The cytokine receptor gp130: faithfully promiscuous

The IL6-like Cytokine Family: Role and Biomarker Potential in Breast Cancer

IL6-like cytokines are a family of regulators with a complex, pleiotropic role in both the healthy organism, where they regulate immunity and homeostasis, and in different diseases, including cancer. Here we summarise how these cytokines exert their effect through the shared signal transducer IL6ST (gp130) and we review the extensive evidence on the role that different members of this family play in breast cancer. Additionally, we discuss how the different cytokines, their related receptors and downstream effectors, as well as specific polymorphisms in these molecules, can serve as predictive or prognostic biomarkers with the potential for clinical application in breast cancer. Lastly, we also discuss how our increasing understanding of this complex signalling axis presents promising opportunities for the development or repurposing of therapeutic strategies against cancer and, specifically, breast neoplasms.

Regulation of gene expression in the bovine blastocyst by colony-stimulating factor 2 is disrupted by CRISPR/Cas9-mediated deletion of CSF2RA

Colony-stimulating factor 2 (CSF2) functions in the reproductive tract to modulate the function of the preimplantation embryo. The β subunit of the CSF2 receptor (CSF2RB) is not expressed in the embryo, and signal transduction is therefore different than for myeloid cells where the receptor is composed of α (CSF2RA) and β subunits. Here, we produced embryos in which exons 5 and 6 of CSF2RA were disrupted using the CRISPR/Cas 9 system to test whether CSF2RA signaling was essential for actions of CSF2 in the bovine embryo. Wild-type and CSF2RA knockout embryos were treated with 10 ng/mL CSF2 or vehicle at day 5 of development. Blastocysts were harvested at day 8 to determine transcript abundance of 90 genes by real-time polymerase chain reaction (PCR). Responses in female blastocysts were examined separately from male blastocysts because actions of CSF2 are sex-dependent. For wild-type embryos, CSF2 altered expression of 10 genes in females and 20 in males. Only three genes were affected by CSF2 in a similar manner for both sexes. Disruption of CSF2RA prevented the effect of CSF2 on expression for 9 of 10 CSF2-regulated genes in females and 19 of 20 genes in males. The results confirm the importance of CSF2RA for regulation of gene expression by CSF2 in the blastocyst.

Metformin inhibits IL-6 signaling by decreasing IL-6R expression on multiple myeloma cells

IL-6 signaling plays a crucial role in the pathogenesis of a number of diseases, including multiple myeloma, primary amyloidosis, cytokine release syndrome and other inflammatory conditions. It is central for the growth and survival of malignant plasma cells. IL-6R and IL-6ST receptors transduce IL-6 signaling. Molecular mechanisms regulating expression of IL-6R are not well understood and current therapies are based on monoclonal antibody to target IL-6 signaling. Small molecule inhibitors targeting IL-6 signaling are highly desirable. Metformin specifically decreased IL-6R expression which is mediated via AMPK, mTOR, and miR34a. This is a novel finding and adds to existing therapies targeting IL-6 signaling.

A Subset of TREM2+ Dermal Macrophages Secretes Oncostatin M to Maintain Hair Follicle Stem Cell Quiescence and Inhibit Hair Growth

Hair growth can be induced from resting mouse hair follicles by topical application of JAK inhibitors, suggesting that JAK-STAT signaling is required for maintaining hair follicle stem cells (HFSCs) in a quiescent state. Here, we show that Oncostatin M (OSM), an IL-6 family cytokine, negatively regulates hair growth by signaling through JAK-STAT5 to maintain HFSC quiescence. Genetic deletion of the OSM receptor or STAT5 can induce premature HFSC activation, suggesting that the resting telogen stage is actively maintained by the hair follicle niche. Single-cell RNA sequencing revealed that the OSM source is not intrinsic to the hair follicle itself and is instead a subset of TREM2⁺ macrophages that is enriched within the resting follicle and deceases immediately prior to HFSC activation. In vivo inhibition of macrophage function was sufficient to induce HFSC proliferation and hair cycle induction. Together these results clarify how JAK-STAT signaling actively inhibits hair growth.

STAT3-mediated SMAD3 activation underlies Oncostatin M-induced Senescence

Cytokines in the developing tumor microenvironment (TME) can drive transformation and subsequent progression toward metastasis. Elevated levels of the Interleukin-6 (IL-6) family cytokine Oncostatin M (OSM) in the breast TME correlate with aggressive, metastatic cancers, increased tumor recurrence, and poor patient prognosis. Paradoxically, OSM engages a tumor-suppressive, Signal Transducer and Activator of Transcription 3 (STAT3)-dependent senescence response in normal and non-transformed human mammary epithelial cells (HMEC). Here, we identify a novel link between OSM-activated STAT3 signaling and the Transforming Growth Factor-β (TGF-β) signaling pathway that engages senescence in HMEC. Inhibition of functional TGF-β/SMAD signaling by expressing a dominant-negative TGF-β receptor, treating with a TGF-β receptor inhibitor, or suppressing SMAD3 expression using a SMAD3-shRNA prevented OSM-induced senescence. OSM promoted a protein complex involving activated-STAT3 and SMAD3, induced the nuclear localization of SMAD3, and enhanced SMAD3-mediated transcription responsible for senescence. In contrast, expression of MYC (c-MYC) from a constitutive promoter abrogated senescence and strikingly, cooperated with OSM to promote a transformed phenotype, epithelial-mesenchymal transition (EMT), and invasiveness. Our findings suggest that a novel STAT3/SMAD3-signaling axis is required for OSM-mediated senescence that is coopted during the transformation process to confer aggressive cancer cell properties. Understanding how developing cancer cells bypass OSM/STAT3/SMAD3-mediated senescence may help identify novel targets for future "pro-senescence" therapies aiming to reengage this hidden tumor-suppressive response.

Classical and non-classical proangiogenic factors as a target of antiangiogenic therapy in tumor microenvironment

Angiogenesis is sustained by classical and non-classical proangiogenic factors (PFs) acting in tumor microenvironment and these factors are also potential targets of antiangiogenic therapies. All PFs induce the overexpression of several signaling pathways that lead to migration and proliferation of endothelial cells contributing to tumor angiogenesis and survival of cancer cells. In this review, we have analyzed each PF with its specific receptor/s and we have summarized the available antiangiogenic drugs (e.g. monoclonal antibodies) targeting these PFs, some of these agents have already been approved, others are currently in development for the treatment of several human malignancies.

miR-203, a tumor suppressor frequently down-regulated by promoter hypermethylation in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma found in children and young adults. It is characterized by the expression of a number of skeletal muscle-specific proteins, including MyoD and muscle α-actin. However, unlike normal myoblasts, RMS cells differentiate poorly both in vivo and in culture. As microRNAs are known to regulate tumorigenesis, intensive efforts have been made to identify microRNAs that are involved in RMS development. In this work, we found that miR-203 was frequently down-regulated by promoter hypermethylation in both RMS cell lines and RMS biopsies and could be reactivated by DNA-demethylating agents. Re-expression of miR-203 in RMS cells inhibited their migration and proliferation and promoted terminal myogenic differentiation. Mechanistically, miR-203 exerts its tumor-suppressive effect by directly targeting p63 and leukemia inhibitory factor receptor in RMS cells, which promotes myogenic differentiation by inhibiting the Notch and the JAK1/STAT1/STAT3 pathways, respectively. Our work reveals that miR-203 functions as a tumor suppressor in RMS development.

Stress in the adult rat exacerbates muscle pain induced by early-life stress

BACKGROUND

Early-life stress and exposure to stressful stimuli play a major role in the development of chronic widespread pain in adults. However, how they interact in chronic pain syndromes remains unclear.

METHODS

Dams and neonatal litters were submitted to a restriction of nesting material (neonatal limited bedding [NLB]) for 1 week. As adults, these rats were exposed to a painless sound stress protocol. The involvement of sympathoadrenal catecholamines interleukin 6 (IL-6) and tumor necrosis factor alpha (TNFα) in nociception was evaluated through behavioral and enzyme-linked immunosorbent assays, surgical interventions, and intrathecal antisense treatments.

RESULTS

Adult NLB rats exhibited mild muscle hyperalgesia, which was markedly aggravated by sound stress (peaking 15 days after exposure). Adrenal medullectomy did not modify hyperalgesia in NLB rats but prevented its aggravation by sound stress. Sustained administration of epinephrine to NLB rats mimicked sound stress effect. Intrathecal treatment with antisense directed to IL-6 receptor subunit gp130 (gp130), but not to tumor necrosis factor receptor type 1 (TNFR1), inhibited hyperalgesia in NLB rats. However, antisense against either gp130 or TNFR1 inhibited sound stress-induced enhancement of hyperalgesia. Compared with control rats, NLB rats exhibit increased plasma levels of IL-6 but decreased levels of TNFα, whereas sound stress increases IL-6 plasma levels in control rats but not in NLB rats.

CONCLUSIONS

Early-life stress induces a persistent elevation of IL-6, hyperalgesia, and susceptibility to chronic muscle pain, which is unveiled by exposure to stress in adults. This probably depends on an interaction between adrenal catecholamines and proinflammatory cytokines acting at muscle nociceptor level.

Gastric epithelial expression of IL-12 cytokine family in Helicobacter pylori infection in human: is it head or tail of the coin?

Recently, there has been a growing interest in an expanding group of cytokines known as "IL-12 family". The so far gained knowledge about these cytokines, as crucial playmakers in mucosal immunity, has not yet been sufficiently investigated in the context of Helicobacter pylori infection. All genes encoding the monomeric components of these cytokines and their corresponding receptors were examined in gastric epithelial cell lines (AGS and MKN-28) after being infected with 4 H. pylori strains: BCM-300, P1 wild-type, and P1-derived isogenic mutants lacking cytotoxin-associated gene A (cagA) or virulence gene virB7 (multiplicity of infection=50). Both infected and uninfected samples were analyzed after 24h and 48h using real-time quantitative polymerase chain reaction (RT-qPCR). Gene expression analysis demonstrated a strong upregulation of IL23A (encodes p19) by infection, whereas IL23R, Epstein-Barr virus-induced gene 3 (EBI3), IL6ST, IL12A, and IL27RA were found to be expressed, but not regulated, or to a lesser extent. Transcripts of IL12RB2, IL12B, IL12RB1, and IL27A were not detected. Interestingly, P1 resulted in stronger alterations of expression than CagA mutant and BCM-300, particularly for IL23A (59.7-fold versus 32.4- and 6.7-fold, respectively in AGS after 48h, P<.05), whereas no changes were seen with VirB7 mutant. In a proof-of-principle experiment, we demonstrated epithelial-derived expression of IL-12, p19, and Ebi3 in gastric mucosa of gastritis patients using immunohistochemistry (IHC). Unlike IL-12 and Ebi3, increased immunostaining of p19 was observed in H. pylori gastritis. Herein, we highlight the potential role of gastric epithelial cells in mucosal immunity, not only because they are predominant cell type in mucosa and initial site of host-bacterial interaction, but also as a major contributor to molecules that are thought to be primarily expressed by immune cells so far. Of these molecules, p19 was the most relevant one to H. pylori infection in terms of expression and localization.

Interleukin-6: an angiogenic target in solid tumours

During the past decade, incorporating anti-angiogenic agents into the therapeutic management of a myriad of malignancies has in certain cases made a significant impact on survival. However, the development of resistance to these drugs is inevitable and swift disease progression on their cessation often ensues. Hence, there is a drive to devise strategies that aim to enhance response to anti-angiogenic therapies by combining them with other targeted agents that facilitate evasion from resistance. The pleiotropic cytokine, interleukin-6 (IL-6), exerts pro-angiogenic effects in the tumour microenvironment of several solid malignancies and there is emerging evidence that reveals significant relationships between IL-6 signalling and treatment failure with antibodies directed against vascular endothelial growth factor (VEGF). This review summarises the role of IL-6 in pivotal angiogenic processes and preclinical/clinical research to support the future introduction of anti-IL-6 therapies to be utilised either in combination with other anti-angiogenic drugs or as a salvage therapy for patients with diseases that become refractory to these approaches.

Leptin-activity blockers: development and potential use in experimental biology and medicine

The first adipokine, leptin, discovered almost 20 years ago, is secreted into circulation mainly from adipose tissue and acts both centrally and peripherally. Leptin regulates energy metabolism, reproductive function, bone metabolism, and immune response. However in some physiological or pathological situations such as enhancement of undesired immune responses in autoimmune diseases, tumorigenesis, elevated blood pressure, and certain cardiovascular pathologies, leptin activity may be harmful. In this review we screen different approaches to blocking leptin action, in vitro and in vivo. The recent development of superactive leptin muteins exhibiting antagonistic properties, and other leptin-action-blocking peptides, proteins, monoclonal antibodies, and nanobodies, opens new perspectives for their use in research, and eventually, therapy for cachexia, autoimmune disease, cancer, and other pathologies.

Genetic evidence for an essential role of neuronally expressed IL-6 signal transducer gp130 in the induction and maintenance of experimentally induced mechanical hypersensitivity in vivo and in vitro

Tenderness and mechanical allodynia are key symptoms of malignant tumor, inflammation and neuropathy. The proinflammatory cytokine interleukin-6 (IL-6) is causally involved in all three pathologies. IL-6 not only regulates innate immunity and inflammation but also causes nociceptor sensitization and hyperalgesia. In general and in most cell types including immune cells and sensory neurons, IL-6 binds soluble μ receptor subunits which heteromerizes with membrane bound IL-6 signal transducer gp130. In the present study, we used a conditional knock-out strategy to investigate the importance of signal transducer gp130 expressed in C nociceptors for the generation and maintenance of mechanical hypersensitivity. Nociceptors were sensitized to mechanical stimuli by experimental tumor and this nociceptor sensitization was preserved at later stages of the pathology in control mice. However, in mice with a conditional deletion of gp130 in Nav1.8 expressing nociceptors mechanical hypersensitivity by experimental tumor, nerve injury or inflammation recovery was not preserved in the maintenance phase and nociceptors exhibited normal mechanical thresholds comparable to untreated mice. Together, the results argue for IL-6 signal transducer gp130 as an essential prerequisite in nociceptors for long-term mechanical hypersensitivity associated with cancer, inflammation and nerve injury.

Enhanced cytokine-induced mechanical hyperalgesia in skeletal muscle produced by a novel mechanism in rats exposed to unpredictable sound stress

Stress exacerbates both experimental and clinical pain, most well-characterized in irritable bowel and fibromyalgia syndromes. Since it has been hypothesized that cytokines play an etiopathogenic role in fibromyalgia and other chronic widespread pain conditions, we investigated the relationship between stress and cytokines in a model of stress-induced chronic somatic pain. A series of experiments were performed to evaluate the impact of stress on the hyperalgesia-induced by endotoxin (lipopolysaccharide, LPS) and the role of two pro-inflammatory cytokines, interleukin-6 (IL-6) and tumor necrosis α (TNFα). Fourteen days after exposure to a 4-day protocol of unpredictable sound stress, the ability of systemic LPS (100 μg/kg, i.p) to elicit cytokine-mediated mechanical hyperalgesia was measured in gastrocnemius muscle. LPS-induced hyperalgesia was significantly greater in stressed rats, but when rats were treated intrathecally with antisense oligodeoxynucleotide (ODN), to decrease either the gp130 subunit of the IL-6 receptor or the TNFα receptor, in nociceptors, skeletal muscle hyperalgesia in sound stressed, but not control, rats was prevented. These data suggest that chronic stress alters signaling in the primary afferent nociceptor for the hyperalgesia induced by endogenously produced pro-inflammatory cytokines.

Transgenic overexpression of HSP56 does not result in cardiac hypertrophy nor protect from ischaemia/reperfusion injury

Heat shock proteins are known to be induced during and following different forms of cardiac stress. It has previously been shown that their expression is beneficial for the heart following trauma such as ischaemia-reperfusion (I/R) injury. Heat shock protein 56 (HSP56) belongs to the family of FK506-binding immunophilin proteins and is found in steroid receptor complexes, notably the glucocorticoid receptor. We have previously shown that HSP56 and other HSPs are induced in cardiac myocytes treated with cardiotrophin-1, a cytokine with potent hypertrophic and protective properties on cardiac cells. The hypertrophic action of cardiotrophin-1 on cardiac cells is dependent on HSP56 induction and overexpression of HSP56 is sufficient for inducing hypertrophy in cardiac cells. To investigate this phenomenon in vivo, we have generated transgenic mice overexpressing HSP56 and assessed them for the development cardiac hypertrophy and resistance of their hearts to I/R-injury by Langendorff perfusion. Mice generated demonstrated stable, yet varying expression levels of HSP56. Initial characterisation identified a sex-specific phenotype where male overexpressing mice exhibited a moderate, but significant, reduced body weight compared to wild-type controls. In ex vivo stress analyses we found, unexpectedly, that significant overexpression of HSP56 does not induce myocardial hypertrophy and nor does it protect the intact heart from I/R-injury. These observations now suggest a more intricate HSP56-Sp. Cardiophenotype that requires further studies to determine if HSP56 is necessary in mediating hypertrophy induced by other myocardial stimuli.

A selection fit mechanism in BMP receptor IA as a possible source for BMP ligand-receptor promiscuity

Background

Members of the TGF-β superfamily are characterized by a highly promiscuous ligand-receptor interaction as is readily apparent from the numeral discrepancy of only seven type I and five type II receptors available for more than 40 ligands. Structural and functional studies have been used to address the question of how specific signals can be deduced from a limited number of receptor combinations and to unravel the molecular mechanisms underlying the protein-protein recognition that allow such limited specificity.

Principal Findings

In this study we have investigated how an antigen binding antibody fragment (Fab) raised against the extracellular domain of the BMP receptor type IA (BMPR-IA) recognizes the receptor's BMP-2 binding epitope and thereby neutralizes BMP-2 receptor activation. The crystal structure of the complex of the BMPR-IA ectodomain bound to the Fab AbD1556 revealed that the contact surface of BMPR-IA overlaps extensively with the contact surface for BMP-2 interaction. Although the structural epitopes of BMPR-IA to both binding partners coincides, the structures of BMPR-IA in the two complexes differ significantly. In contrast to the structural differences, alanine-scanning mutagenesis of BMPR-IA showed that the functional determinants for binding to the antibody and BMP-2 are almost identical.

Conclusions

Comparing the structures of BMPR-IA bound to BMP-2 or bound to the Fab AbD1556 with the structure of unbound BMPR-IA shows that binding of BMPR-IA to its interaction partners follows a selection fit mechanism, possibly indicating that the ligand promiscuity of BMPR-IA is inherently encoded by structural adaptability. The functional and structural analysis of the BMPR-IA binding antibody AbD1556 mimicking the BMP-2 binding epitope may thus pave the way for the design of low-molecular weight synthetic receptor binders/inhibitors.

Eccentric exercise induces chronic alterations in musculoskeletal nociception in the rat

Eccentric muscle exercise is a common cause of acute and chronic (lasting days to weeks) musculoskeletal pain. To evaluate the mechanisms involved, we have employed a model in the rat, in which eccentric hind limb exercise produces both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia to subsequent exposure to an inflammatory mediator. Eccentric exercise of the hind limb produced mechanical hyperalgesia, measured in the gastrocnemius muscle, which returned to baseline at 120 h post-exercise. When nociceptive thresholds had returned to baseline, intramuscular injection of prostaglandin E(2) (PGE(2) ) induced hyperalgesia that was unattenuated 240 h later, much longer than PGE(2) -induced hyperalgesia in unexercised rats (4 h). This marked prolongation of PGE(2) hyperalgesia induced by eccentric exercise was prevented by the spinal intrathecal injection of oligodeoxynucleotide antisense to protein kinase Cε, a second messenger in nociceptors implicated in the induction of chronic pain. Exercise-induced hyperalgesia and prolongation of PGE(2) hyperalgesia were inhibited by the spinal intrathecal administration of antisense for the interleukin-6 but not the tumor necrosis factor α type 1 receptor. These findings provide further insight into the mechanism underlying exercise-induced chronic muscle pain, and suggest novel approaches for the prevention and treatment of exercise- or work-related chronic musculoskeletal pain syndromes.

Immunohistochemical evaluation of inflammatory and proliferative markers in adjacent normal thyroid tissue in patients undergoing total thyroidectomy: results of a preliminary study

Background

Total thyroidectomy is the treatment of choice in the majority of thyroid malignancies, preventing the risk of reoperative surgery due to recurrences. In order to assess the usefulness of such an approach, expression levels of inflammatory and proliferative markers were evaluated immunohistochemically in non-lesional adjacent thyroid tissues from a group of patients who underwent total thyroidectomy for different thyroid diseases.

Methods

Nineteen consecutive patients treated by total thyroidectomy for different thyroid diseases entered the study. IL-6Rb gp130 component of the IL-6 cytokine family members receptor complexes, STAT3 cytokine signalling transduction and transcription activation factor, p53 as tumour suppressor and CK19 cytokeratin as proliferation marker were analyzed in non-lesional thyroid tissues.

Results

Gp 130 expression was detected in all tissue samples with a scattered distribution while STAT3 and p53 positivity was observed in 17 out of 19 patients with a prevailing cytoplasmic localization. Cytokeratin 19 positivity was found in patients with papillary carcinoma, in one case of follicular adenoma, 3 multinodular goiters and one Basedow disease.

Conclusion

Based on the results of this preliminary study, it may be concluded that the presence of a persisting cytokine-mediated activation associated with cytoplasmic localization of p53 is frequently observed in different thyroid diseases. Such a process seems to occur in the thyroid gland as a whole. Moreover, STAT3 activation as well as mutant p53 are risk factors for the development of neoplastic diseases. Total thyroidectomy may be supported as an adequate therapeutic approach for all the patients in whom overexpression of cytokine-dependent markers is detected.

IL-31-IL-31R interactions limit the magnitude of Th2 cytokine-dependent immunity and inflammation following intestinal helminth infection

IL-31 is a recently identified cytokine made predominantly by CD4(+) Th2 cells and its receptor, IL-31R, is expressed by a number of cell types including monocytes, epithelial cells, and T cells. Originally identified as a potential mediator of inflammation in the skin, we recently reported a novel function for endogenous IL-31R interactions in limiting type 2 inflammation in the lung. However, whether IL-31-IL-31R interactions regulate immunity or inflammation at other mucosal sites, such as the gut, is unknown. In this study, we report a regulatory role for IL-31-IL-31R interactions in the intestine following infection with the gastrointestinal helminth Trichuris muris, immunity to which is critically dependent on CD4(+) Th2 cells that produce IL-4 and IL-13. IL-31Ralpha was constitutively expressed in the colon and exposure to Trichuris induced the expression of IL-31 in CD4(+) T cells. In response to Trichuris infection, IL-31Ralpha(-/-) mice exhibited increased Th2 cytokine responses in the mesenteric lymph nodes and elevated serum IgE and IgG1 levels compared with wild type mice. IL-31Ralpha(-/-) mice also displayed enhanced goblet cell hyperplasia and a marked increase in secretion of goblet cell-derived resistin-like molecule beta into the intestinal lumen. Consistent with their exacerbated type 2 inflammatory responses, IL-31Ralpha(-/-) mice exhibited accelerated expulsion of Trichuris with significantly decreased worm burdens compared with their wild type counterparts early following infection. Collectively, these data provide the first evidence of a function for IL-31-IL-31R interactions in limiting the magnitude of type 2 inflammatory responses within the intestine.

Interleukin-35: odd one out or part of the family?

Advances in cytokine biology have helped us understand the complex communication that takes place between antigen-presenting cells and cells of the adaptive immune system, such as T cells, which collectively mediate an appropriate immune response to a plethora of pathogens while maintaining tolerance to self-antigens. The interleukin-12 (IL-12) cytokine family remains one of the most important and includes IL-12, IL-23, IL-27, and the recently identified IL-35. All four are heterodimeric cytokines, composed of an alpha chain (p19, p28, or p35) and a beta chain (p40 or Ebi3), and signal through unique pairings of five receptor chains (IL-12Rbeta1, IL-12Rbeta2, IL-23R, gp130, and WSX-1). Despite the interrelationship between the cytokines themselves and their receptors, their source, activity, and kinetics of expression are quite different. Studies using genetically deficient mice have greatly enhanced our understanding of the biology of these cytokines. However, interpretation of these data has been complicated by the recent realization that p40(-/-), p35(-/-), and Ebi3(-/-) mice all lack more than one cytokine (IL-12/IL-23, IL-12/IL-35, and IL-27/IL-35, respectively). In this review, we compare and contrast the biology of this expanded IL-12 family and re-evaluate data derived from the analysis of these dual cytokine-deficient mice. We also discuss how the opposing characteristics of the IL-12 family siblings may help to promote a balanced immune response.

A ligand peptide motif selected from a cancer patient is a receptor-interacting site within human interleukin-11

Interleukin-11 (IL-11) is a pleiotropic cytokine approved by the FDA against chemotherapy-induced thrombocytopenia. From a combinatorial selection in a cancer patient, we isolated an IL-11-like peptide mapping to domain I of the IL-11 (sequence CGRRAGGSC). Although this motif has ligand attributes, it is not within the previously characterized interacting sites. Here we design and validate in-tandem binding assays, site-directed mutagenesis and NMR spectroscopy to show (i) the peptide mimics a receptor-binding site within IL-11, (ii) the binding of CGRRAGGSC to the IL-11R alpha is functionally relevant, (iii) Arg4 and Ser8 are the key residues mediating the interaction, and (iv) the IL-11-like motif induces cell proliferation through STAT3 activation. These structural and functional results uncover an as yet unrecognized receptor-binding site in human IL-11. Given that IL-11R alpha has been proposed as a target in human cancer, our results provide clues for the rational design of targeted drugs.

LIF promotes neurogenesis and maintains neural precursors in cell populations derived from spiral ganglion stem cells

Background

Stem cells with the ability to form clonal floating colonies (spheres) were recently isolated from the neonatal murine spiral ganglion. To further examine the features of inner ear-derived neural stem cells and their derivatives, we investigated the effects of leukemia inhibitory factor (LIF), a neurokine that has been shown to promote self-renewal of other neural stem cells and to affect neural and glial cell differentiation.

Results

LIF-treatment led to a dose-dependent increase of the number of neurons and glial cells in cultures of sphere-derived cells. Based on the detection of developmental and progenitor cell markers that are maintained in LIF-treated cultures and the increase of cycling nestin-positive progenitors, we propose that LIF maintains a pool of neural progenitor cells. We further provide evidence that LIF increases the number of nestin-positive progenitor cells directly in a cell cycle-independent fashion, which we interpret as an acceleration of neurogenesis in sphere-derived progenitors. This effect is further enhanced by an anti-apoptotic action of LIF. Finally, LIF and the neurotrophins BDNF and NT3 additively promote survival of stem cell-derived neurons.

Conclusion

Our results implicate LIF as a powerful tool to control neural differentiation and maintenance of stem cell-derived murine spiral ganglion neuron precursors. This finding could be relevant in cell replacement studies with animal models featuring spiral ganglion neuron degeneration. The additive effect of the combination of LIF and BDNF/NT3 on stem cell-derived neuronal survival is similar to their effect on primary spiral ganglion neurons, which puts forward spiral ganglion-derived neurospheres as an in vitro model system to study aspects of auditory neuron development.

Interactions of interleukin-1 with neurotrophic factors in the central nervous system: beneficial or detrimental?

Interleukin (IL)-1 is a multifunctional cytokine that plays a key role in mediating inflammation in the brain. Many different cell types in the brain express the IL-1 receptor and respond to this cytokine by activating cell-type-specific signaling pathways leading to distinct functional responses, which collectively comprise the inflammatory response in the brain. One key effect of IL-1 in the brain is the induction of trophic factor production by glial cells, which has traditionally been considered a neuroprotective response to injury or disease. However, recent studies have shown that nerve growth factor, which is regulated by IL-1, can induce neuronal survival or apoptosis via different receptors. This article examines the interaction of IL-1 with different trophic factors in the brain.

Cytokines and chronic liver disease

From an immunological point of view, the healthy liver has been usually associated with the phenomenon of tolerance. A microenvironment of regulatory cytokines produced by liver Kuppfer cells and liver sinusoidal endothelial cells has contributed, together with resident dendritic cells, to generate a tolerogenic environment in this tissue. In this review we discussed the intrahepatic responses to different sorts of liver injury, such as hepatotrophic viruses, alcohol or putative self-antigens. In each case we analyzed the impact of different cytokines in the clinical outcome of the different pathological situations.

Characterization of the Interleukin (IL)-6 Inhibitor IL-6-RFP

Although fusion proteins of the extracellular parts of receptor subunits termed cytokine traps turned out to be promising cytokine inhibitors for anti-cytokine therapies, their mode of action has not been analyzed. We developed a fusion protein consisting of the ligand binding domains of the IL-6 receptor subunits IL-6Ralpha and gp130 that acts as a highly potent IL-6 inhibitor. Gp130 is a shared cytokine receptor also used by the IL-6-related cytokines oncostatin M and leukemia inhibitory factor. In this study, we have shown that the IL-6 receptor fusion protein (IL-6-RFP) is a specific IL-6 inhibitor that does not block oncostatin M or leukemia inhibitory factor. We characterized the complex of IL-6-RFP and fluorescently labeled IL-6 (YFPIL-6) by blue native PAGE and gel filtration. A 2-fold molar excess of IL-6-RFP over IL-6 was sufficient to entirely bind IL-6 in a complex with IL-6-RFP. As shown by treatment with urea and binding competition experiments, the complex of IL-6 and IL-6-RFP is more stable than the complex of IL-6, soluble IL-6Ralpha, and soluble gp130. By live cell imaging, we have demonstrated that YFP-IL-6 bound to the surface of cells expressing gp130-CFP is removed from the plasma membrane upon the addition of IL-6-RFP. The apparent molecular mass of the IL-6.IL-6-RFP complex determined by blue native PAGE and gel filtration suggests that IL-6 is trapped in a structure analogous to the native hexameric IL-6 receptor complex. Thus, fusion of the ligand binding domains of heteromeric receptors leads to highly specific cytokine inhibitors with superior activity compared with the separate soluble receptors.

Biliary wound healing, ductular reactions, and IL-6/gp130 signaling in the development of liver disease

Basic and translational wound healing research in the biliary tree lag significantly behind similar studies on the skin and gastrointestinal tract. This is at least partly attributable to lack of easy access to the biliary tract for study. But clinical relevance, more interest in biliary epithelial cell (BEC) pathophysiology, and widespread availability of BEC cultures are factors reversing this trend. In the extra-hepatic biliary tree, ineffectual wound healing, scarring and stricture development are pressing issues. In the smallest intra-hepatic bile ducts either impaired BEC proliferation or an exuberant response can contribute to liver disease. Chronic inflammation and persistent wound healing reactions in large and small bile ducts often lead to liver cancer. General concepts of wound healing as they apply to the biliary tract, importance of cellular processes dependent on IL-6/gp130/STAT3 signaling pathways, unanswered questions, and future directions are discussed.

Mapping leptin-interacting sites in recombinant leptin-binding domain (LBD) subcloned from chicken leptin receptor

The binding domain of the chicken leptin receptor [chLBD (chicken leptin-binding domain)], subcloned from the full-size chicken leptin receptor and prepared in an Escherichia coli system, was subjected to site-directed mutagenesis to identify the amino acids involved in leptin binding. A total of 22 electrophoretically pure, >90% monomer-containing mutants were expressed, refolded and purified. The effects of the mutations were tested by the ability to form complexes with ovine leptin, and the kinetic parameters of interaction were determined by surface plasmon resonance. Six mutants were used to determine whether mutations of several amino acids that differ between chLBD and mammalian LBDs will affect affinity: none showed any such effect, except the mutant A105D (Ala(105)-->Asp), which exhibited some decrease in affinity. Surface plasmon resonance analysis identified six mutants in which binding activity was totally abolished (F73A, Y14A/F73A, V76A/F77A, L78A/L79A, V76A/F77A/L78A/L79A and A105D/D106V) and six mutants (Y14A, R41A, R41A/S42A/K43A, V103A, V135A/F136A and F136A) in which affinity for the hormone was reduced, mainly by increased dissociation rates. Gel-filtration experiments indicated the formation of a 1:1 ovine or human leptin-chLBD complex with a molecular mass of approx. 41 kDa. Gel-filtration experiments yielded 1:1 complexes with those mutants in which affinity had decreased, but not with the six mutants, which had totally lost their binding capacity. Modelling the leptin-chLBD complex indicated that the binding domain of the latter is located mainly in the L3 loop, which contributes nine amino acid residues interacting with leptin. Contact-surface analysis identified the residues having the highest contribution to the recognition site to be Phe73, Phe77 and Leu79.

Identification of the hydrophobic strand in the A-B loop of leptin as major binding site III: implications for large-scale preparation of potent recombinant human and ovine leptin antagonists

Interaction of leptin with its receptors resembles that of interleukin-6 and granulocyte colony-stimulating factor, which interact with their receptors through binding sites I-III. Site III plays a pivotal role in receptors' dimerization or tetramerization and subsequent activation. Leptin's site III also mediates the formation of an active multimeric complex through its interaction with the IGD (immunoglobulin-like domain) of LEPRs (leptin receptors). Using a sensitive hydrophobic cluster analysis of leptin's and LEPR's sequences, we identified hydrophobic stretches in leptin's A-B loop (amino acids 39-42) and in the N-terminal end of LEPR's IGD (amino acids 325-328) that are predicted to participate in site III and to interact with each other in a beta-sheet-like configuration. To verify this hypothesis, we prepared and purified to homogeneity (as verified by SDS/PAGE, gel filtration and reverse-phase chromatography) several alanine muteins of amino acids 39-42 in human and ovine leptins. CD analyses revealed that those mutations hardly affect the secondary structure. All muteins acted as true antagonists, i.e. they bound LEPR with an affinity similar to the wild-type hormone, had no agonistic activity and specifically inhibited leptin action in several leptin-responsive in vitro bioassays. Alanine mutagenesis of LEPR's IGD (amino acids 325-328) drastically reduced its biological but not binding activity, indicating the importance of this region for interaction with leptin's site III. FRET (fluorescence resonance energy transfer) microscopy experiments have documented that the transient FRET signalling occurring upon exposure to leptin results not from binding of the ligand, but from ligand-induced oligomerization of LEPRs mediated by leptin's site III.

Adaptive randomized study of idarubicin and cytarabine alone or with interleukin-11 as induction therapy in patients aged 50 or above with acute myeloid leukemia or high-risk myelodysplastic syndromes

A higher complete remission (CR) rate was observed in patients with acute myeloid leukemia (AML) who, on a prior randomized study of induction therapy, received gemtuzumab ozogamicin (GO) plus interleukin-11 (IL-11) rather than GO alone. An adaptive randomized phase III study of the addition of IL-11 to idarubicin and cytarabine (IA) induction in 100 patients >/=50 years of age with AML or high-risk myelodysplastic syndrome (MDS) was conducted. Median patient age was 67 years (range 50-82). Twenty-four of the 45 (53%) patients randomized to IA plus IL-11 achieved CR. Eight (33%) subsequently relapsed, 4 (17%) died in CR; median time to treatment failure (TTF) was 37 weeks. Twenty-nine of the 55 (53%) patients treated without IL-11 achieved CR. Eight (28%) subsequently relapsed, 2 (7%) died in CR; median TTF was 46 weeks. Median overall survivals were 21 and 59 weeks for the IA plus IL-11 and IA cohorts, respectively (p=0.271, log rank test; 0.435, Gehan-Breslow test). Ten episodes of the following grade 3 or 4 cardiopulmonary toxicities were observed in patients receiving IA plus IL-11, 12 such episodes in those receiving IA alone: atrial fibrillation, pleural effusions, myocardial infarction, bradycardia or hypotension. Two patients in each arm experienced grade 3 peripheral edema. There was no significant difference in incidence of any grade 3 or 4 adverse event, including thrombocytopenia, between treatment arms. There was no significant impact on CR rates, TTF, survival, or toxicity of adding an IL-11 regimen to IA induction in patients >/=50 years of age with AML.

IL-11 receptor alpha in the pathogenesis of IL-13-induced inflammation and remodeling

IL-13 is a major stimulator of inflammation and tissue remodeling at sites of Th2 inflammation. In Th2-dominant inflammatory disorders such as asthma, IL-11 is simultaneously induced. However, the relationship(s) between IL-11 and IL-13 in these responses has not been defined, and the role(s) of IL-11 in the genesis of the tissue effects of IL-13 has not been evaluated. We hypothesized that IL-11, signaling via the IL-11Ralpha-gp130 receptor complex, plays a key role in IL-13-induced tissue responses. To test this hypothesis we compared the expression of IL-11, IL-11Ralpha, and gp130 in lungs from wild-type mice and transgenic mice in which IL-13 was overexpressed in a lung-specific fashion. We simultaneously characterized the effects of a null mutation of IL-11Ralpha on the tissue effects of transgenic IL-13. These studies demonstrate that IL-13 is a potent stimulator of IL-11 and IL-11Ralpha. They also demonstrate that IL-13 is a potent stimulator of inflammation, fibrosis, hyaluronic acid accumulation, myofibroblast accumulation, alveolar remodeling, mucus metaplasia, and respiratory failure and death in mice with wild-type IL-11Ralpha loci and that these alterations are ameliorated in the absence of IL-11Ralpha. Lastly, they provide insight into the mechanisms of these processes by demonstrating that IL-13 stimulates CC chemokines, matrix metalloproteinases, mucin genes, and gob-5 and stimulates and activates TGF-beta1 via IL-11Ralpha-dependent pathways. When viewed in combination, these studies demonstrate that IL-11Ralpha plays a key role in the pathogenesis of IL-13-induced inflammation and remodeling.

Erythropoietin mediates tissue protection through an erythropoietin and common beta-subunit heteroreceptor

The cytokine erythropoietin (Epo) is tissue-protective in preclinical models of ischemic, traumatic, toxic, and inflammatory injuries. We have recently characterized Epo derivatives that do not bind to the Epo receptor (EpoR) yet are tissue-protective. For example, carbamylated Epo (CEpo) does not stimulate erythropoiesis, yet it prevents tissue injury in a wide variety of in vivo and in vitro models. These observations suggest that another receptor is responsible for the tissue-protective actions of Epo. Notably, prior investigation suggests that EpoR physically interacts with the common beta receptor (betacR), the signal-transducing subunit shared by the granulocyte-macrophage colony stimulating factor, and the IL-3 and IL-5 receptors. However, because betacR knockout mice exhibit normal erythrocyte maturation, betacR is not required for erythropoiesis. We hypothesized that betacR in combination with the EpoR expressed by nonhematopoietic cells constitutes a tissue-protective receptor. In support of this hypothesis, membrane proteins prepared from rat brain, heart, liver, or kidney were greatly enriched in EpoR after passage over either Epo or CEpo columns but covalently bound in a complex with betacR. Further, antibodies against EpoR coimmunoprecipitated betacR from membranes prepared from neuronal-like P-19 cells that respond to Epo-induced tissue protection. Immunocytochemical studies of spinal cord neurons and cardiomyocytes protected by Epo demonstrated cellular colocalization of Epo betacR and EpoR. Finally, as predicted by the hypothesis, neither Epo nor CEpo was active in cardiomyocyte or spinal cord injury models performed in the betacR knockout mouse. These data support the concept that EpoR and betacR comprise a tissue-protective heteroreceptor.