Abrogation of experimental colitis correlates with increased apoptosis in mice deficient for CD44 variant exon 7 (CD44v7)

Hyaluronic acid application strategies for plant bioactive component delivery: A review

Despite the notable therapeutic effects of bioactive components derived from naturally occurring medicinal plants, various factors such as low solubility, poor bioavailability, possible toxicity, and inadequate tumor targeting capabilities generally hinder their full potential. Hyaluronic Acid (HA), a naturally occurring polysaccharide, has recently attracted significant research interest from scientists owing to its ability to precisely target tumors, anionic polysaccharide properties, and easily modifiable unique structure. In addition to offering a solid backing for delivering plant bioactive constituents, these remarkable attributes also have considerable implications for drug delivery systems in the future. This review delves into HA's application in delivering plant bioactive components, starting with a summary of HA's functional characteristics and detailing its strategies for single and dual-component delivery. The review also provides a forward-looking analysis of the challenges encountered in developing HA-based drug delivery systems.

Advances in the treatment of inflammatory bowel disease: Focus on polysaccharide nanoparticulate drug delivery systems

The complex pathogenesis of inflammatory bowel disease (IBD) explains the several hurdles for finding an efficient approach to cure it. Nowadays, therapeutic protocols aim to reduce inflammation during the hot phase or maintain remission during the cold phase. Nonetheless, these drugs suffer from severe side effects or poor efficacy due to low bioavailability in the inflamed region of the intestinal tract. New protocols based on antibodies that target proinflammatory cytokines are clinically relevant. However, besides being expensive, their use is associated with a primary nonresponse or a loss of response following a long administration period. Accordingly, many researchers exploited the physiological changes of the mucosal barrier for designing nanoparticulate drug delivery systems to target inflamed tissues. Others exploited biocompatibility and relative affordability of polysaccharides to test their intrinsic anti-inflammatory and healing properties in IBD models. This critical review updates state of the art on advances in IBD treatment. Data on using polysaccharide nanoparticulate drug delivery systems for IBD treatment are reviewed and discussed.

Targeted delivery of Chinese herb pair-based berberine/tannin acid self-assemblies for the treatment of ulcerative colitis

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A colon-targeted hyaluronic acid-coated berberine/tannin acid nanostructure (HTB) was developed

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HTB could localize in inflamed colon in colitis mice

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HTB exerted strong therapeutic efficacy in mouse model of colitis

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HTB regulated gut barrier function and apoptosis in colitis mice

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HTB partially recovered DSS-mediated gut microbiome alteration

Introduction

Ulcerative colitis (UC) is a chronic recurrent idiopathic disease characterized by damage to the colonic epithelial barrier and disruption of inflammatory homeostasis. At present, there is no curative therapy for UC, and the development of effective and low-cost therapies is strongly advocated.

Objectives

Multiple lines of evidence support that tannic acid (TA) and berberine (BBR), two active ingredients derived from Chinese herb pair (Rhei Radix et Rhizoma and Coptidis Rhizoma), have promising therapeutic effects on colonic inflammation. This study aims to develop a targeted delivery system based on BBR/TA-based self-assemblies for the treatment of UC.

Methods

TA and BBR self-assemblies were optimized, and hyaluronic acid (HA) was coated to achieve targeted colon delivery via HA-cluster of differentiation 44 (CD44) interactions. The system was systematically characterized and dextran sodium sulfate (DSS)-induced mouse colitis model was further used to investigate the biodistribution behavior, effect and mechanism of the natural system.

Results

TA and BBR could self-assemble into stable particles (TB) and HA-coated TB (HTB) further increased cellular uptake and accumulation in inflamed colon lesions. Treatment of HTB inhibited pro-inflammatory cytokine levels, restored expression of tight junction-associated proteins and recovered gut microbiome alteration, thereby exerting anti-inflammatory effects against DSS-induced acute colitis.

Conclusion

Our targeted strategy may provide a convenient and powerful platform for UC and reveal new modes of application of herbal combinations.

Emerging Pathological Engagement of Ferroptosis in Gut Diseases

Inflammatory bowel disease (IBD), including ulcerative colitis and Crohn's disease, is mainly characterized by chronic and progressive inflammation that damages the gastrointestinal mucosa. Increasing studies have enlightened that dysregulated cell death occurs in the inflamed sites, leading to the disruption of the intestinal barrier and aggravating inflammatory response. Ferroptosis, a newly characterized form of regulated cell death, is driven by the lethal accumulation of lipid peroxides catalyzed by cellular free iron. It has been widely documented that the fundamental features of ferroptosis, including iron deposition, GSH exhaustion, GPX4 inactivation, and lipid peroxidation, are manifested in the injured gastrointestinal tract in IBD patients. Furthermore, manipulation of the critical ferroptotic genes could alter the progression, severity, or even morbidity of the experimental colitis. Herein, we critically summarize the recent advances in the field of ferroptosis, focusing on interpreting the potential engagement of ferroptosis in the pathogenesis of IBD. Moreover, we are attempting to shed light on a perspective insight into the possibility of targeting ferroptosis as novel therapeutic designs for the clinical intervention of these gastrointestinal diseases.

Analysis of prognostic factors in 171 patients with myxofibrosarcoma of the trunk and extremities: a cohort study

Background

Myxofibrosarcoma (MFS) of the trunk and extremities has unique clinical features. However, it is not clear which indicators are the influencing factors of recurrence, metastasis, and survival of trunk and limb MFS. The aim of the present study was to analyze clinical features and prognosis of trunk and limb MFS.

Methods

The data of 171 patients with MFS of the trunk and extremities and a median follow-up period of 67 months from January 1999 to July 2018 were retrospectively analyzed. Risk factors for survival, recurrence and metastasis following resection of MFS of trunk and extremities were analyzed. The Kaplan-Meier method (log-rank test) was used for the univariate analysis and a Cox regression model was used for the multivariate analysis.

Results

The median age of the patients was 53 years; there were 111 males and 60 females. A total of 132 cases had French Federation of Cancer Centers grade 1, 24 cases had grade 2, and 15 cases had grade 3 MFS. The 3-year recurrence, 3-year metastasis, and 5-year survival rates were 29.2%, 19.3%, and 93.6%, respectively. Kaplan-Meier survival analysis showed that the surgical margin (χ²=22.228, P<0.001) and tumor size (χ²=6.697, P=0.010) were associated with recurrence. The surgical margin (χ²=12.353, P<0.001) and CD44 expression (χ²=5.227, P=0.022) were associated with metastasis. The multivariate analysis showed that the surgical margin [hazard ratio (HR) =3.635, 95% confidence interval (CI): 1.883-7.016, P<0.001] and tumor size (HR =1.889, 95% CI: 1.039-3.435, P=0.037) were risk factors for local recurrence. In addition, the surgical margin (HR =4.475, 95% CI: 1.918-10.438, P=0.001) and presence of CD44 (HR =3.406, 95% CI: 1.462-8.405, P=0.005) were risk factors for distant metastasis.

Conclusions

A negative surgical margin can be reduced effectively the rate of recurrence and metastasis in patients with MFS of the trunk and limbs. In addition, CD44 may be used to assess the metastatic risk of patients with MFS.

Recent advances and prospects of hyaluronan as a multifunctional therapeutic system

Hyaluronan (HA) is a naturally occurring non-sulfated glycosaminoglycan (GAG), cell-surface-associated biopolymer and is the key component of tissue extracellular matrix (ECM). Along with remarkable physicochemical properties, HA also has multifaceted biological effects that include but not limited to ECM organization, immunomodulation, and various cellular processes. Environmental cues such as tissue injury, infection or cancer change downstream signaling functionalities of HA. Unlike native HA, the fragments of HA have diversified effects on inflammation, cancer, fibrosis, angiogenesis and autoimmune response. In this review, we aim to discuss HA as a therapeutic delivery system development process, source, biophysical-chemical properties, and associated biological pathways (especially via cell surface receptors) of native and fragmented HA. We also tried to address an overview of the potential role of HA (native HA vs fragments) in the modulation of inflammation, immune response and various cancer targeting delivery applications. This review will also highlight the HA based therapeutic systems, medical devices and future perspectives of various biomedical applications were discussed in detail.

CD44 polymorphisms and its variants, as an inconsistent marker in cancer investigations

Among cell surface markers, CD44 is considered the main marker for identifying and isolating the cancer stem cells (CSCs) among other cells and has attracted significant attention in a variety of research areas. Many studies have shown the essential roles of CD44 in initiation, metastasis, and tumorigenesis in different types of cancer; however, the validity of CD44 as a therapeutic or diagnostic target has not been fully confirmed in some other studies. Whereas the association of specific single nucleotide polymorphisms (SNPs) in the CD44 gene and related variants with cancer risk have been observed in clinical investigations, the significance of these findings remains controversial. Here, we aimed to provide an up-to-date overview of recent studies on the association of CD44 polymorphisms and its variants with different kinds of cancer to determine whether or not it can be used as an appropriate candidate for cancer tracking.

Absence of specific alternatively spliced exon of CD44 in macrophages prevents colitis

CD44 is a transmembrane molecule appearing in numerous isoforms generated by insertions of alternatively spliced variant exons (CD44v) and having various binding partners. CD44v7 on T cells was proposed to promote colitis by preventing T-cell apoptosis. Here we demonstrate that Cd44v7-deficient T cells - like Cd44 wild-type (Cd44^WT) T cells - provoked disease in two different colitis models: the model induced by CD4⁺CD45RB^high T-cell transfer into Rag2-deficient mice and a new model based on ovalbumin (OVA)-specific T-cell transfer into Rag-sufficient, OVA-challenged mice. In contrast, CD44v7 absence on macrophages in recipient mice prevented colitis. Prevention was associated with the downregulation of signal transducer and activator of transcription 3 (STAT3)-activating and Foxp3-counteracting interleukin-6 (IL-6), lower numbers of phospho-STAT3-containing lymphocytes, and higher Foxp3⁺ T-cell counts in the colon. Consequently, the protected colons showed lower IL-12, IL-1β expression, and decreased interferon-γ levels. Importantly, stimulation of T cells by Cd44v7-deficient macrophages induced upregulation of Foxp3 in vitro, while cotransfer of Cd44^WT macrophages into Cd44v7-deficient mice reduced Foxp3⁺ T-cell counts and caused colitis. Accordingly, the CD44v7 ligand osteopontin, whose levels were elevated in Crohn's disease, specifically induced IL-6 in human monocytes, a cytokine also increased in these patients. We suggest macrophage-specific targeting of the CD44v7 pathway as a novel therapeutic option for Crohn's disease.

Combined Treatment with Hyaluronic Acid and Mesalamine Protects Rats from Inflammatory Bowel Disease Induced by Intracolonic Administration of Trinitrobenzenesulfonic Acid

Drugs such as mesalamine (5-ASA) are currently recommended for the treatment of inflammatory bowel disease (IBD). To reduce the frequency of their administration and improve their therapeutic effect, this study investigated the adhesion efficacy, wound healing promotion, and decrease in inflammation in ulcers in the colonic tissue of rats with colitis after combined treatment with hyaluronic acid (HA) and 5-ASA (IBD98-M). HA-fluoresceinamine (FL) conjugates successfully adhered to the mucosal layer and were conjugated in the vascular tissue. In addition, macroscopic and microscopic observations indicated that colonic injuries reduced significantly after treatment with IBD98-M. Compared with PBS and 5-ASA treatment alone, treatment with IBD98-M more effectively reduced bowel inflammation and promoted colonic mucosal healing in TNBS-induced colitis. IBD98-M treatment also reduced myeloperoxidase activity and the expression levels of cyclooxygenase 2 and tumor necrosis factor-αin the colitis tissue. In conclusion, IBD98-M treatment strongly promoted wound healing in colonic injuries and significantly inhibited MPO activity in the inflamed colon tissue of rats. Combined treatment with HA and 5-ASA can accelerate wound healing and reduce inflammatory reaction in rat colitis.

CD44, Hyaluronan, the Hematopoietic Stem Cell, and Leukemia-Initiating Cells

CD44 is an adhesion molecule that varies in size due to glycosylation and insertion of so-called variant exon products. The CD44 standard isoform (CD44s) is highly expressed in many cells and most abundantly in cells of the hematopoietic system, whereas expression of CD44 variant isoforms (CD44v) is more restricted. CD44s and CD44v are known as stem cell markers, first described for hematopoietic stem cells and later on confirmed for cancer- and leukemia-initiating cells. Importantly, both abundantly expressed CD44s as well as CD44v actively contribute to the maintenance of stem cell features, like generating and embedding in a niche, homing into the niche, maintenance of quiescence, and relative apoptosis resistance. This is surprising, as CD44 is not a master stem cell gene. I here will discuss that the functional contribution of CD44 relies on its particular communication skills with neighboring molecules, adjacent cells and, last not least, the surrounding matrix. In fact, it is the interaction of the hyaluronan receptor CD44 with its prime ligand, which strongly assists stem cells to fulfill their special and demanding tasks. Recent fundamental progress in support of this “old” hypothesis, which may soon pave the way for most promising new therapeutics, is presented for both hematopoietic stem cell and leukemia-initiating cell. The contribution of CD44 to the generation of a stem cell niche, to homing of stem cells in their niche, to stem cell quiescence and apoptosis resistance will be in focus.

Interactions between Hyaluronan and Its Receptors (CD44, RHAMM) Regulate the Activities of Inflammation and Cancer

The glycosaminoglycan hyaluronan (HA), a major component of extracellular matrices, and cell surface receptors of HA have been proposed to have pivotal roles in cell proliferation, migration, and invasion, which are necessary for inflammation and cancer progression. CD44 and receptor for HA-mediated motility (RHAMM) are the two main HA-receptors whose biological functions in human and murine inflammations and tumor cells have been investigated comprehensively. HA was initially considered to be only an inert component of connective tissues, but is now known as a “dynamic” molecule with a constant turnover in many tissues through rapid metabolism that involves HA molecules of various sizes: high molecular weight HA (HMW HA), low molecular weight HA, and oligosaccharides. The intracellular signaling pathways initiated by HA interactions with CD44 and RHAMM that lead to inflammatory and tumorigenic responses are complex. Interestingly, these molecules have dual functions in inflammations and tumorigenesis. For example, the presence of CD44 is involved in initiation of arthritis, while the absence of CD44 by genetic deletion in an arthritis mouse model increases rather than decreases disease severity. Similar dual functions of CD44 exist in initiation and progression of cancer. RHAMM overexpression is most commonly linked to cancer progression, whereas loss of RHAMM is associated with malignant peripheral nerve sheath tumor growth. HA may similarly perform dual functions. An abundance of HMW HA can promote malignant cell proliferation and development of cancer, whereas antagonists to HA-CD44 signaling inhibit tumor cell growth in vitro and in vivo by interfering with HMW HA-CD44 interaction. This review describes the roles of HA interactions with CD44 and RHAMM in inflammatory responses and tumor development/progression, and how therapeutic strategies that block these key inflammatory/tumorigenic processes may be developed in rodent and human diseases.

Hyaluronan, a crucial regulator of inflammation

Hyaluronan (HA), a major component of the extracellular matrix (ECM), plays a key role in regulating inflammation. Inflammation is associated with accumulation and turnover of HA polymers by multiple cell types. Increasingly through the years, HA has become recognized as an active participant in inflammatory, angiogenic, fibrotic, and cancer promoting processes. HA and its binding proteins regulate the expression of inflammatory genes, the recruitment of inflammatory cells, the release of inflammatory cytokines, and can attenuate the course of inflammation, providing protection against tissue damage. A growing body of evidence suggests the cell responses are HA molecular weight dependent. HA fragments generated by multiple mechanisms throughout the course of inflammatory pathologies, elicit cellular responses distinct from intact HA. This review focuses on the role of HA in the promotion and resolution of inflammation.

Anti-inflammatory properties of kaempferol via its inhibition of aldosterone signaling and aldosterone-induced gene expression

Osteopontin (OPN), also called cytokine Eta-1, is a pro-inflammatory cytokine. Recent studies have shown that aldosterone increases OPN gene expression in endothelial cells. As a flavonoid compound, kaempferol has potent anti-inflammatory properties, but whether kaempferol regulates aldosterone signaling and aldosterone-induced gene expression is still unknown. Human umbilical vein endothelial cells (HUVECs) were pretreated with kaempferol (0, 1, 3, or 10 μmol/L) for 1 h prior to exposure to aldosterone (10−6 mol/L) for 24 h. Aldosterone induced generation of reactive oxygen species; OPN and cluster of differentiation 44 gene expression; phospho-p38 MAPK and NF-κB binding activity. The effect of aldosterone was abrogated by kaempferol and spironolactone (10−6 mol/L). The present results suggest that kaempferol exerts its anti-inflammatory properties via its inhibition of aldosterone signaling and aldosterone-induced gene expression in HUVECs.

ETS-1-mediated transcriptional up-regulation of CD44 is required for sphingosine-1-phosphate receptor subtype 3-stimulated chemotaxis

Sphingosine-1-phosphate (S1P)-regulated chemotaxis plays critical roles in various physiological and pathophysiological conditions. S1P-regulated chemotaxis is mediated by the S1P family of G-protein-coupled receptors. However, molecular details of the S1P-regulated chemotaxis are incompletely understood. Cultured human lung adenocarcinoma cell lines abundantly express S1P receptor subtype 3 (S1P3), thus providing a tractable in vitro system to characterize molecular mechanism(s) underlying the S1P3 receptor-regulated chemotactic response. S1P treatment enhances CD44 expression and induces membrane localization of CD44 polypeptides via the S1P3/Rho kinase (ROCK) signaling pathway. Knockdown of CD44 completely diminishes the S1P-stimulated chemotaxis. Promoter analysis suggests that the CD44 promoter contains binding sites of the ETS-1 (v-ets erythroblastosis virus E26 oncogene homolog 1) transcriptional factor. ChIP assay confirms that S1P treatment stimulates the binding of ETS-1 to the CD44 promoter region. Moreover, S1P induces the expression and nuclear translocation of ETS-1. Knockdown of S1P3 or inhibition of ROCK abrogates the S1P-induced ETS-1 expression. Furthermore, knockdown of ETS-1 inhibits the S1P-induced CD44 expression and cell migration. In addition, we showed that S1P3/ROCK signaling up-regulates ETS-1 via the activity of JNK. Collectively, we characterized a novel signaling axis, i.e., ROCK-JNK-ETS-1-CD44 pathway, which plays an essential role in the S1P3-regulated chemotactic response.

Effect of the alcohol consumption on osteocyte cell processes: a molecular imaging study

We have previously shown microarchitectural tissue changes with cellular modifications in osteocytes following high chronic alcohol dose. The aim of this study was to assess the dose effect of alcohol consumption on the cytoskeleton activity, the cellular lipid content and modulation of differentiation and apoptosis in osteocyte. Male Wistar rats were divided into three groups: Control (C), Alcohol 25% v/v (A25) or Alcohol 35% v/v (A35) for 17 weeks. Bone mineral density (BMD) was assessed by DXA, osteocyte empty lacunae, lacunae surface, bone marrow fat with bright field microscopy. Osteocyte lipid content was analysed with transmission electron microscopy (TEM) and epifluorescence microscopy. Osteocyte apoptosis was analysed with immunolabelling and TEM. Osteocyte differentiation and cytoskeleton activity were analysed with immunolabelling and real time quantitative PCR. At the end of the protocol, BMD was lower in A25 and A35 compared with C, while the bone marrow lipid content was increased in these groups. More empty osteocyte lacunae and osteocyte containing lipid droplets in A35 were found compared with C and A25. Cleaved caspase-3 staining and chromatin condensation were increased in A25 and A35 versus C. Cleaved caspase-3 was increased in A35 versus A25. CD44 and phosphopaxillin stainings were higher in A35 compared with C and A25. Paxillin mRNA expression was higher in A35 versus A25 and C and sclerostin mRNA expression was higher in A35 versus C. We only observed a dose effect of alcohol consumption on cleaved caspase-3 osteocyte immunostaining levels and on the number of lipid droplets in the bone marrow.

A switch between topological domains underlies HoxD genes collinearity in mouse limbs

Hox genes are major determinants of the animal body plan, where they organize structures along both the trunk and appendicular axes. During mouse limb development, Hoxd genes are transcribed in two waves: early on, when the arm and forearm are specified, and later, when digits form. The transition between early and late regulations involves a functional switch between two opposite topological domains. This switch is reflected by a subset of Hoxd genes mapping centrally into the cluster, which initially interact with the telomeric domain and subsequently swing toward the centromeric domain, where they establish new contacts. This transition between independent regulatory landscapes illustrates both the modularity of the limbs and the distinct evolutionary histories of its various pieces. It also allows the formation of an intermediate area of low HOX proteins content, which develops into the wrist, the transition between our arms and our hands. This regulatory strategy accounts for collinear Hox gene regulation in land vertebrate appendages.

CD44 variant isoforms control experimental autoimmune encephalomyelitis by affecting the lifespan of the pathogenic T cells

CD44 variant (CD44(v)) isoforms play important roles in the development of autoimmune disorders, including colitis and arthritis, but their role in multiple sclerosis (MS) has been explored only to a limited extent. We determined the functional relevance of CD44(v) isoforms in MS and its animal model, experimental autoimmune encephalomyelitis (EAE). Genetic ablation of CD44(v7) and CD44(v10) isoforms significantly reduced the clinical EAE burden, as well as the number of inflammatory infiltrates. CD44(v7) and CD44(v10) expression on both memory T and antigen-presenting cells, participated in the development of adoptive transfer EAE. Significantly reduced mRNA expression of Th1 signature genes was detected in the brains of CD44(v10-/-) mice compared with those of CD44(WT) mice. Furthermore, forkhead transcription factor 3 (Foxp3), Bcl-2, and inducible nitric oxide synthase (iNOS) levels were reduced in CD44(v10-/-) brains, whereas active caspase-3 was elevated. Brain-infiltrating CD4(hi)CD44(v10+) T cells preceded EAE onset and paralleled disease severity in wild-type but not in CD44(v7-/-) and CD44(v10-/-) mice. CD44(v7) and CD44(v10) expression contributed to EAE by increasing the longevity of autoreactive CD4(hi)panCD44(hi) T cells. Accordingly, the absence of CD44(v7) and CD44(v10) led to increased apoptosis in the inflammatory infiltrates and reduced Th1 responses, resulting in marked disease reduction. Although absent in noninflamed human brains, we detected CD44(v3), CD44(v7), and CD44(v10) isoforms on glial cells and on perivascular infiltrating cells of MS lesions. We conclude that CD44(v7) and CD44(v10), expressed on autoreactive CD4(hi)panCD44(hi) T cells, are critically involved in the pathogenesis of classic EAE by increasing their life span. Targeting these short CD44(v) isoform regions may reduce inflammatory processes and clinical symptoms in MS.

Suppression of tunicamycin-induced CD44v6 ectodomain shedding and apoptosis is correlated with temporal expression patterns of active ADAM10, MMP-9 and MMP-13 proteins in Caki-2 renal carcinoma cells

CD44v6 has been shown to coordinate the activation of anti-apoptotic molecules as well as resistance to apoptosis. Here, we investigated CD44v6 ectodomain shedding in Caki-2 human renal carcinoma cells as well as its underlying mechanisms. Exposure of cells to tunicamycin (TM)-induced apoptosis was accompanied by cleavage of caspase-3, PARP-1 and CD44v6 ectodomain. TM-induced apoptosis was also closely associated with endoplasmic reticulum (ER) stress, as shown by increased expression of GRP-78 and CHOP proteins. Furthermore, induction of matrix metallo-proteinase (MMP)-13, MMP-9 and ADAM10 expression was highly stimulated by tunicamycin in a time- and dose-dependent manner. TM-induced PARP-1 cleavage was significantly inhibited by treatment with GM6001 (a broad spectrum MMP inhibitor), MMP-9/-13 inhibitor and GI254023X (specific ADAM10 inhibitor). In addition, inhibition of all examined MMPs resulted in reversal of TM-induced apoptosis as well as increased cell viability. When considering the functional implications of MMP-9 and ADAM10, it is likely that active MMP-9 and ADAM10 help regulate the cellular levels of CD44v6 through cleavage of CD44v6 ectodomain during TM-induced apoptosis of Caki-2 cells. Collectively, these findings suggest that multiple TM-induced MMPs may cooperate to induce apoptosis.

Vidofludimus inhibits colonic interleukin-17 and improves hapten-induced colitis in rats by a unique dual mode of action

Vidofludimus (Vido) is a novel oral immunomodulatory drug that inhibits dihydro-orotate dehydrogenase and lymphocyte proliferation in vitro. Vido inhibits interleukin (IL)-17 secretion in vitro independently of effects on lymphocyte proliferation. Our primary goal was to evaluate the in vivo effects of Vido on IL-17 secretion and the parameters of trinitrobenzene sulfonic acid (TNBS)-induced colitis in rats. To further delineate the mechanism of action for Vido, rats were dosed concomitantly with uridine (Uri). Young Wistar rats received a 150-μl enema of either phosphate-buffered saline (PBS) or TNBS on study day 1. The ex vivo effects of Vido on 24-h colonic IL-17 secretion were determined by using colonic strips from PBS- or TNBS-treated rats. Some rats were dosed with vehicle, Vido, or Vido + Uri for 6 days. On day 6, the parameters of colitis were determined from colonic tissue. These parameters included macroscopic, histological, and transcription factor measurements, IL-17 production, and numbers of CD3+ T cells. Ex vivo Vido completely blocked IL-23 + IL-1β-stimulated secretion of IL-17 by colonic strips. In vivo Vido treatment alone most effectively reduced macroscopic and histological pathology and the numbers of CD3+ T cells. In contrast, similarly reduced nuclear signal transducer and activator of transcription 3 (STAT3) binding and IL-17 levels were observed from animals treated with Vido alone and Vido + Uri. Vido improves TNBS-induced colonic inflammation by a unique dual mode of action: 1) inhibiting expansion of colonic T lymphocytes, and 2) suppressing colonic IL-17 production, which is independent from the control of T-lymphocyte proliferation, by inhibition of STAT3 and nuclear factor-κB activation.

CD44 variant isoforms are specifically expressed on peripheral blood lymphocytes from asthmatic patients

Asthma is a disease characterized by chronic airway inflammation, and Th2 cells play a critical role in initiating and sustaining asthmatic inflammation. It has been shown that CD44 expressed on CD4(+) T cells plays a critical role in the accumulation of antigen-specific Th2 cells in the development of airway hyperresponsiveness induced by antigen challenge in the airways. The aim of this study was to determine whether there are specific CD44 variant isoforms (CD44v) expressed on lymphocytes from asthmatic patients. We collected whole blood samples from 103 normal subjects, 165 subjects with asthma and 104 with pneumonia. Peripheral blood lymphocyte isolation was performed, and total RNA was extracted from the isolated lymphocytes, using nested PCR for specific CD44v amplification on lymphocytes. Demographic variables were analyzed using linear regression in order to determine whether the expression of CD44v was correlated with these demographic features. The nested PCR results revealed that CD44v5 was expressed by 55.2% of asthma patients, which was significantly higher than levels of expression in the other groups. Lower percentages of individuals in the normal subject group exhibited expression of CD44v5 and CD44v6. The data demonstrated that the percentage of individuals in the pneumonia group expressing CD44v5 was 29.0%, but a higher percentage of these patients expressed CD44v6. CD44v5 expression was positively correlated with IgE levels (p=0.032) in the asthmatic patient group, and CD44v6 was significantly positively correlated with the neutrophil count (p<0.05). CD44v5 was expressed by a higher proportion of asthmatic patients than other subjects and thus may play an important role in the pathogenesis of asthma. These findings may offer a new target for the diagnosis and treatment of asthma and may also provide insights into the mechanisms of asthma development.

Gottron's papules exhibit dermal accumulation of CD44 variant 7 (CD44v7) and its binding partner osteopontin: a unique molecular signature

The accumulated mucin in non-Gottron’s dermatomyositis (DM) lesions is primarily chondroitin-4-sulfate (C4S), which is immunomodulatory in vitro. Gottron’s papules are a particularly resistant manifestation of DM that often persist after other lesions have resolved with therapy. We examined non-Gottron’s DM lesions and Gottron’s papule skin biopsies for C4S, CD44v7, a CS-binding isoform causally implicated in autoimmunity, and osteopontin, a CD44v7 ligand implicated in chronic inflammation. Gottron’s papule dermis contained more C4S and CD44v7 than non-Gottron’s lesions. Normal skin showed less CD44v7 over joints relative to Gottron’s lesions. All DM dermis had increased osteopontin compared to healthy skin. Mechanically stretching cultured fibroblasts for six hours induced CD44v7 mRNA and protein, while IFN-γ treatment induced OPN mRNA and protein. Osteopontin alone did not induce CD44v7, but stretching dermal fibroblasts in the presence of osteopontin increased THP-1 monocyte binding, which is blunted by anti-CD44v7 blocking antibody. C4S, CD44v7, and osteopontin are three molecules uniquely present in Gottron’s papules that contribute to inflammation individually and in association with one another. We propose that stretch-induced CD44v7 over joints, in concert with dysregulated osteopontin levels in the skin of DM patients, increases local inflammatory cell recruitment and contributes to the pathogenesis and resistance of Gottron’s papules.

Regulation of Antigen-Experienced T Cells: Lessons from the Quintessential Memory Marker CD44

Despite the widespread use of the cell-surface receptor CD44 as a marker for antigen (Ag)-experienced, effector and memory T cells, surprisingly little is known regarding its function on these cells. The best-established function of CD44 is the regulation of cell adhesion and migration. As such, the interactions of CD44, primarily with its major ligand, the extracellular matrix (ECM) component hyaluronic acid (HA), can be crucial for the recruitment and function of effector and memory T cells into/within inflamed tissues. However, little is known about the signaling events following engagement of CD44 on T cells and how cooperative interactions of CD44 with other surface receptors affect T cell responses. Recent evidence suggests that the CD44 signaling pathway(s) may be shared with those of other adhesion receptors, and that these provide contextual signals at different anatomical sites to ensure the correct T cell effector responses. Furthermore, CD44 ligation may augment T cell activation after Ag encounter and promote T cell survival, as well as contribute to regulation of the contraction phase of an immune response and the maintenance of tolerance. Once the memory phase is established, CD44 may have a role in ensuring the functional fitness of memory T cells. Thus, the summation of potential signals after CD44 ligation on T cells highlights that migration and adhesion to the ECM can critically impact the development and homeostasis of memory T cells, and may differentially affect subsets of T cells. These aspects of CD44 biology on T cells and how they might be modulated for translational purposes are discussed.

Identification of specific chondroitin sulfate species in cutaneous autoimmune disease

Cutaneous lupus erythematosus and dermatomyositis (DM) are chronic inflammatory diseases of the skin with accumulated dermal mucin. Earlier work has shown chondroitin sulfate (CS) accumulation within the dermis of discoid lupus erythematosus (DLE), subacute cutaneous lupus erythematosus (SCLE), and DM lesions compared with control skin. Immunohistochemistry for C4S revealed a greater density in DLE and DM lesions, whereas SCLE lesions did not differ from controls. Scleredema and scleromyxedema are attributed to increased hyaluronic acid, and lesional samples from these diseases also demonstrated accumulated dermal C4S. Interferon-γ and interleukin-1α, but not interferon-α, treatment of cultured dermal fibroblasts induced mRNA expression of CHST-11, which attaches sulfates to the 4-position of unsulfated chondroitin. These studies on possible CS core proteins revealed that serglycin, known to have C6S side chains in endothelial cells, had greater density within DM dermal endothelia but not in DLE or SCLE, following the pattern of C6S overexpression reported previously. CD44 variants expand the CS binding repertoire of the glycoprotein; CD44v7 co-localized to the distribution of C4S in DLE lesions, a finding not observed in DM, SCLE lesions, or controls. Because C4S and C6S have immunologic effects, their dysregulation in cutaneous mucinoses may contribute to the pathogenesis of these disorders.

Low bone accrual is associated with osteocyte apoptosis in alcohol-induced osteopenia

INTRODUCTION

Alcohol is known to decrease bone mineral density (BMD) and to induce trabecular microarchitecture deterioration. However, little is known about the effects of chronic alcohol consumption on osteocytes in situ. The aim of this study was to assess the effects of a high alcohol dose on osteocytes in an alcohol-induced osteopenia model.

MATERIALS AND METHODS

24 male Wistar rats, 2-months old were separated in 2 groups: Control (C) or Alcohol (A35). The rats in the A35 group drank a beverage composed of 35% ethanol v/v mixed to water for 17 weeks. BMD was assessed by DXA, while the microarchitecture was analyzed using μCT. Bone remodeling was studied measuring serum concentration of osteocalcin, NTx and TRAP. Bone marrow adiposity, osteoblastic lineage differentiation, osteocyte morphology and apoptosis were assessed using bright field, epifluorescence, transmission electron and confocal microscopy.

RESULTS

BMD, trabecular thickness, TRAP and NTx concentration were significantly decreased in A35, while cortical thickness was thinner. There were 10 fold more cells stained with cleaved caspase-3, and 35% more empty lacunae in A35, these data indicating a large increase in osteocyte apoptosis in the A35 group. The number of lipid droplets in the marrow was increased in A35 (7 fold). Both the osteocyte apoptosis and the fat bone marrow content strongly correlated with femur BMD (p=0.0017, r = -0.72 and p=0.002, r = -0.70) and whole body BMD.

CONCLUSION

These data suggest that low BMD is associated with osteocyte apoptosis and bone marrow fat content in alcohol-induced osteopenia.

Multifaceted regulation of T cells by CD44

CD44 is a widely-expressed adhesion receptor that is associated with diverse biological processes involving migrating cells, including inflammation, angiogenesis, bone metabolism and wound healing. In the immune system, CD44 is upregulated after activation of naive T lymphocytes during their responses against invading microbes. Once an infection is cleared, elevated levels of CD44 remain on the surface of memory T cells that mediate protection against re-infection. While this has led to the use of highly sustained CD44 expression on T cells as an indicator of a previous immune response, the relevance to T-cell responses or homeostasis has been largely unexplored. Our recent studies demonstrate that CD44 selectively regulates the survival of the Th1 subset of CD4 T cells, but not other T-cell subpopulations. These findings, together with studies of CD44 in other cell types, suggest that differences in the engagement of signaling mechanisms are likely to underlie differential regulation of T-cell responses and underscore the importance of this adhesion receptor to immune cell regulation and protection against viruses and intracellular bacteria.

Mast cell adhesion to bronchial smooth muscle in asthma specifically depends on CD51 and CD44 variant 6

BACKGROUND

Mast cells infiltrate the bronchial smooth muscle (BSM) in asthmatic patients, but the mechanism of mast cell adhesion is still unknown. The adhesion molecules CD44 (i.e. hyaluronate receptor) and CD51 (i.e. vitronectin receptor) are widely expressed and bind to many extracellular matrix (ECM) proteins. The aims of the study are (i) to identify the role of ECM in mast cell adhesion to BSM and (ii) to examine the role of CD51 and CD44 in this adhesion.

METHODS

Human lung mast cells, human mast cell line (HMC-1), and BSM cells from control donors or asthmatic patients were cultured in the presence/absence of various cytokines. Mast cell-BSM interaction was assessed using (3)H-thymidine-pulsed mast cells, confocal immunofluorescence, or electron microscopy. Adhesion molecules expression and collagen production on both cell types were evaluated by quantitative RT-PCR, western blot, and flow cytometry.

RESULTS

Mast cell adhesion to BSM cells mostly involved type I collagen of the ECM. Such an adhesion was increased in normal BSM cells under inflammatory condition, whereas it was maximal in asthmatic BSM cells. Blockade of either CD51 or CD44 significantly decreased mast cell adhesion to BSM. At the molecular level, protein and the transcriptional expression of type I collagen, CD51 or CD44 remained unchanged in asthmatic BSM cells or in mast cells/BSM cells under inflammatory conditions, whereas that of CD44 variant isoform 6 (v6) was increased.

CONCLUSIONS

Mast cell-BSM cell adhesion involved collagen, CD44, and CD51, particularly under inflammatory conditions. CD44v6 expression is increased in asthmatic BSM cells.

CD44 regulates survival and memory development in Th1 cells

Optimal immunity to microorganisms depends upon the regulated death of clonally expanded effector cells and the survival of a cohort of cells that become memory cells. After activation of naive T cells, CD44, a widely expressed receptor for extracellular matrix components, is upregulated. High expression of CD44 remains on memory cells and despite its wide usage as a "memory marker," its function is unknown. Here we report that CD44 was essential for the generation of memory T helper 1 (Th1) cells by promoting effector cell survival. This dependency was not found in Th2, Th17, or CD8(+) T cells despite similar expression of CD44 and the absence of splice variants in all subsets. CD44 limited Fas-mediated death in Th1 cells and its ligation engaged the phosphoinositide 3-kinase-Akt kinase signaling pathway that regulates cell survival. The difference in CD44-regulated apoptosis resistance in T cell subpopulations has important implications in a broad spectrum of diseases.

The role of CD44 in cutaneous inflammation

CD44 is a transmembrane glycoprotein expressed in various tissues including the skin. Previous studies indicated that CD44 is required for epidermal permeability barrier homeostasis and keratinocyte differentiation. Yet, while some studies have demonstrated that CD44 is critical for the development of inflammation, others have shown that CD44 is not essential for the development of cutaneous inflammation. In this study, we evaluated the changes in epidermal CD44 expression in a variety of skin inflammatory models and determined whether CD44 is required for the development of cutaneous inflammation. Inflammatory responses were compared in CD44 KO versus wild-type mice in acute models of irritant and allergic contact dermatitis, as well as in a subacute allergic contact dermatitis induced by repeated hapten treatment. Inflammatory responses were assessed by measuring ear thickness and epidermal hyperplasia in haematoxylin & eosin-stained sections. Our results demonstrate that: (i) epidermal CD44 expression increases in both acute and subacute cutaneous inflammatory models; and (ii) acute disruption of the epidermal permeability barrier function increases epidermal CD44 expression. Whereas inflammatory responses did not differ between CD44 KO and wild-type mice in acute models of irritant and allergic contact dermatitis, both inflammatory responses and epidermal hyperplasia increased in CD44 KO mice following repeated hapten challenges. These results show first, that permeability barrier disruption and inflammation stimulate epidermal CD44 expression, and second, that CD44 modulates epidermal proliferation and inflammatory responses in a subacute murine allergic contact dermatitis model.

CD44 deficiency attenuates chronic murine ileitis

BACKGROUND & AIMS

Lymphocyte recruitment to sites of inflammation requires the sequential engagement of adhesion molecules and chemokine receptors. In the current studies we analyzed the role of CD44 for the development of chronic small-intestinal inflammatory infiltrates in vivo.

METHODS

By using a tumor necrosis factor (TNF)-driven model of chronic ileitis (ie, B6.129P-TNF(DeltaAU-rich element [ARE])) that recapitulates many features of Crohn's disease, we noticed dynamic changes in the expression and functional state of CD44 and its ligand hyaluronan via enzyme-linked immunosorbent assay, real-time reverse-transcription polymerase chain reaction, immunohistochemistry, and flow cytometry. In addition, we assessed the role of lymphocyte populations during induction of ileitis through adoptive transfer studies, and generated CD44-deficient TNFDeltaARE mice to assess the role of CD44 for development of ileitis.

RESULTS

Soluble hyaluronan levels and expression of hyaluronan synthase-1 were increased in TNFDeltaARE mice. This coincided with increased expression of CD44 (including variant 7) and reactivity towards hyaluronan on CD4(+) T cells. CD44 was spatially colocalized with the gut-homing integrin alpha(4)beta(7), spatially linking lymphocyte rolling with arrest. These cells had an effector phenotype because they lacked L-selectin and a higher proportion in diseased mice produced TNF and interleukin-2 compared with wild-type littermates. Lastly, CD4(+) but not CD8(+) T cells conferred ileitis to RAG(-/-) recipients and deficiency of one or both alleles of the CD44 gene resulted in attenuation of the severity of ileitis in TNFDeltaARE mice.

CONCLUSIONS

Our findings support an important role of CD44 expressed by CD4(+) and CD8(+) for development of ileitis mediated by TNF overproduction.

Osteopontin as two-sided mediator of intestinal inflammation

Osteopontin (OPN) is characterized as a major amplifier of Th1-immune responses. However, its role in intestinal inflammation is currently unknown. We found considerably raised OPN levels in blood of wild-type (WT) mice with dextran sodium sulfate (DSS)-induced colitis. To identify the role of this mediator in intestinal inflammation, we analysed experimental colitis in OPN-deficient (OPN(-/-)) mice. In the acute phase of colitis these mice showed more extensive colonic ulcerations and mucosal destruction than WT mice, which was abrogated by application of soluble OPN. Within the OPN(-/-) mice, infiltrating macrophages were not activated and showed impaired phagocytosis. Reduced mRNA expression of interleukin (IL)-1 beta and matrix metalloproteinases was found in acute colitis of OPN(-/-) mice. This was associated with decreased blood levels of IL-22, a Th17 cytokine that may mediate epithelial regeneration. However, OPN-(/-) mice showed increased serum levels of tumour necrosis factor (TNF)-alpha, which could be due to systemically present lipopolysaccharide translocated to the gut. In contrast to acute colitis, during chronic DSS-colitis, which is driven by a Th1 response of the lamina propria infiltrates, OPN(-/-) mice were protected from mucosal inflammation and demonstrated lower serum levels of IL-12 than WT mice. Furthermore, neutralization of OPN in WT mice abrogated colitis. Lastly, we demonstrate that in patients with active Crohn's disease OPN serum concentration correlated significantly with disease activity. Taken together, we postulate a dual function of OPN in intestinal inflammation: During acute inflammation OPN seems to activate innate immunity, reduces tissue damage and initiates mucosal repair whereas during chronic inflammation it promotes the Th1 response and strengthens inflammation.

Critical role of CD44 in hepatotoxin-mediated liver injury

BACKGROUND/AIMS

Blocking of adhesion molecules is considered to be one of the therapeutic strategies inflammatory diseases, although it remains unclear whether this strategy is beneficial.

METHODS

We used CD44-deficient mice to assess whether inhibition of CD44 could control liver injury caused by carbon tetrachloride (CCl(4)).

RESULTS

CD44-deficient mice exhibited suppressed liver inflammation during the early phase (within 6h) after CCl(4) injection due to reduced inflammatory cell infiltration and cytokine production, but showed severe liver inflammation with increased numbers of apoptotic hepatocytes at the late phase (after 12h). The induction of hepatocyte apoptosis was triggered by reduced NF-kappaB activity, which was induced by the low inflammatory cytokine concentrations. Furthermore, macrophages contributed to the induction of hepatocyte apoptosis, since neutralization by an anti-CD11b antibody significantly protected against hepatocyte apoptosis. Finally, we found that blocking of MIP-2 and TNF-alpha reduced hepatocyte apoptosis with decreased numbers of intrahepatic leukocytes and reduced inflammatory cytokine production.

CONCLUSIONS

These findings suggest that targeting of CD44 as a therapeutic approach for inflammatory liver diseases may require caution for particular immune systems in the liver.

The CD44 standard/ezrin complex regulates Fas-mediated apoptosis in Jurkat cells

The transmembrane receptor CD44 conveys important signals from the extracellular microenvironment to the cytoplasm, a phenomena known as "outside-in" signaling. CD44 exists as several isoforms that result from alternative splicing, which differ only in the extracellular domain but yet exhibit different activities. CD44 is a binding partner for the membrane-cytoskeleton cross-linker protein ezrin. In this study, we demonstrate that only CD44 standard (CD44s) colocalizes and interacts with the actin cross-linkers ezrin and moesin using well-characterized cell lines engineered to express different CD44 isoforms. Importantly, we also show that the association CD44s-ezrin-actin is an important modulator of Fas-mediated apoptosis. The results highlight a mechanism by which signals from the extracellular milieu regulate intracellular signaling activities involved in programmed cell death.

Neonatal co-infection with helicobacter species markedly accelerates the development of inflammation-associated colonic neoplasia in IL-10(-/-) mice

BACKGROUND

Inflammatory bowel disease (IBD) is hypothesized to represent an aberrant immune response against enteric bacteria that occurs in a genetically susceptible host. Humans and mice with IBD are at markedly increased risk for colonic neoplasia. However, the long lead time required before development of inflammation-associated colon neoplasia in commonly used murine models of IBD slows the development of effective chemopreventative therapies.

MATERIALS AND METHODS

Neonatal coinfection with Helicobacter typhlonius and Helicobacter rodentium was used to trigger the onset of IBD in mice deficient in the immunoregulatory cytokine interleukin (IL)-10. The severity of colon inflammation and incidence of neoplasia was determined histologically.

RESULTS

IL-10(-/-) mice demonstrated early onset, severe colon inflammation following neonatal infection with H. typhlonius and H. rodentium. The incidence of inflammation-associated colon neoplasia was approximately 95% at a mean age of 21 +/- 2 weeks. Mutation of endoglin, an accessory receptor for TGF-beta, did not affect the severity of IBD or the incidence of neoplasia in this model.

CONCLUSIONS

The rapid onset of severe colon inflammation and multiple neoplastic lesions in the colons of IL-10(-/-) mice neonatally coinfected with H. typhlonius and H. rodentium makes this model well-suited for investigating the mechanisms involved in inflammation-associated colon cancer as well as its chemoprevention.

CD44v7 ligation downregulates the inflammatory immune response in Crohn's disease patients by apoptosis induction in mononuclear cells from the lamina propria

Deletion of exon CD44v7 abrogates experimental colitis by apoptosis induction in intestinal mononuclear cells. Here we show that CD44v7 expression was upregulated upon CD40 ligation in human mononuclear cells, and examined whether ligation of CD44v7 also affects activation and apoptosis in lamina propria mononuclear cells (LPMC) from Crohn's disease (CD) patients. Thirty five patients with chronic inflammatory bowel disease (IBD), fourteen controls and four patients with diverticulitis were evaluated. CD44v7 was upregulated predominantly in the inflamed mucosa of CD patients. Furthermore, incubation with an anti-CD44v7 antibody induced apoptosis in LPMC isolated from inflamed mucosa of CD patients, but not from non-inflamed mucosa, from patients with ulcerative colitis (UC) or from normal controls. CD40 ligation and simultaneous incubation with anti-CD44v7 significantly downregulated CD80 in dendritic cells, thus inhibiting a critical second signal for naive T-cell activation. The apoptotic signal was mediated via the intrinsic mitochondrial pathway with decreased Bcl-2 and increased 7A6 (a mitochondrial membrane protein) expression. It was Fas independent and required caspases-3 and -9 activation. The process is highly specific for macrophage activation via CD40. These findings point to a novel mechanism of apoptosis induction in CD patients mediated by CD44v7 ligation.

R-spondin1, a novel intestinotrophic mitogen, ameliorates experimental colitis in mice

BACKGROUND & AIMS

R-spondin 1 (Rspo1) is a novel epithelial mitogen that stimulates the growth of mucosa in both the small and large intestine.

METHODS

We investigated the therapeutic potential of Rspo1 in ameliorating experimental colitis induced by dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) as well as nonsteroidal anti-inflammatory drug-induced colitis in interleukin (IL)-10-deficient mice.

RESULTS

Therapeutic administration of recombinant Rspo1 protein reduced the loss of body weight, diarrhea, and rectal bleeding in a mouse model of acute or chronic DSS-induced colitis. Histologic evaluation revealed that Rspo1 improved mucosal integrity in both villus and/or crypt compartments in the small intestine and colon by stimulating crypt cell growth and mucosal regeneration in DSS-treated mice. Moreover, Rspo1 significantly reduced DSS-induced myeloperoxidase activity and inhibited the overproduction of proinflammatory cytokines, including tumor necrosis factor-alpha, IL-1alpha, IL-6, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, in mouse intestinal tissue, indicating that Rspo1 may reduce DSS-induced inflammation by preserving the mucosal barrier function. Likewise, Rspo1 therapy also alleviated TNBS-induced interstitial inflammation and mucosal erosion in the mouse colon. Furthermore, Rspo1 substantially decreased the histopathologic severity of chronic enterocolitis by repairing crypt epithelium and simultaneously suppressing inflammatory infiltration in piroxicam-exposed IL-10(-/-) mice. Endogenous Rspo1 protein was localized to villus epithelium and crypt Paneth cells in mouse small intestine.

CONCLUSIONS

Our results show that Rspo1 may be clinically useful in the therapeutic treatment of inflammatory bowel disease by stimulating crypt cell growth, accelerating mucosal regeneration, and restoring intestinal architecture.

CD44 variant DNA vaccination with virtual lymph node ameliorates experimental autoimmune encephalomyelitis through the induction of apoptosis

Standard CD44 (CD44s) and its alternatively spliced variants (CD44v) were found to be associated with the metastatic potential of tumor cells, and with cell migration of autoimmune inflammatory cells, including cells involved in experimental autoimmune encephalomyelitis (EAE). The aim of the present study was to evaluate whether induction of anti-CD44 immune reactivity, through cDNA vaccination could down-regulate EAE. Our vaccination technique involved the insertion of CD44s or CD44v cDNA into a silicone tube filled with 2.5 cm long segment of hydroxylated-polyvinyl acetate wound dressing sponge (forming a virtual lymph node) which was implanted under the skin of SJL/J mice immunized with myelin antigens for EAE induction. Animals vaccinated with CD44v cDNA developed significantly less severe EAE when compared with sham vaccinated animals or animals vaccinated with CD44s cDNA. The in vitro proliferation of lymphocytes was preserved regarding myelin antigens and mitogens. Histopathological examinations revealed a significant reduction of EAE lesions and enhanced apoptosis in central nervous system (CNS)-infiltrating cells of the successfully vaccinated animals. Such methods of cDNA vaccination with CD44 could be applicable in inflammatory CNS diseases, like multiple sclerosis.

Expression of extra trinucleotide in CD44 variant of rheumatoid arthritis patients allows generation of disease-specific monoclonal antibody

Selective targeting of cells engaged in pathological activities is a major challenge for medical research. We generated monoclonal antibodies (mAbs) that exclusively bind, at concentrations ranging from 2 to 100 microg/ml, to a modified CD44 variant (designated CD44vRA) expressed on synovial fluid cells from joints of rheumatoid arthritis (RA) patients. These mAbs cross-reacted with keratinocytes expressing wild type CD44vRA (CD44v3-v10) only at a relatively high concentration (200 microg/ml). Sequence analysis of CD44vRA cDNA revealed, in 33 out of 43 RA and psoriatic arthritis patients, an extra intron-derived trinucleotide, CAG, which allows translation of an extra alanine. This insertion imposes a configurational change on the cell surface CD44 of RA synovial fluid cells, creating an immunogenic epitope and potentiating the ability to produce disease-specific antibodies. Indeed, the anti-CD44vRA mAbs (designated F8:33) were able to induce apoptosis in synovial fluid cells from RA patients, but not in peripheral blood leukocytes from the same patients, in keratinocytes from normal donors or in synovial fluid cells from osteoarthritis patients. Furthermore, injection of anti-CD44vRA mAbs reduced joint inflammation in DBA/1 mice with collagen-induced arthritis. These findings show that anti-CD44vRA mAbs are both bioactive and RA-specific.

Osteopontin-induced relapse and progression of autoimmune brain disease through enhanced survival of activated T cells

Relapses and disease exacerbations are vexing features of multiple sclerosis. Osteopontin (Opn), which is expressed in multiple sclerosis lesions, is increased in patients' plasma during relapses. Here, in models of multiple sclerosis including relapsing, progressive and multifocal experimental autoimmune encephalomyelitis (EAE), Opn triggered recurrent relapses, promoted worsening paralysis and induced neurological deficits, including optic neuritis. Increased inflammation followed Opn administration, whereas its absence resulted in more cell death of brain-infiltrating lymphocytes. Opn promoted the survival of activated T cells by inhibiting the transcription factor Foxo3a, by activating the transcription factor NF-kappaB through induction of phosphorylation of the kinase IKKbeta and by altering expression of the proapoptotic proteins Bim, Bak and Bax. Those mechanisms collectively suppressed the death of myelin-reactive T cells, linking Opn to the relapses and insidious progression characterizing multiple sclerosis.

Exacerbated tissue destruction in DSS-induced acute colitis of OPN-null mice is associated with downregulation of TNF-alpha expression and non-programmed cell death

Osteopontin (OPN), a pro-inflammatory mediator, is constitutively expressed in normal gut and is upregulated in inflammatory colitis. To determine the significance of OPN in inflammatory bowel disease, we studied the development of acute, experimental colitis induced by dextran sulfate sodium (DSS) in OPN-null and wild-type (WT) mice. OPN expression was markedly increased in WT diseased colons, while a higher disease activity index, including spleen enlargement, bowel shortening, and mucosal destruction, was observed in OPN-null mice. Although peripheral blood neutrophil numbers were lower in DSS-treated OPN-null mice, tissue myeloperoxidase levels, reflecting enhanced neutrophil activity, were increased in the diseased colons. In comparison, lymphocyte numbers in peripheral blood were increased earlier than in DSS-treated WT mice. Despite a significantly greater spleen enlargement, flow cytometric analysis of splenocytes from the DSS-treated OPN-null mice revealed lower numbers of differentiated macrophages and (CD4+ and CD8alpha+) lymphocytes. Whereas pro-inflammatory cytokines, including G-CSF, RANTES, MIP1alpha, and TNF-alpha, were increased < 10-fold in DSS-treated WT splenocytes, expression of these cytokines was dramatically suppressed in the DSS-treated OPN-null splenocytes as well as gut tissues. The suppressed TNF-alpha response in OPN-null mice was reflected in a marked increase in non-apoptotic cell death in diseased colons. Collectively, these studies demonstrate that OPN is required for mucosal protection in acute inflammatory colitis.

SHAP potentiates the CD44-mediated leukocyte adhesion to the hyaluronan substratum

CD44-hyaluronan (HA) interaction is involved in diverse physiological and pathological processes. Regulation of interacting avidity is well studied on CD44 but rarely on HA. We discovered a unique covalent modification of HA with a protein, SHAP, that corresponds to the heavy chains of inter-alpha-trypsin inhibitor family molecules circulating in blood. Formation of the SHAP.HA complex is often associated with inflammation, a well known process involving the CD44-HA interaction. We therefore examined the effect of SHAP on the CD44-HA interaction-mediated lymphocyte adhesion. Under both static and flowing conditions, Hut78 cells (CD44-positive) and CD44-transfected Jurkat cells (originally CD44-negative) adhered preferentially to the immobilized SHAP.HA complex than to HA. The enhanced adhesion is exclusively mediated by the CD44-HA interaction, because it was inhibited by HA, but not IalphaI, and was completely abolished by pretreating the cells with anti-CD44 antibodies. SHAP appears to potentiate the interaction by increasing the avidity of HA to CD44 and altering their distribution on cell surfaces. Large amounts of the SHAP.HA complex accumulate in the hyperplastic synovium of rheumatoid arthritis patients. Leukocytes infiltrated to the synovium were strongly positive for HA, SHAP, and CD44 on their surfaces, suggesting a role for the adhesion-enhancing effect of SHAP in pathogenesis.

A novel antiapoptotic mechanism based on interference of Fas signaling by CD44 variant isoforms

There is growing evidence that one of the central common characteristics of tumor and inflammatory cells is their resistance to programmed cell death. This feature results in the accumulation of harmful cells, which are mostly refractory to Fas (FAS, APO-1)-mediated apoptosis. A molecule found on these cells is the transmembrane receptor CD44 with its variant isoforms (CD44v). The establishment of transfectants expressing different CD44v isoforms allowed us to demonstrate that the CD44v6 and CD44v9 isoforms exhibit an antiapoptotic effect and can block Fas-mediated apoptosis. Moreover, we observed that CD44v6 and CD44v9 colocalize and interact with Fas. Importantly, an anti-CD44v6 antibody can abolish the antiapoptotic effect of CD44v6. These results are the first to show that CD44v isoforms interfere with Fas signaling. Our findings improve the understanding of the pathogenesis of cancer and autoimmunity and open new strategies to treat such disorders.

The involvement of osteopontin and its receptors in multiple myeloma cell survival, migration and invasion in the murine 5T33MM model

Multiple myeloma (MM) is a malignancy characterised by the accumulation of monoclonal plasma cells in the bone marrow. Different reports indicate the expression of CD44 variant isoforms (CD44v) by MM cells. Osteopontin (OPN), which is expressed by MM cells, is known to be a ligand for CD44v6. In this study, we investigated the role of OPN with emphasis on a functional correlation between OPN and CD44v in the 5T33MM model. Our group reported the expression of CD44v by 5T33MM cells. Using this model, we have demonstrated the secretion of OPN by 5T33MM cells. OPN affected 5T33MM cell survival by increasing proliferation and inhibiting apoptosis. OPN also stimulated 5T33MM cell migration, transendothelial migration and matrix metalloproteinase-9 activity. We confirmed the proliferative and migratory effects of OPN on human MM cells. By applying inhibiting anti-CD44v6 antibodies, we found that OPN stimulated cell proliferation by engaging this isoform. Anti-CD44v antibodies and RGD peptides both inhibited cell migration, suggesting an involvement of both, CD44v isoforms and integrins. In conclusion, OPN may act as a mediator of MM cell survival by engaging CD44v. The protein is further involved in migration and invasion of MM cells through the activation of either alphavbeta3 integrin or CD44v isoforms.

The osteopontin – CD44 pathway is superfluous for the development of autoimmune myocarditis

Osteopontin (OPN) and CD44 have been implicated in the development of autoimmune diseases, including arthritis and multiple sclerosis, as well as chronic inflammatory diseases, such as atherosclerosis and colitis. To investigate their roles in autoimmune myocarditis induced by immunization with heart alpha-myosin (MyHC-alpha), a mouse model of human cardiomyopathy, we analyzed mice lacking OPN or CD44v6/v7, a CD44 isoform that binds OPN. Both, OPN(-/-) and CD44v6/v7(-/-) mice developed myocarditis with the same prevalence and severity as BALB/c wild-type controls. Furthermore, treatment of BALB/c mice with a pan-neutralizing anti-CD44 antibody did not affect the disease outcome. Consistently, expansion of MyHC-alpha-specific autoimmune CD4(+) T cells and MyHC-alpha autoantibody responses from either CD44v6/v7(-/-) mice or OPN(-/-) mice was indistinguishable from their wild-type controls. Thus, OPN and CD44v6/v7 are merely spectators rather than protagonists in autoimmune myocarditis.