B cells

B cells and atherosclerosis: A HIV perspective

Atherosclerosis remains a leading cause of cardiovascular disease (CVD) globally, with the complex interplay of inflammation and lipid metabolism at its core. Recent evidence suggests a role of B cells in the pathogenesis of atherosclerosis; however, this relationship remains poorly understood, particularly in the context of HIV. We review the multifaceted functions of B cells in atherosclerosis, with a specific focus on HIV. Unique to atherosclerosis is the pivotal role of natural antibodies, particularly those targeting oxidized epitopes abundant in modified lipoproteins and cellular debris. B cells can exert control over cellular immune responses within atherosclerotic arteries through antigen presentation, chemokine production, cytokine production, and cell-cell interactions, actively participating in local and systemic immune responses. We explore how HIV, characterized by chronic immune activation and dysregulation, influences B cells in the context of atherosclerosis, potentially exacerbating CVD risk in persons with HIV. By examining the proatherogenic and antiatherogenic properties of B cells, we aim to deepen our understanding of how B cells influence atherosclerotic plaque development, especially within the framework of HIV. This research provides a foundation for novel B cell-targeted interventions, with the potential to mitigate inflammation-driven cardiovascular events, offering new perspectives on CVD risk management in PLWH.

Endolysosomal transient receptor potential mucolipins and two-pore channels: implications for cancer immunity

Past research has identified that cancer cells sustain several cancer hallmarks by impairing function of the endolysosomal system (ES). Thus, maintaining the functional integrity of endolysosomes is crucial, which heavily relies on two key protein families: soluble hydrolases and endolysosomal membrane proteins. Particularly members of the TPC (two-pore channel) and TRPML (transient receptor potential mucolipins) families have emerged as essential regulators of ES function as a potential target in cancer therapy. Targeting TPCs and TRPMLs has demonstrated significant impact on multiple cancer hallmarks, including proliferation, growth, migration, and angiogenesis both in vitro and in vivo. Notably, endosomes and lysosomes also actively participate in various immune regulatory mechanisms, such as phagocytosis, antigen presentation, and the release of proinflammatory mediators. Yet, knowledge about the role of TPCs and TRPMLs in immunity is scarce. This prompts a discussion regarding the potential role of endolysosomal ion channels in aiding cancers to evade immune surveillance and destruction. Specifically, understanding the interplay between endolysosomal ion channels and cancer immunity becomes crucial. Our review aims to comprehensively explore the current knowledge surrounding the roles of TPCs and TRPMLs in immunity, whilst emphasizing the critical need to elucidate their specific contributions to cancer immunity by pointing out current research gaps that should be addressed.

Comprehensive spectroscopic, metabolomic, and proteomic liquid biopsy in the diagnostics of hepatocellular carcinoma

Liquid biopsy is a very topical issue in clinical diagnostics research nowadays. In this study, we explored and compared various analytical approaches to blood plasma analysis. Finally, we proposed a comprehensive procedure, which, thanks to the utilization of multiple analytical techniques, allowed the targeting of various biomolecules in blood plasma reflecting diverse biological processes underlying disease development. The potential of such an approach, combining proteomics, metabolomics, and vibrational spectroscopy along with preceding blood plasma fractionation, was demonstrated on blood plasma samples of patients suffering from hepatocellular carcinoma in cirrhotic terrain (n = 20) and control subjects with liver cirrhosis (n = 20) as well as healthy subjects (n = 20). Most of the applied methods allowed the classification of the samples with an accuracy exceeding 80.0 % and therefore have the potential to be used as a stand-alone method in clinical diagnostics. Moreover, a final panel of 48 variables obtained by a combination of the utilized analytical methods enabled the discrimination of the hepatocellular carcinoma samples from cirrhosis with 94.3 % cross-validated accuracy. Thus, this study, although limited by the cohort size, clearly demonstrated the benefit of the multimethod approach in clinical diagnosis.

Immune and inflammatory responses of human macrophages, dendritic cells, and T-cells in presence of micro- and nanoplastic of different types and sizes

Environmental pollution by microplastics (MPs) is a growing concern regarding their impact on aquatic and terrestrial systems and human health. Typical exposure routes of MPs are dermal contact, digestion, and inhalation. Recent in vitro and in vivo studies observed alterations in immunity after MPs exposure, but systemic studies using primary human immune cells are scarce. In our investigation, we addressed the effect of polystyrene (PS) and poly methyl methacrylate (PMMA) in three different sizes (50-1100 nm) as well as amino-modified PS (PS-NH2; 50 nm) on cells of the adaptive and innate immune system. T-cells isolated from human peripheral blood mononuclear cells (PBMCs) were least affected regarding the cytotoxicity but displayed increased activation marker expression after 72 h, and strongly modulated cytokine secretion patterns. Conversely, phagocytic dendritic cells and macrophages derived from isolated monocytes were highly sensitive to pristine MPs. Their marker expression suggested a downregulation of the inflammatory phenotypes indicative of M2 macrophage induction after MPs exposure for 24 h. Our results showed that even pristine MPs affected immune cell function and inflammatory phenotype dependent on MPs polymers, size, and immune cell type.

Protein O-GlcNAcylation in multiple immune cells and its therapeutic potential

O-GlcNAcylation is a post-translational modification of proteins that involves the addition of O-GlcNAc to serine or threonine residues of nuclear or cytoplasmic proteins, catalyzed by O-GlcNAc transferase (OGT). This modification is highly dynamic and can be reversed by O-GlcNAcase (OGA). O-GlcNAcylation is widespread in the immune system, which engages in multiple physiologic and pathophysiologic processes. There is substantial evidence indicating that both the hexosamine biosynthesis pathway (HBP) and O-GlcNAcylation are critically involved in regulating immune cell function. However, the precise role of O-GlcNAcylation in the immune system needs to be adequately elucidated. This review offers a thorough synopsis of the present research on protein O-GlcNAcylation, accentuating the molecular mechanisms that control immune cells' growth, maturation, and performance via this PTM.

The role of transient receptor potential channels in metastasis

Metastasis is the hallmark of failed tumor treatment and is typically associated with death due to cancer. Transient receptor potential (TRP) channels affect changes in intracellular calcium concentrations and participate at every stage of metastasis. Further, they increase the migratory ability of tumor cells, promote angiogenesis, regulate immune function, and promote the growth of tumor cells through changes in gene expression and function. In this review, we explore the potential mechanisms of action of TRP channels, summarize their role in tumor metastasis, compile inhibitors of TRP channels relevant in tumors, and discuss current challenges in research on TRP channels involved in tumor metastasis.

Role of B cells as antigen presenting cells

B cells have been long studied for their role and function in the humoral immune system. Apart from generating antibodies and an antibody-mediated memory response against pathogens, B cells are also capable of generating cell-mediated immunity. It has been demonstrated by several groups that B cells can activate antigen-specific CD4 and CD8 T cells, and can have regulatory and cytotoxic effects. The function of B cells as professional antigen presenting cells (APCs) to activate T cells has been largely understudied. This, however, requires attention as several recent reports have demonstrated the importance of B cells within the tumor microenvironment, and B cells are increasingly being evaluated as cellular therapies. Antigen presentation through B cells can be through antigen-specific (B cell receptor (BCR) dependent) or antigen non-specific (BCR independent) mechanisms and can be modulated by a variety of intrinsic and external factors. This review will discuss the pathways and mechanisms by which B cells present antigens, and how B cells differ from other professional APCs.

Contribution of Dysregulated B-Cells and IgE Antibody Responses to Multiple Sclerosis

Multiple sclerosis (MS), a debilitating autoimmune inflammatory disease that affects the brain and spinal cord, causes demyelination of neurons, axonal damage, and neurodegeneration. MS and the murine experimental autoimmune encephalomyelitis (EAE) model have been viewed mainly as T-cell-mediated diseases. Emerging data have suggested the contribution of B-cells and autoantibodies to the disease progression. However, the underlying mechanisms by which dysregulated B-cells and antibody response promote MS and EAE remain largely unclear. Here, we provide an updated review of this specific subject by including B-cell biology and the role of B-cells in triggering autoimmune neuroinflammation with a focus on the regulation of antibody-producing B-cells. We will then discuss the role of a specific type of antibody, IgE, as it relates to the potential regulation of microglia and macrophage activation, autoimmunity and MS/EAE development. This knowledge can be utilized to develop new and effective therapeutic approaches to MS, which fits the scope of the Research Topic "Immune Mechanism in White Matter Lesions: Clinical and Pathophysiological Implications".

A novel digital PCR-based method to quantify (switched) B cells reveals the extent of allelic involvement in different recombination processes in the IGH locus

B cells fulfill an important role in the adaptive immunity. Upon activation and immunoglobulin (IG) class switching, these cells function in the humoral immunity compartment as plasma cells. For clinical applications, it can be important to quantify (switched) B cells accurately in a variety of body fluids and tissues of benign, inflammatory and malignant origin. For decades, flow cytometry and immunohistochemistry (IHC) have been the preferred methods for quantification. Although these methods are widely used, both depend on the accessibility of B cell epitopes and therefore require intact (fixed) cells. Whenever samples are low in quantity and/or quality, accurate quantification can be difficult. By shifting the focus from epitopes to DNA markers, quantification of B cells remains achievable. During differentiation and maturation, B cells are subjected to programmed genetic recombination processes like VDJ rearrangements and class switch recombination (CSR), which result in deletion of specific sequences of the IGH locus. These cell type-specific DNA "scars" (loss of sequences) in IG genes can be exploited as B cell markers in digital PCR (dPCR) based quantification methods. Here, we describe a novel, specific and sensitive digital PCR-based method to quantify mature and switched B cells in DNA specimens of benign and (copy number unstable) malignant origin. We compared this novel way of B cell quantitation with flow cytometric and immunohistochemical methods. Through cross-validation with flow cytometric sorted B cell subpopulations, we gained quantitative insights into allelic involvement in different recombination processes in the IGH locus. Our newly developed method is accurate and independent of the cellular context, offering new possibilities for quantification, even for (limited) small samples like liquid biopsies.

Serum free light chain is associated with histological activity and cirrhosis in patients with chronic hepatitis B

BACKGROUND

The antiviral immune response is the main cause of hepatocyte damage and inflammatory necrosis. The serum free light chain, reflecting the immune function of B-cells, is strongly associated with inflammation and disease activity. We aimed to investigate the association of serum free light chain with the progression of chronic hepatitis B.

METHODS

A total of 208 eligible chronic hepatitis B patients who had undergone a liver biopsy were studied. Serum free light chains of all patients were measured by turbidimetry using an immunoassay. Liver histology was assessed according to the METAVIR scoring system (which grades the stage of fibrosis on a five-point scale, F0 = no fibrosis to F4 = cirrhosis, and histological activity on a four-point scale, A0 = no activity to A3 = severe activity). The association of serum free light chains with histological activity and fibrosis progression was evaluated.

RESULTS

The concentration of serum free light chains in CHB patients increased gradually with histological activity and fibrosis progression. The intensity of histological activity was significantly correlated with the serum free kappa chain (r = 0.658, P < 0.001) and the serum free lambda chain (0.675, P < 0.001). The stages of fibrosis were correlated with the serum free kappa chain (r = 0.683, P < 0.001) and serum free lambda chain (0.664, P < 0.001). After adjusting for age, sex and other synergic factors, the serum free kappa chain remained a potential risk factor, but the serum free lambda chain was no longer associated with liver cirrhosis. Similar to FIB-4 and RPR, the serum free kappa chain exhibited excellent performance in the prediction of liver cirrhosis. The AUCs of serum free Kappa chain, FIB-4 and RPR were 0.873, 0.880 and 0.895, respectively, which were significantly higher than those of the AAR and APRI (0.718 and 0.746).

CONCLUSION

Our work revealed that serum free light chains were associated with histological activity and cirrhosis in chronic hepatitis B, which could play a crucial role in the immunopathogenesis of HBV-associated cirrhosis. In addition, free kappa light chain could be a useful predictor of liver cirrhosis.

IgIT-Mediated Signaling Inhibits the Antimicrobial Immune Response in Oyster Hemocytes

The long-term evolutionary interaction between the host and symbiotic microbes determines their cooperative relationship. It is well known that the symbiotic microbes have evolved various mechanisms to either benefit or exploit the mammalian host immune system to maintain homeostasis. However, the strategies employed by the symbiotic microbes to overcome host immune responses in invertebrates are still not clear. In the current study, the hemolymph microbes in oyster Crassostrea gigas were found to be able to directly bind an oyster Ig superfamily member (IgSF) (designated as CgIgIT) to inhibit the immune responses of hemocytes. The mRNA transcripts of CgIgIT in hemocytes increased significantly after the stimulation with hemolymph microbes. CgIgIT was found to be located on the hemocyte membrane and it was able to directly bind the hemolymph microbes and polysaccharides via its three Ig domains and recruited the protein tyrosine phosphatase CgSHP2 through its ITIM. The recruited CgSHP2 inhibited the activities of CgERK, CgP38 and CgJNK proteins to reduce the productions of dual oxidase 2 (CgDuox2) and defensin 2 (CgDef2), which eventually protected the hemolymph microbes from CgDuox2/CgDef2-mediated elimination. Collectively, the results suggest that the oyster IgIT-SHP2 signaling pathway can recognize bacteria capable of residing in oyster hemolymph and inhibit innate immune responses, which contributes to the maintenance, colonization, and survival of hemolymph microbes.

Influence of Androgens on Immunity to Self and Foreign: Effects on Immunity and Cancer

It is well-known that sex hormones can directly and indirectly influence immune cell function. Different studies support a suppressive role of androgens on different components of the immune system by decreasing antibody production, T cell proliferation, NK cytotoxicity, and stimulating the production of anti-inflammatory cytokines. Androgen receptors have also been detected in many different cells of hematopoietic origin leading to direct effects of their ligands on the development and function of the immune system. The immunosuppressive properties of androgens could contribute to gender dimorphisms in autoimmune and infectious disease and thereby also hamper immune surveillance of tumors. Consistently, females generally are more prone to autoimmunity, while relatively less susceptible to infections, and have lower incidence and mortality of the majority of cancers compared to males. Some studies show that androgen deprivation therapy (ADT) can induce expansion of naïve T cells and increase T-cell responses. Emerging clinical data also reveal that ADT might enhance the efficacy of various immunotherapies including immune checkpoint blockade. In this review, we will discuss the potential role of androgens and their receptors in the immune responses in the context of different diseases. A particular focus will be on cancer, highlighting the effect of androgens on immune surveillance, tumor biology and on the efficacy of anti-cancer therapies including emerging immune therapies.

TRPML Cation Channels in Inflammation and Immunity

Background: In 1883, Ilya Mechnikov discovered phagocytes and established the concept of phagocytosis by macrophages. In 1908, he was awarded the Nobel Prize in Physiology/Medicine for his findings, which laid the foundations for today's understanding of the innate immune response. Only in the 1960s, Max Cooper and Robert Good significantly advanced our understanding of the immune system by demonstrating that B- and T-cells cooperate to regulate the adaptive immune response. Both, innate and adaptive immune response are essential to effectively protect the individual against infectious agents, such as viruses, bacterial or insect toxins, or allergens. Innate immune responses occur rapidly upon exposure to noxious or infectious agents or organisms, in contrast to the adaptive immune system that needs days rather than hours to develop and acts primarily on the basis of antigen-specific receptors expressed on the surface of B- and T-lymphocytes. In recent years, it has become evident that endosomes and lysosomes are involved in many aspects of immune cell function, such as phagocytosis, antigen presentation and processing by antigen-presenting cells, release of proinflammatory mediators, e.g., by mast cells, or secretion of the pore-forming protein perforin by cytotoxic T lymphocytes. Several lysosomal storage disorders (LSDs) have been associated with defects in immune system function or immune system hyperactivity, such as Gaucher, Fabry, or Niemann-Pick type C1 disease, mucopolysaccharidoses (MPS), gangliosidosis, or juvenile neuronal ceroid lipofuscinosis (JNCL). Beside accumulating evidence on the importance of endolysosomes in immune cell function, recent results suggest direct roles of endolysosomal ion channels, such as the TRPML channels (mucolipins), which are members of the transient receptor potential (TRP) superfamily of non-selective cation channels, for different aspects of immune cell function. The aim of this review is to discuss the current knowledge about the roles of TRPML channels in inflammation and immunity, and to assess their potential as drug targets to influence immune cell functions.

Advances: Examples of recently established roles of TRPML channels in immune system function and immune response include the TRPML1-mediated modulation of secretory lysosomes, granzyme B content, and tuning of effector function in NK cells, TRPML1-dependent directional dendritic cell (DC) migration and DC chemotaxis, and the role of TRPML2 in chemokine release from LPS-stimulated macrophages.

Outlook: Although our understanding of the functional roles of TRPML channels in inflammation and immunity is still in its infancy, a few interesting findings have been made in the past years, encouraging further and more detailed work on the role of TRPMLs, e.g., in intracellular trafficking and release of chemokines, cytokines, or granzyme B, or in phagocytosis and bacterial toxin and virus trafficking through the endolysosomal machinery.

An Ancient BCR-like Signaling Promotes ICP Production and Hemocyte Phagocytosis in Oyster

BCR/TCR-based adaptive immune systems arise in the jawed vertebrates, and B cell receptors (BCRs) play an important role in the clonal selection of B cells and their differentiation into antibody-secreting plasma cells. The existence of BCR-like molecule and the activation mechanism of the downstream response are still not clear in invertebrates. In this study, an ancient BCR-like molecule (designated as CgIgR) with an immunoreceptor tyrosine-based activation motif (ITAM) in its cytoplasmic tail was identified from the Pacific oyster Crassostrea gigas to investigate its involvement in immune response. CgIgR could bind different bacteria through five extracellular Ig domains and formed dimers. The activated CgIgR recruited CgSyk to promote CgERK phosphorylation. The CgIgR-mediated signaling promoted the production of immunoglobulin domain-containing proteins (CgICP-2 and CgLRRIG-1) through inducing CgH3K4me2. The produced CgICPs eventually facilitated hemocytes to phagocytize and eliminate V. splendidus. This study proposed that there was an ancient BCR-like molecule and BCR-like signaling in molluscs.

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An ancient BCR-like molecule (defined as CgIgR) was identified from C. gigas

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We propose IgR-mediated signaling induces CgERK activity in oyster

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IgR-mediated signaling induced CgH3K4me2 to promote the production of CgICPs

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CgICPs facilitated the hemocytes to phagocytize and eliminate V. splendidus

Primary Human B Cells at Different Differentiation and Maturation Stages Exhibit Distinct Susceptibilities to Vaccinia Virus Binding and Infection

Vaccinia virus (VACV), the prototypical member of the poxvirus family, was used as a live-virus vaccine to eradicate smallpox worldwide and has recently received considerable attention because of its potential as a prominent vector for the development of vaccines against infectious diseases and as an oncolytic virus for cancer therapy. Studies have demonstrated that VACV exhibits an extremely strong bias for binding to and infection of primary human antigen-presenting cells (APCs), including monocytes, macrophages, and dendritic cells. However, very few studies have assessed the interactions of VACV with primary human B cells, a main type of professional APCs. In this study, we evaluated the susceptibility of primary human peripheral B cells at various differentiation and maturation stages to VACV binding, infection, and replication. We found that plasmablasts were resistant to VACV binding, while other B subsets, including transitional, mature naive, memory, and plasma cells, were highly susceptible to VACV binding. VACV binding preference was likely associated with differential expression of chemokine receptors, particularly CXCR5. Infection studies showed that plasmablast, plasma, transitional, and mature naive B cells were resistant to VACV infection, while memory B cells were preferentially infected. VACV infection in ex vivo B cells was abortive, which occurred at the stage of late viral gene expression. In contrast, activated B cells were permissive to productive VACV infection. Thus, primary human B cells at different differentiation stages exhibit distinct susceptibilities to VACV binding and infection, and the infections are abortive and productive in ex vivo and activated B cells, respectively.IMPORTANCE Our results provide critical information to the field of poxvirus binding and infection tropism. We demonstrate that VACV preferentially infects memory B cells that play an important role in a rapid and vigorous antibody-mediated immune response upon reinfection by a pathogen. Additionally, this work highlights the potential of B cells as natural cellular models to identify VACV receptors or dissect the molecular mechanisms underlying key steps of the VACV life cycle, such as binding, penetration, entry, and replication in primary human cells. The understanding of VACV biology in human primary cells is essential for the development of a safe and effective live-virus vector for oncolytic virus therapy and vaccines against smallpox, other pathogens, and cancer.

Immunotherapy of gynecological cancers

Oncology treatments have evolved from intuitive, via empiric, to the present precision medicine, with the integration of molecular targeted therapies in our treatment arsenal. The use of the patients' powerful immune system has long been contemplated and recently led to the integration of immunotherapy to overturn the well-documented inhibitory effects of the tumor on the immune system and restore it to a state of activity against the cancer. Recent favorable results have shown the value and effectiveness of immunotherapy against gynecological cancers. In particular, the checkpoint inhibitors, targeting the programmed death-1 (PD-1) pathway, have shown durable clinical responses with manageable toxicity. Several phase II and III clinical trials testing the association of different regimen of chemotherapy and immunotherapy are ongoing in gynecological cancers, and important results are expected. In this chapter, we outline the main principles of immunotherapy for gynecological cancers and summarize the current strategies used in clinical trials.

Immune-enhancing effects of polysaccharides from purple sweet potato

Immune-enhancing effects of three kinds of purple sweet potato polysaccharides (PSPPs) including water-soluble polysaccharide (WSP), dilute alkali-soluble polysaccharide (DASP) and concentrated alkali-soluble polysaccharide (CASP) were evaluated. Scanning electron microscope analysis showed that all PSPPs could stimulate the formation of microvilli-like structures in cellular surfaces, which was possibly related to activation of macrophages. Neutral red uptake assay showed that PSPPs could increase the phagocytic activity of cells. High dose (400 μg/mL) of PSPPs could notably augment the level of nitric oxide (NO). ELISA analysis revealed that 200 and 400 μg/mL of PSPPs distinctly elevated the production of IL-1β. Cells received 200 and 400 μg/mL of WSP as well as 400 μg/mL of DASP exhibited higher level of IL-6. Results of animal experiments showed that WSP treatment (400 mg/kg) could promote the secretions of IgA, IgG, IgM and sIgA in both normal and immunosuppressed mice. Moreover, CASP treatment (400 mg/kg) elevated the production of IgM in the serum of normal and immunosuppressive mice, while DASP (400 mg/kg) only improved the secretion of IgM in normal mice. In summary, all three polysaccharides can stimulate immune responses of macrophages and positively regulate adaptive immunity by enhancing the production of immunoglobulins in mice.

Immuno-enhancement effects of Yifei Tongluo Granules on cyclophosphamide-induced immunosuppression in Balb/c mice

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine Yifei Tongluo Granules has been employed clinically with the combination of chemotherapy agents to treat patients with multidrug-resistant tuberculosis. However, the mechanisms underlying the therapeutic potential have not been well elucidated. The present study was employed to verify immunomodulatory effect and to investigate the underlying mechanisms which have not been explored.

MATERIALS AND METHODS

The study samples of total extracts (FB-E) and polysaccharides (FB-P) were prepared by the extraction of the Yifei Tongluo Granules using appropriate techniques. A simple immunodeficient mice model was established by challenging Balb/c mice with cyclophosphamide in order to avoid the handling of tuberculosis viruses. The in vivo study was thus designed to systematically elucidate the immuno-enhancement effects of Yifei Tongluo Granules extracts in immunosuppressed mice induced by cyclophosphamide. Balb/c mice were orally ingested once daily with the low and high doses of two different extracts for ten consecutive days, respectively, accompanied by intraperitoneal injection of cyclophosphamide (60mg/kg) on days 1-3 and 10.

RESULTS

Compared with the model group, the treatment of immunodeficient mice with the low and high doses of the extracts FB-E or FB-P enhanced spleen and thymus indices, T- and B-cell proliferation as well as increased the activities of splenic natural killer, lymphokine activated killer, cytotoxic T lymphocyte cells and peritoneal macrophage phagocytosis. In addition, the FB-E or FB-P treatment balanced the ratio of Th1/Th2 and up-regulated the CD4+/CD8+ ratio in the serum.

CONCLUSIONS

These results demonstrate, for the first time, that the treatment of the cyclophosphamide-challenged mice with the Yifei Tongluo Granules extracts resulted in accelerated recovery of immunosuppression, sugguesting that the immunomodulation might be the mechanism for the observed clinical benefits of Yifei Tongluo Granules. Our findings provide preliminary mechanistic study evidences for clinical application of Yifei Tongluo Granules in patients with immunodeficient diseases such as tuberculosis.

In vitro quantitative determination of the concentration of the polymerization agent methyl 2-benzoylbenzoate in intravenous injection solution and the cytotoxic effects of the chemical on normal human peripheral blood mononuclear cells

In previous studies, we detected the photoinitiators 1-hydroxycyclohexyl phenyl ketone (1-HCHPK) and 2-methyl-4'-(methylthio)-2-morpholinopropiophenone (MTMP) in an intravenous injection solution. Importantly, 1-HCHPK and MTMP have been demonstrated to be cytotoxic to normal human peripheral blood (PB) mononuclear cells (MNC). Cell death (apoptosis) pathways can be classified into two modes, caspase-dependent and -independent pathways. However, it is unclear whether methyl 2-benzoylbenzoate (MBB) induces the caspase-dependent and/or -independent pathway in normal human PBMNC. In the present in vitro study, we examined the levels of MBB in a solution from an intravenous fluid bag and the cytotoxicity of MBB towards normal human PBMNC via the caspase-8-, caspase-9-, or apoptosis-inducing factor (AIF)-mediated apoptosis pathways. We found that extracts from the injection solution had been contaminated with approximately 80 μM of the photoinitiator MBB. In addition, MBB induced apoptosis in the high concentration range in normal human PBMNC in vitro. Moreover, we found that MBB-induced apoptosis occurs via the caspase-9 pathway, but not the AIF pathway. In conclusion, we suggest that MBB has cytotoxic effects on normal human PBMNC in vitro, which are mediated via the caspase-dependent pathway.

Contribution of pseudogenes to sequence diversity

Pseudogenes are very common in the genomes of a wide range of organisms and, although they were originally considered as genetic junk, now several functions have been attributed to them. One important function of pseudogenes, as discussed in this chapter, is to provide material for genetic diversity. This is most prominent in the case of immunological recognition molecules such as immunoglobulins and B- and T-cell receptors, as well as in the case of antigenic variation in intracellular pathogens. Other examples discussed are olfactory receptors, ribosomal proteins, cytochrome P450s, and pseudokinases.

Prolactin levels correlate with abnormal B cell maturation in MRL and MRL/lpr mouse models of systemic lupus erythematosus-like disease

Prolactin (PRL) plays an important role in modulating the immune response. In B cells, PRL enhances antibody production, including antibodies with self-specificity. In this study, our aims were to determine the level of PRL receptor expression during bone-marrow B-cell development and to assess whether the presence of high PRL serum concentrations influences absolute numbers of developing populations and disease outcome in lupus-prone murine models. We observed that the PRL-receptor is expressed in early bone-marrow B-cell; the expression in lupus-prone mice, which had the highest level of expression in pro-B cells and immature cells, differed from that in wild-type mice. These expression levels did not significantly change in response to hyperprolactinemia; however, populations of pro-B and immature cells from lupus-prone strains showed a decrease in the absolute numbers of cells with high PRL-receptor expression in response to PRL. Because immature self-reactive B cells are constantly being eliminated, we assessed the expression of survival factor BIRC5, which is more highly expressed in both pro-B and immature B-cells in response to PRL and correlates with the onset of disease. These results identify an important role of PRL in the early stages of the B-cell maturation process: PRL may promote the survival of self-reactive clones.

Dried blood spot sampling for detection of monoclonal immunoglobulin gene rearrangement

Molecular methods are important tools for diagnosis and monitoring of many lymphoproliferative disorders. The reliability of lymphoma diagnoses is strikingly different between developed and developing countries, partly due to lack of access to these advanced molecular analyses. To overcome these problems, we propose a new application of dried blood spots (DBS) for detecting clonal B-cell populations in peripheral blood (PB). We ensured that the DBS contained sufficient lymphocytes to perform a PCR-based clonality assay without producing false positives. Using the Namalwa B-cell line, we established that the assay is sensitive enough to detect 200 clonal cells in the analyzed sample. Very similar clonal results were obtained between DNA from DBS and fresh whole blood from patients with B-cell chronic lymphocytic leukemia. B-cell clonality can also be detected in DBS from African children with EBV-associated diseases. This is the first study demonstrating that clonality testing can be performed on DBS samples, thus improving the diagnostic and monitoring options for lymphoproliferative diseases in resource-limited settings.

Molecular, Biologic, and Pharmacokinetic Properties of Monoclonal Antibodies: Impact of These Parameters on Early Clinical Development

Currently, 14 intact, unconjugated, monoclonal antibodies (Mabs) are approved for therapeutic use in the United States, and more than 100 Mabs are presently undergoing clinical development or regulatory review. Mabs are large molecular weight glycoproteins that embody structural, biochemical, and pharmacologic properties distinct from other biologics or chemically synthesized compounds. Early therapeutic Mabs were murine proteins, and clinical testing of these agents revealed serious immune-mediated toxicities. The side effect profile of murine Mab therapeutic agents restricted the clinical development of these agents to indications with high morbidity and/or mortality (ie, oncology, graft vs host rejection). Advances in genetic engineering and protein expression technologies resulted in the development of Mabs composed either predominately (ie, mouse/human chimeric, "humanized") or completely (ie, "fully human" Mabs) of the human amino acid sequence. The production of chimeric, humanized, and fully human Mabs significantly reduced the immune-mediated toxicities and expanded the utility for these agents in numerous therapeutic areas, particularly in chronic disorders requiring either long-term administration (ie, rheumatoid arthritis) or treatment upon the flare up of disease (Crohn's disease, psoriasis). This review provides an overview of the molecular, biochemical, and pharmacokinetic properties and clinical development history of Mabs and details how these factors currently affect the scope and design of early clinical development strategies for these drug candidates. Emphasis is placed on the criteria for selecting appropriate subject populations for phase I testing of Mabs.

RhoA of the Rho family small GTPases is essential for B lymphocyte development

RhoA is a member of the Rho family small GTPases that are implicated in various cell functions including proliferation and survival. However, the physiological role of RhoA in vivo remains largely unknown. Here, we deleted RhoA in the B cell and hematopoietic stem cell (HSC) populations in RhoA^flox/flox mice with CD19 and Mx promoter-driven Cre expression, respectively. Deletion of RhoA by CD19^Cre/+ significantly blocked B cell development in spleen, leading to a marked reduction in the number of transitional, marginal zone, and follicular B cells. Surprisingly, neither B cell proliferation in response to either LPS or B cell receptor (BCR) engagement nor B cell survival rate in vivo was affected by RhoA deletion. Furthermore, RhoA^−/− B cells, like control cells, were rescued from apoptosis by BCR crosslinking in vitro. In contrast, RhoA deficiency led to a defect in B cell activating factor (BAFF)-mediated B cell survival that was associated with a dampened expression of BAFF receptor and a loss of BAFF-mediated Akt activation. Finally, HSC deletion of RhoA by Mx-Cre severely reduced proB/preB and immature B cell populations in bone marrow while common lymphoid progenitors were increased, indicating that RhoA is also required for B cell progenitor/precursor differentiation. Taken together, our results uncover an important role for RhoA at multiple stages of B cell development.

An increase in mouse tumor growth by an in vivo immunomodulating effect of titanium dioxide nanoparticles

Here, we investigated whether titanium dioxide (TiO₂) nanoparticles affect in vivo tumor growth through the modulation of mononuclear leukocytes. In vitro lymphocyte proliferation by lipopolysaccharide (LPS) or concanavalin A (ConA) was reduced by < 25 nm TiO₂ with a dose-dependent manner. Similarly, TiO₂ nanoparticles inhibited nitric oxide (NO) production from bone marrow-derived macrophages obtained from naïve mice. When mice were intraperitoneally (IP) injected with < 25 or < 100 nm TiO₂ once a day for 7 days, total cell number of splenocytes was reduced in the spleen of TiO₂ nanoparticle-exposed mice. Both CD4+ and CD8+ T-lymphocyte numbers were significantly decreased and B-lymphocyte development was retarded by host exposure to the TiO₂ nanoparticles. LPS-stimulated spleen cell proliferation was significantly reduced by host exposure to < 25 or < 100 nm TiO₂, but no changes were detected in ConA-stimulated spleen cell proliferation. Further, LPS-stimulated cytokine production by peritoneal macrophages and the percentage of NK1.1+ natural killer cells among splenocytes was reduced by the host exposures to the TiO₂ nanoparticles. When mice were IP injected with TiO₂ nanoparticles once a day for 28 days prior to the subcutaneous implantation of B16F10 melanoma cells, tumor growth was subsequently significantly increased. Collectively, these results show that TiO₂ nanoparticles may damage the development and proliferation of B- and T-lymphocytes, reduce the activity of macrophages, and decrease natural killer (NK) cell population levels, outcomes that appear to lead to an increase in tumor growth in situ. These studies allow us to suggest that TiO₂ nanoparticles might have the potential to enhance tumor growth through immunomodulation of B- and T-lymphocytes, macrophages, and NK cells.

Secondary immunization generates clonally related antigen-specific plasma cells and memory B cells

Rechallenge with T cell-dependent Ags induces memory B cells to re-enter germinal centers (GCs) and undergo further expansion and differentiation into plasma cells (PCs) and secondary memory B cells. It is currently not known whether the expanded population of memory B cells and PCs generated in secondary GCs are clonally related, nor has the extent of proliferation and somatic hypermutation of their precursors been delineated. In this study, after secondary tetanus toxoid (TT) immunization, TT-specific PCs increased 17- to 80-fold on days 6-7, whereas TT-specific memory B cells peaked (delayed) on day 14 with a 2- to 22-fold increase. Molecular analyses of V(H)DJ(H) rearrangements of individual cells revealed no major differences of gene usage and CDR3 length between TT-specific PCs and memory B cells, and both contained extensive evidence of somatic hypermutation with a pattern consistent with GC reactions. This analysis identified clonally related TT-specific memory B cells and PCs. Within clusters of clonally related cells, sequences shared a number of mutations but also could contain additional base pair changes. The data indicate that although following secondary immunization PCs can derive from memory B cells without further somatic hypermutation, in some circumstances, likely within GC reactions, asymmetric mutation can occur. These results suggest that after the fate decision to differentiate into secondary memory B cells or PCs, some committed precursors continue to proliferate and mutate their V(H) genes.

Identification and characterization of a novel immunoglobulin Z isotype in zebrafish: implications for a distinct B cell receptor in lower vertebrates

It was generally believed that teleost fish possess only few immunoglobulin isotypes such as IgM and IgD. The newly discovered IgZ/IgZ-like molecules in zebrafish and several other fish species greatly enriched our knowledge of immunoglobulin family in lower vertebrates. In the present study, we report a second IgZ-like isotype in zebrafish, which was designated as IgZ-2, adding a novel member to the immunoglobulin family in teleost fish. The IgZ-2 heavy chain encoding gene exhibited 76.5% nucleotide sequence identity to the previously reported IgZ. The putative IgZ-2 protein consists of four constant regions in its extracellular region, a transmembrane domain, and a short cytoplasmic tail. A number of conserved domains or residues such as the four Ig domains, cysteines required for Ig fold, hydrophobic and hydrophilic residues consistent with the CART domain, and Thr, Ser, Tyr residues known to be essential for association with the B cell co-receptors CD79A/B, were identified. Phylogenetic analysis showed that IgZ-2 grouped with IgZ and other known teleost IgZ-like sequences. The IgZ-2 transcripts were widely expressed in immune-related tissues, and could be significantly up-regulated by in vivo stimulation with LPS in various tissues including head kidney, spleen, intestine, skin, and gill. However, hardly IgZ-2 transcripts were detected during embryonic development until 2 weeks after fertilization. Double immunofluorescence staining showed that IgZ-2 and IgM were co-localized on B cell surfaces. Flow cytometric analysis showed the percentage of IgZ-2-positive cells could be dramatically up-regulated by interleukin-4 (IL-4), a cytokine known to activate the proliferation and differentiation of B cells. These observations indicated that the newly cloned IgZ-2 could be a novel B cell receptor. Our results will add new insights into the immunoglobulin class diversity of teleost fish, and also help us understand better the evolutionary history of adaptive immunity from fish to mammals as a whole.

IGH and IGK gene rearrangements as PCR targets for pediatric Burkitt's lymphoma and mature B-ALL MRD analysis

We recently reported that minimal residual disease (MRD) and minimal disseminated disease (MDD), assessed by long-distance PCR (LD-PCR) for t(8;14), are negative prognostic factors in mature B-cell acute lymphoblastic leukemia (B-ALL) and in Burkitt's lymphoma (BL). However, t(8;14) is detectable in only about 70% of patients, thus preventing MRD studies by this approach in the remaining patients. At present, no molecular assays have been reported for MRD and MDD analysis in t(8;14)-negative patients. The aim of our study was to evaluate the characteristics of patient-specific immunoglobulin (Ig) gene rearrangements as RQ-PCR targets for MRD analysis, in order to extend MRD studies to those patients who are not eligible for the LD-PCR assay. The study was performed according to the guidelines of the European Study Group on MRD detection in ALL (ESG-MRD-ALL). Overall, 36 B-ALL and 19 BL cases were analyzed. Multiple PCR reactions were performed for each sample to identify heavy and kappa light-chain rearrangements. A total of 97 RQ-PCR targets (62 for B-ALL, 35 for BL) were analyzed for sensitivity. The rearrangement pattern identified was similar to that reported for normal peripheral blood lymphocytes. In 88% of the targets, a sensitivity of at least 10(-4) was achieved. In 87% of patients (84% of B-ALLs, 95% of BLs) at least one sensitive target was available. All PCR targets identified at diagnosis were preserved at relapse. Our results suggest that MDD and MRD can be successfully studied using a single sensitive Ig target in the great majority of B-ALL and BL cases. The combination of LD-PCR and Ig-based assays will allow MRD analysis in virtually all of the patients.

Rho GTPase Cdc42 is essential for B-lymphocyte development and activation

Cdc42 is a member of the Rho GTPase family that has been implicated in several cell functions including proliferation and migration, but its physiologic role needs to be dissected in each cell type. We achieved B-cell and hematopoietic stem cell deletion of Cdc42 by conditional gene targeting in mice. Deletion of Cdc42 from proB/preB-cell stage significantly blocked B-cell development at T1 and later stages, resulting in reduced mature B-cell populations and reduced antigen-specific immunoglobulin M (IgM), IgG1, and IgG3 production. The Cdc42(-/-) B cells, themselves, were abnormal with impaired proliferation and survival. The mutant B cells were further characterized by a B-cell receptor (BCR) signaling defect with increased Erk and decreased Akt activation, as well as a defect in BCR-mediated B-cell-activating factor (BAFF) receptor up-regulation and subsequent BAFF receptor signaling in mature resting B cells. Surprisingly, Cdc42 was dispensable for stromal cell-derived factor-1alpha (SDF-1alpha)- or B-lymphocyte chemoattractant (BLC)-induced B-cell migration. Finally, loss of Cdc42 from hematopoietic stem cells did not alter common lymphoid progenitor production but severely reduced proB/preB- and immature B-cell populations, indicating that Cdc42 is also involved in B-cell precursor differentiation. These results reveal multifaceted roles of Cdc42 in B-cell development and activation.

CD38 induces differentiation of immature transitional 2 B lymphocytes in the spleen

CD38 is a surface receptor able to induce activation, proliferation, and survival of human and mouse lymphocytes; this molecule is expressed on the surface of both mature and immature B cells. In this work, the function of CD38 in the maturation of murine B lymphocytes in the spleen was analyzed. The results showed that CD38 is highly expressed on Transitional 2 (T2) B lymphocytes with an intermediate expression on Transitional 1 (T1) and mature follicular B cells (M). Correlating with a high expression of CD38, T2 cells are also larger and more granular than T1 or M B cells. T2 cells also showed high levels of other molecules, which indicate an activated phenotype. CD38 crosslinking induced proliferation and maturation of T2 B lymphocytes; in contrast, T1 subset died by apoptosis. Finally, CD38 stimulation of T2 B lymphocytes obtained from Btk-, Lyn-, or Fyn-deficient mice showed a defective differentiation; similarly, drugs interfering with PI3K or ERK decreased the proliferation or differentiation of this subset. This suggests that these molecules participate in the CD38 signaling pathway. As a whole, the results indicate that CD38 plays an important role in the regulation of B-cell maturation in the spleen.

Immunological systems biology: Gene expression analysis of B-cell development in Ramos B-cells

B-cell development into antibody producing cells is a complex process that relies on the tightly controlled production of hundreds of genes and proteins. A B-cell is activated through the B-cell receptor (BCR) and this activation is modified by different co-stimulatory or inhibitory co-receptors. The concerted action of signals from BCR and from co-receptors decides the fate of the B-cells. The majority of B-cells enter apoptosis, while some of them progress through the cell cycle and become, for example, antibody producing plasma cells. We studied BCR stimulated Ramos B-cells to explore the expression of BCR pathway, cell cycle and apoptosis related genes. We followed, using microarrays, the gene expression for several days after BCR engagement. Several bioinformatics methods were used to investigate the properties and common features of co-expressed genes. Certain gene ontologies have statistically significant enrichment into clusters of similarly expressed genes. The cell signaling pathways and gene expression data were combined to reveal detailed information about biological processes and B-cell systems biology. The results provide knowledge of the development of adaptive immunity and clues about how the pathways are affected by regulation of the expression of genes.

BAFF, a new target for intravenous immunoglobulin in autoimmunity and cancer

Intravenous immunoglobulin (IVIg) has been used to treat autoimmune diseases and lymphoid malignancies with some therapeutic effect. In both these pathological conditions, there is an overproduction of BAFF (for "B-cell-activating factor of the TNF family"), and APRIL (for "a proliferation-inducing ligand"). The presence of antibodies (Abs) with BAFF and APRIL specificities in IVIg preparations was investigated by enzyme-linked immunosorbent assay, and Western Blot analysis. Apoptosis was measured by the annexin-V binding method, and confirmed using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique. Nonglycosylated recombinant BAFF, glycosylated affinity-purified BAFF, and recombinant APRIL (but not TNFalpha), were recognized by certain IgG in IVIg, and their F(ab')(2) fragments. Steric hindrance prevented the antiapoptotic effects of BAFF on B-lymphocytes. This work documents the presence of anti-BAFF and anti-APRIL Abs in IVIg. These can functionally neutralize the role of BAFF in B-cell survival. These anti-BAFF IgG might amend deleterious effects of BAFF in B-cell-mediated autoimmune diseases.

A costimulatory function for T cell CD40

CD40 plays a significant role in the pathogenesis of inflammation and autoimmunity. B cell CD40 directly activates cells, which can result in autoantibody production. T cells can also express CD40, with an increased frequency and amount of expression seen in CD4(+) T lymphocytes of autoimmune mice, including T cells from mice with collagen-induced arthritis. However, the mechanisms of T cell CD40 function have not been clearly defined. To test the hypothesis that CD40 can serve as a costimulatory molecule on T lymphocytes, CD40(+) T cells from collagen-induced arthritis mice were examined in parallel with mouse and human T cell lines transfected with CD40. CD40 served as effectively as CD28 in costimulating TCR-mediated activation, including induction of kinase and transcription factor activities and production of cytokines. An additional enhancement was seen when both CD40 and CD28 signals were combined with AgR stimulation. These findings reveal potent biologic functions for T cell CD40 and suggest an additional means for amplification of autoimmune responses.

Immune properties of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent progenitor cells isolated by various relatively easily accessible tissues, such as bone marrow and cord blood. MSCs gained attention because of their ease for in vitro expansion together with their multilineage potential. More recently, in vitro and in vivo immunosuppressive properties have been ascribed to them, as they are able to modulate the function of all major immune cell populations, thus impeding immune responses. The underlying mechanisms of their differentiation and function are not thoroughly understood, but still they represent important candidates for tissue regeneration and manipulation of the immune response in graft rejection, graft versus host disease, and autoimmune disorders. Characteristics and immunogenic profile of MSCs, their interface with immune system and their potential use as immunosuppressive elements in cellular therapeutic protocols are reviewed in this chapter.

Proteome analysis of B-cell maturation

Proteins affected by anti-mIgM stimulation during B-cell maturation were identified using 2-DE-based proteomics. We investigated the proteome profiles of stimulated and nonstimulated Ramos B-cells at eight time points during 5 d and compared the obtained proteomic data to the corresponding data from DNA-microarray studies. Anti-mIgM stimulation of the cells resulted in significant differences (> or =twofold) in the protein abundance close to 100 proteins and differences in post-translational protein modifications. Forty-eight up- or down-regulated proteins were identified by mass spectrometric methods and database searches. The identities of a further nine proteins were revealed by comparing their positions to the known proteins in other lymphocyte 2-DE databases. Several of the proteins are directly related to the functional and morphological characteristics of B-cells, such as cytoskeleton rearrangement and intracellular signalling triggered by the crosslinking of B-cell receptors. In addition to proteins known to be involved in human B-cell maturation, we identified several proteins that were not previously linked to lymphocyte differentiation. The results provide deeper insights into the process of B-cell maturation and may lead to novel therapeutic strategies for immunodeficiencies. An interactive 2-DE reference map is available at http://bioinf.uta.fi/BcellProteome.