Serum Leukemia Inhibitory Factor Levels Research Articles

Serum leukemia inhibitory factor (LIF) levels in patients with Takayasu's and Giant cell arteritis: A cross-sectional study

Introduction and objectivesIn this study, we aimed to evaluate LIF levels and its possible relationship with disease activity in patients with Takayasu's (TAK) and Giant cell arteritis (GCA) patients. Materials and methods23 Takayasu's arteritis, 9 Giant cell arteritis patients and 25 healthy volunteers were included in the study. Serum LIF levels were measured ELISA. ResultsThe mean age of Giant cell arteritis patients was statistically significantly higher than the other groups (p<0.001). The rate of women was found to be higher in Takayasu's arteritis (p=0.021). When healthy control, patients with GCA and Takayasu arteritis were compared, there was a difference in LIF values (p=0.018). In subgroup analyzes, LIF values were found to be higher in GCA patients compared to healthy controls (p<0.05). There was no statistically significant correlation between LIF and CRP (Rho=−0.038, p=0.778), ESR (Rho=0.114, p=0.399) and ITAS (Rho=−0.357, p=0.094). While CRP was statistically significantly higher in patients with disease activity (p=0.003), there was no statistically significant difference between patients in terms of ESR and LIF values. While there was a statistically significant relationship between CRP (OR=1.19 [1.03–1.37], p=0.018) and disease activity in univariate analyses, no statistically significant variable was found in multivariable analyses. ConclusionsLIF values were significantly higher in patients with Giant cell arteritis compared to healthy controls.

CircFARP1 enables cancer-associated fibroblasts to promote gemcitabine resistance in pancreatic cancer via the LIF/STAT3 axis

BackgroundCancer-associated fibroblasts (CAFs) are critically involved in gemcitabine (GEM) resistance in pancreatic ductal adenocarcinoma (PDAC). However, the underlying mechanism by which CAFs promote chemotherapy resistance remains unexplored. Here, we explored the role of circRNAs in CAF-induced GEM resistance in PDAC.MethodscircRNA sequencing and quantitative real-time PCR (qRT–PCR) were utilized to screen CAF-specific circRNAs. The effects of CAF circFARP1 expression on GEM resistance in tumor cells were assessed in vitro and in vivo. RNA-seq, RNA pulldown, RNA immunoprecipitation, and luciferase reporter assays were used to screen the downstream target and underlying mechanism of circFARP1.ResultscircFARP1 (hsa_circ_0002557), a CAF-specific circRNA, was positively correlated with GEM chemoresistance and poor survival in an advanced PDAC cohort. Silencing or overexpressing circFARP1 in CAFs altered the ability of CAFs to induce tumor cell stemness and GEM resistance via leukemia inhibitory factor (LIF). Mechanistically, we found that circFARP1 directly binds with caveolin 1 (CAV1) and blocks the interaction of CAV1 and the E3 ubiquitin-protein ligase zinc and ring finger 1 (ZNRF1) to inhibit CAV1 degradation, which enhances LIF secretion. In addition, circFARP1 upregulated LIF expression by sponging miR-660-3p. Moreover, high circFARP1 levels were positively correlated with elevated serum LIF levels in PDAC and poor patient survival. Decreasing circFARP1 levels and neutralizing LIF significantly suppressed PDAC growth and GEM resistance in patient-derived xenograft models.ConclusionsThe circFARP1/CAV1/miR-660-3p/LIF axis is critical for CAF-induced GEM resistance in PDAC. Hence, circFARP1 may be a potential therapeutic target for PDAC.

Osteoblast and Osteoclast Activity Affect Bone Remodeling Upon Regulation by Mechanical Loading-Induced Leukemia Inhibitory Factor Expression in Osteocytes.

PurposeBone remodeling is affected by mechanical stimulation. Osteocytes are the primary mechanical load-sensing cells in the bone, and can regulate osteoblast and osteoclast activity, thus playing a key role in bone remodeling. Further, bone mass during exercise is also regulated by Leukemia inhibitory factor (LIF). This study aimed to investigate the role of LIF in the mechanical response of the bone, in vivo and in vitro, and to elucidate the mechanism by which osteocytes secrete LIF to regulate osteoblasts and osteoclasts.MethodsA tail-suspension (TS) mouse model was used in this study to mimic muscular disuse. ELISA and immunohistochemistry were performed to detect bone and serum LIF levels. Micro-computed tomography (CT) of the mouse femurs was performed to measure three-dimensional bone structure parameters. Fluid shear stress (FSS) and microgravity simulation experiments were performed to study mechanical stress-induced LIF secretion and its resultant effects. Bone marrow macrophages (BMMs) and bone mesenchymal stem cells (BMSCs) were cultured to induce in vitro osteoclastogenesis and osteogenesis, respectively.ResultsMicro-CT results showed that TS mice exhibited deteriorated bone microstructure and lower serum LIF expression. LIF secretion by osteocytes was promoted by FSS and was repressed in a microgravity environment. Further experiments showed that LIF could elevate the tartrate-resistant acid phosphatase activity in BMM-derived osteoclasts through the STAT3 signaling pathway. LIF also enhanced alkaline phosphatase staining and osteogenesis-related gene expression during the osteogenic differentiation of BMSCs.ConclusionMechanical loading affected LIF expression levels in osteocytes, thereby altering the balance between osteoclastogenesis and osteogenesis.

Leukemia inhibitory factor is a novel biomarker to predict lymph node and distant metastasis in pancreatic cancer.

Pancreatic cancer has a low survival rate, and most patients have lymph node metastasis and distant metastasis at the time of diagnosis. Despite efforts to improve overall survival (OS) and recurrence free survival (RFS), the prognosis of pancreatic cancer remains poor, underscoring the importance of identifying new biomarkers to predict metastasis in patients with pancreatic cancer. Leukemia inhibitory factor (LIF) is overexpressed in many types of cancer and is involved in the development of various malignancies including pancreatic cancer. However, the role of LIF as a biomarker to predict metastasis in pancreatic cancer remains unclear. In this study, univariate and multivariate Cox regression analyses identified LIF expression in pancreatic tumor tissues as an independent risk factor related to worse OS and RFS. LIF overexpression was related to poor clinicopathological features such as lymph node metastasis and Pathological stage (pTNM) stage. Serum LIF levels were higher in pancreatic cancer patients than in healthy controls. The area under the receiver operating characteristic curve indicated that serum LIF is more effective than other biomarkers (CA199 and CEA) for predicting lymph node and distant metastasis.

A possible implication of reduced levels of LIF, LIFR, and gp130 in vasculopathy related to systemic sclerosis.

Leukemia inhibitory factor (LIF) is a member of IL-6 family, which serves as a potent chemoattractant for neutrophils as well as a potent angiostatic factor. LIF has been implicated in various autoimmune inflammatory diseases, but its role still remains elusive in systemic sclerosis (SSc). Therefore, we investigated the potential role of LIF in the development of SSc by evaluating the clinical correlation of serum LIF levels, the expression of LIF and its receptors in skin samples, and in vitro experiments with human dermal microvascular endothelial cells. Serum LIF levels were significantly decreased in patients with SSc, especially in those with disease duration of<1year compared with healthy controls. As for clinical correlation, SSc patients with digital ulcers exhibited serum LIF levels significantly lower than those without. In immunohistochemistry, the expression of LIF and its receptors, LIF receptor and gp130, was remarkably decreased in dermal blood vessels of SSc lesional skin relative to those of healthy control skin. Furthermore, gene silencing of transcription factor Fli1, whose deficiency is involved in the development of SSc vasculopathy, suppressed the expression of LIF, LIF receptor, and gp130 and Fli1 bound to the promoters of those genes in human dermal microvascular endothelial cells. Collectively, these results suggest that decreased serum LIF levels may be associated with vasculopathy in SSc and that Fli1 deficiency may contribute to the inhibition of LIF-dependent biological effects on SSc endothelial cells by suppressing the expression of LIF, LIF receptor, and gp130.

Leukemia inhibitory factor promotes nasopharyngeal carcinoma progression and radioresistance

Radioresistance of EBV-associated nasopharyngeal carcinoma (NPC) is associated with poor prognosis for patients with this form of cancer. Here, we found that NPC patients had increased serum levels of leukemia inhibitory factor (LIF) and that higher LIF levels correlated with local tumor recurrence. Furthermore, in vitro studies with NPC cells and in vivo xenograft mouse studies demonstrated that LIF critically contributes to NPC tumor growth and radioresistance. Using these model systems, we found that LIF treatment activated the mTORC1/p70S6K signaling pathway, enhanced tumor growth, inhibited DNA damage responses, and enhanced radioresistance. Treatment with either soluble LIF receptor (sLIFR), a LIF antagonist, or the mTOR inhibitor rapamycin reversed LIF-mediated effects, resulting in growth arrest and increased sensitivity to γ irradiation. Immunohistochemical (IHC) analyses of human NPC biopsies revealed that LIF and LIFR were overexpressed in tumor cells and that LIF expression correlated with the presence of the activated p-p70S6K. Finally, we found that the EBV-encoded protein latent membrane protein 1 (LMP1) enhances LIF production. Together, our findings indicate that LIF promotes NPC tumorigenesis and suggest that serum LIF levels may predict local recurrence and radiosensitivity in NPC patients.

Clodronate alleviates cachexia and prolongs survival in nude mice xenografted with an anaplastic thyroid carcinoma cell line

Cancer cachexia is one of the most common manifestations of advanced malignant disease and is frequently associated with decreased survival. Previously, we reported the establishment of a new anaplastic thyroid carcinoma cell line, Thena, and its mouse xenograft, Thena-Nu, which induced cachexia in athymic nude mice. Subsequent studies showed that the addition of clodronate to Thena-Nu cultures reduced cell proliferation as well as cytokine production in a dose- and time-dependent manner. Weekly administration of clodronate induced tumor cytostasis, attenuation of cachexia, as well as prolongation of survival in Thena-Nu-bearing mice. Reduced serum interleukin 6, tumor necrosis factor-alpha, and granulocyte colony stimulating factor levels were detected, whereas, serum leukemia inhibitory factor levels were not reduced. Liver necrosis, observed in tumor-bearing mice, was also improved following clodronate treatment. Discontinuation of clodronate treatment, however, resulted in progressive tumor growth and weight loss. Our results demonstrated that clodronate could exert therapeutic efficacy on amelioration of cancer cachexia in the hosts. Nevertheless, this study also points out that a longer period of treatment is required to maintain these effects.

In vivo and in vitro regulation of thyroid leukemia inhibitory factor (LIF): marker of hypothyroidism.

Several cytokines regulate thyroid function and may be involved in the pathogenesis of thyroid disorders, including euthyroid sick syndrome. Leukemia inhibitory factor (LIF), a neuroimmune pleiotropic cytokine, was measured to assess its role in hypothalamic-pituitary-thyroid function. Mean circulating serum LIF levels in 10 hypothyroid patients [TSH, 23+/-0.5 mIU/L (mean+/-SEM); free T4, 0.77+/-0.1 ng/dL] was 0.29+/-0.04 ng/mL, 145% higher (P < 0.04) than in 20 normal subjects (LIF, 0.20+/-0.02 ng/mL; TSH, 2.23+/-0.21 mIU/L; free T4, 1.23+/-0.04 ng/dL) but was not different from those in 10 hyperthyroid patients (LIF, 0.21+/-0.03 ng/mL; TSH, 0.01+/-0.00 mIU/L; free T4, 3.63+/-0.51 ng/dL). Serum LIF concentrations linearly correlated with serum TSH in the 40 samples (r = 0.58, P < 0.001). When T4 (1-8 microg/kg x day) was administered to cynomolgus monkeys with methimazole-induced hypothyroidism, serum T4 and T3 levels increased appropriately, and TSH and LIF concentrations decreased. When methimazole was given alone, both serum TSH (146+/-30 mIU/L) and LIF (8.84+/-0.49 ng/mL) were markedly induced. When methimazole together with T4 (>2 microg/kg x day) was administered, both serum TSH (7.5+/-1.2 mIU/L) and LIF (6.22+/-0.31 ng/mL) were lowered (P < 0.01). Monkey serum LIF levels and log TSH levels also correlated (r = 0.72, P < 0.01). Cultured thyroid carcinoma cells produced LIF (9.2 ng/10(6) cells/48 h). TSH (100 mIU/mL) and interleukin (IL)-6 (10 nmol/L) stimulated in vitro LIF secretion from the cells by 170+/-12% (P < 0.05) and 261+/-8% (P < 0.05), respectively. Dexamethasone (1 micromol/L) inhibited basal LIF concentration by 83% (P < 0.05), whereas TSH and IL-6 stimulated LIF by 52% (P = 0.04) and 42% (P = 0.03), respectively. However, using Northern blot analysis, we could not observe induction of LIF mRNA by TSH, suggesting that LIF regulation by TSH may be due to stimulation of secretion. The results show that the thyroid gland is a source of LIF production; TSH, IL-6, and glucocorticoid influence thyroid cell LIF expression. The correlation between TSH and LIF suggests that LIF may participate in the physiologic regulation of hypothalamic-pituitary-thyroid function.

Leukemia inhibitory factor is synthesized and released by human eosinophils and modulates activation state and chemotaxis

Background: The cytokine leukemia inhibitory factor (LIF) is known to be produced by both inflamed peripheral autonomic nerves and several cell types involved in the regulation of the immune response. We have recently demonstrated that several structural cell types in human airways produce LIF in response to inflammatory stimuli and that LIF augments contractile responses to tachykinins in airway explants. Because the eosinophil is a major effector cell in asthma and often found adjacent to the nerves, we hypothesized that eosinophils produce LIF and that LIF primes and upregulates eosinophil recruitment and function, allowing bidirectional neuroimmune interactions and augmentation of eosinophil-mediated injury. Objective: The purpose of this study was to demonstrate that human eosinophils synthesize and release LIF, to determine the effects of LIF on eosinophil functions (ie, chemotaxis, granule protein release, expression of the activation marker CD69, and apoptosis), and to compare serum LIF levels between atopic and nonatopic individuals. Methods: Reverse-transcription PCR, ELISA, immunocytochemistry, chemotaxis assay, and flow cytometry were used. Results: Peripheral blood eosinophils express LIF and messenger RNA for LIF and LIF receptor. Serum LIF levels were higher in atopic patients with mild asthma than in nonatopic normal donors. Eosinophils from nonatopic donors were stimulated by calcium ionophore to release small amounts of LIF (from almost none to 5.3 ± 1.8 pg/10 6 cells). Eosinophils from atopic donors showed a 10-fold increase (from 45.1 ± 38.7 pg/ 106 cells to 414.5 ± 189.9 pg/10 6 cells). Preincubation of eosinophils with LIF increased eosinophil peroxidase release 4-fold. LIF was not chemotactic for eosinophils but augmented chemotaxis mediated by substance P by 82% and by platelet-activating factor by 31%. LIF did not effect eosinophil apoptosis but increased CD69 expression. Conclusion: LIF has proinflammatory roles in eosinophil-dependent airway disorders. (J Allergy Clin Immunol 1999;104:136-44.)

Measurement of leukemia inhibitory factor in biological fluids by radioimmunoassay.

Leukemia inhibitory factor (LIF) exhibits multiple biological activities in various tissues, and we have shown that LIF activates POMC gene transcription in response to immune signals. As higher serum levels of LIF have been reported in septicemia, we measured LIF values in biological fluids by RIA. Immunoreactive LIF was detected in 303 of 428 human serum samples. Circulating LIF detection rates were 69% in acute inflammatory diseases, 83% in chronic inflammatory diseases, 61% in noninflammatory diseases, and 90% in cancer patients. Serum concentrations of human LIF was higher in patients with inflammatory disease than in noninflammatory disease (0.80 +/- 0.10 vs. 0.53 +/- 0.02 ng/mL; P < 0.05) or in cancer patients (0.44 +/- 0.06; P < 0.05). Higher serum human LIF levels were found in septicemia (0.78 +/- 0.14 ng/mL), pneumonia (0.80 +/- 0.10 ng/mL), acute bronchitis (0.88 +/- 0.09 ng/mL), other infections (1.01 +/- 0.17 ng/mL), and systemic lupus erythematosus (SLE; 0.79 +/- 0.06 ng/mL). In 7 septicemia patients, Gram-negative infection was associated with higher LIF levels (1.06 +/- 0.16 ng/mL) than was Gram-positive infection (0.58 +/- 0.14 ng/mL). In patients with acute inflammatory disease, serum LIF levels decreased within several days after hospitalization. To test circulating mouse (m) LIF changes in response to inflammatory stress, lipopolysaccharide (LPS) was injected ip to mice. LPS increased serum mLIF values concordantly with ACTH levels. After i.p. injection of 80 microg LPS, serum mLIF increased by 144% (P < 0.05), 173% (P < 0.05), and 134% at 30, 90, and 120 min respectively. In vitro, however, LPS did not increase ACTH and mLIF secretion from dispersed mouse primary pituitary cells. These results suggest that LIF is an important participant in the pathogenesis of the acute inflammatory response. The elevated serum LIF levels observed in inflammation do not appear to originate from the pituitary.

Leukemia inhibitory factor protects against experimental lethal Escherichia coli septic shock in mice.

Leukemia inhibitory factor (LIF) has recently been associated with septic shock in humans. In this study we sought to determine, in mice, the role of LIF in septic shock. During sublethal endotoxemia, serum LIF levels, as determined by radio-receptor competition assay, peaked at 2 h and were low (3 ng/ml), whereas in lethal Escherichia coli septic shock serum LIF levels rose progressively (> 30 ng/ml) in the premorbid phase coincident with the development of tissue injury. Single i.v. injections of high doses (up to 50 micrograms per mouse) of recombinant murine LIF had no obvious acute detrimental effects, whereas continued i.p. administration (30 micrograms per mouse per day) for 3-4 days induced a fatal catabolic state without evidence of preceding hemodynamic collapse or shock. Simultaneous or subsequent administration of high doses of LIF had no effect on mortality from sublethal and lethal E. coli septic shock, whereas prior administration conferred significant protection against lethality (P << 0.001 by log-rank test), an effect that was dose and interval dependent. This protective effect resembled endotoxin tolerance and was characterized by suppression of E. coli-induced serum tumor necrosis factor concentration (P < 0.05), reduction in the number of viable bacteria (P < 0.05), and prevention of sepsis-induced tissue injury. These observations suggest that systemic LIF production is part of the host response to both endotoxin and sepsis-induced tissue injury.

The Leukemia Inhibitory Factor and Its Receptor

This chapter focuses on the leukemia inhibitory factor (LIF) and its receptor that exemplifies many features of cytokine biology. The gene encoding LIF has been cloned and its product characterized extensively; LIF binds to receptors on responsive cells with high and low affinity and the molecular basis for the two types of receptors are determined. Many protein factors that affect the growth and differentiation of mammalian cells are characterized and are collectively termed growth factors or cytokines. The biochemical rationale for the two forms of LIF, one soluble and the other immobilized, are discussed and the suggestion made that the immobilized LIF may be deposited as a topological or temporal signal in the developing embryo. LIF expression fluctuates in different tissues during development, there being more in adult brain than in embryonic brain and more in day 1 postnatal heart than in adult heart. The development of primordial germ cells is also affected by LIF. A combination of LIF and steel factor improves primordial germ cell survival and proliferative capacity in vitro. There are two clinically interesting systems in which LIF is demonstrated to be active—namely, inflammation and cachexia. Serum LIF levels are elevated in mice treated with bacterial lipopolysaccharide, and LIF is demonstrated to be identical in structure and function to hepatocyte-stimulating factor III that causes the release of acute-phase plasma proteins (APPs).

Fatal syndrome in mice engrafted with cells producing high levels of the leukemia inhibitory factor.

Cells of the murine hemopoietic cell line FDC-P1 were multiply infected with a retroviral construct containing cDNA encoding the leukemia inhibitory factor (LIF) to produce cells secreting high levels of LIF. Injection of these cells to unirradiated or irradiated syngeneic DBA/2 mice resulted in animals engrafted with LIF-producing cells in the marrow, spleen, and lymph nodes and with elevated serum LIF levels. These mice developed within 12-70 days a fatal syndrome characterized by cachexia, excess new bone formation, calcification in heart and skeletal muscle, pancreatitis, thymus atrophy, and abnormalities in the adrenal cortex and ovarian corpora lutea. Injection of mice with control FDC-P1 cells led to comparable organ engraftment, but the mice developed none of these lesions. The observations suggest that LIF may be a potent cachexia-inducing agent and may have marked effects on osteoblasts and calcium metabolism.