Spontaneous production of immunoglobulin M in human epithelial cancer cells. PLoS One. 2012;7:e51423. [PMID: 23251529 PMCID: PMC3520907 DOI: 10.1371/journal.pone.0051423]

Additional use of α-IgM antibodies potentiates CpG ODN2006-induced B cell activation by targeting mainly naïve and marginal zone-like B cells

CpG ODN2006 is widely used as a potent B cell stimulant in vitro and in vivo. However, it shows a deficit in targeting naïve B cells in vitro. In this study, we investigated whether α-IgM can support ODN2006-induced effects on B cells to obtain enhanced activation with focus on different B cell subsets. Our results delineated robust B cell activation, shown by increased activation marker expression and cytokine secretion by each agent alone, and further augmented when used in combination. Interestingly, α-IgM targeted mainly naïve and marginal zone-like B cells, thus complementing the pronounced effects of ODN2006 on memory B cells and achieving optimal activation for all B cell subsets. Taken together, combining ODN2006 and α-IgM is beneficial for in vitro activation including all B cell subsets. Furthermore, our results suggest that α-IgM could enhance efficacy of ODN2006 in vivo with further need of investigation.

The Gene Rearrangement and Transcriptional Regulation of Non B Cell-Derived Immunoglobulin

Traditionally, immunoglobulin (Ig) expression has been attributed solely to B cells/plasma cells with well-documented and accepted regulatory mechanisms governing Ig expression in B cells. Ig transcription is tightly controlled by a series of transcription factors. However, increasing evidence has recently demonstrated that Ig is not only produced by B cell lineages but also by various types of non-B cells (non-B-Ig). Under physiological conditions, non-B-Ig not only exhibits antibody activity but also regulates cellular biological activities (such as promoting cell proliferation, adhesion, and cytoskeleton protein activity). In pathological conditions, non-B-Ig is implicated in the development of various diseases including tumour, kidney disease, and other immune-related disorders. The mechanisms underline Ig gene rearrangement and transcriptional regulation of Ig genes in non-B cells are not fully understood. However, existing evidence suggests that these mechanisms in non-B cells differ from those in B cells. For instance, non-B-Ig gene rearrangement occurs in an RAG-independent manner; and Oct-1 and Oct-4, rather than Oct-2, are required for the transcriptional regulation of non-B derived Igs. In this chapter, we will describe and compare the mechanisms of gene rearrangement and expression regulation between B-Ig and non-B-Ig.

The Structure Characteristics and Function of Non B Cell-Derived Immunoglobulin

According to classical immunology theory, immunoglobulin (Ig) is exclusively produced by differentiated B lymphocytes, which exhibit a typical tetrapeptide chain structure and are predominantly present on the surface of B cells and in bodily fluids. B-Ig is one of the critical effector molecules for humoral immune responses specifically recognising antigens and eliminating them. However, mounting evidence has demonstrated that Ig is widely expressed in non B lineage cells, especially malignant ones (referred to as non B-Ig). Interestingly, non B-Ig mainly resides in the cytoplasm and secretion, but to some extent on the cell surface. Furthermore non B-Ig not only displays a tetrapeptide chain structure but also shows free heavy chains and free light chains (FLCs). Additionally, Ig derived from non B cancer cell typically displays unique glycosylation modifications. Functionally, non B-Ig demonstrated diversity and versatility, showing antibody activity and cellular biological activity, such as promoting cell proliferation and survival, and it is implicated in cancer progression and some immune-related diseases, such as renal diseases.

Functions and Clinical Relevance of Liver-Derived Immunoglobulins

Liver is the largest internal organ of the body with vital functions. In addition to its endocrine and exocrine activities, liver also plays a pivotal role in the immune system, including haematopoietic functions. Liver parenchymal cells, which are epithelial cells, have been found to possess innate immune functions by expressing pattern-recognition receptors (PRRs), producing complement components, and secreting cytokines. Intriguingly, in recent years, it has been discovered that liver epithelial cells also produce immunoglobulins (Igs), which have long been thought to be produced exclusively by B cells. Notably, even liver epithelial cells from B lymphocyte-deficient mice, including SCID mice and μMT mice, could also produce Igs. Compelling evidence has revealed both the physiological and pathological functions of liver-derived Igs. For instance, liver epithelial cells-derived IgM can serve as a source of natural and specific antibodies that contribute to innate immune responses, while liver-produced IgG can act as a growth factor to promote cell proliferation and survival in normal hepatocytes and hepatocarcinoma. Similar to that in B cells, the toll-like receptor 9 (TLR9)-MyD88 signaling pathway is also actively involved in promoting liver epithelial cells to secrete IgM. Liver-derived Igs could potentially serve as biomarkers, prognostic indicators, and therapeutic targets in the clinical setting, particularly for liver cancers and liver injury. Nevertheless, despite significant advances, much remains unknown about the mechanisms governing Ig transcription in liver cells, as well as the detailed functions of liver-derived Igs and their involvement in diseases and adaptive immunity. Further studies are still needed to reveal these underlying, undefined issues related to the role of liver-derived Igs in both immunity and diseases.

Characteristics and Clinical Implications of Immunoglobulins Derived from Non B Cells in the Skin

Skin is the most prominent tissue and organ, as well as the first line of defence, of the body. Because it is situated on the body's surface, it is constantly exposed to microbial, chemical, and physical factors such as mechanical stimulation. Therefore, skin has evolved substantial immune defences, regenerative ability, and anti-injury capacity. Epidermal cells produce antibacterial peptides that play a role in immune defence under physiological conditions. Additionally, IgG or IgA in the skin also participates in local anti-infective immunity. However, based on the classical theory of immunology, Ig can only be produced by B cells which should be derived from local B cells. This year, thanks to the discovery of Ig derived from non B cells (non B-Ig), Ig has also been found to be expressed in epidermal cells and contributes to immune defence. Epidermal cell-derived IgG and IgA have been demonstrated to have potential antibody activity by binding to pathogens. However, these epidermal cell-derived Igs show different microbial binding characteristics. For instance, IgG binds to Staphylococcus aureus and IgA binds to Staphylococcus epidermidis. Epidermal cells producing IgG and IgA may serve as an effective defense mechanism alongside B cells, providing a novel insight into skin immunity.

The Expression of Non B Cell-Derived Immunoglobulins

Although V(D)J recombination and immunoglobulin (Ig) production are traditionally recognised to occur only in B lymphocytes and plasma cells, the expression of Igs in non-lymphoid cells, which we call non B cell-derived Igs (non B Igs), has been documented by growing studies. It has been demonstrated that non B-Igs can be widely expressed in most cell types, including, but not limited to, epithelial cells, cardiomyocytes, hematopoietic stem/progenitor cells, myeloid cells, and cells from immune-privileged sites, such as neurons and spermatogenic cells. In particular, malignant tumour cells express high level of IgG. Moreover, different from B-Igs that mainly localised on the B cell membrane and in the serum and perform immune defence function mainly, non B-Igs have been found to distribute more widely and play critical roles in immune defence, maintaining cell proliferation and survival, and promoting progression. The findings of non B-Igs may provide a wealthier breakthrough point for more therapeutic strategies for a wide range of immune-related diseases.

Expression and Function of Mammary Epithelial Cell-Derived Immunoglobulins

Over the past 20 years, increasing evidence has demonstrated that immunoglobulins (Igs) can be widely generated from non B cells, including normal and malignant mammary epithelial cells. In normal breast tissue, the expression of IgG and IgA has been identified in epithelial cells of mammary glands during pregnancy and lactation, which can be secreted into milk, and might participate in neonatal immunity. On the other hand, non B-IgG is highly expressed in breast cancer cells, correlating with the poor prognosis of patients with breast cancer. Importantly, a specific group of IgG, bearing a unique N-linked glycan on the Asn162 site and aberrant sialylation modification at the end of the novel glycan (referred to as sialylated IgG (SIA-IgG)), has been found in breast cancer stem/progenitor-like cells. SIA-IgG can significantly promote the capacity of migration, invasiveness, and metastasis, as well as enhance self-renewal and tumorigenicity in vitro and in vivo. These findings suggest that breast epithelial cells can produce Igs with different biological activities under physiological and pathological conditions. During lactation, these Igs could be the main source of milk Igs to protect newborns from pathogenic infections, while under pathological conditions, they display oncogenic activity and promote the occurrence and progression of breast cancer.

Comparison of Non B-Ig and B-Ig

Immunoglobulin (Ig) has been widely acknowledged to be produced solely by B-lineage cells. However, growing evidence has demonstrated the expression of Ig in an array of cancer cells, as well as normal cells including epithelial cells, epidermal cells, mesangial cells, monocytes, and neutrophils. Ig has even been found to be expressed in non-B cells at immune-privileged sites such as neurons and spermatogenic cells. Despite these non-B cell-derived Igs (non-B-Igs) sharing the same symmetric structures with conventional Igs (B-Igs), further studies have revealed unique characteristics of non-B-Ig, such as restricted variable region and aberrant glycosylation. Moreover, non-B-Ig exhibits properties of promoting malignant behaviours of cancer cells, therefore it could be utilised in the clinic as a potential therapeutic biomarker or target. The elucidation of the generation and regulation of non-B-Ig will certainly broaden our understanding of immunology.

Functional analysis of tumor-derived immunoglobulin lambda and its interacting proteins in cervical cancer

BACKGROUND

Immunoglobulin lambda (Igλ) has been reported to be expressed in many normal and tumor tissues and cells. However, the function and clinical significance of tumor-derived Igλ remain unclear.

METHODS

The differential expressions of Immunoglobulin Lambda Constants (IGLCs) in cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) were examined with The Cancer Genome Atlas (TCGA), Genotype-Tissue Expression (GTEx), and Human Protein Atlas (HPA) databases. The effects of IGLCs on patient clinical phenotypes and prognosis were explored via bioinformatics analyses based on the TCGA databases. We used the bioinformatics analyses based on the TCGA and GTEx databases to elucidate the correlations among IGLC expressions, immunomodulator expressions, tumor stemness, and infiltration scores of tumor infiltrating immune cells. Co-immunoprecipitation (Co-IP) and silver staining combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to obtain potential tumor-derived Igλ-interacting proteins. Functional annotation of candidate proteins identified by LC-MS/MS was performed in Database for Annotation, Visualization and Integrated Discovery (DAVID). The bioinformatics analyses of 7 IGLCs in CESC and normal cervical tissues were performed based on TCGA, GTEx, and Gene Expression Profiling Interactive Analysis 2 (GEPIA2) databases. Protein-protein interaction (PPI) network was analyzed based on tumor-derived Igλ-interacting proteins in Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. Immunohistochemistry (IHC) was used to validate the expressions of IGLCs in CESC.

RESULTS

We found that the expressions of the majority of IGLCs (IGLC1, IGLC2, IGLC3, IGLC4, IGLC5, IGLC6, and IGLC7) were upregulated in CESC tissues, compared with those in normal cervical tissues. The expressions of IGLC5 and IGLC7 had significant difference in different pathologic metastasis (M), one of tumor, node, and metastasis (TNM) staging system, categories of CESC. Except for disease-free interval (DFI), 4 IGLC (IGLC1, IGLC2, IGLC3, and IGLC7) expression levels were positively associated with patient overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) respectively in CESC tissues. 5 IGLC (IGLC1, IGLC2, IGLC3, IGLC6, and IGLC7) expressions were positively correlated with the expressions of a majority of immunomodulators respectively in CESC tissues. Tumor stemness was negatively correlated with the expressions of 4 IGLCs (IGLC1, IGLC2, IGLC3, and IGLC7) respectively in CESC tissues. Except for IGLC4, IGLC5, and IGLC7, 4 IGLC (IGLC1, IGLC2, IGLC3, and IGLC6) expressions were positively correlated with infiltration scores of 6 tumor-infiltrating immune cells (B cell, T cell CD4, T cell CD8, neutrophil, macrophage, and DC). After analyses of the above bioinformatics data of tumor-derived Igλ, Co-IP and LC-MS/MS were used to confirm that 4 proteins (RPL7, RPS3, H1-5, and H1-6) might interact with tumor-derived Igλ in cervical cancer cells. Functional analyses of these candidate proteins showed that they interacted with many proteins and were involved in various cellular biological processes. Finally, IHC was used to further confirm the above bioinformatics results, it was indicated that the expression level of Igλ in cervical adenocarcinoma and cervical squamous cell carcinoma was higher than that in normal cervical tissue.

CONCLUSION

This study comprehensively investigated the functions of tumor-derived Igλ and its interacting proteins based on bioinformatics analysis and the potential value of Igλ as a prognostic and therapeutic marker for CESC, providing new direction and evidence for CESC therapy.

SIA-IgG confers poor prognosis and represents a novel therapeutic target in breast cancer

The incidence rate of breast cancer is the highest in the world, and major problem in the clinical treatment is the therapy resistance of breast cancer stem cells (CSCs). Thus, new therapeutic approaches targeting breast CSCs are needed. Our previous study demonstrated cancer-derived sialylated IgG (SIA-IgG) is highly expressed in cancer cells with stem/progenitor features. Furthermore, a high frequency of SIA-IgG in breast cancer tissue predicted metastasis and correlated with poor prognosis factors, and depletion of IgG in breast cancer leads to lower malignancy of cancer cells, suggesting SIA-IgG could be a potential therapeutic target in breast cancer. In this study, we first investigated the relationship of SIA-IgG expression with the clinicopathological characteristics and clinical prognosis of breast carcinoma patients, and the data confirmed that the expression of SIA-IgG confers poor prognosis in breast cancer. Successively, by using a monoclonal antibody specifically against SIA-IgG, we targeted SIA-IgG on the surface of MDA-MB-231 cells and detected their functional changes, and the results suggested SIA-IgG to be a promising antibody therapeutic target in breast cancer. In addition, we explored the mechanism of action at the molecular level of SIA-IgG on breast cancer cell, the findings suggest that SIA-IgG promotes proliferation, metastasis, and invasion of breast cancer cells through the Wnt/β-catenin signaling pathway. Developing therapeutic antibody needs effective therapeutic target, and the antibody should better be a monoclonal antibody with high affinity and high specificity. This study provides a potential prognostic marker and a novel therapeutic target for breast cancer.

Next-Generation Sequencing Revealed a Distinct Immunoglobulin Repertoire with Specific Mutation Hotspots in Acute Myeloid Leukemia

Simple Summary

Identifying new molecular targets is of great importance for prognosis prediction and target therapy of acute myeloid leukemia (AML). We previously reported on frequent expression of immunoglobulin (Ig) in myeloblasts. In this study, we investigated the clinical significance of Ig expression in sorted myeloblasts from 59 AML patients. We found that a higher level of AML-derived Ig expression correlated with a significantly shorter disease-free survival. Furthermore, we performed a comprehensive analysis of AML-derived Ig repertoire by next-generation sequencing (NGS) in 16 patients. The transcripts of AML-derived Ig shared some features with B cell-derived Ig, such as a typical V(D)J recombination and high mutation rates. However, they also showed distinct features. In contrast to the huge diversity of classical Ig, the V_H-D-J_H rearrangements used by AML-derived Ig were biased in each AML patient. In particularly, the Vκ-Jκ rearrangements were skewed in both AML blasts and normal peripheral blood mononucleated cells (PBMCs). However, AML-derived IGK showed high somatic mutation rates (>2%), while IGK in normal PBMCs rarely displayed hypermutation (<2%). More importantly, we identified five mutation hotspots at serine codons of IGKV3-20 in AML blasts, which may be involved in leukemogenesis and serve as a novel marker for disease monitoring and target therapy.

Abstract

Immunoglobulin (Ig) is known as a hallmark of B-lymphocytes exerting antibody functions. However, our previous studies demonstrated that myeloblasts from acute myeloid leukemia (AML) patients could also express Ig with distinct roles. Here, we quantified Ig (IGHG and IGK) transcripts by real-time PCR and performed a comprehensive analysis of Ig repertoire (both heavy chains and light chains) in AML blasts. We found that Ig was frequently expressed by AML blasts. A higher level of AML-derived IGHG expression correlated with a significantly shorter disease-free survival. Next-generation sequencing revealed dysregulated transcripts of all five Ig classes (IGHA, IGHD, IGHE, IGHG, and IGHM) and two Ig types (IGK and IGL) in AML. V_H-D-J_H rearrangements in myeloblasts were biased with individual specificity rather than generally diverse as in B-cells. Compared to AML-derived IgH, AML-derived IGK was more conserved among different AML samples. The frequently shared Vκ-Jκ patterns were IGKV3-20*01/IGKJ1*01, IGKV2D-28*01/IGKJ1*01, and IGKV4-1*01/IGKJ1*01. Moreover, AML-derived IGK was different from classical IGK in B-cells for the high mutation rates and special mutation hotspots at serine codons. Findings of the distinct Ig repertoire in myeloblasts may facilitate the discovery of a new molecular marker for disease monitoring and target therapy.

Macrophage-Derived Immunoglobulin M Inhibits Inflammatory Responses via Modulating Endoplasmic Reticulum Stress

Immunoglobulin (Ig), a characteristic marker of B cells, is a multifunctional evolutionary conserved antibody critical for maintaining tissue homeostasis and developing fully protective humoral responses to pathogens. Increasing evidence revealed that Ig is widely expressed in non-immune cells; moreover, Ig produced by different lineages cells plays different biological roles. Recently, it has been reported that monocytes or macrophages also express Ig. However, its function remains unclear. In this study, we further identified that Ig, especially Ig mu heavy chain (IgM), was mainly expressed in mice macrophages. We also analyzed the IgM repertoire characteristic in macrophages and found that the V_HDJ_H rearrangements of macrophage-derived IgM showed a restricted and conservative V_HDJ_H pattern, which differed from the diverse V_HDJ_H rearrangement pattern of the B cell-expressed IgM in an individual. Functional investigation showed that IgM knockdown significantly promoted macrophage migration and FAK/Src-Akt axis activation. Furthermore, some inflammatory cytokines such as MCP1 and IL-6 increased after IgM knockdown under LPS stimulation. A mechanism study revealed that the IgM interacted with binding immunoglobulin protein (Bip) and inhibited inflammatory response and unfolded protein response (UPR) activation in macrophages. Our data elucidate a previously unknown function of IgM in macrophages that explains its ability to act as a novel regulator of Bip to participate in endoplasmic reticulum stress and further regulate the inflammatory response.

Current insights into the expression and functions of tumor-derived immunoglobulins

Numerous studies have reported expressions of immunoglobulins (Igs) in many human tumor tissues and cells. Tumor-derived Igs have displayed multiple significant functions which are different from classical Igs produced by B lymphocytes and plasma cells. This review will concentrate on major progress in expressions, functions, and mechanisms of tumor-derived Igs, similarities and differences between tumor-derived Igs and B-cell-derived Igs. We also discuss the future research directions of tumor-derived Igs, including their structural characteristics, physicochemical properties, mechanisms for rearrangement and expression regulation, signaling pathways involved, and clinical applications.

Why blood group A individuals are at risk whereas blood group O individuals are protected from SARS-CoV-2 (COVID-19) infection: A hypothesis regarding how the virus invades the human body via ABO(H) blood group-determining carbohydrates

While the angiotensin converting enzyme 2 (ACE2) protein is defined as the primary severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor, the viral serine molecule might be mobilized by the host's transmembrane protease serine subtype 2 (TMPRSS2) enzyme from the viral spike (S) protein and hijack the host's N-acetyl-D-galactosamine (GalNAc) metabolism. The resulting hybrid, serologically A-like/Tn (T nouvelle) structure potentially acts as a host-pathogen functional molecular bridge. In humans, this intermediate structure will hypothetically be replaced by ABO(H) blood group-specific, mucin-type structures, in the case of infection hybrid epitopes, implicating the phenotypically glycosidic accommodation of plasma proteins. The virus may, by mimicking the synthetic pathways of the ABO(H) blood groups, bind to the cell surfaces of the blood group O(H) by formation of a hybrid H-type antigen as the potential precursor of hybrid non-O blood groups, which does not affect the highly anti-glycan aggressive anti-A and anti-B isoagglutinin activities, exerted by the germline-encoded nonimmune immunoglobulin M (IgM). In the non-O blood groups, which have developed from the H-type antigen, these IgM activities are downregulated by phenotypic glycosylation, while adaptive immunoglobulins might arise in response to the hybrid A and B blood group structures, bonds between autologous carbohydrates and foreign peptides, suggesting the exertion of autoreactivity. The non-O blood groups thus become a preferred target for the virus, whereas blood group O(H) individuals, lacking the A/B phenotype-determining enzymes and binding the virus alone by hybrid H-type antigen formation, have the least molecular contact with the virus and maintain the critical anti-A and anti-B isoagglutinin activities, exerted by the ancestral IgM, which is considered the humoral spearhead of innate immunity.

Immune Cells and Immunoglobulin Expression in the Mammary Gland Tumors of Dog

Inflammatory cells have a role in tumor progression and have prognostic and therapeutic potential. The immunohistochemical expression for Mast Cell Tryptase, Macrophage Marker, CD79a, IgA, IgM and IgG on 43 cases of canine mammary gland lesions was analyzed. In hyperplasia, a few B cells (BCs) and Tumor-Associated Macrophages (TAMs) were observed, while the number of Tumor-Associated Mast Cells (TAMCs) was the highest. In the peritumoral stroma of malignant lesions, low number of TAMCs and a high number of TAMAs and BCs were present. Immune cells of each type were always lower in the intratumoral than peritumoral stroma. Positivity to CD79a was also detected in the epithelial cells of simple and micropapillay carcinomas. Immunoglobulin reactivity was mainly located in the epithelial cells where an intense positivity to IgA and IgG and a weak positivity for IgM were detectable. On the basis of our preliminary results and literature data, we suggest that such cells and molecules could be directly involved in the biology of canine mammary gland tumors. In breast cancer, stromal inflammatory cells and cancer derived immunoglobulins have been correlated with the progression, malignancy and poor prognosis of the tumor. The results herein reported show that the dog's mammary gland epithelium also expresses immunoglobulins, and they mostly show a direct relationship with the infiltration of macrophages. In addition, this study shows that the infiltration of mast cells, B-cells and macrophages varies depending on the degree of malignancy of neoplasia.

Immunoglobulin Expression in Cancer Cells and Its Critical Roles in Tumorigenesis

Traditionally, immunoglobulin (Ig) was believed to be produced by only B-lineage cells. However, increasing evidence has revealed a high level of Ig expression in cancer cells, and this Ig is named cancer-derived Ig. Further studies have shown that cancer-derived Ig shares identical basic structures with B cell-derived Ig but exhibits several distinct characteristics, including restricted variable region sequences and aberrant glycosylation. In contrast to B cell-derived Ig, which functions as an antibody in the humoral immune response, cancer-derived Ig exerts profound protumorigenic effects via multiple mechanisms, including promoting the malignant behaviors of cancer cells, mediating tumor immune escape, inducing inflammation, and activating the aggregation of platelets. Importantly, cancer-derived Ig shows promising potential for application as a diagnostic and therapeutic target in cancer patients. In this review, we summarize progress in the research area of cancer-derived Ig and discuss the perspectives of applying this novel target for the management of cancer patients.

Broad Auto-Reactive IgM Responses Are Common In Critically Ill COVID-19 Patients

The pathogenesis of severe COVID-19 remains poorly understood. While several studies suggest that immune dysregulation plays a central role, the key mediators of this process are yet to be defined. Here, we demonstrate that plasma from a high proportion (77%) of critically ill COVID-19 patients, but not healthy controls, contains broadly auto-reactive immunoglobulin M (IgM), and only infrequently auto-reactive IgG or IgA. Importantly, these auto-IgM preferentially recognize primary human lung cells in vitro, including pulmonary endothelial and epithelial cells. By using a combination of flow cytometry, LDH-release assays, and analytical proteome microarray technology, we identified high-affinity, complement-fixing, auto-reactive IgM directed against 263 candidate auto-antigens, including numerous molecules preferentially expressed on cellular membranes in pulmonary, vascular, gastrointestinal, and renal tissues. These findings suggest that broad IgM-mediated autoimmune reactivity may be involved in the pathogenesis of severe COVID-19, thereby identifying a potential target for novel therapeutic interventions.

Inhibition of SYK kinase does not confer a pro-proliferative or pro-invasive phenotype in breast epithelium or breast cancer cells

SYK has been reported to possess both tumour promotor and repressor activities and deletion has been linked to a pro-proliferative / pro-invasive phenotype in breast tumours. It is unclear whether this is a consequence of protein deletion or loss of kinase activity. The SYK inhibitor, BI 1002494, caused no increase in proliferation in breast cancer cells or primary mammary epithelial cells in 2D or 3D cultures, nor changes in proliferation (CD1/2, CDK4, PCNA, Ki67) or invadopodia markers (MMP14, PARP, phospho-vimentin Ser56). BI 1002494 did not alter SYK protein expression. There was no change in phenotype observed in 3D cultures after addition of BI 1002494. Thirteen weeks of treatment with BI 1002494 resulted in no ductal branching or cellular proliferation in the mammary glands of mice. An in silico genetic analysis in breast tumour samples revealed no evidence that SYK has a typical tumour suppressor gene profile such as focal deletion, inactivating mutations or lower expression levels. Furthermore, SYK mutations were not associated with reduction in survival and disease-free period in breast cancer patients. In conclusion, small molecule inhibition of the kinase function of SYK does not contribute to a typical tumour suppressor profile.

Microbiota Alters Urinary Bladder Weight and Gene Expression

We studied the effect of microbiota on the transcriptome and weight of the urinary bladder by comparing germ-free (GF) and specific pathogen-free (SPF) housed mice. In total, 97 genes were differently expressed (fold change > ±2; false discovery rate (FDR) p-value < 0.01) between the groups, including genes regulating circadian rhythm (Per1, Per2 and Per3), extracellular matrix (Spo1, Spon2), and neuromuscular synaptic transmission (Slc18a3, Slc5a7, Chrnb4, Chrna3, Snap25). The highest increase in expression was observed for immunoglobulin genes (Igkv1-122, Igkv4-68) of unknown function, but surprisingly the absence of microbiota did not change the expression of the genes responsible for recognizing microbes and their products. We found that urinary bladder weight was approximately 25% lighter in GF mice (p = 0.09 for males, p = 0.005 for females) and in mice treated with broad spectrum of antibiotics (p = 0.0002). In conclusion, our data indicate that microbiota is an important determinant of urinary bladder physiology controlling its gene expression and size.

Human colorectal cancer cells frequently express IgG and display unique Ig repertoire

BACKGROUND

There is growing evidence proving that many human carcinomas, including colon cancer, can overexpress immunoglobulin (Ig); the non B cancer cell-derived Ig usually displayed unique V(D)J rearrangement pattern that are distinct from B cell-derived Ig. Especially, the cancer-derived Ig plays important roles in cancer initiation, progression, and metastasis. However, it still remains unclear if the colon cancer-derived Ig can display unique V(D)J pattern and sequencing, which can be used as novel target for colon cancer therapy.

AIM

To investigate the Ig repertoire features expressed in human colon cancer cells.

METHODS

Seven cancerous tissue samples of colon adenocarcinoma and corresponding noncancerous tissue samples were sorted by fluorescence-activated cell sorting using epithelial cell adhesion molecule as a marker for epithelial cells. Ig repertoire sequencing was used to analyze the expression profiles of all 5 classes of Ig heavy chains (IgH) and the Ig repertoire in colon cancer cells and corresponding normal epithelial cells.

RESULTS

We found that all 5 IgH classes can be expressed in both colon cancer cells and normal epithelial cells. Surprisingly, unlike the normal colonic epithelial cells that expressed 5 Ig classes, our results suggested that cancer cells most prominently express IgG. Next, we found that the usage of Ig in cancer cells caused the expression of some unique Ig repertoires compared to normal cells. Some V_H segments, such as V_H3-7, have been used in cancer cells, and V_H3-74 was frequently present in normal epithelial cells. Moreover, compared to the normal cell-derived Ig, most cancer cell-derived Ig showed unique V_HDJ_H patterns. Importantly, even if the same V_HDJ_H pattern was seen in cancer cells and normal cells, cancer cell-derived IgH always displayed distinct hypermutation hot points.

CONCLUSION

We found that colon cancer cells could frequently express IgG and unique IgH repertoires, which may be involved in carcinogenesis of colon cancer. The unique IgH repertoire has the potential to be used as a novel target in immune therapy for colon cancer.

Early ovariectomy reveals the germline encoding of natural anti-A- and Tn-cross-reactive immunoglobulin M (IgM) arising from developmental O-GalNAc glycosylations. (Germline-encoded natural anti-A/Tn cross-reactive IgM)

While native blood group A-like glycans have not been demonstrated in prokaryotic microorganisms as a source of human "natural" anti-A isoagglutinin production, and metazoan eukaryotic N-acetylgalactosamine O-glycosylation of serine or threonine residues (O-GalNAc-Ser/Thr-R) does not occur in bacteria, the O-GalNAc glycan-bearing ovarian glycolipids, discovered in C57BL/10 mice, are complementary to the syngeneic anti-A-reactive immunoglobulin M (IgM), which is not present in animals that have undergone ovariectomy prior to the onset of puberty. These mammalian ovarian glycolipids are complementary also to the anti-A/Tn cross-reactive Helix pomatia agglutinin (HPA), a molluscan defense protein, emerging from the coat proteins of fertilized eggs and reflecting the snail-intrinsic, reversible O-GalNAc glycosylations. The hexameric structure of this primitive invertebrate defense protein gives rise to speculation regarding an evolutionary relationship to the mammalian nonimmune, anti-A-reactive immunoglobulin M (IgM) molecule. Hypothetically, this molecule obtains its complementarity from the first step of protein glycosylations, initiated by GalNAc via reversible O-linkages to peptides displaying Ser/Thr motifs, whereas the subsequent transferase depletion completes germ cell maturation and cell renewal, associated with loss of glycosidic bonds and release of O-glycan-depleted proteins, such as complementary IgM revealing the structure of the volatilely expressed "lost" glycan carrier through germline Ser residues. Consequently, the evolutionary/developmental first glycosylations of proteins appear metabolically related or identical to that of the mucin-type, potentially "aberrant" monosaccharide GalNAcα1-O-Ser/Thr-R, also referred to as the Tn (T "nouvelle") antigen, and explain the anti-Tn cross-reactivity of human innate or "natural" anti-A-specific isoagglutinin and the pronounced occurrence of cross-reactive anti-Tn antibody in plasma from humans with histo-blood group O. In fact, A-allelic, phenotype-specific GalNAc glycosylation of plasma proteins does not occur in human blood group O, affecting anti-Tn antibody levels, which may function as a growth regulator that contributes to a potential survival advantage of this group in the overall risk of developing cancer when compared with non-O blood groups.

Recombinant Human IFNα-2b Response Promotes Vaginal Epithelial Cells Defense against Candida albicans

Classical antifungal drugs have been subjected to restrictions due to drug toxicity, drug resistance, bioavailability, and detrimental drug interactions. Type I interferon (IFN) exerts direct distinct immunostimulatory or immunomodulatory actions; however, little is known regarding the anti-fungal reactions of vaginal epithelial cells (VECs) induced by the type I IFN response. Therefore, in the present study, we evaluated the cytotoxic activity, immunocompetent cytokine responses, and non-B IgG production of the VK2/E6E7 VEC line following recombinant human IFN α-2b (rhIFNα-2b) treatment in response to Candida albicans. When treated with rhIFNα-2b, the production of IL-2, IL-4, and IL-17 were significantly up-regulated compared to the infected control cells (P < 0.05). Our scanning electron microscopy results revealed that C. albicans can invade VECs by inducing both endocytosis and active penetration. RhIFNα-2b was able to transform the VECs into a thallus and stretched pattern, promoting the fusion of filopodia to form a lamellipodium and enhancing the mobility and the repair capacity of the VECs. In addition, rhIFNα-2b could effectively inhibit the adhesion, hyphal formation, and proliferation of C. albicans. Collectively, these responses restored the immune function of the infected VECs against C. albicans in vitro, providing a theoretical basis for this novel treatment strategy.

Identification of Liver Epithelial Cell-derived Ig Expression in μ chain-deficient mice

Growing evidence indicates that B cells are not the only source of immunoglobulin (Ig). To investigate this discovery further, we used μMT mice, which have a disruption of the first transmembrane exon of the μ heavy chain and do not express the membrane form of IgM. These mice lack mature B cells and thus serve as a good model to explore Ig expression by liver epithelial cells. We found that Ig heavy chains (μ, δ, γ and α) and light chains (κ and λ) were expressed in sorted liver epithelial cells of μMT mice. Surprisingly, each heavy chain class showed its respective variable region sequence characteristics in their variable region, instead of sharing the same VDJ usage, which suggests that class switching does not occur in liver epithelial cells. Moreover, the γ and α chains, but not the μ and δ chains, showed mutations in the variable region, thus indicating that different classes of Ig have different activities. Our findings support the concept that non-B cells, liver epithelial cells here, can produce different classes of Ig.

Epithelial cells are a source of natural IgM that contribute to innate immune responses

Currently, natural IgM antibodies are considered to be the constitutively secreted products of B-1 cells in mice and humans. In this study, we found that mouse epithelial cells, including liver epithelial cells and small intestinal epithelial cells (IECs), could express IgM that also showed natural antibody activity. Moreover, similar to the B-1 cell-derived natural IgM that can be upregulated by TLR9 agonists (mimicking bacterial infection), the expression of epithelial cell-derived natural IgM could also be significantly increased by TLR9 signaling. More importantly, the epithelial cell-derived IgM was polyreactive, and it could recognize single-stranded DNA (ssDNA), double-stranded DNA (dsDNA), lipopolysaccharide (LPS), and insulin with low affinity; additionally, TLR9 agonists could enhance it in a MyD88-dependent manner. Furthermore, epithelial cell-derived IgM could bind various bacteria; therefore, it could be involved in anti-infection responses. Together, these results highlight the fact that epithelial cells are an important source of natural IgM, in addition to that produced by B-1 cells, and IgM contributes to the innate immune responses in local tissues, further demonstrating that the epithelium is a first line of defense in the protection against invading microbes.

Aberrant high expression of immunoglobulin G in epithelial stem/progenitor-like cells contributes to tumor initiation and metastasis

High expression of immunoglobulin G (IgG) in many non-B cell malignancies and its non-conventional roles in promoting proliferation and survival of cancer cells have been demonstrated. However, the precise function of non-B IgG remains incompletely understood. Here we define the antigen specificity of RP215, a monoclonal antibody that specifically recognizes the IgG in cancer cells. Using RP215, our study shows that IgG is overexpressed in cancer cells of epithelial lineage, especially cells with cancer stem/progenitor cell-like features. The RP215-recognized IgG is primarily localized on the cell surface, particularly lamellipodia-like structures. Cells with high IgG display higher migration, increased invasiveness and metastasis, and enhanced self-renewal and tumorgenecity ability in vitro and in vivo. Importantly, depletion of IgG in breast cancer leads to reduced adhesion, invasion and self-renewal and increased apoptosis of cancer cells. We conclude that high expression of IgG is a novel biomarker of tumor progression, metastasis and cancer stem cell maintenance and demonstrate the potential therapeutic benefits of RP215-recognized IgG targeted strategy.

IgG and IgA with potential microbial-binding activity are expressed by normal human skin epidermal cells

The innate immune system of the skin is thought to depend largely on a multi-layered mechanical barrier supplemented by epidermis-derived antimicrobial peptides. To date, there are no reports of antimicrobial antibody secretion by the epidermis. In this study, we report the expression of functional immunoglobulin G (IgG) and immunoglobulin A (IgA), previously thought to be only produced by B cells, in normal human epidermal cells and the human keratinocyte line HaCaT. While B cells express a fully diverse Ig, epidermal cell-expressed IgG or IgA showed one or two conservative V_HDJ_H rearrangements in each individual. These unique VDJ rearrangements in epidermal cells were found neither in the B cell-derived Ig VDJ databases published by others nor in our positive controls. IgG and IgA from epidermal cells of the same individual had different VDJ rearrangement patterns. IgG was found primarily in prickle cells, and IgA was mainly detected in basal cells. Both epidermal cell-derived IgG and IgA showed potential antibody activity by binding pathogens like Staphylococcus aureus, the most common pathogenic skin bacteria, but the microbial-binding profile was different. Our data indicates that normal human epidermal cells spontaneously express IgG and IgA, and we speculate that these Igs participate in skin innate immunity.

Immunoglobulin expressions are only associated with MCPyV-positive Merkel cell carcinomas but not with MCPyV-negative ones: comparison of prognosis

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer, often associated with Merkel cell polyomavirus (MCPyV). Recently, immunoglobulin (Ig) expression was reported in MCC, thereby suggesting that B cells might be their cellular ancestors. We tested 30 MCCs (20 MCPyV-positive and 10 MCPyV-negative) using immunohistochemistry for the expressions of IgG, IgA, IgM, Igκ, Igλ, terminal desoxynucleotidyl transferase, paired box gene 5 (PAX5), octamer transcription factor-2 (Oct-2), and sex-determining region Y-box 11 (SOX11). We performed in situ hybridization for Igκ-mRNA or Igλ-mRNA and Ig heavy chain (IgH) gene rearrangement (IgH-R) analyses. The expressions of PAX5, TdT, Oct-2, and SOX11 were not significantly different between MCPyV-positive and MCPyV-negative MCCs. At least 1 of IgG, IgA, IgM, or Igκ was expressed in MCPyV-positive (14/20, 70%) and none in MCPyV-negative MCCs (P=0.0003). There was a higher tendency for Igκ-mRNA expression (7/19, using in situ hybridization) and IgH-R (10/20, using polymerase chain reaction) in MCPyV-positive than in MCPyV-negative MCCs (0/10 and 2/10, respectively), thus suggesting a different Ig production pattern and pathogenesis between the 2 types of MCC. Ig expression or IgH-R in MCPyV-positive MCCs might be associated with MCPyV gene integration or expression in cancer cells but do not necessarily suggest a B-cell origin for MCCs. IgH expression or IgH-R nonsignificantly correlated with improved prognosis. However, these might be important factors that influence the survival of neoplastic cells and might allow the development of novel therapies for patients with MCPyV-positive MCCs.

The immunoglobulin heavy chain VH6-1 promoter regulates Ig transcription in non-B cells

Background

Non-B cell immunoglobulins (Igs) are widely expressed in epithelial cancer cells. The past 20 years of research have demonstrated that non-B cell Igs are associated with cancer cell proliferation, the cellular cytoskeleton and cancer stem cells. In this study we explored the transcriptional mechanism of IgM production in non-B cells.

Methods

The promoter region of a V-segment of the heavy mu chain gene (VH6-1) was cloned from a colon cancer cell line HT-29. Next, the promoter activities in non-B cells and B-cells were detected using the dual-luciferase reporter assay. Then the transcription factor binding to the promoter regions was evaluated by electrophoretic mobility shift assays (EMSAs) and gel supershift experiments.

Results

Our data showed that the sequence 1200 bp upstream of VH6-1 exhibited promoter activity in both B and non-B cells. No new regulatory elements were identified within the region 1200 bp to 300 bp upstream of VH6-1. In addition, Oct-1 was found to bind to the octamer element of the Ig gene promoter in cancer cells, in contrast to B cells, which utilize the transcriptional factor Oct-2.

Conclusion

The regulatory mechanisms among different cell types controlling the production of IgM heavy chains are worth discussing.

Toll-like receptors expressed by synovial fibroblasts perpetuate Th1 and th17 cell responses in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by synovial fibroblast hyperplasia and bone and cartilage erosion. Synovial fibroblast- and T cell-mediated inflammation plays crucial roles in the pathogenesis of RA. However how this inflammation is initiated, propagated, and maintained remains controversial. Here, we systemically examined the contribution of toll-like receptors (TLRs) to the inflammatory mediator production as well as Th1 and Th17 cell hyperactivity in RA. Our results show that rheumatoid arthritis synovial fibroblasts (RASF) express a series of TLRs, including TLR2, TLR3, TLR4, and TLR9, with the predominant expression of TLR3. Moreover, the expression levels of these TLRs were higher than those in osteoarthritis synovial fibroblasts (OASF). Ligation of TLR3, as well as TLR2 and TLR4, resulted in vigorous production of inflammatory cytokines, matrix metalloproteinases (MMPs), and vascular endothelial growth factor (VEGF) in RASF, with activation of the NF-κB, MAPK, and IRF3 pathways. More important, activation of these TLRs expressed by RASF exacerbated inflammatory Th1 and Th17 cell expansion both in cell-cell contact-dependent and inflammatory cytokine-dependent manners, which induced more IFN-γ and IL-17 accumulation. Targeting TLRs may modulate the inflammation in RA and provide new therapeutic strategies for overcoming this persistent disease.

Complementary innate (anti-A-specific) IgM emerging from ontogenic O-GalNAc-transferase depletion: (Innate IgM complementarity residing in ancestral antigen completeness)

The murine and the human genome have global properties in common. So the murine anti-A-specific complementary IgM and related human innate isoagglutinin represent developmental, 2-mercaptoethanol-sensitive, complement-binding glycoproteins, which do not arise from any measurable environmentally-induced or auto- immune response. The murine anti-A certainly originates from a cell surface- or cell adhesion molecule, which in the course of germ cell development becomes devoid of O-GalNAc-transferase and is released into the circulation. In human sera the enzyme occurs exclusively in those of blood group A- and AB subjects, while in group O(H) an identically encoded protein lets expect an opposite function and appears in conjunction with a complementary anti-A reactive glycoprotein. Since O-glycosylations rule the carbohydrate metabolism in growth and reproduction processes, we propose that the ancestral histo-(blood)-group A molecule arises in the course of O-GalNAc-glycosylations of glycolipids and protein envelops at progenitor cell surfaces. Germ cell development postulates embryonic stem cell fidelity, which is characterised by persistent production of α-linked O-GalNAc-glycans. They are determined by the A-allele within the human, "complete" histo (blood) group AB(O) structure that in early ontogeny is hypothesised to be synthesised independently from the final phenotype. The structure either passes "completely" through the germline, in transferase-secreting mature tissues becoming the "complete" phenotype AB, or disappears in exhaustive glycotransferase depletion from the differentiating cell surfaces and leaves behind the "incomplete" blood group O-phenotype, which has released a transferase- and O-glycan-depleted, complementary glycoprotein (IgM) into the circulation. The process implies, that in humans the different blood phenotypes evolve from a "complete" AB(O) molecular complex in a distinct enzymatic and/or complement cascade suggesting O-glycanase involvements. While the murine and human oocyte zona pellucida express identical O-glycans, the human phenotype O might be explainable by the kinetics of the murine ovarian O-GalNAc glycan synthesis and the complementary anti-A released in parallel. The maturing murine ovary may provide insight into encoding of the physiologically superior α-linked GalNAc ancestral epitope that becomes essential in reproduction as well as in tissue renewal events. According to recent reports, O-GalNAc-transferase-determined blood group A suggests superiority in human female fertility and was called even "protective". So the minor fertility of blood-group-O females may reside in a critical timing in developmental shifting of enzyme functions affecting the formation of GalNAc-determined hormone receptors on the way to maturation. Experiments that had inserted an oocyte genome into a somatic one to generate pluripotent stem cells, might elucidate a developmental dilemma by testing oocytes from different blood group AB donors donors. Perhaps they will unmask the molecular basis of an evolutionary trend, while stem cell generation itself capitalises on the enzymatically-advantaged, lineage-maintaining (histo) blood group A-allele, which guaranties ancestral functional completeness.

Prognostic significance of immunoglobulin M overexpression in laryngeal squamous cell carcinoma

CONCLUSIONS

Immunoglobulin (Ig) M is overexpressed in laryngeal squamous cell carcinoma (LSCC), and its expression has an independent protective impact on disease-free survival in LSCC.

OBJECTIVE

A number of studies have reported on the ectopic expression of Ig in cancer cells, yet there has been a lack of understanding of its clinical and prognostic significance. This study aimed to investigate the expression of IgM in resected specimens of LSCC and to evaluate its clinical significance and prognostic value.

METHODS

Immunohistochemistry (IHC) and Western blotting were used to detect the expression of IgM in LSCC and normal laryngeal tissues. The serum level of IgM was also analyzed by immunoturbidimetric assay.

RESULTS

IHC and Western blot studies demonstrated that IgM was overexpressed in LSCC specimens (p < 0.001), while the serum level of IgM in patients with LSCC was not different from healthy controls. Chi-squared analysis revealed that the expression level of IgM was negatively correlated with regional lymph node metastasis and tumor stage (p = 0.011 and 0.025, respectively). Univariate analysis showed that IgM expression was significantly correlated with enhanced disease-free survival (DFS) (p = 0.004). In multivariate analysis, IgM retained its independent prognostic value for DFS (p = 0.048, HR = 0.506, 95% CI = 0.257-0.995).