Functional role of CD44 (Pgp-1) on activated B cells

Soluble CD44 in oral rinses for the early detection of cancer: a prospective cohort study in high-risk individuals

BACKGROUND

There are 54,000 new cases of oral cavity and oropharyngeal cancer in the United States and more than 476,000 worldwide each year. Oral cavity and oropharyngeal squamous cell carcinoma make up most tumors with five-year survival rates of 50% due to prevalence of late-stage diagnoses. Improved methods of early detection in high-risk individuals are urgently needed. We aimed to assess the tumorigenic biomarkers soluble CD44 (solCD44) and total protein (TP) measured using oral rinses as affordable convenient screening tools for cancer detection.

METHODS

In this prospective cohort study, we recruited 150 healthy current or former smokers through a community screening program. Baseline and four annual visits were conducted from March 2011-January 2016 with records followed until August 2020. Participants provided oral rinses, received head and neck exams, and completed questionnaires. SolCD44 and TP levels were measured and compared across groups and time. Participants were placed in the cancer group if malignancy developed in the study period, the suspicious group if physical exams were concerning for premalignant disease or cancer in the head and neck, and the healthy group if there were no suspicious findings. This analysis used two-sample t-test for comparison of means and two-sample Wilcoxon Test for comparison of medians. For subjects with follow-ups, estimated means of biomarkers were obtained from a fitted Repeated Measures Analysis of Variance (RANOVA) model including group, visit, and their interaction. Pairwise comparisons of mean solCD44 were made, including intergroup and intragroup comparison of values at different years.

RESULTS

Most participants were males (58.7%), < 60 years of age. (90.7%), and Black (100%). Baseline mean solCD44 was elevated (2.781 ng/ml) in the cancer group compared to the suspicious group (1.849 ng/ml) and healthy group (1.779 ng/ml).

CONCLUSION

This study supports the feasibility of a CD44-based oral rinse test as an affordable and convenient adjunctive tool for early detection of aerodigestive tract and other cancers in high-risk populations.

Hyaluronan in immune dysregulation and autoimmune diseases

The tissue microenvironment contributes to local immunity and to the pathogenesis of autoimmune diseases - a diverse set of conditions characterized by sterile inflammation, immunity against self-antigens, and destruction of tissues. However, the specific factors within the tissue microenvironment that contribute to local immune dysregulation in autoimmunity are poorly understood. One particular tissue component implicated in multiple autoimmune diseases is hyaluronan (HA), an extracellular matrix (ECM) polymer. HA is abundant in settings of chronic inflammation and contributes to lymphocyte activation, polarization, and migration. Here, we first describe what is known about the size, amount, and distribution of HA at sites of autoimmunity and in associated lymphoid structures in type 1 diabetes, multiple sclerosis, and rheumatoid arthritis. Next, we examine the recent literature on HA and its impact on adaptive immunity, particularly in regards to the biology of lymphocytes and Foxp3+ regulatory T-cells (Treg), a T-cell subset that maintains immune tolerance in healthy individuals. We propose that HA accumulation at sites of chronic inflammation creates a permissive environment for autoimmunity, characterized by CD44-mediated inhibition of Treg expansion. Finally, we address potential tools and strategies for targeting HA and its receptor CD44 in chronic inflammation and autoimmunity.

The disease progression in the keratin 14 IL-4-transgenic mouse model of atopic dermatitis parallels the up-regulation of B cell activation molecules, proliferation and surface and serum IgE

We have previously characterized the keratin 14 interleukin-4-transgenic (IL-4-Tg) mouse model of atopic dermatitis as a chronic pruritic inflammatory skin disease typified by skin infiltration of inflammatory cells and early up-regulation of Th2 cytokines and late surge of Th1 cytokines. In the present study, we examined the involvement of B cells. Systematic examinations of the following immunological parameters on B cells were carried out in non-Tg control mice and in IL-4-Tg mice at before disease onset and early and late disease stages so that we could determine the immunological sequence of events leading to the disease development: surface expressions of IA/IE, activation and costimulatory molecules, proliferation under LPS or IgM stimulation, quantification of cell surface and serum IgE, IgG1, and IgG2a. Our results showed that as the disease progresses from before onset to early disease and to late disease, there is a parallel increase in surface markers of B cell activation (IA/IE, CD44, CD69, CD80 and CD86), in B cell proliferation, and in cell surface and serum IgE. Significant increases of Th2-driven serum IgG1 and IgE in early disease was followed by significant increase of Th1-driven IgG2a in late disease. Importantly the significant increases of activation molecule (IA/IE), proliferation (to LPS), and surface IgE on B cells of the IL-4-Tg mice precedes the up-regulation of serum IgE and disease onset. These data suggest that activated B cells may play a role in atopic dermatitis disease development by up-regulating serum IgE concentration, which serves as a marker of disease onset.

Homing-associated cell adhesion molecule (H-CAM/CD44) on human CD34+ hematopoietic progenitor cells

Human CD34+ hematopoietic progenitor cells (HPCs) express CD44 and can directly adhere to hyaluronate (HA) via CD44. Furthermore, CD44 may also be involved in the regulation of CD34+ HPC proliferation and development. The expression of CD44 molecules on CD34+ hematopoietic progenitor cells is significantly lower on bone marrow (BM) CD34+ cells compared with circulating CD34+ cells in cord blood and peripheral blood. Myeloid and erythroid progenitor cells are found predominantly in CD34+ CD44+ cell fractions. More interestingly, CD34+ CD44- cells expressing B-lymphocyte-associated CD10 and CD19 would represent unique B-lymphocyte committed precursors in the BM, which might undergo apoptotic cell death in the early steps of B-cell differentiation.

Co-ligation of CD44 on naive human tonsillar B cells induces progression towards a germinal center phenotype

The precise signaling pathways to induce a germinal center (GC) phenotype and somatic mutations in human B cells are presently not understood. Major phenotypical hallmarks of a human GC B cell are up-regulated expression of CD10 and CD95 together with a heterogeneous expression of CD77. Activation of resting human tonsillar B cells using anti-CD40 and anti-IgM antibodies normally only induces up-regulation of CD38 and CD71 but has no effect on the typical GC markers. However, we show here that an additional co-ligation of the glycoprotein CD44 on such tonsillar B cells up-regulated the typical human GC markers CD10, CD38, CD77 and CD95, and down-regulated CD24 and CD39 as well as induced progression towards apoptosis in these cells; all characteristics of GC B cells. These data indicate a functional role of CD44 during activation of human naive B lymphocytes and in the generation of GC B cells.

A Directly Spliced Exon 10–Containing CD44 Variant Promotes the Metastasis and Homotypic Aggregation of Aggressive Non-Hodgkin's Lymphoma

Variants of the CD44 cell-surface adhesion molecule include additional sequences encoded by combinations of exons from the membrane proximal domain (exons 6–14). Preliminary studies suggest that these additional variable membrane proximal sequences may alter the ligand specificity, glycosylation, and biologic function of CD44. In earlier studies, we found that primary extranodal and widely disseminated aggressive non-Hodgkin's lymphomas (NHLs) and normal activated B cells expressed a directly spliced exon 10–containing variant (CD44ex10), whereas normal resting B cells expressed larger exon 10–containing variants (CD44ex10-14 and CD44ex7-14). To obtain additional information regarding the function of exon 10–containing CD44 variants in aggressive NHL, we generated aggressive NHL transfectants that expressed CD44ex10, CD44ex10-14, CD44ex7-14, the standard CD44 isoform (CD44H), or vector alone, and evaluated the local tumorogenicity, aggregation, and metastatic potential of these transfectants. CD44ex10 aggressive NHL transfectants were more likely to cause local tumor formation in nude mice than transfectants expressing the larger exon 10–containing variants, CD44H, or vector alone. In addition, cell suspensions derived from CD44ex10 local tumors exhibited far greater homotypic aggregation than those obtained from other CD44 or vector-only local tumors. In nude mice that received CD44ex10 transfectants, distant metastases were also significantly more likely to develop than in animals that were given either the CD44ex10-14, CD44ex7-14, CD44H, or vector-only transfectants. These data provide the first evidence that the directly spliced exon 10–containing CD44 variant (CD44ex10) has a unique biologic function in aggressive NHL.

A Directly Spliced Exon 10–Containing CD44 Variant Promotes the Metastasis and Homotypic Aggregation of Aggressive Non-Hodgkin's Lymphoma

Variants of the CD44 cell-surface adhesion molecule include additional sequences encoded by combinations of exons from the membrane proximal domain (exons 6–14). Preliminary studies suggest that these additional variable membrane proximal sequences may alter the ligand specificity, glycosylation, and biologic function of CD44. In earlier studies, we found that primary extranodal and widely disseminated aggressive non-Hodgkin's lymphomas (NHLs) and normal activated B cells expressed a directly spliced exon 10–containing variant (CD44ex10), whereas normal resting B cells expressed larger exon 10–containing variants (CD44ex10-14 and CD44ex7-14). To obtain additional information regarding the function of exon 10–containing CD44 variants in aggressive NHL, we generated aggressive NHL transfectants that expressed CD44ex10, CD44ex10-14, CD44ex7-14, the standard CD44 isoform (CD44H), or vector alone, and evaluated the local tumorogenicity, aggregation, and metastatic potential of these transfectants. CD44ex10 aggressive NHL transfectants were more likely to cause local tumor formation in nude mice than transfectants expressing the larger exon 10–containing variants, CD44H, or vector alone. In addition, cell suspensions derived from CD44ex10 local tumors exhibited far greater homotypic aggregation than those obtained from other CD44 or vector-only local tumors. In nude mice that received CD44ex10 transfectants, distant metastases were also significantly more likely to develop than in animals that were given either the CD44ex10-14, CD44ex7-14, CD44H, or vector-only transfectants. These data provide the first evidence that the directly spliced exon 10–containing CD44 variant (CD44ex10) has a unique biologic function in aggressive NHL.

Lymphocyte-fibroblast interactions

Chronic inflammatory reactions are usually characterized by inflammatory cell accumulation in the extravascular connective tissue. In such sites, inappropriate activation of circulating or resident lymphocytes becomes self-perpetuating and can lead to chronic tissue destruction. In addition to that, the locally infiltrated lymphocytes should have an opportunity to interact directly with fibroblasts composing the connective tissue. The direct interactions of those different cell types seem to play important roles in lymphocyte lodging and retention in such sites. Thus, for clarification of the immunopathogenesis of the chronic inflammatory diseases, including periodontitis, it is important that the molecular mechanisms involved in the heterotypic cell-cell interactions be revealed. In fact, it has been demonstrated that lymphocytes interact with various non-hematopoietic cells, such as epithelial cells and endothelial cells. Regarding interactions with fibroblasts, it has been shown that IFN gamma-stimulated fibroblasts can regulate the proliferative responses of T-lymphocytes both positively and negatively. Furthermore, activated lymphocytes have demonstrated strong binding ability to various fibroblast cell lines. Blocking experiments utilizing monoclonal antibodies specific to various cell adhesion molecules revealed that very late antigen (VLA) integrins, lymphocyte-function-associated antigen (LFA-1)/intercellular adhesion molecule-1 (ICAM-I), CD44/hyarulonate are, at least in part, involved in lymphocyte-fibroblast interactions. In addition, recent findings raised the possibility that the adhesive interactions between lymphocytes and fibroblasts influenced the various cellular functions of each cell type. In fact, it was recently demonstrated that the adhesive interactions stimulated fibroblasts to increase expression of inflammatory cytokine mRNA. These results strongly suggest that fibroblasts are not merely innocent bystanders but actively participate in local inflammatory reactions by directly interacting with locally infiltrated lymphocytes.

Hyaluronan (HA) fragments induce chemokine gene expression in alveolar macrophages. The role of HA size and CD44

Hyaluronan (HA) is a glycosaminoglycan constituent of extracellular matrix. In its native form HA exists as a high molecular weight polymer, but during inflammation lower molecular weight fragments accumulate. We have identified a collection of inflammatory genes induced in macrophages by HA fragments but not by high molecular weight HA. These include several members of the chemokine gene family: macrophage inflammatory protein-1alpha, macrophage inflammatory protein-1beta, cytokine responsive gene-2, monocyte chemoattractant protein-1, and regulated on activation, normal T cell expressed and secreted. HA fragments as small as hexamers are capable of inducing expression of these genes in a mouse alveolar macrophage cell line, and monoclonal antibody to the HA receptor CD44 completely blocks binding of fluorescein-labeled HA to these cells and significantly inhibits HA-induced gene expression. We also investigated the ability of HA fragments to induce chemokine gene expression in human alveolar macrophages from patients with idiopathic pulmonary fibrosis and found that interleukin-8 mRNA is markedly induced. These data support the hypothesis that HA fragments generated during inflammation induce the expression of macrophage genes which are important in the development and maintenance of the inflammatory response.

CD44-hyaluronate interaction participates in the adherence of T-lymphocytes to gingival fibroblasts

It has already been clarified that peripheral blood T-lymphocytes which had been activated with phorbol 12-myristate 13-acetate (PMA) acquired the ability to bind to human gingival fibroblasts (HGF) and that the adherence was mediated by VLA integrins. However, these studies also raised the possibility that molecules other than VLA integrins should be involved in the adherence between T-lymphocytes and HGF. In this study, the possible involvement of CD44, a hyaluronate receptor, in heterotypic cell-cell interactions was investigated. It was confirmed that PMA-activated T-lymphocytes strongly adhered to plate-coated hyaluronate and that the hyaluronate binding was clearly inhibited by the addition of OS/37, a newly established mAb specific for the hyaluronate-binding epitope on CD44. Interestingly, OS/37 also blocked the HGF binding of the activated T-lymphocytes when the adherence to HGF was assessed at 4 degrees C, at which temperature the adhesion of integrin molecules diminished, while that of CD44 functioned normally. Immunofluorescence staining revealed that hyaluronate was anchored along the cell surface of HGF. Furthermore, the binding of activated T-lymphocytes to HGF was significantly inhibited by the treatment of HGF with hyaluronidase. These results clearly demonstrated that CD44-hyaluronate interactions participated at least in part in the adhesiveness of T-lymphocytes to HGF.

Role of EGR1 in regulation of stimulus-dependent CD44 transcription in B lymphocytes

The immediate-early gene egr-1 encodes a transcription factor (EGR1) that links B-cell antigen receptor (BCR) signals to downstream activation events through the regulation of previously unidentified target genes. Here we identify the gene encoding the lymphocyte homing and migration protein CD44 as a target of EGR1 regulation in B cells. BCR-induced increases in CD44 mRNA expression and transcription levels are shown to occur in EGR1-expressing but not in nonexpressing subclones of the B-cell line WEHI-231. Kinetics of egr-1 transcription and the appearance of nuclear EGR1 protein precede CD44 induction and occur within 30 min after stimulation in the EGR1-expressing subclone. A single EGR1 binding motif is demonstrated at bp -301 of the human CD44 promoter. Cotransfection of a CD44 promoter-chloramphenicol acetyltransferase reporter construct with an egr-1 expression vector resulted in a 6.5- to 8.5-fold induction of transcriptional activity relative to an empty expression vector. The EGR1 binding motif was shown to be necessary for stimulus-induced expression of a CD44 promoter-chloramphenicol acetyltransferase reporter construct in nontransformed B lymphocytes and was required for transactivation by an EGR1 expression vector in a B-cell line. These studies identify EGR1 as an intermediary linking BCR-derived signals to the induction of CD44. The relevance of these molecular events to BCR signal transduction and antigen-stimulated B-cell-mediated immune responses is discussed.

Expression of the CD44 variant isoforms 6 and 4/5 in breast cancer. Correlation with established prognostic parameters

Eighty one invasive breast cancers were analysed immunohistochemically to detect if they expressed the adhesion molecules CD44 v6 and v4/5, and the results were evaluated using the semiquantitative IR-score. The results were further divided into four groups: negative, weak positive, moderate positive and strong positive. Fifteen benign breast tumors were also analysed. Sixty eight breast cancers were CD44v6 and v4/5 positive. T3 and T4 cancers showed statistically significant higher positive CD44 rates than T1 and T2 cancers (P < 0.05). We also found a statistically significant correlation between the estrogen receptor and the CD44 status and between the CD44 status and the cathepsin-D status, whereas no correlation between CD44 and the lymph node status, the M status, the grading of the tumors, the progesterone receptor and the menopausal status could be found. Eleven benign tumors were CD44v6 and v4/5 positive. We could not establish any correlation between the expression of CD44 and the metastasizing capacity of breast cancer.

The involvement of adhesion molecules in the biology of multiple myeloma

Multiple myeloma represents a B cell malignancy characterized by a monoclonal proliferation of plasma cells. A striking feature of the disease is the tendency of the malignant plasma cells to affect mainly the bone marrow environment and to invade the peripheral blood only in the terminal stage. The growth of myeloma plasma cells is believed to be regulated by a functional interplay between the tumor cells and the bone marrow stroma, involving the action of various cytokines. This growth control is most probably mediated by close cellular contact of the myeloma cells and marrow stromal components. Therefore it can be assumed that myeloma plasma cells possess the ability to interact with the bone marrow stroma. Until now the adhesive mechanisms that may underlie this interaction, remain undetermined. We investigated the expression of several adhesion molecules on bone marrow plasma cells in myeloma patients and normal controls. Normal as well as malignant plasma cells were found to be strongly positive for the intercellular adhesion molecule ICAM-1, the fibronectin receptor VLA-4 and the lymphocyte homing receptor CD44. In addition, a much weaker expression of the second fibronectin receptor VLA-5, the laminin receptor VLA-6 and the vitronectin receptor CD51 was demonstrated. In contrast to normal plasma cells, myeloma cells can also express the neural cell adhesion molecule N-CAM. In this report we discuss the possible role of adhesion molecules in the pathogenesis and clinical evolution of multiple myeloma.

CD45 expression by murine B cells and T cells: alteration of CD45 isoforms in subpopulations of activated B cells

The CD45 family of high molecular weight cell surface glycoproteins is abundantly expressed by virtually all hematopoietic cells. CD45 molecules exist as multiple isoforms whose extracellular portions vary in protein structure and carbohydrate content but whose intracellular portions are highly conserved and possess tyrosine phosphatase activity. In this review we summarize current studies describing CD45 isoform expression on peripheral and thymic lymphocytes. Further, we analyze changes in CD45 isoform expression by selective populations of activated B cells.