Interleukin-11: A Potential Biomarker and Molecular Therapeutic Target in Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) accounts for 85% of lung cancer and is a fast progressive disease when left untreated. Identification of potential biomarkers in NSCLC is an ongoing area of research that aims to detect, diagnose, and prognosticate patients early to optimize treatment. We review the role of interleukin-11 (IL11), a stromal-cell derived pleiotropic cytokine with profibrotic and cellular remodeling properties, as a potential biomarker in NSCLC. This review identifies the need for biomarkers in NSCLC, the potential sources of IL11, and summarizes the available information leveraging upon published literature, publicly available datasets, and online tools. We identify accumulating evidence suggesting IL11 to be a potential biomarker in NSCLC patients. Further in-depth studies into the pathophysiological effects of IL11 on stromal-tumor interaction in NSCLC are warranted and current available literature highlights the potential value of IL11 detection as a diagnostic and prognostic biomarker in NSCLC.

[Cytokines and osteogenesis]

Many cytokines associate with proliferation, differentiation and activation of osteoblasts which have an important role in osteogenesis. TGF-β, BMP, IGF, FGF, Hedgehog, Notch, IL and WNT signaling pathways and their inhibitors have been revealed to correlate to osteogenesis, and those gene mutations have been shown to cause various bone disorders. It has been suggested that there are common pathways or crosstalk in these cytokine signaling each other, but mechanism of their complicated regulation on osteogenesis has been unclear. It was expected that the knowledge about these cytokines will apply to clinical therapies of bone diseases.

Dependency of colorectal cancer on a TGF-β-driven program in stromal cells for metastasis initiation

A large proportion of colorectal cancers (CRCs) display mutational inactivation of the TGF-β pathway, yet, paradoxically, they are characterized by elevated TGF-β production. Here, we unveil a prometastatic program induced by TGF-β in the microenvironment that associates with a high risk of CRC relapse upon treatment. The activity of TGF-β on stromal cells increases the efficiency of organ colonization by CRC cells, whereas mice treated with a pharmacological inhibitor of TGFBR1 are resilient to metastasis formation. Secretion of IL11 by TGF-β-stimulated cancer-associated fibroblasts (CAFs) triggers GP130/STAT3 signaling in tumor cells. This crosstalk confers a survival advantage to metastatic cells. The dependency on the TGF-β stromal program for metastasis initiation could be exploited to improve the diagnosis and treatment of CRC.

Proteomic analysis identifies interleukin 11 regulated plasma membrane proteins in human endometrial epithelial cells in vitro

BACKGROUND

During the peri-implantation period, the embryo adheres to an adequately prepared or receptive endometrial surface epithelium. Abnormal embryo adhesion to the endometrium results in embryo implantation failure and infertility. Endometrial epithelial cell plasma membrane proteins critical in regulating adhesion may potentially be infertility biomarkers or targets for treating infertility. Interleukin (IL) 11 regulates human endometrial epithelial cells (hEEC) adhesion. Its production is abnormal in women with infertility. The objective of the study was to identify IL11 regulated plasma membrane proteins in hEEC in vitro using a proteomic approach.

METHODS

Using a 2D-differential in-gel electrophoresis (DIGE) electrophoresis combined with LCMS/MS mass spectrometry approach, we identified 20 unique plasma membrane proteins differentially regulated by IL11 in ECC-1 cells, a hEEC derived cell line. Two IL11 regulated proteins with known roles in cell adhesion, annexin A2 (ANXA2) and flotillin-1 (FLOT1), were validated by Western blot and immunocytochemistry in hEEC lines (ECC-1 and an additional cell line, Ishikawa) and primary hEEC. Flotilin-1 was further validated by immunohistochemistry in human endometrium throughout the menstrual cycle (n = 6-8/cycle).

RESULTS

2D-DIGE analysis identified 4 spots that were significantly different between control and IL11 treated group. Of these 4 spots, there were 20 proteins that were identified with LCMS/MS. Two proteins; ANXA2 and FLOT1 were chosen for further analyses and have found to be significantly up-regulated following IL11 treatment. Western blot analysis showed a 2-fold and a 2.5-fold increase of ANXA2 in hEEC membrane fraction of ECC-1 and Ishikawa cells respectively. Similarly, a 1.8-fold and a 2.3/2.4-fold increase was also observed for FLOT1 in hEEC membrane fraction of ECC-1 and Ishikawa cells respectively. In vitro, IL11 induced stronger ANXA2 expression on cell surface of primary hEEC and ECC-1 whilst, the lipid-raft protein FLOT1 demonstrated punctate staining in the apical surface of ECC-1 plasma membranes and was upregulated in the epithelium in the receptive phase of the menstrual cycle (p lower or equal 0.05).

CONCLUSIONS

This is the first study to use a proteomics approach to identify hEEC plasma membrane proteins that may be useful as infertility markers or pharmacological targets for fertility regulation.

Interleukin 11 is upregulated in uterine lavage and endometrial cancer cells in women with endometrial carcinoma

BACKGROUND

Interleukin (IL) 11 is produced by human endometrium and endometrial cancer tissue. It has roles in endometrial epithelial cell adhesion and trophoblast cell invasion, two important processes in cancer progression. This study aimed to determine the levels of IL11 in uterine lavage fluid in women with endometrial cancer and postmenopausal women. It further aimed to determine the levels of IL11 protein and its signaling molecules in human endometrial cancer of varying grades, and endometrium from postmenopausal women and IL11 signalling mechanisms in endometrial cancer cell lines.

METHODS

IL11 levels in uterine lavage were measured by ELISA. IL11, IL11 receptor(R) alpha, phosphorylated (p) STAT3 and SOCS3 were examined by immunohistochemistry in endometrial carcinomas and in control endometrium from postmenopausal women and normal cycling women. The effect of IL11 on pSTAT3/STAT3 and SOCS3 protein abundance in endometrial cancer cell lines and non-cancer endometrial epithelial cells was determined by Western blot.

RESULTS

IL11 was present in uterine flushings and was significantly higher in women with Grade 1 carcinomas compared to postmenopausal women (p < 0.05). IL11 immunostaining was significantly elevated in the endometrial tumour epithelial cells from Grade 1 and 3 compared to endometrial epithelium from postmenopausal and cycling women. IL11R alpha immunostaining intensity was increased in cancer epithelium in the Grades 1 and 2 tumours compared to epithelium from postmenopausal women. Both IL11 and IL11R alpha localized to vascular endothelial and smooth muscle cells while IL11 also localized to subsets of leucocytes in the cancer tissues. pSTAT3 was found in both the tumour epithelial and stromal compartments but was maximal in the tumour epithelial cells, while SOCS3 was predominantly found in the tumour epithelial cells. pSTAT3 staining intensity was significantly higher in Grade 1 and 2 tumour epithelial cells compared to epithelial cells from cycling and postmenopausal women. SOCS3 staining intensity did not differ between between each tumour and postmenopausal endometrial epithelium but SOCS3 in cycling endometrium was significantly higher compared to postmenopausal and Tumour Grades 2 and 3. IL11 increased pSTAT3/STAT3 in all tumour cell lines, while SOCS3 abundance was increased only in one tumour cell line.

CONCLUSIONS

The present study suggests that IL11 in uterine washings may be useful as a diagnostic marker for early stage endometrial cancer. It indicates that IL11, along with its specific receptor, IL11R alpha, and downstream signalling molecules, STAT3 and SOCS3, are likely to play a role in the progression of endometrial carcinoma. The precise role of IL11 in endometrial cancer remains to be elucidated.

The role of interleukin-11 to prevent chemotherapy-induced thrombocytopenia in patients with solid tumors, lymphoma, acute myeloid leukemia and bone marrow failure syndromes

Thrombocytopenia occurs at various grades of severity in patients with malignancies undergoing myelosuppressive chemotherapy. In most instances, this is the major dose-limiting hematologic toxicity, especially in the treatment of potentially curable cancers. The standard preventive measure against chemotherapy-induced thrombocytopenia has been dose reduction and/or dose delay. This can often lead to poor outcomes, including reduced disease free periods and overall survival. With the availability of a platelet growth factor, recombinant human interleukin (IL)-11, an effective way to prevent chemotherapy-induced thrombocytopenia and accelerate platelet recovery, can now be provided to patients. The use of recombinant human IL-11 has also been extended to include patients with prolonged thrombocytopenia, such as those with bone marrow failure syndromes. With the use of recombinant human IL-11 in both malignant and non-malignant conditions, adverse reactions often seen with platelet transfusions, such as transfusion reactions, viral and bacterial infections and platelet refractoriness, can now be decreased or avoided.

Role of Interleukins and Transforming Growth Factor-β in Chronic Rhinosinusitis and Nasal Polyposis

OBJECTIVES

To determine the role of interleukin (IL)-4, IL-4 receptor (R), IL-6, IL-8, IL-11, and transforming growth factor (TGF)-beta in chronic rhinosinusitis (CRS) and chronic rhinosinusitis with nasal polyposis (CRS/NP).

METHODS

Sinus tissue from patients undergoing endoscopic sinus surgery for CRS and CRS/NP was collected. Sinus tissue was then analyzed using reverse-transcription polymerase chain reaction (RT-PCR) to detect transcription of IL-4R, IL-6, IL-8, and IL-11. Sinus tissue samples were also cultured in vitro, treated with IL-4 for 24 hours, and real-time PCR was used to quantify the transcription of TGF-beta.

RESULTS

Twenty patients were evaluated, 9 with CRS/NP and 11 with CRS alone. The mean age was 43 (20-74) years, with 13 females and 7 males. IL-4R, IL-6, IL-8, and IL-11 were identified by RT-PCR in all 20 patients. The transcription of TGF-beta was found to be 3.2 times greater in patients with CRS/NP than in patients with CRS alone (P = .047).

CONCLUSION

IL-6, IL-8, and IL-11 are nonspecific markers of sinus inflammation being transcribed in patients with CRS and patients with CRS/NP. However, patients with CRS/NP demonstrate increased transcription of TGF-beta in response to IL-4 treatment, suggesting an IL-4 mediated mechanism for stromal proliferation in the formation of nasal polyposis.

Five new species of Rhinonyssidae (Mesostigmata) and one new species of Dermanyssus (Mesostigmata: Dermanyssidae) from birds of Alberta and Manitoba, Canada

Three major lineages of mites are parasitic in the nasal passages of birds, i.e., Rhinonyssidae (Mesostigmata), Ereynetidae (Prostigmata), Cytoditidae, and Turbinoptidae (Astigmata). The most diverse family of avian nasal mites is Rhinonyssidae, which include obligate hematophagous endoparasites of nonratite birds worldwide. Nasal mites have been surveyed extensively in the United States, yet there has never been a Canadian survey. There are only 4 published, and 3 unpublished, rhinonyssid species records from birds in Canada. While surveying the nasal mites associated with birds of Alberta and Manitoba (western Canada), 1 new species of Dermanyssus and 5 new species of Rhinonyssidae were recovered. Herein, I describe and illustrate Dermanyssus diphyes n. sp., Ptilonyssus calvaria n. sp., P. nivalis n. sp., P. pinicola n. sp., P. plesiotypicus n. sp., and Sternostoma setifer n. sp.

The role of IL-6 and IL-11 in hyperoxic injury in developing lung

We examined the cytoprotective effect of interleukin-6 (IL-6) and interleukin-11 (IL-11) during oxidant injury in neonatal lung and the regulators of cell death in vitro and in vivo after oxidant exposure. Type II cells from day 21 fetal neonatal rat lungs were treated with varying concentrations of either IL-6 or IL-11 for 24 hr prior to exposure to H(2)O(2). Three-day-old transgenic lung-specific IL-11 and IL-6 overexpressing and wild type (WT) mouse pups were exposed to hyperoxia or room air for 3 days. Type II cells exposed to either IL-6 or IL-11 prior to oxidant injury exhibited improved survival compared to controls, 67% +/- 2.6 survivals in IL-6 pretreated cells compared to 48% +/- 1.6 in control; 63% +/- 3 survivals in IL-11 pretreated cells compared to 49% +/- 2.6 in control. The number of TUNEL positive cells in hyperoxia-exposed lungs was increased compared to room air animals (27 +/- 0.9 vs. 4 +/- 0.4; mean +/- SEM; P < 0.05). In contrast, the number of TUNEL positive cells was reduced in hyperoxia-exposed lungs from IL-11 (+) mice (15.2 +/- 2.2; mean +/- SEM; P < 0.05). There was an enhanced accumulation of Bcl-2 and reduction of Bax protein in hyperoxia-exposed IL-11 (+) compared to room air-exposed mice. This was not seen in hyperoxia-exposed IL-6 (+) pups. An increase in caspase-3 was seen in hyperoxia-exposed lungs of WT pups compared to IL-11 (+) pups. IL-11 and IL-6 provide protective effects against oxidant-mediated injury in fetal type II cells and IL-11 provides protection in vivo by down-regulation of caspase-mediated cell death.

Identification of cardiac myocytes as the target of interleukin 11, a cardioprotective cytokine

Interleukin (IL)-6 family cytokines, which share glycoprotein 130 (gp130) as a signal-transducing receptor component, play important roles in the maintenance of cardiac homeostasis. IL-11, a member of IL-6 family cytokines, is expressed in cardiac myocytes, though it remains to be elucidated how IL-11 functions in the hearts. In the present study, first, we showed that IL-11 administration reduced the ischemia/reperfusion injury in the hearts. IL-11 receptor alpha was expressed in cardiomyocytes. IL-11 treatment rapidly activated signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) 1/2 in cardiac myocytes. IL-11 stimulation resulted in the translocation of phosphorylated STAT3 into nuclei. Immunofluorescence microscopic analyses revealed that IL-11 treatment led to the cell elongation, as is the case with other cardiotrophic members of IL-6 family, such as leukemia inhibitory factor. Finally we showed that IL-11 treatment conferred the resistance to cell death induced by hydrogen peroxide, which was abrogated by adenoviral transfer of dominant negative STAT3, but not by the inhibition of ERK1/2 with U0126. These findings indicate that IL-11 mediates cytoprotective signals in cardiomyocytes, proposing that IL-11 has the potential to exhibit cardioprotection as a novel biological function.

The role of interleukin-11 in pregnancy involves up-regulation of alpha2-macroglobulin gene through janus kinase 2-signal transducer and activator of transcription 3 pathway in the decidua

IL-11 expressed by endometrial stromal cells is crucial for normal pregnancy. IL-11 receptor alpha (IL-11Ralpha) null mice are infertile due to abnormal development of the placenta. In these mice, the mesometrial decidual tissue, which is the site of trophoblast invasion, thins and disappears at mid-pregnancy. Degeneration of the decidua is accompanied by uncontrolled trophoblast invasion. In this report, we show, using IL-11Ralpha null mice, that a defect in IL-11 signaling in the decidua leads to severe down-regulation of alpha(2)-macroglobulin (alpha(2)-MG), a metalloproteinase inhibitor crucial for limiting trophoblast invasion. We also present evidence, using uterine stromal cells that decidualize in culture, that IL-11 robustly stimulates the endogenous alpha(2)-MG expression and enhances alpha(2)-MG promoter activity. Serial 5' deletion and internal deletion of the promoter reveal two important signal transducer and activator of transcription (Stat) binding sites. Mutation of either one of these motifs decreases IL-11 stimulation, whereas double mutation prevents IL-11 action. We also found that IL-11 activates Janus kinase 2 (Jak2) and induces rapid phosphorylation, nuclear translocation, and promoter binding activity of Stat3 in decidual cells, whereas Jak1, Tyk2, and Stat5 activities are not affected. In addition, Jak2 inhibitor totally prevents alpha(2)-MG expression in decidual cells. Taken together, results of this investigation provide, at least in part, an explanation for the overinvasiveness of the trophoblast in IL-11Ralpha null mice and reveal, for the first time, that IL-11 signals through the Jak2/Stat3 pathway in decidual cells to stimulate the expression of alpha(2)-MG, a protease inhibitor essential for normal placentation in pregnancy.

Hormonal and cytokine regulation of early implantation

Implantation of the blastocyst into the endometrium is a delicately controlled process and a prerequisite for the furtherance of the mammalian species. A complex network of molecules is involved in preparing both the endometrium and blastocyst for a successful interaction. However, the exact molecular steps are poorly understood. Studies so far have shown that disruption of certain pathways results in fertility defects. Impaired implantation is currently considered to be the most important limiting factor for the establishment of viable pregnancies in assisted reproduction. It is expected that elucidating the molecular background of the process will enable accurate diagnosis and effective treatment of infertility.

Investigation of arthritic joint destruction by a novel fibroblast-based model

The key pathologic mechanism in rheumatoid arthritis (RA) is the destruction of cartilage by fibroblasts. In a severe combined immunodeficient (SCID) mouse model, this process can be modulated by gene transfer using invasive LS48 fibroblasts. This study aims to investigate the effect of interleukins (IL) -11 and -12 on cartilage destruction when transferred into LS48, and of IL-15 when transfected into non-invasive 3T3 cells; to compare three transduction systems (a lentiviral vector system, a retroviral vector system, and a particle-mediated gene transfer); and to establish an in vitro cartilage destruction system based on LS48 cells. Transduced fibroblasts were injected into SCID mice knee joints, and disease progression assessed microscopically. Distinctive morphologic pattern revealed invasion of fibroblasts into the articular cartilage by transfected, as well as non-transfected, LS48 cells. IL-12 and IL-15 did not alter swelling or cartilage destruction. Animals treated with IL-11-transfected cells showed reduced cartilage damage but no changes in swelling. Efficacy of gene transfer to establish transfected fibroblasts was shown to be >85% for lentiviral transfer, compared to <10% for retroviral transfer and gene gun. Furthermore, cells were co-incubated with porcine cartilage. Transduction of IL-11 led to a reduction of apoptosis in chondrocytes. These findings suggest that cartilage destruction by invasive fibroblasts can be modulated by gene transfer. Lentiviral vector systems offer the most effective approach for gene transduction. In vitro fibroblast/cartilage co-cultures present a convenient system for the assessment of novel therapeutic strategies toward reduction of articular destruction.

Cytokines, chemokines and growth factors in endometrium related to implantation

The complexity of the events of embryo implantation and placentation is exemplified by the number and range of cytokines with demonstrated roles in these processes. Disturbance of the normal expression or action of these cytokines results in complete or partial failure of implantation and abnormal placental formation in mice or humans. Of known importance are members of the gp130 family such as interleukin-11 (IL-11) and leukaemia inhibitory factor (LIF), the transforming growth factor beta (TGFbeta) superfamily including the activins, the colony-stimulating factors (CSF), the IL-1 system and IL-15 system. New data are also emerging for roles for a number of chemokines (chemoattractive cytokines) both in recruiting specific cohorts of leukocytes to implantation sites and in trophoblast differentiation and trafficking. This review focuses on those cytokines and chemokines whose expression pattern in the human endometrium is consistent with a potential role in implantation and placentation and for which some relevant actions are known. It examines what is known of their regulation and action along with alterations in clinically relevant situations.

Endogenous IL-11 is pro-inflammatory in acute methylated bovine serum albumin/interleukin-1-induced (mBSA/IL-1)arthritis

OBJECTIVE

To evaluate the role of interleukin-11 (IL-11) in acute mBSA/IL-1-induced inflammatory arthritis.

METHODS

IL-11 was administered via intra-articular (IA) injection into knee joints of C57BL/6 mice and joint histology was assessed. The mitogenic response to IL-11 was measured in wild-type (WT) synovial fibroblasts. IL-1 was used as a comparator in both the studies. The severity of acute methylated bovine serum albumin (mBSA)/IL-1 arthritis was determined in WT and IL-11 receptor null (IL-11Ra1-/-) mice. In parallel experiments, a neutralising antibody to IL-11 was administered to WT mice throughout this model.

RESULTS

IA injections of IL-11 resulted in mild-to-moderate joint inflammation which was less than that due to IA IL-1. IL-11 had a dose-dependent mitogenic effect on WT synovial fibroblasts (P<0.01). mBSA/IL-1 acute arthritis was reduced in IL-11Ra1-/- versus WT mice (histological arthritis score: 10.1+/-0.5 versus 12.8+/-0.7, respectively; P=0.01). Administration of an IL-11 neutralising antibody to WT mice reduced mBSA/IL-1 acute arthritis scores compared to control antibody (10.6+/-0.7 versus 13.3+/-0.6, respectively; P=0.02).

CONCLUSIONS

These data demonstrate that endogenous IL-11 exerts relatively mild but consistent pro-inflammatory effects in acute inflammatory arthritis.

[Possible mechanisms of A beta(1-40)- or A beta(1-42)-induced cell death and their rescue factors]

Amyloidbetapeptide (A beta) is implicated in neuronal cell death in Alzheimer's disease, but the molecular mechanisms are still unclear. We analyzed its mechanism and found several potential rescue factors against A beta-mediated apoptosis. A beta(1-40) stimulated phosphorylation of tau and JNK and induced cell death in SH-SY5Y cells. The cell death was inhibited by insulin-like growth factor-1, suggesting that the JNK pathway may be involved in A beta(1-40)-induced cytotoxicity. Using the human fetus brain cDNA library-targeted differential display technique, a new gene BF5-1 (32aa) was found as a rescue factor against A beta(1-40). BF5-1 has partially the same amino acid sequences as those of the C-terminus of cytochrome c oxidase subunit VIIb (COX-VIIb). COX-VIIb mRNA is increased in AD brains and its overexpression in cells enhanced A beta(1-40)-toxicity. These data suggest that BF5-1 may act as a dominant negative mutant of COX-VIIb. A beta(1-42) also induced cell death in rat neuroblastoma B104 cells, which was abolished by addition of IL-11. By cDNA subtraction analysis in the cell death, the enhanced expression of L-phosphoserine phosphatase was found, but this was also abolished by IL-11. The glutamate neurotoxicity was stimulated in the presence of D-serine, suggesting that NMDA receptors may be involved in A beta(1-42)-induced cytotoxicity. A beta(1-42) also induced increase of a new gene p18A beta rP (p18-amyloid-beta-responsive protein; 166 aa) mRNA expression; overexpression of this gene in PC12 cells induced cell death. By the application of a death trap method, a new gene, p60TRP (p60-Transcription-Regulating-Protein; rat:539 aa, human:547aa), was found as a potential rescue factor against the cell death by p18A beta rP. Thus, our cell death systems and/or new rescue proteins may provide suitable tools for the establishment of drug screening systems leading to the identification of new low-molecular candidates applicable for the treatment of AD.

Reciprocal changes in trefoil 1 and 2 expression in stomachs of mice with gastric unit hypertrophy and inflammation

H+/K+-ATPase beta-subunit-deficient mice (129/Sv background) display numerous pathologies in the stomach. Expression of the mutation in BALB/cCrSlc mice results in the development of an aberrant 'mucus-rich' cell population. 'Mucus-rich' cells have been described in stomachs of mice with autoimmune gastritis, a disease mediated by CD4+ T cells. Other pathological features of autoimmune gastritis are similar to those in H+/K+ beta-deficient mice and include a mononuclear cell infiltrate in the gastric mucosa, non-functional or absent parietal cells, depletion of zymogenic cells, hypergastrinaemia, and gastric unit hypertrophy caused by immature cell hyperplasia. The present study investigates further the aberrant gastric 'mucus-rich' cell lineage and analyses the mRNA expression of mucus cell products TFF1 and TFF2. 'Mucus-rich' cells stained for both acidic and neutral mucins, and with a TFF2-specific antibody. Stomachs from both models expressed decreased TFF1 mRNA and reciprocally increased TFF2 mRNA. The involvement of gastrin in regulating trefoil mRNA expression was also investigated using gastrin-deficient mice. In contrast to previous findings, gastrin did not positively regulate TFF1 mRNA expression, but there was possible augmentation of TFF2. Additionally, a clear role for inflammation was established involving both polymorphonuclear and mononuclear cells in these models, and a link was found between mucosal hypertrophy and increased interleukin-11 (IL-11) expression.

Interleukin-11 expression: its significance in eutopic and ectopic human implantation

Embryo implantation and subsequent decidualization, trophoblast invasion and formation of a functional placenta are crucial for establishment and maintenance of pregnancy. Interleukin-11 signalling has been shown to be obligatory for adequate decidualization and trophoblast invasion in mice. Defects in IL-11 signalling in mice result in trophoblast over-invasion and fetal loss. The pathological situation of human tubal pregnancy resembles that of IL-11Ralpha(-/-) mice concerning these symptoms. As our interest is focused on the human early pregnancy, we compared IL-11 expression at the implantation site of ectopic tubal pregnancy (EP) to 1st and 2nd trimester of normal intrauterine pregnancies (IP), and to the normal cycling endometrium. The mRNA expression of IL-11 and IL-11Ralpha was analysed by semiquantitative RT-PCR. Protein expression was detected by western blotting and immunohistochemistry. IL-11Ralpha is expressed constitutively in all tissue specimens analysed. IL-11 is expressed predominantly during follicular and early luteal phase of the menstrual cycle. In IP, IL-11 expression peaks during the 1st trimester and declines from the beginning of the 2nd trimester onwards. In tubal abortions, IL-11 expression is reduced in comparison to vital EP and IP. Cultured primary endometrial and decidual epithelial cells were analysed for hormonal regulation of IL-11 by enzyme-linked immunosorbent assay and RT-PCR. IL-11 is up-regulated by estrogen and down-regulated by progesterone. Overall, our results indicate that in humans, IL-11 signalling is significantly involved in regulation of trophoblast invasion. In the case of tubal abortion, inadequate IL-11 signalling may therefore result in dysregulation of trophoblast invasion.

A protective role of interleukin 11 on hepatic injury in acute endotoxemia

The liver is one of the major target organs affected in sepsis, and its failure always results in critical consequences. It has been reported that recombinant human interleukin 11 (rhIL-11), a pleiotropic cytokine, may be useful in the treatment of sepsis. However, the effect of IL-11 specifically on the hepatic failure in sepsis has not been evaluated. In the present study, we examined the effect of rhIL-11 on the hepatic injury in a rat endotoxemia model. Acute endotoxemia was induced in male Sprague-Dawley rats by intraperitoneal injection (i.p.) of bacterial lipopolysaccharide (LPS, 20 mg/kg). Immediately after injection of LPS, rats were treated with rhIL-11 (150 microg/kg, i.p.) or the vehicle. LPS treatment induced severe hepatic injury as revealed by marked increases in serum alanine transaminase (ALT) and aspartate transaminase (AST) activities, extensive hepatocyte necrosis, tumor necrosis factor-alpha (TNF-alpha) mRNA, inducible nitric oxide synthase (iNOS) mRNA, and DNA-binding activity of nuclear factor-kappaB (NF-kappaB). In contrast, rhIL-11 treatment significantly ameliorated the LPS-induced hepatic injury, as judged by marked improvement in all these indices. In addition, rhIL-11 treatment markedly decreased LPS-induced mortality. These results indicate that rhIL-11 plays a significant protective role in LPS-induced hepatic injury in acute endotoxemia.

Interleukin-11 as an osteoprotegerin-inducing factor in culture medium of blastic cells from a patient with acute megakaryocytic leukemia complicated with osteosclerosis

We came across a rare case of acute megakaryocytic leukemia, the clinical course of which was relatively chronic and nonaggressive. This case was complicated with generalized severe osteosclerosis (OS). The medium in which blastic cells from the patient were cultured showed a strong activity to enhance the expression of an osteosclerotic cytokine, osteoprotegerin (OPG), as revealed by real-time quantitative RT-PCR and Western blot analysis. The OPG-inducing activity of the culture medium was neutralized by the anti-interleukin-11 (IL-11) antibody. These results indicate that IL-11 produced by the blasts was a causative factor of the OS observed in this patient.

Thrombocytopenia in the newborn

Thrombocytopenia is the most common hemostatic abnormality in sick newborn infants. Although many conditions may be associated with neonatal thrombocytopenia, low platelet counts in the first few days of life are often caused by fetomaternal problems, whereas thrombocytopenia developing after the third day is usually secondary to sepsis or necrotizing enterocolitis. Despite the frequency of thrombocytopenia in sick neonates, the underlying kinetic mechanisms are not always clear. The commonly accepted theories of decreased platelet production or increased consumption are being scrutinized in the light of new evidence. Thrombopoietin and interleukin-11 are being investigated to unravel the complex pathophysiology of thrombocytopenia in neonates and they are also being explored as potential therapeutic agents. Guidelines for platelet transfusions continue to be variable and controversial.

IL-11 and IL-11Ralpha immunolocalisation at primate implantation sites supports a role for IL-11 in placentation and fetal development

Embryo implantation, endometrial stromal cell decidualization and formation of a functional placenta are critical processes in the establishment and maintenance of pregnancy. Interleukin (IL)-11 signalling is essential for adequate decidualization in the mouse uterus and IL-11 promotes decidualization in the human. IL-11 action is mediated via binding to the specific IL-11 receptor alpha (IL-11Ralpha). The present study examined immunoreactive IL-11 and IL-11Ralpha in cycling rhesus monkey endometrium, at implantation sites in cynomolgus and rhesus monkeys and in human first trimester decidua and defined distinct spatial and temporal patterns. In cycling rhesus monkey endometrium, IL-11 and IL-11Ralpha increased in both basalis and functionalis regions during the secretory compared with the proliferative phase, with changing cellular locations in luminal and glandular epithelium and stroma. The patterns were similar overall to those previously described in human endometrium. Differences were seen in immunostaining during implantation in cynomologus and rhesus monkey. In the cynomolgus, very little staining for IL-11 or IL-11Ralpha was seen in syncytio- and cyto-trophoblast cells in the villi between days 12 and 150 of pregnancy although there was moderate staining in cytotrophoblast in the shell between days 12 and 17 and in subpopulations of cytotrophoblast cells invading the arteries at day 17. By contrast in the rhesus monkey between days 24 and 35 of pregnancy and in human first trimester placenta, cyto- and syncytio-trophoblast in the villi but not cytotrophoblast in the shell were positively stained. The most intense staining for both IL-11 and IL-11Ralpha was present within the decidua in the maternal component of implantation sites in all three primates but moderate staining was also present in maternal vascular smooth muscle and glands perivascular cells and epithelial plaques. These results are consistent with a role for IL-11 both during decidualization and placentation in primates.

Complex regulation of decidualization: a role for cytokines and proteases--a review

Decidualization of the endometrial stroma is a precondition for successful establishment of pregnancy. While the local molecular mechanisms driving decidualization are still largely unknown, a number of autocrine/paracrine factors have been identified as differentiation factors in this process. These include the cytokines, interleukin 11, activin A and monoclonal non-specific suppressor factor beta (MNSFbeta). Furthermore, locally produced proteases, including proprotein convertase 6 and matrix metalloproteinases, enable expansion of the tissue and processing of regulatory molecules. This article reviews recent work from our laboratory on the roles of these factors in decidualization.

Autocrine down-regulation of glucocorticoid receptors by interleukin-11 in human osteoblast-like cell lines

It has recently been suggested that interleukin (IL)-11 plays a role in the pathogenesis of glucocorticoid (GC)-induced osteoporosis. IL-11 belongs to the gp130 cytokine family, which includes also IL-6. We have previously investigated GC-IL-6 interplay, showing that GC inhibits IL-6 release and IL-6 up-regulates GC receptor (GR) numbers in the human osteoblast-like cell lines Saos-2 and MG-63, which constitutively have an opposite pattern of expression for GR, IL-11, IL-6, alkaline phosphatase and osteoprotegerin (OPG). The aim of this study was to investigate GC-IL-11 interplay in the same two cell lines. First, cells were incubated with cortisol (0.01-1 microM) for 20 h in the presence and in the absence of a known IL-11 secretagogue (IL-1beta); cell media were assayed for IL-11 by ELISA. Secondly, cells were incubated with IL-11 (0.1-100 ng/ml) or specific anti-IL-11 monoclonal antibody for 20 h, and then assayed for GR by a radioligand binding assay. Similar to IL-6, both constitutive and IL-1beta-inducible IL-11 release were dose-dependently inhibited by cortisol (P<0.01); at variance with IL-6, exogenous IL-11 dose-dependently decreased GR numbers in MG-63 cells (P<0.05), while anti-IL-11 antibody significantly increased GR numbers in both cell lines (P<0.05). IL-11-induced reduction of GR in MG-63 cells was confirmed by Western blot analysis. While exerting opposite effects on GR numbers, neither IL-6 nor IL-11 significantly modified GC-dependent inhibition of OPG release. Our data indicate that even physiological concentrations of cortisol negatively modulate IL-11 secretion and demonstrate, for the first time, an inhibitory effect of the cytokine on GR. Thus, the concept of autocrine-paracrine loops that modulate GC action and involve gp130 cytokines is corroborated. These loops could have clinical relevance for the dynamics of bone loss in patients given GC and having high concentrations of these cytokines in the bone microenvironment.

Expression and function of interleukin-11 and its receptor alpha in the human endometrium

The interleukin-11 (IL-11) receptor alpha has an important function in decidualization of mouse endometrial stroma but the function of IL-11 and its receptor in the human endometrium remains unknown. The mRNA for IL-11 and its receptor alpha in human endometrial tissue samples were analysed by semi-quantitative RT-PCR and RNase protection assays respectively. The proteins were detected in frozen endometrial tissue samples by immunofluorescence. The effect of heparin-binding epidermal growth factor (HB-EGF) on secretion of IL-11 by cultured endometrial stromal cells was assessed by enzyme-linked immunosorbent assay. The proliferative potential of IL-11 in endometrial stromal cells was assessed by [(3)H]thymidine uptake. IL-11 and its receptor alpha mRNAs and proteins were detected in the endometrium throughout the cycle. Distinct patterns of localization of the ligand and receptor were observed. HB-EGF induced IL-11 secretion by cultured stromal cells, and IL-11 induced [(3)H]thymidine uptake by these cells. Our data suggest that IL-11-receptor interactions may perform different functions in the human endometrium at different stages of the cycle, and that secretion of IL-11 is modulated by local growth factors.

Neutralization of interleukin-11 activity decreases osteoclast formation and increases cancellous bone volume in ovariectomized mice

The issue of whether interleukin-11 (IL-11) contributes to bone loss during states of estrogen deficiency has not been previously determined. We therefore randomized ovariectomized (OVX) mice to once daily interperitoneal injections of either sheep anti-murine IL-11 Ab or normal sheep IgG (NSIgG) for 21 days, and then determined the effects on bone using bone histomorphometry. Here we report that treatment of OVX mice with anti-IL-11 Ab significantly increases both trabecular width and cancellous bone volume. Osteoblast activity, as measured by the percentage of trabecular surface covered by osteoid and rates of bone formation, were also significantly increased following treatment with anti-IL-11 Ab. In contrast, treatment of OVX mice with anti-IL-11 Ab significantly decreased both osteoclast number and activity. Ex-vivo assays of osteoclast formation and activity confirmed the histomorphometric data. Thus, bone marrow cells isolated from anti-IL-11 Ab treated OVX mice formed fewer osteoclasts and resorbed less bone in culture than did marrow cells isolated from either untreated or NSIgG-treated OVX mice. Based on these results we conclude that IL-11 contributes to the bone loss which is observed during states of estrogen deficiency.

Leukemia inhibitory factor and interleukin-11: cytokines with key roles in implantation

Members of the interleukin-6 family of cytokines include leukaemia inhibitory factor (LIF), interleukin-6, interleukin-11, cardiotrophin, ciliary neurotropic growth factor, oncostatin M and the recently discovered cardiotropin-like cytokine (NNT-1). These ligands signal via heterodimeric receptors composed of ligand-specific alpha chains and the common signal-transducing subunit gp130. Gene targeting in mice provided the first indication of a role for interleukin 6 family cytokines in implantation with the generation of mice with a null mutation of the gene encoding LIF. LIF null female mice were infertile because of failure of blastocyst implantation. More recently, interleukin-11 signalling has been shown to be required for the uterine decidualization response. This review describes the insights into the role of interleukin-6 family cytokines in female fertility that have come from gene targeting experiments in mice.

Characterization of the bone-resorptive effect of interleukin-11 in cultured mouse calvarial bones

Interleukin-11 (IL-11) is a stromal cell-derived cytokine that can enhance osteoclast formation and stimulate bone resorption. In the present study, the characteristics of the resorptive effect of IL-11 in mouse calvarial bones were investigated. Both recombinant mouse IL-11 and human IL-11 caused concentration- and time-dependent stimulations of (45)Ca release from prelabeled mouse calvariae. Half-maximal responses were obtained at 0.7 ng/mL (approximately 40 pmol/L). Mouse and human IL-11 also stimulated release of (3)H from [(3)H]-proline-labeled bones. The magnitude of the (45)Ca and (3)H release (1.4-1.6-fold) caused by a maximally effective concentration of IL-11 was less than the stimulation (2.5-4.0-fold) elicited by a maximum concentration of parathyroid hormone (PTH). Release of (45)Ca by IL-11 was unaffected by the mitotic inhibitors, hydroxyurea and aphidicolin. In addition to resorption of bone, IL-11 caused a small (1.5-2.0-fold) enhancement of prostaglandin E(2) (PGE(2)) biosynthesis in calvariae, but had no effect on the mRNA expression of cyclooxygenase-1 and -2, or cytosolic phospholipase A(2). Indomethacin and flurbiprofen abolished the formation of PGE(2) and partially reduced (45)Ca release stimulated by IL-11. When either mouse interleukin-4 (IL-4) or interleukin-13 (IL-13) was added to calvariae treated with IL-11, (45)Ca release was inhibited. Resorption caused by IL-11 was also inhibited by both anti-mouse glycoprotein 130 (gp130) and an antibody neutralizing IL-11, but these agents had no effect on (45)Ca release caused by PTH or 1,25(OH)(2)vitamin D(3) (D(3)). Real-time, quantitative polymerase chain reaction (PCR) analysis (TaqMan PCR) and semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) demonstrated that IL-11 caused concentration-dependent enhancements of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) mRNA, without affecting the mRNA expression of RANK. Mouse RANKL stimulated (45)Ca release in the calvarial bones. The stimulatory effects of RANKL and IL-11 were inhibited by mouse OPG. These data demonstrate that IL-11 stimulates osteoclastic resorption in mouse calvariae by mechanisms that are independent of cell proliferation; partially dependent on prostaglandin biosynthesis; sensitive to inhibition by IL-4, IL-13, and OPG; and associated with enhanced expression of RANKL and OPG. In addition, IL-11 was not found to play an essential role in resorption stimulated by other calciotropic agents in calvariae.

Human gingival fibroblasts rescue butyric acid-induced T-cell apoptosis

We previously demonstrated that butyric acid, an extracellular metabolite from periodontopathic bacteria, induces cytotoxicity and apoptosis in murine thymocytes, splenic T cells, and human Jurkat T cells. In this study, we used a cell-to-cell interaction system to examine the contribution of gingival fibroblasts to the regulation of T-cell death induced by butyric acid. Butyric acid slightly suppressed fibroblast viability in a concentration-dependent fashion. However, DNA fragmentation assays indicated that butyric acid did not induce apoptosis for up to 21 h in human gingival fibroblasts (Gin 1, F41-G, and H. pulp cells). The culture supernatants were assayed for interleukin 1alpha (IL-1alpha), IL-1beta, IL-6, IL-8, IL-11, tumor necrosis factor alpha, and transforming growth factor beta, but only the IL-6, IL-8, and IL-11 levels were significantly increased by addition of butyric acid. Butyric acid- or Fas-induced Jurkat-cell apoptosis was attenuated when Jurkat cells were cocultured with either F41-G or Gin 1 cells that had been preincubated for 6 h with butyric acid. IL-8 slightly stimulated butyric acid- or Fas-induced Jurkat-cell apoptosis in a dose-dependent manner, although a low dose of IL-8 had a mildly inhibitory effect on apoptosis. In contrast, IL-6 and IL-11 significantly suppressed butyric acid- or Fas-induced apoptosis in a dose-dependent fashion. Furthermore, the addition of monoclonal antibodies against human IL-6 and IL-11 to cocultures of gingival fibroblasts and Jurkat cells partially eliminated T-cell recovery. These results suggest that the proinflammatory cytokines such as IL-6 and IL-11, produced in fibroblasts stimulated with butyric acid, are involved in the attenuation of T-cell apoptosis by gingival fibroblasts.

Interleukin-11 induces proliferation of human T-cells and its activity is associated with downregulation of p27(kip1)

BACKGROUND AND OBJECTIVES

We have recently shown that interleukin (IL-)11 induces polarization of human T-cells by inhibiting macrophage production of IL-12 and by exerting a direct effect on CD4+ T-cells. In this study, we investigated the effects of IL-11 on the kinetic activation and apoptosis of T-cell subsets stimulated with anti-CD3/CD28 antibodies, anti-CD3 and IL-2 or dendritic cells.

DESIGN AND METHODS

Apoptosis and cell cycle analysis of T-cells were assessed by double staining with propidium iodide and intracellular Ki-67 and by acridine orange staining. The expression of the negative regulator of the cell cycle p27Kip1 (p27) was also determined by flow cytometry.

RESULTS

Our results show that 18 hours of incubation with IL-11 resulted in a significantly higher number of cycling CD4+ cells, CD4+CD45RA+ naive T-cells and CD4+CD45RO+ memory T-cells, but not of CD8+ cells. The kinetic activity of IL-11 was observed up to 72 hours, when the peak value of S-phase cells occurred. IL-11 also significantly enhanced CD4+ and CD4+CD45RA+ cell proliferation when T-cells were co-incubated with allogeneic dendritic cells. Conversely, IL-11 did not protect any of the T-cell subsets from apoptosis. At the functional level, a type-2 cytokine pattern of cultured T-lymphocytes was observed after 5 days of incubation with IL-11. Proliferation and functional activation of T-cells were preceeded by downregulation of p27, which occurred as early as 12 hours after incubation with IL-11.

INTERPRETATION AND CONCLUSIONS

IL-11 induces Th-2 polarization and cell-cycle entry of human CD4+, CD4+CD45RA+ and CD4+CD45RO+cells and their activation is associated with the downregulation of p27.

Inflammatory cytokines and mucosal injury

The cause of mucosal injury in inflammatory bowel disease (IBD) is not clear but likely involves infectious agents or other toxins followed by an abnormal immune response in genetically susceptible individuals. The inflammatory cytokines appear to play a key role in both the susceptibility of some individuals and the tissue damage that accompanies IBD. The generation of transgenic and gene-targeted (knockout) animals has provided invaluable information regarding the cytokines and cellular immune effectors that are important in IBD. Information from these and other preclinical animal models, such as those involving interleukin 11, has led to human trials testing novel therapies for IBD and other diseases in which inflammation of the gut mucosa is an important component. Thus, expression of inflammatory cytokines appears to be an important target for the development of novel therapies for IBD and other diseases in which intestinal mucosal damage occurs, such as mucositis and graft-versus-host disease.

Airway inflammation and remodeling in asthma. Lessons from interleukin 11 and interleukin 13 transgenic mice

Noninflammatory structural alterations, variously referred to as airway remodeling, are well documented in the asthmatic airway. However, the pathogenesis of these alterations, the importance of airway remodeling in generating the asthma phenotype, and the natural history of airway remodeling responses have not been adequately defined. Because exaggerated cytokine production is a characteristic feature of the asthmatic airway, we used constitutive and inducible overexpression transgenic systems to investigate the contributions that interleukin 11 (IL-11) and IL-13 might make to airway remodeling responses. These studies demonstrated that both cytokines produce responses in the murine airway with features similar to those in human asthmatic tissues. IL-11 caused airway fibrosis with the enhanced accumulation of interstitial collagens, myocytes, and myofibroblasts. IL-13 caused mucous metaplasia, enhanced mucin gene expression, enhanced tissue hyaluronic acid accumulation, and subepithelial fibrosis. Importantly, IL-11 was detected most readily in tissues from asthmatic subjects with severe airway remodeling that was similar to that seen in the IL-11 transgenic mice. In addition, IL-11 was shown to inhibit asthma-like inflammation while stimulating airway fibrosis. This suggests that IL-11 elaboration is, in part, an attempt at airway healing. Last, a novel triple transgenic system is described that allows transgene expression to be regulated in a true "on/off" manner. This system may be useful in defining the reversibility of transgene-induced airway remodeling responses.

Disparate effects of interleukin 11 and thrombopoietin on megakaryocytopoiesis in vitro

The effects of interleukin-11 (IL-11) and thrombopoietin (TPO) on murine megakaryocytopoiesis were studied using a serum-free culture system. Acting alone, both IL-11 and TPO increased the number of acetylcholinesterase (AchE)(+)cells (megakaryocytes), the latter being more potent than the former. TPO, but not IL-11, increased the mean AchE activity per megakaryocyte (AchE activity/megakaryocyte). TPO increased both the number of megakaryocytes with high ploidy, and of those with low ploidy. In contrast, IL-11 increased only the number of megakaryocytes with high ploidy. The effect of TPO on megakaryocyte ploidy was stronger than that of IL-11. Both IL-11 and TPO increased the proportion of large megakaryocytes, but the latter was more potent than the former. While the stimulatory effects of IL-11 and TPO on the number of megakaryocytes were enhanced by IL-3 or stem cell factor (SCF), synergism of IL-11 or TPO with IL-3 or SCF in stimulating AchE activity/megakaryocyte was inconsistent. IL-11 and TPO stimulated the formation of colony-forming units of megakaryocyte in the presence of IL-3, but not alone, with similar maximum colony numbers for both cytokines. Our findings thus demonstrate that IL-11 principally stimulates megakaryocyte maturation rather than the proliferation of megakaryocytes, whereas TPO stimulates both.

Tumor necrosis factor alpha and interleukin 11 secreted by malignant breast epithelial cells inhibit adipocyte differentiation by selectively down-regulating CCAAT/enhancer binding protein alpha and peroxisome proliferator-activated receptor gamma: mechanism of desmoplastic reaction

The dense layer of fibroblasts that accumulate around malignant breast epithelial cells (i.e., desmoplastic reaction) arises from the breast adipose tissue and provides structural and biochemical support for breast cancer. We report herein a number of epithelial-stromal interactions responsible for desmoplastic reaction in breast cancer using cultured 3T3-L1 murine fibroblasts and human adipose fibroblasts, which can be activated with a mixture of hormones to differentiate to mature adipocytes. Adipocyte differentiation was inhibited by coculturing fibroblasts with various breast cancer cell lines (T47D, MCF-7, SSC202, SSC78, and SSC30) completely or by breast cancer cell conditioned media in a dose-dependent manner; on the other hand, adipocyte differentiation was not inhibited by coculturing with normal human primary mammary epithelial cell conditioned medium. This tumor effect was eliminated using neutralizing antibodies against tumor necrosis factor (TNF)-alpha or interleukin (IL)-11. TNF-alpha and IL-11 levels were 2.5-3 times higher in T47D conditioned medium compared with control medium, and TNF-alpha transcripts were detectable in T47D but not in 3T3-L1 cells in culture, indicating that the malignant epithelial cell is the major site of cytokine production. This was confirmed in vivo in mastectomy specimens, where immunoreactive TNF-alpha and IL-11 were readily detectable in malignant epithelial cells but not in the majority of the surrounding fibroblasts. Adipocyte differentiation is mediated by the expression of a cascade of adipogenic transcription factors, including CCAAT/enhancer binding protein (C/EBP)beta, C/EBPdelta, peroxisome proliferator-activated receptor (PPAR)gamma and C/EBPalpha. C/EBPalpha and PPARgamma are essential for this process. We demonstrated by Northern analysis that exposure of activated 3T3-L1 cells to T47D cell conditioned medium strikingly decreased the levels of PPARgamma and C/EBPalpha transcripts and increased the levels of C/EBPbeta and C/EBPdelta transcripts. In these 3T3-L1 cells, inhibition of differentiation was also confirmed by markedly suppressed levels of aP2 mRNA, which is an adipocyte-specific gene. These in vitro observations were confirmed in sections of human malignant breast tumors, where immunoreactive C/EBPalpha was readily detectable in adipose flbroblasts distant to the tumor but not in intratumoral fibroblasts. Treatment of 3T3-L1 cells with T47D cell conditioned medium or TNF-alpha changed neither the numbers of cells in G0-G1, S, and G2 phases nor the rate of [3H]thymidine incorporation, thus ruling out a proliferative effect of malignant cells on the surrounding fibroblasts. In summary, desmoplastic reaction primarily occurs via the action of cytokines (TNF-alpha and IL-11) secreted by the malignant epithelial cells to inhibit differentiation of adipose fibroblasts to mature adipocytes. This tumor-induced block in adipocyte differentiation is mediated by the selective inhibition of expression of the essential adipogenic transcription factors, i.e., PPARgamma and C/EBPalpha.

The role of recombinant interleukin 11 in megakaryocytopoiesis

Recombinant human interleukin 11 (rHuIL-11) is a multifunctional cytokine with activities on a broad range of hematopoietic cells including primitive stem cells and mature progenitor cells. Analysis of rHuIL-11 in vitro has revealed that its hematopoietic activities are predominantly a result of synergistic interactions with other early-acting factors such as IL-3 and Steel factor. Studies indicate that rHuIL-11 acts directly on purified stem and progenitor cell populations and can support the growth of colony forming units-megakaryocyte in these cultures. In normal animals, rHuIL-11 has a potent effect on cells of the megakaryocyte (MK) lineage. Administration of rHuIL-11 results in a two- to threefold increase in circulating platelets, stimulation of bone marrow (BM) and spleen progenitor numbers, and enhanced MK maturation as measured by a shift to higher ploidy values. rHuIL-11 administration in preclinical models of myelosuppression induced by chemotherapy and/or irradiation has shown a reproducible acceleration of platelet recovery and, in some models, enhanced neutrophil and red blood cell recovery. rHuIL-11 has been tested in a non-human primate myelosuppression model using carboplatin. Administration of rHuIL-11 following carboplatin treatment was found to eliminate the period of severe thrombocytopenia (<20,000 platelets/ml) and enhance the recovery of platelets to normal levels (>100,000/ml). Recently, human clinical trials conducted with rHuIL-11 in patients treated with chemotherapy have demonstrated its potent thrombopoietic activity, including improved platelet nadirs, enhanced platelet recovery and a significant decrease in the number of patients who require platelet transfusions. Combined with the preclinical results, these studies confirm that this cytokine will be an effective agent in the treatment of myelosuppression and thrombocytopenia associated with cancer chemotherapy and BM transplantation.

Interleukin-11 modulates Th1/Th2 cytokine production from activated CD4+ T cells

Recombinant human interleukin-11 (rHuIL-11) is a pleiotropic cytokine with effects on multiple cell types. rHuIL-11 reduces activated macrophage activity and downregulates production of proinflammatory mediators, such as tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO). In vitro and in vivo, rHuIL-11 inhibits production of key immunostimulatory cytokines, including IL-12 and interferon-gamma (IFN-gamma). rHuIL-11 has recently demonstrated immunomodulatory activity to downregulate IFN-gamma production, increase IL-4 production, and reduce inflammatory tissue injury in a human psoriasis clinical trial. The cellular mechanisms of these effects are not fully elucidated. We demonstrate here that expression of gp130 and IL-11 receptor (IL-11R) alpha mRNA, components of the IL-11R complex, are detected in human and murine CD4(+) and CD8(+) lymphocytes, suggesting that rHuIL-11 can directly interact with T cells. In a cell culture model of murine T cell differentiation, rHuIL-11 acts to inhibit IL-2 production as well as IL-12-induced IFN-gamma production and enhances IL-4 and IL-10 production. rHuIL-11 had no effect on T cell proliferation. The ability of rHuIL-11 to modulate cytokine production from activated CD4(+) T cells provides a mechanism through which rHuIL-11 may ameliorate such inflammatory diseases as psoriasis.

Thrombopoietin, interleukin-11, and early-acting megakaryocyte growth factors in human myeloid leukemia cells

In this study we report our data on effects of early-acting megakaryocyte growth factors, particularly the c-mpl ligand also known as thrombopoietin (TPO) and interleukin-11 (IL-11), on cell proliferation and apoptosis (Apo) of primary acute myeloid leukemia (AML) cells. A proliferative response to TPO was noticed in the majority of AML samples (17/19) with an average increase of S-phase cells from 7.8% +/- 1.5 to 14.5% +/- 2.1 (p=0.0006). Resulting cell cycle activation did not always correlate with expression of the c-mpl receptor, although it was coupled, in the majority of samples, by an average decrease of apoptotic cells from 13% +/- 0.7 to 8.8% +/- 1.8 (p=0.05). Clonogenic cell growth (CFU-L) was confirmed in 5/17 of the samples with a mean colony number of 21.4 +/- 9.6 x 10(5) cells plated. Conversely, effects of IL-11 on AML cells demonstrated that cell cycle changes (recruitment from G0 to S phase) were promoted only in a minority of samples (2/14) and there was little, if any, effect on CFU-L growth (mean colony number=17.5 +/- 9.5) or Apo (from 13% +/- 0.7 to 13.3 +/- 1.9). Combination of TPO with IL-11 induced a slight increase of clonogenic cell growth, while the addition of IL-3 or SCF to the c-mpl ligand significantly raised the mean colony numbers up to 119.2 +/- 68.3 and 52.9 +/- 22.1 x 10(5) cells plated, respectively. In summary, TPO shows activity on AML cells by stimulating their proliferation in a significant proportion of cases and generally protecting the majority of AML blast cells from induction of Apo. Conversely, IL-11 exerts little effect on the cell cycle activation and Apo. These data help to understand regulation of myeloid leukemia cell growth and should be considered in the clinical use of early-acting megakaryocyte growth factors in acute leukemia.

Preclinical pharmacologic basis for clinical use of rhIL-11 as an effective platelet-support agent

Preclinical studies have shown that rhIL-11, also known as oprelvekin (Neumega), stimulates early and later stages of megakaryocytopoiesis (including proliferation and differentiation of megakaryocyte precursors and maturation of megakaryocytes), to produce an increase in peripheral platelet count. Because of these effects, rhIL-11 must be administered to patients with cancer sufficiently in advance of the platelet nadir (within 6 to 24 hours postchemotherapy) to allow adequate time for megakaryocyte maturation and platelet formation. Therefore, the maximum platelet response coincides with the time when the platelet nadir would normally be experienced. In myelosuppressed, nonhuman primates, optimal platelet response occurred following 14 days of treatment at a dose equivalent to the 50-microgram/kg daily dose recommended in humans; lower doses and shorter durations were less effective. These data support the current dosing recommendation in humans, which states that rhIL-11 dosing continues until platelet recovery to > or = 50,000/microL has been achieved for 2 consecutive days or for a total of 10 to 21 days in each cycle. The nonhematopoietic effects of rhIL-11 include a renal effect, resulting in plasma-volume expansion, as well as potential beneficial clinical effects in damaged or inflamed intestinal mucosa, including potential mitigation of mucositis and a rationale for future studies in inflammatory bowel disease.

The gp130 cytokines interleukin-11 and ciliary neurotropic factor regulate through specific receptors the function and growth of lactosomatotropic and folliculostellate pituitary cell lines

Two of the most potent cytokines regulating anterior pituitary cell function are leukemia inhibitory factor and interleukin-6 (IL-6), which belong to the cytokine receptor family using the common gp130 signal transducer. We studied the actions of two other members of this family, IL-11 and ciliary neurotropic factor (CNTF), on folliculostellate (FS) cells (TtT/GF cell line) and lactosomatotropic cells (GH3 cell line). The messenger RNA (mRNA) for the alpha-chain specific for the IL-11 receptor (1.7 kb) and CNTF receptor (2 kb) are expressed on both cell types. In addition, we detected CNTF receptor mRNA in normal rat anterior pituitary cells. IL-11 (1.25-5 nM) dose dependently stimulated the proliferation of FS cells. CNTF, at doses from 0.4-2 nM, also significantly stimulated the growth of these cells. In addition, both cytokines significantly stimulated proliferation of lactosomatotropic GH3 cells, and CNTF stimulated hormone production (GH and PRL) at 24 h by these cells. At 16-72 h, IL-11 stimulates the secretion of the angiogenic factor vascular endothelial growth factor by FS cells. In addition, both GH3 and FS cells express CNTF mRNA. These data suggest that IL-11 and CNTF may act as growth and regulatory factors in anterior pituitary cells.

IL-11 activates human endothelial cells to resist immune-mediated injury

IL-11, a gp130-signaling cytokine, is protective in several in vivo models of immune-mediated and inflammatory injury. HUVECs express IL-11 receptor alpha-chain and gp130. Human IL-11 causes rapid (2-10 min) tyrosine phosphorylation of gp130. IL-11 at 0.1 and 10 ng/ml induces tyrosine phosphorylation of STAT3 and STAT1, respectively, although maximal responses require 50 ng/ml. Phospho-STAT3 and phospho-STAT1 levels peak rapidly (2.5 min) and disappear by 60 min. The p42 and p44 mitogen-activated protein kinases (MAPKs) are phosphorylated in response to 0.3 ng/ml IL-11 with maximal activation at 30 ng/ml IL-11. Phosphorylation of p42 and p44 MAPKs, which can be prevented by a mitogen-activated protein/extracellular signal-related kinase kinase-1 inhibitor, peaks by 15-20 min and largely disappears by 40 min. IL-11 does not activate NF-kappaB nor does it inhibit NF-kappaB activation by TNF. Similarly, IL-11 neither induces E-selectin or ICAM-1 nor blocks induction by TNF. Although IL-11 does not alter class I MHC complex molecule expression, pretreatment with 0.5 ng/ml IL-11 partially protects HUVECs against lysis by allospecific class I MHC-restricted cytolytic T lymphocytes or by anti-class I MHC Ab plus heterologous C. IL-11-induced cytoprotection is protein synthesis dependent and may depend on mitogen-activated protein/extracellular signal-related kinase kinase-1. Our results indicate that low (i.e., STAT3- and MAPK-activating) concentrations of IL-11 confer resistance to immune-mediated injury in cultured HUVECs without inhibiting proinflammatory responses.

Biologic and structural differences of thrombopoietic growth factors

The search for a thrombopoietic agent has resulted in the identification of numerous cytokines and growth factors with thrombopoietic activity. However, with the exception of interleukin (IL)-11 and thrombopoietin (TPO), the megakaryopoietic activity of most of these molecules has not produced clearly identifiable clinical benefits. Despite the relatively modest effect of IL-11 on megakaryocyte and platelet production in vitro and in vivo, it does reduce the need for platelet transfusions in specialized clinical settings. In contrast, the c-Mpl ligand TPO has been shown to be a potent stimulator of megakaryocyte and platelet production both in vitro and in vivo. Clinical studies are being conducted with two different preparations of the c-Mpl ligand: recombinant human thrombopoietin (rhTPO) and pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF). A recombinant form of the complete human molecule, rhTPO is glycosylated and produced in mammalian cells. PEG-rHuMGDF consists of only the receptor-binding domain linked to a polyethylene glycol (PEG) moiety and is generated in Escherichia coil. Although c-Mpl ligands are still being evaluated, preliminary evidence indicates that these molecules can elevate platelet counts and may be useful in a range of clinical contexts. This report discusses aspects of the biology behind the clinical actions of IL-11 and the c-Mpl ligands.

Use of thrombopoietic growth factors in acute leukemia

Several hematopoietic growth factors have been shown to affect megakaryocyte development, and two, interleukin (IL)-11 and thrombopoietin (TPO) are presently being evaluated for use in patients with thrombocytopenia. In two studies patients who required one or more platelet transfusions during their first course of chemotherapy were found to require fewer platelet transfusions if their second cycle was augmented with IL-11. The drug was generally safe, with cardiovascular compromise the only significant complication occurring in a minority of patients. Although these reports included patients with various malignancies, studies of IL-11 in patients with myeloproliferative disorders have not been presented. In several clinical trials in cancer patients treatment with TPO was safe, and when administered early following a moderately aggressive cytotoxic insult was effective in accelerating platelet recovery. In addition, in both pre-clinical and clinical trials, TPO given to stem cell donors during mobilization lead to accelerated hematopoietic recovery. Finally, TPO appears safe when administered to patients with acute myelogenous leukemia (AML), both with respect to acute toxicity and long-term outcome of the leukemia. However, when used following a 7-day course of standard chemotherapy, the agent does not appear to accelerate platelet recovery. As such, additional clinical trials to test different growth factor regimens are ongoing. A number of studies have suggested that megakaryocytic growth factors may play a role in the biology of myeloproliferative disorders. Given the potential for adversely affecting patients with these disorders, the affects of IL-11 or TPO in patients with AML must continue to be carefully studied.

Interleukin-11 enhances small intestine absorptive function and mucosal mass after intestinal adaptation

BACKGROUND/PURPOSE

Interleukin-11 (IL-11) recently has been shown to enhance mucosal mass after massive small bowel resection (MSBR). However, enhanced mucosal mass may not correlate with increased substrate absorption. This study was designed to examine the effect of systemic administration of increasing doses of IL-11 on small intestine absorptive function and mucosal mass after MSBR.

METHODS

Twenty-five Sprague-Dawley rats underwent an 80% small bowel resection and end-to-end jejunoileal anastomosis. Seven days after resection, all rats had placement of a jugular venous catheter connected to a subcutaneously placed osmotic pump. The rats were divided into 5 groups based on the content of the pump: group 1 (control, n = 5) received 0.1% bovine serum albumin (BSA) and groups 2 through 5 (n = 5 each) received IL-11 at 250, 500, 750, and 1,000 microg/kg/d, respectively. After a 14-day infusion period, [14C] galactose and [14C] glycine absorption was measured using an in vivo closed-recirculation technique. Mucosal DNA content also was determined for each group. Statistical analysis was performed by analysis of variance and expressed as mean +/-SEM.

RESULTS

IL-11 administered at 250 microg/kg/d, a dose used in previous studies, did not significantly affect substrate absorption. However, compared with the control group, administration of higher doses of IL-11 produced a significant increase in substrate absorption and mucosal mass. The dose of IL-11 producing the overall optimal response based on the parameters measured (galactose absorption, 72% increase over control; glycine absorption, 112% increase over control; and DNA content, 98% increase over control) was 750 microg/kg/d.

CONCLUSIONS

In addition to an increase in mucosal mass, these data show for the first time that IL-11 enhances absorptive function beyond the normal adaptive response after MSBR. Furthermore, the maximum effect of IL-11 on absorptive function was shown at 750 microg/kg/d, which is 3 times the dose used in previously reported studies. This study suggests that IL-11 may be useful clinically in patients with inadequate intestinal function.

The residual megakaryocyte and platelet production in c-mpl-deficient mice is not dependent on the actions of interleukin-6, interleukin-11, or leukemia inhibitory factor

Mice lacking thrombopoietin (TPO) or its receptor c-Mpl are severely thrombocytopenic, consistent with a dominant physiological role for this cytokine in megakaryocytopoiesis. However, these mice remain healthy and show no signs of spontaneous hemorrhage, implying that TPO-independent mechanisms for platelet production exist and are sufficient for hemostasis. To investigate the roles of cytokines that act through the gp130 signaling chain in the residual platelet production of mpl (-/-) mice, mpl (-/-)IL-6(-/-), mpl(-/-)LIF(-/-), and mpl(-/-)IL-11Ralpha(-/-) double-mutant mice were generated. In each of these compound mutants, the number of circulating platelets was no lower than that observed in mice lacking only the c-mpl gene. Moreover, the deficits in the numbers of megakaryocytes and megakaryocyte progenitor cells in the bone marrow and spleen were no further exacerbated in mpl(-/-)IL-6(-/-), mpl(-/-)LIF(-/-), or mpl(-/-)IL-11Ralpha(-/-) double-mutant mice compared with those in Mpl-deficient animals. In single IL-6(-/-), LIF(-/-), and IL-11Ralpha(-/-) mutant mice, platelet production was normal. These data establish that, as single regulators, IL-6, IL-11, and LIF have no essential role in normal steady-state megakaryocytopoiesis, and are not required for the residual megakaryocyte and platelet production seen in the c-mpl(-/-) mouse. (Blood. 2000;95:528-534)

Importance of the membrane-proximal extracellular domains for activation of the signal transducer glycoprotein 130

The transmembrane glycoprotein gp130 is the common signal transducing receptor subunit of the IL-6-type cytokines. The gp130 extracellular part is predicted to consist of six individual domains. Whereas the role of the three membrane-distal domains (D1-D3) in binding of IL-6 and IL-11 is well established, the function of the membrane-proximal domains (D4-D6) is unclear. Mapping of a neutralizing mAb to the membrane-proximal part of gp130 suggests a functional role of D4-D6 in receptor activation. Individual deletion of these three domains differentially interferes with ligand binding of the soluble and membrane-bound receptors. All deletion mutants do not signal in response to IL-6 and IL-11. The deletion mutants Delta4 and, to a lesser extent, Delta6 are still activated by agonistic monoclonal gp130 Abs, whereas the deletion mutant Delta5 does not respond. Because membrane-bound Delta5 binds IL-6/soluble IL-6R as does wild-type gp130, but does not transduce a signal in response to various stimuli, this domain plays a prominent role in coupling of ligand binding and signal transduction. Replacement of the fifth domain of gp130 by the corresponding domain of the homologous G-CSF receptor leads to constitutive activation of the chimera upon overexpression in COS-7 cells. In HepG2 cells this mutant responds to IL-6 comparable to wild-type gp130. Our findings suggest a functional role of the membrane-proximal domains of gp130 in receptor activation. Thus, within the hematopoietic receptor family the mechanism of receptor activation critically depends on the architecture of the receptor ectodomain.