Inflammation-induced cancer: crosstalk between tumours, immune cells and microorganisms

Inflammation is a fundamental innate immune response to perturbed tissue homeostasis. Chronic inflammatory processes affect all stages of tumour development as well as therapy. In this Review, we outline the principal cellular and molecular pathways that coordinate the tumour-promoting and tumour-antagonizing effects of inflammation and we discuss the crosstalk between cancer development and inflammatory processes. In addition, we discuss the recently suggested role of commensal microorganisms in inflammation-induced cancer and we propose that understanding this microbial influence will be crucial for targeted therapy in modern cancer treatment.

Role of the intestinal microbiome in liver disease

The liver integrates metabolic outcomes with nutrient intake while preventing harmful signals derived from the gut to spread throughout the body. Direct blood influx from the gastrointestinal tract through the portal vein makes the liver a critical firewall equipped with a broad array of immune cells and innate immune receptors that recognize microbial-derived products, microorganisms, toxins and food antigens that have breached the intestinal barrier. An overwhelming amount of evidence obtained in the last decade indicates that the intestinal microbiota is a key component of a wide variety of physiological processes, and alterations in the delicate balance that represents the intestinal bacterial communities are now considered important determinants of metabolic syndrome and immunopathologies. Moreover, it is now evident that the interaction between the innate immune system and the intestinal microbiota during obesity or autoimmunity promotes chronic liver disease progression and therefore it might lead to novel and individualized therapeutic approaches. In this review, we discuss a growing body of evidence that highlights the central relationship between the immune system, the microbiome, and chronic liver disease initiation and progression.

IL-22 deficiency alters colonic microbiota to be transmissible and colitogenic

IL-22 is a good candidate to play a critical role in regulating gut microbiota because it is an important inducer of antimicrobial peptides and mucins in the gut. However, whether IL-22 participates in immune homeostasis by way of modulating gut microbiota remains to be elucidated. In this study, we find, through 16S rRNA gene-pyrosequencing analysis, that healthy IL-22-deficient mice had altered colonic microbiota, notably with decreased abundance of some genera, including Lactobacillus, and increased levels of others. Mice harboring this altered microbiota exhibited more severe disease during experimentally induced colitis. Interestingly, this altered gut microbiota can be transmitted to cohoused wild-type animals along with the increased susceptibility to this colitis, indicating an important role for IL-22 in shaping the homeostatic balance between immunity and colonic microbiota for host health.

Harnessing nanomedicine for mucosal theranostics--a silver bullet at last?

Inflammatory bowel disease (IBD) has been extensively studied in the last four decades both in animal models and humans. The treatment options remain disappointing, nonspecific, and associated with multiple systemic adverse effects. In this Perspective, we highlight issues related to emerging nanotechnologies designed particularly for treatment and disease management of IBD and discuss potential therapeutic target options with novel molecular imaging modalities.

Integrative inflammasome activity in the regulation of intestinal mucosal immune responses

The mammalian intestinal tract harbors a vast and diverse ecosystem of microbes that are separated from the sterile host milieu by a single layer of epithelial cells. While this bio-geographical configuration is critical for host biological processes, it imposes a risk for microbial penetration and life-threatening systemic invasion. Inflammasomes are cytosolic multi-protein platforms that sense both microbial and damage-associated molecular patterns and initiate a potent innate immune anti-microbial response. In this review, we will highlight the role of inflammasomes in the orchestration and regulation of the intestinal immune response, focusing on the roles of inflammasomes in maintenance of intestinal homeostasis, enteric infection, auto-inflammation, and tumorigenesis. We highlight the centrality of inflammasome signaling in the complex cross-talk between host mucosal immune arms and the environment, in particular the microflora, with emphasis on the spatial and temporal integration of inflammasome activation with signals from other innate signaling platforms.

Analysis of microbiota alterations in inflammasome-deficient mice

Inflammasomes have emerged as central regulators of intestinal infection, immunity, and inflammation. Inflammasome activity mediates intestinal epithelial integrity, antimicrobial responses, and initiates inflammation through generation of the cytokines interleukin (IL-)1 and IL-18. Recent studies have identified an additional layer of inflammasome function in the intestine, namely, the control of intestinal microflora composition. Inflammasome-deficient mice show an aberrant microbial community which is dominantly transmissible to healthy mice. This dysbiosis in inflammasome-deficient mice has a profound impact on their physiology and pathophysiology, both locally in the intestine and systemically. Therefore, it is essential to consider the influence of the composition of microbial communities on experiments performed with inflammasome-deficient and other innate molecule-deficient mice, and to conduct experiments to control for potential dominant effects of the microflora on host responses. In this chapter, we provide experimental procedures to monitor inflammasome-mediated modifications of the intestinal microflora composition in mice and to test the resultant functional consequences of these changes in microbial communities and their transmission to cohoused mice.

Preparation and characterization of mouse IL-22 and its four single-amino-acid muteins that act as IL-22 receptor-1 antagonists

Recombinant mouse interleukin 22 (mIL-22) and its variants encoding four muteins (Y51A, N54A, R55A and E117A) were expressed in Escherichia coli, refolded and purified to homogeneity as monomeric proteins by one-step ion-exchange chromatography. The binding of IL-22 and its four muteins to immobilized mIL-22 receptor α1 extracellular domain (mIL-22 Rα1-ECD) exhibited similar affinity, indicating that the single-amino-acid mutations do not affect its binding properties. Similarly, no differences were found in binding to IL-22 binding protein expressed on the surface of yeast cells, although the affinity of all five proteins to the binding protein was higher than that to IL-22 Rα1-ECD. In an in vitro bioassay, recombinant mIL-22 stimulated signal transducer and activator of transcription-3 phosphorylation in HepG2 cells, whereas the four muteins were completely (Y51A) or almost completely (N54A, R55A and E117A) devoid of this agonistic activity. Furthermore, the agonistic activity of mIL-22 could be inhibited in a dose-dependent manner by the four muteins with almost identical efficiency. mIL-22 and its Y51A mutein were pegylated by methoxy polyethylene glycol-propionylaldehyde-20 kDa, yielding a mixture of mono (75-80%) and double (20-25%) pegylated proteins. The pegylated proteins showed lower affinity (50 and 25%) toward immobilized mIL-22 Rα1-ECD than their non-pegylated analogs. Wild-type pegylated IL-22 exhibited 5- to 10-fold lower activity in the HepG2 bioassay than its non-pegylated counterpart. Preparation of recombinant mIL-22 antagonists provides new tools for the study of IL-22 activity and of eventual therapeutic means for attenuating its negative effects.

NLRP10 is a NOD-like receptor essential to initiate adaptive immunity by dendritic cells

NLRs (nucleotide-binding domain leucine-rich-repeat-containing receptors; NOD-like receptors) are a class of pattern recognition receptor (PRR) that respond to host perturbation from either infectious agents or cellular stress. The function of most NLR family members has not been characterized and their role in instructing adaptive immune responses remains unclear. NLRP10 (also known as PYNOD, NALP10, PAN5 and NOD8) is the only NLR lacking the putative ligand-binding leucine-rich-repeat domain, and has been postulated to be a negative regulator of other NLR members, including NLRP3 (refs 4-6). We did not find evidence that NLRP10 functions through an inflammasome to regulate caspase-1 activity nor that it regulates other inflammasomes. Instead, Nlrp10(-/-) mice had a profound defect in helper T-cell-driven immune responses to a diverse array of adjuvants, including lipopolysaccharide, aluminium hydroxide and complete Freund's adjuvant. Adaptive immunity was impaired in the absence of NLRP10 because of a dendritic cell (DC) intrinsic defect in emigration from inflamed tissues, whereas upregulation of DC costimulatory molecules and chemotaxis to CCR7-dependent and -independent ligands remained intact. The loss of antigen transport to the draining lymph nodes by a subset of migratory DCs resulted in an almost absolute loss in naive CD4(+) T-cell priming, highlighting the critical link between diverse innate immune stimulation, NLRP10 activity and the immune function of mature DCs.

Inflammasome-mediated dysbiosis regulates progression of NAFLD and obesity

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and the leading cause of chronic liver disease in the Western world. Twenty per cent of NAFLD individuals develop chronic hepatic inflammation (non-alcoholic steatohepatitis, NASH) associated with cirrhosis, portal hypertension and hepatocellular carcinoma, yet the causes of progression from NAFLD to NASH remain obscure. Here, we show that the NLRP6 and NLRP3 inflammasomes and the effector protein IL-18 negatively regulate NAFLD/NASH progression, as well as multiple aspects of metabolic syndrome via modulation of the gut microbiota. Different mouse models reveal that inflammasome-deficiency-associated changes in the configuration of the gut microbiota are associated with exacerbated hepatic steatosis and inflammation through influx of TLR4 and TLR9 agonists into the portal circulation, leading to enhanced hepatic tumour-necrosis factor (TNF)-α expression that drives NASH progression. Furthermore, co-housing of inflammasome-deficient mice with wild-type mice results in exacerbation of hepatic steatosis and obesity. Thus, altered interactions between the gut microbiota and the host, produced by defective NLRP3 and NLRP6 inflammasome sensing, may govern the rate of progression of multiple metabolic syndrome-associated abnormalities, highlighting the central role of the microbiota in the pathogenesis of heretofore seemingly unrelated systemic auto-inflammatory and metabolic disorders.

Inflammasomes in health and disease

Inflammasomes are a group of protein complexes built around several proteins, including NLRP3, NLRC4, AIM2 and NLRP6. Recognition of a diverse range of microbial, stress and damage signals by inflammasomes results in direct activation of caspase-1, which subsequently induces secretion of potent pro-inflammatory cytokines and a form of cell death called pyroptosis. Inflammasome-mediated processes are important during microbial infections and also in regulating both metabolic processes and mucosal immune responses. We review the functions of the different inflammasome complexes and discuss how aberrations in them are implicated in the pathogenesis of human diseases.

Regulation of the antimicrobial response by NLR proteins

Nucleotide-binding, oligomerization domain (NOD)-like receptor (NLR) proteins are a family of innate immune receptors that play a pivotal role in microbial sensing, leading to the initiation of antimicrobial immune responses. Dysregulation of the function of multiple NLR family members has been linked, both in mice and humans, to a propensity for infection and autoinflammatory disease. Despite our increased understanding of NLR function and interactions, many aspects related to mechanisms of sensing, downstream signaling, and in vivo functions remain elusive. In this review, we focus on key members of the NLR family, describing their activation by diverse microbes, downstream effector functions, and interactions with each other and with other innate sensor protein families. Also discussed is the role of microbial sensing by NLR receptors leading to activation of the adaptive immune arm that collaborates in the antimicrobial defense.

Inflammasome-mediated suppression of inflammation-induced colorectal cancer progression is mediated by direct regulation of epithelial cell proliferation

Chronic inflammation is a risk factor for many types of human cancers, yet the precise mechanism of this strong association is largely unknown. The inflammasome is a multiprotein complex that has recently been shown to orchestrate multiple innate and adaptive immune responses, yet its potential role in inflammation-induced cancer has been little studied. We recently reported a surprising link between the inflammasome and colorectal inflammation-induced tumorigenesis. In the model, the role of caspase-1 and NLRC4 in tumorigenesis was found to be mediated by direct and profound effects on colonic epithelial cell proliferation and cell death, rather than through regulation of colonic inflammation. Herein, we discuss the recent advances and discoveries related to the role of inflammasome in inflammation-induced colorectal tumorigenesis.

NLRP6 inflammasome regulates colonic microbial ecology and risk for colitis

Inflammasomes are multiprotein complexes that function as sensors of endogenous or exogenous damage-associated molecular patterns. Here, we show that deficiency of NLRP6 in mouse colonic epithelial cells results in reduced IL-18 levels and altered fecal microbiota characterized by expanded representation of the bacterial phyla Bacteroidetes (Prevotellaceae) and TM7. NLRP6 inflammasome-deficient mice were characterized by spontaneous intestinal hyperplasia, inflammatory cell recruitment, and exacerbation of chemical colitis induced by exposure to dextran sodium sulfate (DSS). Cross-fostering and cohousing experiments revealed that the colitogenic activity of this microbiota is transferable to neonatal or adult wild-type mice, leading to exacerbation of DSS colitis via induction of the cytokine, CCL5. Antibiotic treatment and electron microscopy studies further supported the role of Prevotellaceae as a key representative of this microbiota-associated phenotype. Altogether, perturbations in this inflammasome pathway, including NLRP6, ASC, caspase-1, and IL-18, may constitute a predisposing or initiating event in some cases of human IBD.

Development and characterization of high affinity leptins and leptin antagonists

Leptin is a pleiotropic hormone acting both centrally and peripherally. It participates in a variety of biological processes, including energy metabolism, reproduction, and modulation of the immune response. So far, structural elements affecting leptin binding to its receptor remain unknown. We employed random mutagenesis of leptin, followed by selection of high affinity mutants by yeast surface display and discovered that replacing residue Asp-23 with a non-negatively charged amino acid leads to dramatically enhanced affinity of leptin for its soluble receptor. Rational mutagenesis of Asp-23 revealed the D23L substitution to be most effective. Coupling the Asp-23 mutation with alanine mutagenesis of three amino acids (L39A/D40A/F41A) previously reported to convert leptin into antagonist resulted in potent antagonistic activity. These novel superactive mouse and human leptin antagonists (D23L/L39A/D40A/F41A), termed SMLA and SHLA, respectively, exhibited over 60-fold increased binding to leptin receptor and 14-fold higher antagonistic activity in vitro relative to the L39A/D40A/F41A mutants. To prolong and enhance in vivo activity, SMLA and SHLA were monopegylated mainly at the N terminus. Administration of the pegylated SMLA to mice resulted in a remarkably rapid, significant, and reversible 27-fold more potent increase in body weight (as compared with pegylated mouse leptin antagonist), because of increased food consumption. Thus, recognition and mutagenesis of Asp-23 enabled construction of novel compounds that induce potent and reversible central and peripheral leptin deficiency. In addition to enhancing our understanding of leptin interactions with its receptor, these antagonists enable in vivo study of the role of leptin in metabolic and immune processes and hold potential for future therapeutic use in disease pathologies involving leptin.

CCL2 (pM levels) as a therapeutic agent in Inflammatory Bowel Disease models in mice

BACKGROUND

Chemokines regulate the pathways that restrict homing of specific subsets of immune cells, and thereby fine tune the immune response at specific lymphoid and peripheral tissues. CCL2 is a chemokine that induces migration of monocytes, memory T cells, and dendritic cells. Previously, we demonstrated that pM levels of CCL2 dramatically inhibit migration of T cells. The aim was to test whether subphysiological doses of CCL2 can ameliorate murine colitis and inflammation-induced colorectal cancer.

METHODS

TNBS (2,4,6 trinitrobenzene sulfonic acid) colitis and dextran sodium sulfate (DSS) colitis were induced in Balb/c and C57BL/6 mice, respectively. Mice were treated daily with intraperitoneal CCL2 injections. Disease activity was assessed clinically, histologically, and by measuring inflammatory cytokine levels. In addition, an inflammatory cancer model was induced by azoxymethane-DSS (AOM-DSS) in Balb/c mice. Mice were treated daily with CCL2 for 11 weeks and then assessed for number of tumors in the colons.

RESULTS

Daily administration of CCL2 (60-120 ng) significantly decreased the development of TNBS- and DSS-induced colitis. In a DSS-AOM model, CCL2-treated mice developed significantly fewer tumors (P < 0.005) at 11 weeks. Chronic inflammation in the CCL2-treated mice was significantly less pronounced as compared to phosphate-buffered saline-treated mice.

CONCLUSIONS

Administration of pM levels of CCL2 significantly inhibits migration of T cells in amelioration of TNBS and DSS colitis and inhibits development of colorectal cancer in an AOM-DSS colitis model in mice. Thus, pM levels of CCL2 may be clinically beneficial as an antiinflammatory agent in IBD.

Hierarchy of T cell lineage decision is regulated by thymic self-reactive signaling (36.45)

During T cell development, thymic recognition of self antigens leads to negative selection of effector T cells with high TCR avidity. Similar interactions are implicated with emergence of regulatory subsets, including Tregs, NKT, and CD8αα cells. How the degree of self-reactive signaling coordinates the development of the effector and regulatory subpopulations is not fully understood. To elucidate this, we employed transgenic mice, featuring gradually increasing self-reactivity by expression of different levels of a cross-reactive tripartite chimeric receptor targeting 2,4,6-trinitrophenol (TNP). In these mice, increasing cell self-reactivity inversely correlated with effector cell numbers, and led to skewing towards CD4 phenotype, compatible with the kinetic signaling model. In parallel, coreceptor levels of expression were diminished in correlation with gradually increasing self-reactivity, reflecting coreceptor tuning. Higher levels of self-reactive signaling promoted the thymic expansion of CD8αα and NKT cells. T cells with the highest self-reactive TPCR featured defective TCR rearrangement stemming from down regulation of RAG1, RAG2 and PTα. Altogether, we demonstrate a hierarchical order in coping of the immune system with auto-reactivity. In case of weak self-reactivity, coreceptor tuning is implemented, while in stronger self-reactivity, regulatory subsets develop, as possible means of modulating dangerous autoreactive cells into protective guardians of host.

Intestinal lamina propria dendritic cell subsets have different origin and functions

The intestinal immune system discriminates between tolerance toward the commensal microflora and robust responses to pathogens. Maintenance of this critical balance is attributed to mucosal dendritic cells (DCs) residing in organized lymphoid tissue and dispersed in the subepithelial lamina propria. In situ parameters of lamina propria DCs (lpDCs) remain poorly understood. Here, we combined conditional cell ablation and precursor-mediated in vivo reconstitution to establish that lpDC subsets have distinct origins and functions. CD103(+) CX(3)CR1(-) lpDCs arose from macrophage-DC precursors (MDPs) via DC-committed intermediates (pre-cDCs) through a Flt3L growth-factor-mediated pathway. CD11b(+) CD14(+) CX(3)CR1(+) lpDCs were derived from grafted Ly6C(hi) but not Ly6C(lo) monocytes under the control of GM-CSF. Mice reconstituted exclusively with CX(3)CR1(+) lpDCs when challenged in an innate colitis model developed severe intestinal inflammation that was driven by graft-derived TNF-alpha-secreting CX(3)CR1(+) lpDCs. Our results highlight the critical importance of the lpDC subset balance for robust gut homeostasis.

Pegylated leptin antagonist is a potent orexigenic agent: preparation and mechanism of activity

Leptin, a pleiotropic adipokine, is a central regulator of appetite and weight and a key immunomodulatory protein. Although inborn leptin deficiency causes weight gain, it is unclear whether induced leptin deficiency in adult wild-type animals would be orexigenic. Previous work with a potent competitive leptin antagonist did not induce a true metabolic state of leptin deficiency in mice because of a short circulating half-life. In this study, we increased the half-life of the leptin antagonist by pegylation, which resulted in significantly increased bioavailability and retaining of antagonistic activity. Mice administered the pegylated antagonist showed a rapid and dramatic increase in food intake with weight gain. Resulting fat was confined to the mesenteric region with no accumulation in the liver. Serum cholesterol, triglyceride, and hepatic aminotransferases remained unaffected. Weight changes were reversible on cessation of leptin antagonist treatment. The mechanism of severe central leptin deficiency was found to be primarily caused by blockade of transport of circulating leptin across the blood-brain barrier with antagonisms at the arcuate nucleus playing a more minor role. Altogether we introduce a novel compound that induces central and peripheral leptin deficiency. This compound should be useful in exploring the involvement of leptin in metabolic and immune processes and could serve as a therapeutic for the treatment of cachexia.

Amelioration of colitis by genetically engineered murine regulatory T cells redirected by antigen-specific chimeric receptor

BACKGROUND & AIMS

The therapeutic application of regulatory T cells (Tregs) for the treatment of inflammatory diseases is limited by the scarcity of antigen-specific Tregs. A preferred approach to endow effector T cells (Teff) with a desired specificity uses chimeric immune receptors with antibody-type specificity. Accordingly, employing such chimeric immune receptors to redirect Tregs to sites of inflammation may be a useful therapeutic approach to alleviate a broad scope of diseases in which an uncontrolled inflammatory response plays a major role.

METHODS

To enable application of the approach in clinical setting, which requires the genetic modification of the patient's own Tregs, we describe here a novel protocol that allows the efficient retroviral transduction and 2,4,6-trinitrophenol-specific expansion of murine naturally occurring regulatory T cells (nTregs), with a 2,4,6-trinitrophenol-specific tripartite chimeric receptor.

RESULTS

Transduced Tregs maintained their Foxp3 level, could undergo repeated expansion upon ex vivo encounter with their cognate antigen in a major histocompatibility complex-independent, costimulation-independent, and contact-dependent manner and specifically suppressed Teff cells. Adoptive transfer of small numbers of the transduced nTregs was associated with antigen-specific, dose-dependent amelioration of trinitrobenzenesulphonic acid colitis.

CONCLUSIONS

This study demonstrates that nTregs can be efficiently transduced to express functional, antigen-specific chimeric receptors that enable the specific suppression of effector T cells both in vitro and in vivo. This approach may enable future cell-based therapeutic application in inflammatory bowel disease, as well as other inflammatory disorders.

Antibiotic prophylaxis for spontaneous bacterial peritonitis in cirrhotic patients with ascites, without gastro-intestinal bleeding

BACKGROUND

Spontaneous bacterial peritonitis is frequent among cirrhotic patients, associated with significant morbidity and mortality. Selective intestinal decontamination employing antibiotics is a proposed prophylactic measure. While data regarding this modality among cirrhotic patients with gastrointestinal bleeding exist, there is insufficient data synthesis regarding cirrhotic patients with ascites and no gastrointestinal bleeding.

OBJECTIVES

To assess whether antibiotic prophylaxis decreases spontaneous bacterial peritonitis and mortality among cirrhotic patients with ascites and no gastrointestinal bleeding.

SEARCH STRATEGY

We identified relevant randomised trials by searching trial registries of The Cochrane Hepato-Biliary Group and The Cochrane Collaboration, medical literature search engines, and reviewing all literature we found on the topic until February 2009.

SELECTION CRITERIA

We searched for randomised clinical trials assessing prophylactic treatment among adult cirrhotic patients with ascites and no gastrointestinal bleeding, comparing antibiotic therapy with no intervention, placebo, or with another antibiotic regimen.

DATA COLLECTION AND ANALYSIS

Three independent authors searched for and collected the trials and extracted relevant data. Four other independent authors validated the findings and assessed them. The studies were assessed for design, patient and intervention characteristics, and quality. A meta-analysis was performed to estimate measures of association between antibiotic prophylaxis and spontaneous bacterial peritonitis or mortality.

MAIN RESULTS

Nine trials were included in the review. Seven trials, comparing antibiotics to placebo or no treatment, were meta-analysed. Systematic bias in design or publication is suggested by trial results. The randomisation results suggest that the probability that true randomisation took place in all trials is very small and the report of most trials regarding design was poor. The proportion of participants with spontaneous bacterial peritonitis varied between the trials from 15% to 50%. The calculated relative risks (95% confidence interval) of spontaneous bacterial peritonitis and mortality among patients treated with antibiotics compared with no treatment/placebo were 0.20 (0.11 to 0.37) and 0.61 (0.43 to 0.87). There were very few reports of adverse events.

AUTHORS' CONCLUSIONS

The pooled estimates suggest that antibiotic prophylaxis might be prudent among cirrhotic patients with ascites and no gastrointestinal bleeding. However, poor trial methodology and report coupled with findings suggesting systematic bias in publication and design reflect the fragility of these findings. Potential hazard to society and the patients themselves from resistant pathogens should be considered when promoting long-lasting antibiotic prophylaxis. It seems that recommending antibiotic prophylaxis is still far from being a substantiated prevention strategy. Trials of better design, well reported, and of longer follow-up are greatly needed.

Utilization of murine laparoscopy for continuous in-vivo assessment of the liver in multiple disease models

Background

Current strategies for follow up of murine models of liver disease are flawed by inability to continuously monitor disease progression in the tissue level, and necessitate sacrifice of animals for tissue sampling.

Aims

In this study we aimed at developing a safe repetitive tool for sampling livers in vivo, by utilization of a miniaturized endoscopy system for laparoscopic liver biopsies and for injection of tumor cells into livers.

Results

We report the development of a protocol for murine laparoscopy that allows repeated visualization of murine intra-abdominal organs. The system enables safe and repeated liver biopsies in mice and rats, yielding adequate tissue for histological staining and RNA extraction. In addition, injection of tumor cells into livers facilitates under-vision implantation of hepatic tumors in liver, followed by visualization of tumor growth.

Conclusions

Murine laparoscopy may be employed as a novel imaging modality for continuous assessment and manipulation of chronic liver disease models.

Competitive inhibition of leptin signaling results in amelioration of liver fibrosis through modulation of stellate cell function

Leptin signaling is involved in T-cell polarization and is required for profibrotic function of hepatic stellate cells (HSCs). Leptin-deficient ob/ob mice do not develop liver fibrosis despite the presence of severe long-standing steatohepatitis. Here, we blocked leptin signaling with our recently generated mouse leptin antagonist (MLA), and examined the effects on chronic liver fibrosis in vivo using the chronic thioacetamide (TAA) fibrosis model, and in vitro using freshly-isolated primary HSCs. In the chronic TAA fibrosis model, leptin administration was associated with significantly enhanced liver disease and a 100% 5-week to 8-week mortality rate, while administration or coadministration of MLA markedly improved survival, attenuated liver fibrosis, and reduced interferon gamma (IFN-gamma) levels. No significant changes in weight, serum cholesterol, or triglycerides were noted. In vitro administration of rat leptin antagonist (RLA), either alone or with leptin, to rat primary HSCs reduced leptin-stimulated effects such as increased expression of alpha-smooth muscle actin (alpha-SMA), and activation of alpha1 procollagen promoter.

CONCLUSION

Inhibition of leptin-enhanced hepatic fibrosis may hold promise as a future antifibrotic therapeutic modality.

Redirection of regulatory T cells with predetermined specificity for the treatment of experimental colitis in mice

BACKGROUND & AIMS

Treatment with ex vivo expanded regulatory T cells (Tregs) is regarded as a promising therapeutic approach in inflammatory bowel disease but is hampered by impaired Treg accumulation and function at inflammatory sites. We aim to study whether antigen-specific redirected Tregs can overcome these limitations.

METHODS

We developed transgenic mice whose T cells, including Tregs, express chimeric receptor (CR) made of antibody variable region as recognition unit and T-cell stimulatory and costimulatory domains to activate specifically in response to the predetermined model antigen 2,4,6-trinitrophenol (TNP).

RESULTS

TNP-specific CR-bearing Tregs were potently and specifically activated by exogenous TNP and suppressed effector T cells in the absence of costimulatory B7-CD28 interaction. TNP-specific transgenic (Tg) mice were resistant to 2,4,6-trinitrobenzene sulphonic acid (TNBS) colitis but not to other hapten-mediated colitis. Adoptive transfer of CR-bearing Tregs to wild-type mice with TNBS colitis was associated with significant amelioration of colitis and improved survival. Although TNP-specific CR-bearing Tregs did not suppress oxazolone colitis, they cured it after addition of traces of TNBS to oxazolone-inflamed colons, demonstrating a "bystander" effect. In vivo imaging of adoptively transferred CR-bearing Tregs demonstrated that they preferentially migrate to TNBS-induced colonic mucosal lesions within hours of induction of colitis.

CONCLUSIONS

Tregs can be redirected with specificity distinct from that of pathogenic lymphocytes, accumulate at colonic inflammatory lesions, and suppress effector T cells in a specific, nonmajor histocompatibility complex-restricted, and noncostimulatory-dependent manner, resulting in significant amelioration of colitis. Hopefully, this approach will lead to a novel therapy for inflammatory bowel disease, as well as other inflammatory diseases.

Association between consumption of Herbalife nutritional supplements and acute hepatotoxicity

BACKGROUND/AIMS

Nutritional supplements are frequently considered to be harmless but indiscriminate use of unlabelled ingredients may lead to significant adverse reactions.

METHODS

In 2004, identification of four index cases of acute hepatitis associated with Herbalife intake led to a ministry of health investigation in all Israeli hospitals. Twelve patients with acute idiopathic liver injury in association with consumption of Herbalife products were investigated.

RESULTS

Eleven of the patients were females, aged 49.5+/-13.4 y. One patient had stage I primary biliary cirrhosis and another had hepatitis B. Acute liver injury was diagnosed after 11.9+/-11.1 months of initiation of Herbalife consumption. Liver biopsies demonstrated active hepatitis, portal inflammation rich with eosinophils, ductular reaction and parenchymal inflammation with peri-central accentuation. One patient developed sub-fulminant and two fulminant episodes of hepatic failure. Hepatitis resolved in eleven patients, while one patient succumbed to complications following liver transplantation. Three patients resumed consumption of Herbalife products following normalization of liver enzymes, resulting in a second bout of hepatitis.

CONCLUSIONS

An association between intake of Herbalife products and acute hepatitis was identified in Israel. We call for prospective evaluation of Herbalife products for possible hepatotoxicity. Until then, caution should be exercised by consumers, especially among individuals suffering from underlying liver disease.