factor and interleukin (IL)-1 and IL-6. The introduction of these therapies should be considered a breakthrough in the management of several rheumatic diseases. However, many patients will exhibit no or only partial response to these therapies, thus emphasising the importance of exploring other therapeutic strategies. In this article, we review the most recent information on novel cytokines that are often members of previously described cytokine families such as the IL-1 superfamily (IL-18 and IL-33), the IL-12 superfamily (IL-27 and IL-35), the IL-2 superfamily (IL-15 and IL-21), and IL-17. Several data derived from experimental models and clinical samples indicate that some of these cytokines contribute to the pathophysiology of arthritis and other inflammatory diseases. Targeting of some of these cytokines has already been tested in clinical trials with interesting results.

Tumor necrosis factor alpha-induced interleukin-32 is positively regulated via the Syk/protein kinase Cdelta/JNK pathway in rheumatoid synovial fibroblasts

OBJECTIVE

Interleukin-32 (IL-32) is a recently discovered cytokine that appears to play a critical role in human rheumatoid arthritis (RA). It is highly expressed in synovium and fibroblast-like synoviocytes (FLS) from RA patients, but not in patients with osteoarthritis (OA). This study was undertaken to assess IL-32 levels in RA synovial fluid (SF) and to investigate the secretion and regulation of IL-32 in RA FLS.

METHODS

FLS and SF were obtained from the joints of RA patients. The secretion and expression of IL-32 and activation of signaling molecules were examined by enzyme-linked immunosorbent assay, immunoblotting, immunoprecipitation, reverse transcriptase-polymerase chain reaction, and small interfering RNA (siRNA) transfection.

RESULTS

IL-32 levels were high in RA SF compared with OA SF. Furthermore, RA FLS expressed and secreted IL-32 when stimulated with tumor necrosis factor alpha (TNFalpha). TNFalpha-induced expression of IL-32 was significantly suppressed, in a dose-dependent manner, by inhibitors of Syk, protein kinase Cdelta (PKCdelta), and JNK and by knockdown of these kinases and c-Jun with siRNA. We also observed that PKCdelta mediated the activation of JNK and c-Jun, and experiments using specific inhibitors and siRNA demonstrated that Syk was the upstream kinase for the activation of PKCdelta.

CONCLUSION

The present findings suggest that IL-32 may be a newly identified prognostic biomarker in RA, thereby adding valuable knowledge to the understanding of this disease. The results also demonstrate that the production of IL-32 in RA FLS is regulated by Syk/PKCdelta-mediated signaling events.

Interleukin-32 expression in the pancreas

Interleukin (IL)-32 is a recently described proinflammatory cytokine characterized by the induction of nuclear factor (NF)-kappaB activation. We studied IL-32 expression in human pancreatic tissue and pancreatic cancer cell lines. Tissue samples were obtained surgically. IL-32 expression was evaluated by standard immunohistochemical procedures. IL-32 mRNA expression was analyzed by Northern blotting and real time PCR analyses. IL-32 was weakly immunoexpressed by pancreatic duct cells. In the inflamed lesions of chronic pancreas, the ductal expression of IL-32 was markedly increased. A strong expression of IL-32alpha was detected in the pancreatic cancer cells. In pancreatic cancer cell lines (PANC-1, MIA PaCa-2, and BxPC-3 cells), the expression of IL-32 mRNA and protein was enhanced by IL-1beta, interferon (IFN)-gamma, and tumor necrosis factor (TNF)-alpha. An inhibitor of phosphatidylinositol 3-kinase (LY294002) significantly suppressed the IL-1beta-, IFN-gamma- and TNF-alpha-induced IL-32 mRNA expression. The blockade of NF-kappaB and activated protein-1 activation markedly suppressed the IL-1beta-, IFN-gamma-, and/or TNF-alpha-induced IL-32 mRNA expression. Furthermore, IL-32-specific small interfering RNA significantly decreased the uptake of [3H]thymidine and increased the annexin V-positive population (apoptotic cells) in PANC-1 cells. IL-32 knockdown also suppressed the mRNA expression of antiapoptotic proteins (Bcl-2, Bcl-xL, and Mcl-1). Pancreatic duct cells are the local source of IL-32, and IL-32 may play an important role in inflammatory responses and pancreatic cancer growth.

IL-32-dependent effects of IL-1beta on endothelial cell functions

Increasing evidence demonstrates that interleukin (IL)-32 is a pro-inflammatory cytokine, inducing IL-1alpha, IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha, and chemokines via nuclear factor (NF)-kappaB, p38 mitogen-activated protein kinase (MAPK), and activating protein (AP)-1 activation. Here we report that IL-32 is expressed and is also functional in human vascular endothelial cells (EC) of various origins. Compared with primary blood monocytes, high levels of IL-32 are constitutively produced in human umbilical vein EC (HUVEC), aortic macrovascular EC, and cardiac as well as pulmonary microvascular EC. At concentrations as low as 0.1 ng/ml, IL-1beta stimulated IL-32 up to 15-fold over constitutive levels, whereas 10 ng/ml of TNFalpha or 100 ng/ml of lipopolysaccharide (LPS) were required to induce similar quantities of IL-32. IL-1beta-induced IL-32 was reduced by inhibition of the IkappaB kinase-beta/NF-kappaB and ERK pathways. In addition to IL-1beta, pro-coagulant concentrations of thrombin or fresh platelets increased IL-32 protein up to 6-fold. IL-1beta and thrombin induced an isoform-switch in steady-state mRNA levels from IL-32alpha/gamma to beta/epsilon. Adult EC responded in a similar fashion. To prove functionality, we silenced endogenous IL-32 with siRNA, decreasing intracellular IL-32 protein levels by 86%. The knockdown of IL-32 resulted in reduction of constitutive as well as IL-1beta-induced intercellular adhesion molecule-1 (ICAM-1) (of 55% and 54%, respectively), IL-1alpha (of 62% and 43%), IL-6 (of 53% and 43%), and IL-8 (of 46% and 42%). In contrast, the anti-inflammatory/anti-coagulant CD141/thrombomodulin increased markedly when IL-32 was silenced. This study introduces IL-32 as a critical regulator of endothelial function, expanding the properties of this cytokine relevant to coagulation, endothelial inflammation, and atherosclerosis.

Oncostatin M enhances the antiviral effects of type I interferon and activates immunostimulatory functions in liver epithelial cells

Oncostatin M (OSM) is released together with type I interferon (IFN) by activated dendritic cells, suggesting a concerted action of these cytokines in the biological response against infection. We found that OSM increases the antiviral effect of IFN-alpha in Huh7 hepatoma cells infected with hepatitis A or hepatitis C virus and synergizes with IFN-alpha in the induction of antiviral genes. The combination of OSM and IFN-alpha led to upregulation of both STAT1 and STAT3 together with intense and prolonged activation of STAT1, STAT3, and Jak1. OSM with or without IFN-alpha also activated p38 mitogen-activated protein kinase, which is known to enhance transcription of IFN-alpha-inducible genes. Interestingly, OSM combined with IFN-alpha strongly induced immunoproteasome genes and other genes involved in antigen processing and presentation. Moreover, OSM, alone or in combination with IFN-alpha, upregulated relevant innate immunity molecules and increased the expression of intracellular adhesion molecule 1 and interleukin-15 receptor alpha (IL-15Ralpha) in liver cells. Hepatoma cells transfected with a plasmid encoding a viral antigen were able to activate effector T cells when pretreated with IFN-alpha plus OSM but not with each cytokine separately. Also, OSM, more than IFN-alpha, augmented the ability of Huh7 cells to transpresent IL-15 to responding lymphocytes and increased the immunostimulatory activity of liver epithelial cells by presenting a short viral peptide to sensitized cytotoxic T cells. In conclusion, OSM enhances the antiviral effects of type I interferon and cooperates with it in the induction of adaptive immune responses to pathogens. These findings may have therapeutic implications.

A proinflammatory cytokine interleukin-32beta promotes the production of an anti-inflammatory cytokine interleukin-10

A new proinflammatory cytokine interleukin-32 (IL-32) has six isoforms. Although IL-32 can be detected in sera from patients suffering from Crohn's disease and rheumatoid arthritis, it is unclear which isoforms are involved. To this end, we investigated the functions of the most abundant IL-32beta by generating K562-IL-32beta stable cell lines. This report confirms, using IL-32 small interfering RNA, that IL-32beta induces an anti-inflammatory cytokine IL-10 in K562-IL-32beta cells and U937 promonocytic cells, which express endogenous IL-32beta upon phorbol 12-myristate 13-acetate (PMA) treatment, and monocyte-derived dendritic cells (DC) upon lipopolysaccharide (LPS) treatment. Interleukin-32beta was induced in monocyte-derived macrophages by LPS and in monocyte-derived DC by LPS, poly(I:C), or anti-CD40 antibody, but was not induced by PMA. We showed that IL-32beta expression was increased in a time-dependent manner in monocyte-derived DC upon LPS treatment and peaked at 24 hr. Production of IL-10 was exactly coincident with IL-32beta expression, but IL-1beta and tumour necrosis factor-alpha production peaked at 6 hr after LPS treatment, then steeply declined. Interleukin-12 p40 was induced at 9 hr and gradually increased until 48 hr, at which time IL-32beta and IL-10 were no longer increased. Knock-down of IL-32beta by IL-32 small interfering RNA led to the decrease of IL-10, but the increase of IL-12 in monocyte-derived DC, which means that IL-32beta promotes IL-10 production, but limits IL-12 production. We also showed that IL-10 neutralization increases IL-12, IL-1beta and tumour necrosis factor-alpha production, which implies that IL-10 suppresses such proinflammatory cytokines. Taken together, our results suggest that IL-32beta upregulates the production of an anti-inflammatory cytokine IL-10, and then IL-10 suppresses proinflammatory cytokines.

Gene expression profiling in limb-girdle muscular dystrophy 2A

Limb-girdle muscular dystrophy type 2A (LGMD2A) is a recessive genetic disorder caused by mutations in calpain 3 (CAPN3). Calpain 3 plays different roles in muscular cells, but little is known about its functions or in vivo substrates. The aim of this study was to identify the genes showing an altered expression in LGMD2A patients and the possible pathways they are implicated in. Ten muscle samples from LGMD2A patients with in which molecular diagnosis was ascertained were investigated using array technology to analyze gene expression profiling as compared to ten normal muscle samples. Upregulated genes were mostly those related to extracellular matrix (different collagens), cell adhesion (fibronectin), muscle development (myosins and melusin) and signal transduction. It is therefore suggested that different proteins located or participating in the costameric region are implicated in processes regulated by calpain 3 during skeletal muscle development. Genes participating in the ubiquitin proteasome degradation pathway were found to be deregulated in LGMD2A patients, suggesting that regulation of this pathway may be under the control of calpain 3 activity. As frizzled-related protein (FRZB) is upregulated in LGMD2A muscle samples, it could be hypothesized that beta-catenin regulation is also altered at the Wnt signaling pathway, leading to an incorrect myogenesis. Conversely, expression of most transcription factor genes was downregulated (MYC, FOS and EGR1). Finally, the upregulation of IL-32 and immunoglobulin genes may induce the eosinophil chemoattraction explaining the inflammatory findings observed in presymptomatic stages. The obtained results try to shed some light on identification of novel therapeutic targets for limb-girdle muscular dystrophies.