The CD40-CD154 interaction in B cell-T cell liaisons

Harnessing immunotherapeutic molecules and diagnostic biomarkers as human-derived adjuvants for MERS-CoV vaccine development

The pandemic potential of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) highlights the critical need for effective vaccines due to its high fatality rate of around 36%. In this review, we identified a variety of immunotherapeutic molecules and diagnostic biomarkers that could be used in MERS vaccine development as human-derived adjuvants. We identified immune molecules that have been incorporated into standard clinical diagnostics such as CXCL10/IP10, CXCL8/IL-8, CCL5/RANTES, IL-6, and the complement proteins Ca3 and Ca5. Utilization of different human monoclonal antibodies in the treatment of MERS-CoV patients demonstrates promising outcomes in combatting MERS-CoV infections in vivo, such as hMS-1, 4C2H, 3B11-N, NBMS10-FC, HR2P-M2, SAB-301, M336, LCA60, REGN3051, REGN3048, MCA1, MERs-4, MERs-27, MERs-gd27, and MERs-gd33. Host-derived adjuvants such as CCL28, CCL27, RANTES, TCA3, and GM-CSF have shown significant improvements in immune responses, underscoring their potential to bolster both systemic and mucosal immunity. In conclusion, we believe that host-derived adjuvants like HBD-2, CD40L, and LL-37 offer significant advantages over synthetic options in vaccine development, underscoring the need for clinical trials to validate their efficacy.

Meta-analysis of the Selected Genetic Variants in Immune-Related Genes and Multiple Sclerosis Risk

Previous studies have suggested that certain variants in immune-related genes may participate in the pathogenesis of multiple sclerosis (MS), including rs17824933 in the CD6 gene, rs1883832 in the CD40 gene, rs2300747 in the CD58 gene, rs763361 in the CD226 gene, rs16944 in the IL-1β gene, rs2243250 in the IL-4 gene, and rs12722489 and rs2104286 in the IL-2Rα gene. However, the results remained inconclusive and conflicting. In view of this, a comprehensive meta-analysis including all eligible studies was conducted to investigate the association between these 8 selected genetic variants and MS risk. Up to June 2023, 64 related studies were finally included in this meta-analysis. The odds ratios (ORs) and corresponding 95% confidence intervals (CIs) calculated by the random-effects model were used to evaluate the strength of association. Publication bias test, sensitivity analyses, and trial sequential analysis (TSA) were conducted to examine the reliability of statistical results. Our results indicated that rs17824933 in the CD6 gene, rs1883832 in the CD40 gene, rs2300747 in the CD58 gene, rs763361 in the CD226 gene, and rs12722489 and rs2104286 in the IL-2Rα gene may serve as the susceptible factors for MS pathogenesis, while rs16944 in the IL-1β gene and rs2243250 in the IL-4 gene may not be associated with MS risk. However, the present findings need to be confirmed and reinforced in future studies.

NF-κB in biology and targeted therapy: new insights and translational implications

NF-κB signaling has been discovered for nearly 40 years. Initially, NF-κB signaling was identified as a pivotal pathway in mediating inflammatory responses. However, with extensive and in-depth investigations, researchers have discovered that its role can be expanded to a variety of signaling mechanisms, biological processes, human diseases, and treatment options. In this review, we first scrutinize the research process of NF-κB signaling, and summarize the composition, activation, and regulatory mechanism of NF-κB signaling. We investigate the interaction of NF-κB signaling with other important pathways, including PI3K/AKT, MAPK, JAK-STAT, TGF-β, Wnt, Notch, Hedgehog, and TLR signaling. The physiological and pathological states of NF-κB signaling, as well as its intricate involvement in inflammation, immune regulation, and tumor microenvironment, are also explicated. Additionally, we illustrate how NF-κB signaling is involved in a variety of human diseases, including cancers, inflammatory and autoimmune diseases, cardiovascular diseases, metabolic diseases, neurological diseases, and COVID-19. Further, we discuss the therapeutic approaches targeting NF-κB signaling, including IKK inhibitors, monoclonal antibodies, proteasome inhibitors, nuclear translocation inhibitors, DNA binding inhibitors, TKIs, non-coding RNAs, immunotherapy, and CAR-T. Finally, we provide an outlook for research in the field of NF-κB signaling. We hope to present a stereoscopic, comprehensive NF-κB signaling that will inform future research and clinical practice.

Carcinogenic mechanisms of virus-associated lymphoma

The development of lymphoma is a complex multistep process that integrates numerous experimental findings and clinical data that have not yet yielded a definitive explanation. Studies of oncogenic viruses can help to deepen insight into the pathogenesis of lymphoma, and identifying associations between lymphoma and viruses that are established and unidentified should lead to cellular and pharmacologically targeted antiviral strategies for treating malignant lymphoma. This review focuses on the pathogenesis of lymphomas associated with hepatitis B and C, Epstein-Barr, and human immunodeficiency viruses as well as Kaposi sarcoma-associated herpesvirus to clarify the current status of basic information and recent advances in the development of virus-associated lymphomas.

The rs1883832 Polymorphism (CD40-1C>T) Affects the Intensity of IgA Responses after BNT162b2 Vaccination

The effectiveness of coronavirus disease 2019 (COVID-19) vaccination strategies is affected by several factors, including the genetic background of the host. In our study, we evaluated the contribution of the functional polymorphism rs1883832 affecting the Kozak sequence of the TNFSF5 gene (c.-1C>T), encoding CD40, to humoral immune responses after vaccination with the spike protein of SARS-CoV-2. The rs1883832 polymorphism was analyzed by PCR-RFLP in 476 individuals (male/female: 216/260, median age: 55.0 years, range: 20−105) of whom 342 received the BNT162b2 mRNA vaccine and 134 received the adenovirus-based vector vaccines (67 on ChAdOx1-nCoV-19 vaccine, 67 on Ad.26.COV2.S vaccine). The IgG and IgA responses were evaluated with chemiluminescent microparticle and ELISA assays on days 21, 42, and 90 after the first dose. The T allele of the rs1883832 polymorphism (allele frequency: 32.8%) was significantly associated with lower IgA levels and represented, as revealed by multivariable analysis, an independent risk factor for reduced anti-spike protein IgA levels on days 42 and 90 following BNT162b2 mRNA vaccination. Similar to serum anti-spike IgA levels, a trend of lower anti-spike IgA concentrations in saliva was found in individuals with the T allele of rs1883832. Finally, the intensity of IgA and IgG responses on day 42 significantly affected the prevalence of COVID-19 after vaccination. The rs1883832 polymorphism may be used as a molecular predictor of the intensity of anti-spike IgA responses after BNT162b2 mRNA vaccination.

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.

RelB contributes to the survival, migration and lymphomagenesis of B cells with constitutively active CD40 signaling

Activation of CD40-signaling contributes to the initiation, progression and drug resistance of B cell lymphomas. We contributed to this knowledge by showing that constitutive CD40-signaling in B cells induces B cell hyperplasia and finally B cell lymphoma development in transgenic mice. CD40 activates, among others, the non-canonical NF-ĸB signaling, which is constitutively activated in several human B cell lymphomas and is therefore presumed to contribute to lymphopathogenesis. This prompted us to study the regulatory role of the non-canonical NF-ĸB transcription factor RelB in lymphomagenesis. To this end, we crossed mice expressing a constitutively active CD40 receptor in B cells with conditional RelB-KO mice. Ablation of RelB attenuated pre-malignant B cell expansion, and resulted in an impaired survival and activation of long-term CD40-stimulated B cells. Furthermore, we found that hyperactivation of non-canonical NF-кB signaling enhances the retention of B cells in the follicles of secondary lymphoid organs. RNA-Seq-analysis revealed that several genes involved in B-cell migration, survival, proliferation and cytokine signaling govern the transcriptional differences modulated by the ablation of RelB in long-term CD40-stimulated B cells. Inactivation of RelB did not abrogate lymphoma development. However, lymphomas occurred with a lower incidence and had a longer latency period. In summary, our data suggest that RelB, although it is not strictly required for malignant transformation, accelerates the lymphomagenesis of long-term CD40-stimulated B cells by regulating genes involved in migration, survival and cytokine signaling.

Immunosuppression Profile of CFZ533 (Iscalimab), a Non-Depleting Anti-CD40 Antibody, and the Presence of Opportunistic Infections in a Rhesus Monkey Toxicology Study

CFZ533 (iscalimab) is a nondepleting anti-CD40 antibody intended for inhibition of transplant organ rejection and treatment of autoimmune diseases. In a safety assessment in rhesus monkeys, CFZ533 was administered for 13 weeks up to 150 mg/kg/week subcutaneously. CFZ533 was shown previously to completely inhibit primary and secondary T-cell-dependent antibody responses. CD40 is expressed on B cells, antigen-presenting cells, and endothelial and epithelial cells, but is not expressed on T cells. Here, we demonstrate the complete suppression of germinal center formation in lymphoid organs. CFZ533 was well tolerated and did not cause any dose-limiting toxicity. However, the histological evaluation revealed increased numbers of CD4⁺ and CD8⁺ T cells in the T-cell-rich areas of lymph nodes enlarged in response to observed adenovirus and Cryptosporidium infections which suggest that T-cell immune function was unaffected. Background infections appear as the condition leading to unraveling the differential immunosuppressive effects by CFZ533. The presence of T cells at lymph nodes draining sites of infections corroborates the immunosuppressive mechanism, which is different from calcineurin-inhibiting drugs. Furthermore, CFZ533 did not show any hematological or microscopic evidence of thromboembolic events in rhesus monkeys, which were previously shown to respond with thromboembolism to treatment with anti-CD154 antibodies.

B-cell maturation antigen targeting strategies in multiple myeloma treatment, advantages and disadvantages

B cell maturation antigen (BCMA), a transmembrane glycoprotein member of the tumor necrosis factor receptor superfamily 17 (TNFRSF17), highly expressed on the plasma cells of Multiple myeloma (MM) patients, as well as the normal population. BCMA is used as a biomarker for MM. Two members of the TNF superfamily proteins, including B-cell activating factor (BAFF) and A proliferation-inducing ligand (APRIL), are closely related to BCMA and play an important role in plasma cell survival and progression of MM. Despite the maximum specificity of the monoclonal antibody technologies, introducing the tumor-specific antigen(s) is not applicable for all malignancies, such as MM that there plenty of relatively specific antigens such as GPCR5D, MUC1, SLAMF7 and etc., but higher expression of BCMA on these cells in comparison with normal ones can be regarded as a relatively exclusive marker. Currently, different monoclonal antibody (mAb) technologies applied in anti-MM therapies such as daratuzumab, SAR650984, GSK2857916, and CAR-T cell therapies are some of these tools that are reviewed in the present manuscript. By the way, the structure, function, and signaling of the BCMA and related molecule(s) role in normal plasma cells and MM development, evaluated as well as the potential side effects of its targeting by different CAR-T cells generations. In conclusion, BCMA can be regarded as an ideal molecule to be targeted in immunotherapeutic methods, regarding lower potential systemic and local side effects.

Bursty gene expression and mRNA decay pathways orchestrate B cell activation

It is well established that the helix-loop-helix proteins, E2A and E2-2, promote B cell activation. Here, we examined how during the course of B cell activation E2A and E2-2 gene expression is regulated. We found that E2A and E2-2 mRNA abundance concomitantly increased in activated B cells. The increase in E2A and E2-2 mRNA abundance correlated with increased cell growth. Elevated E2A and E2-2 mRNA abundance was instructed by increased transcriptional bursting frequencies and elevated E2A and E2-2 mRNA half-lives. The increase in E2A and E2-2 bursting frequencies often occurred at shared interchromosomal transcriptional hubs. We suggest that in naïve B cells low E2A and E2-2 bursting frequencies and high E2A and E2-2 mRNA decay rates instruct noisy gene expression that allows a clonal and swift response to invading pathogens whereas in activated B cells increased transcriptional bursting and low mRNA decay rates dictate an activated B lineage gene program.

The Role of Coinfections in the EBV-Host Broken Equilibrium

The Epstein–Barr virus (EBV) is a well-adapted human virus, and its infection is exclusive to our species, generally beginning in the childhood and then persisting throughout the life of most of the affected adults. Although this infection generally remains asymptomatic, EBV can trigger life-threatening conditions under unclear circumstances. The EBV lifecycle is characterized by interactions with other viruses or bacteria, which increases the probability of awakening its pathobiont capacity. For instance, EBV infects B cells with the potential to alter the germinal center reaction (GCR)—an adaptive immune structure wherein mutagenic-driven processes take place. HIV- and Plasmodium falciparum-induced B cell hyperactivation also feeds the GCR. These agents, along with the B cell tropic KSHV, converge in the ontogeny of germinal center (GC) or post-GC lymphomas. EBV oral transmission facilitates interactions with local bacteria and HPV, thereby increasing the risk of periodontal diseases and head and neck carcinomas. It is less clear as to how EBV is localized in the stomach, but together with Helicobacter pylori, they are known to be responsible for gastric cancer. Perhaps this mechanism is reminiscent of the local inflammation that attracts different herpesviruses and enhances graft damage and chances of rejection in transplanted patients. In this review, we discussed the existing evidence suggestive of EBV possessing the potential to synergize or cooperate with these agents to trigger or worsen the disease.

Berberine Delays Onset of Collagen-Induced Arthritis through T Cell Suppression

There is evidence that berberine (BBR), a clinically relevant plant compound, ameliorates clinically apparent collagen-induced arthritis (CIA) in vivo. However, to date, there are no studies involving the use of BBR which explore its prophylactic potential in this model of rheumatoid arthritis (RA). The aim of this study was to determine if prophylactic BBR use during the preclinical phase of collagen-induced arthritis would delay arthritic symptom onset, and to characterize the cellular mechanism underlying such an effect. DBA/1J mice were injected with an emulsion of bovine type II collagen (CII) and complete Freund’s adjuvant (day 0) and a booster injection of CII in incomplete Freund’s adjuvant (day 18) to induce arthritis. Mice were then given i.p. injections of 1 mg/kg/day of BBR or PBS (vehicle with 0.01% DMSO) from days 0 to 28, were left untreated (CIA control), or were in a non-arthritic control group (n = 15 per group). Incidence of arthritis in BBR-treated mice was 50%, compared to 90% in both the CIA and PBS controls. Populations of B and T cells from the spleens and draining lymph nodes of mice were examined on day 14 (n = 5 per group) and day 28 (n = 10 per group). BBR-treated mice had significantly reduced populations of CD4⁺T_h and CD4⁺CXCR5⁺ T_fh cells, and an increased proportion of Foxp3⁺ T_reg at days 14 and 28, as well as reduced expression of co-stimulatory molecules CD28 and CD154 at both endpoints. The effect seen on T cell populations and co-stimulatory molecule expression in BBR-treated mice was not mirrored in CD19⁺ B cells. Additionally, BBR-treated mice experienced reduced anti-CII IgG2a and anti-CII total IgG serum concentrations. These results indicate a potential role for BBR as a prophylactic supplement for RA, and that its effect may be mediated specifically through T cell suppression. However, the cellular effector involved raises concern for BBR prophylactic use in the context of vaccine efficacy and other primary adaptive immune responses.

Injection of CD40 DNA vaccine ameliorates the autoimmune pathology of non-obese diabetic mice with Sjögren's syndrome

BACKGROUND

Overexpression of CD40 has been reported in patients with primary Sjögren's syndrome (pSS). The increased CD40 expression promote autoimmune response and enhance inflammation in pSS. The aim of this study is to block CD40-CD154 interaction with CD40 DNA vaccine to slow the disease progression of SS in non-obese diabetic (NOD) mice.

METHODS

Female NOD mice were treated with CD40 DNA vaccine, empty vector and normal saline. The salivary flow rate was measured, whereas lymphocytes infiltration in the salivary glands was assessed by histopathology. Expression of CD40 and B220 in salivary were examined by immunohistochemistry. Splenic lymphocyte phenotypes were analyzed by flow cytometry. CD40, IL-1β, TNF-α and IL-6 levels in the salivary glands were detected by PCR. Serum anti-CD40 antibody was measured by ELISA. Serum anti-nuclear antibody (ANA) was monitored by immunofluorescence.

RESULTS

NOD mice treated with CD40 DNA vaccine showed higher levels of anti-CD40 antibody compared with the controls. The expression of CD40 in the salivary glands of NOD mice in CD40 DNA vaccine group was decreased. The infiltration of lymphocytes was reduced in the salivary glands and saliva secretion was increased in the treatment group. The expression level of TNF-α and IL-6 in salivary glands were declined. The splenic dendritic cell and plasma cell populations were reduced and the level of ANA was decreased in NOD mice with CD40 DNA vaccine treatment.

CONCLUSIONS

CD40 DNA vaccine inhibits the immune response and reduce inflammation in epithelial tissues SS in non-obese diabetic (NOD) mice, suggesting that CD40 DNA vaccine could be a new therapeutic approach in treatment of pSS.

A Highly Immunogenic, Protective, and Safe Adenovirus-Based Vaccine Expressing Middle East Respiratory Syndrome Coronavirus S1-CD40L Fusion Protein in a Transgenic Human Dipeptidyl Peptidase 4 Mouse Model

Background

Infection control measures have played a major role in limiting human/camel-to-human transmission of Middle East respiratory syndrome coronavirus (MERS-CoV); however, development of effective and safe human or camel vaccines is warranted.

Methods

We extended and optimized our previous recombinant adenovirus 5 (rAd5)–based vaccine platform characterized by in vivo amplified and CD40-mediated specific responses to generate MERS-CoV S1 subunit-based vaccine. We generated rAd5 constructs expressing CD40-targeted S1 fusion protein (rAd5-S1/F/CD40L), untargeted S1 (rAd5-S1), and Green Fluorescent Protein (rAd5-GFP), and evaluated their efficacy and safety in human dipeptidyl peptidase 4 transgenic (hDPP4 Tg⁺) mice.

Results

Immunization of hDPP4 Tg⁺ mice with a single dose of rAd5-S1/F/CD40L elicited as robust and significant specific immunoglobulin G and neutralizing antibodies as those induced with 2 doses of rAd5-S1. After MERS-CoV challenge, both vaccines conferred complete protection against morbidity and mortality, as evidenced by significantly undetectable/reduced pulmonary viral loads compared to the control group. However, rAd5-S1– but not rAd5-S1/F/CD40L–immunized mice exhibited marked pulmonary perivascular hemorrhage post–MERS-CoV challenge despite the observed protection.

Conclusions

Incorporation of CD40L into rAd5-based MERS-CoV S1 vaccine targeting molecule and molecular adjuvants not only enhances immunogenicity and efficacy but also prevents inadvertent pulmonary pathology after viral challenge, thereby offering a promising strategy to enhance safety and potency of vaccines.

Membrane IgM+ plasma cells in grass carp (Ctenopharyngodon idella): Insights into the conserved evolution of IgM+ plasma cells in vertebrates

Teleost fish are the most primitive bony vertebrates that contain B cells; thus, comparative analysis of teleost naïve/mature B cells and plasma cells can provide helpful evidence for understanding the evolution paradigms of these two B-cell subpopulations in vertebrates. In this study, we developed monoclonal antibody against grass carp IgM and identified two different IgM⁺ cell subsets: IgM⁺ lymphocytes (Lym), resembling naïve/mature B cells, and IgM⁺ myeloid cells (Mye), resembling plasma cells. Like plasma cells in mammals, the size of IgM⁺ Mye is significantly larger than that of IgM⁺ Lym, as revealed by flow cytometric analysis and transmission electron microscopy. The IgM⁺ Mye were further verified as plasma cells because they showed gene expression patterns similar with those of human plasma cells and a great capacity to secrete IgM. Like mammalian IgM⁺ and IgA⁺ plasma cells, not IgG⁺ plasma cells, grass carp IgM⁺ Mye also expressed membrane immunoglobulins, a feature conserved in IgM⁺ plasma cells in vertebrates. Furthermore, recombinant CD40L or IL-21 alone could induce the plasma cell generation and IgM secretion, while the combination of CD40L and IL-21 had greater effect on IgM secretion, but not on plasma cell generation. This study fills an important gap in the knowledge of plasma cells in teleost fish and provides critical insights into the conserved evolution of IgM⁺ plasma cells in vertebrates.

Regulatory T cells in patients with early untreated rheumatoid arthritis: Phenotypic changes in the course of methotrexate treatment

Rheumatoid arthritis (RA) is frequent systemic autoimmune disease characterized by excessive activation of collagen-specific T helper cells, and elevated level of autoantibodies in the serum. Development of RA is associated with defect in compartment of regulatory CD4+Foxp3+ T cells (Treg), but data concerning suppressive potential of Treg population in RA patients are contradictory and depend on the stage of disease. In this study we aimed to characterize abundance and phenotypic markers of CD4+Foxp3+ Treg in peripheral blood of healthy donors compared to untreated early RA patients to find potential correlations with the disease activity, antibody level, and absolute numbers and proportion of different subpopulations of T cells. Moreover, we assessed the influence of methotrexate (MT) treatment on percentage and absolute numbers of CD4+Foxp3+ Treg from the peripheral blood of untreated early RA patients. We demonstrate that increase and phenotypic changes in Treg population correlate well with response to MT. Analysis of the cohorts of matched RA patients (n = 45) and healthy controls (n = 20) revealed that patients with untreated early RA demonstrate substantial decrease in blood Treg percentage and absolute number, as well as low level of activated Treg surface markers in comparison to healthy control. The defect in Treg compartment negatively correlates with both RA activity and antibody level. MT treatment of patients with early untreated RA increases both proportion and absolute number of Treg with high level of activation markers, suggesting an increase of their functional capacity. Here we speculate the role of Tregs as specific cellular marker of successful RA treatment.

Optimizing TNFR2 antagonism for immunotherapy with tumor microenvironment specificity

Most approved cancer immunotherapies lack T-regulatory (Treg) or tumor specificity. TNF receptor 2 (TNFR2) antibody antagonism is emerging as an attractive immunotherapy due to its tumor microenvironment (TME) specificity. Here we show that the human TNFR2 receptor is overexpressed on both human tumor cells and on human tumor-residing Tregs, but negligibly expressed on beneficial T effectors (Teffs). Further, we found widespread, if variable, TNFR2 expression on 788 human tumor cell lines from diverse cancer tissues. These findings provided strong rationale for developing a targeted immunotherapy using a TNFR2 antibody antagonist. We designed a novel, human-directed TNFR2 antibody antagonist and tested it for function using three cell-based TME assays. The antagonist showed TME specificity by killing of TNFR2-expressing tumor cells and Tregs, but sparing Teffs, which proliferated. However, the antagonist shuffled between five isoforms, only one of which showed the desirable function. We designed and tested several new chimeric human versions of the antagonist, finding that the IgG2 isotype functioned better than the IgG1 isotype. To further improve function, we introduced targeted mutations to its amino acid sequence to stabilize the natural variability of the IgG2 isotype's hinge. Altogether, our findings suggest that optimal TNFR2 antagonists are of the human IgG2 isotype, have hinge stabilization, and have wide separation of antibody arms to bind to newly synthesized TNFR2 on rapidly growing tumor cells. Antagonistic antibodies with these characteristics, when bound to TNFR2, can form a nonsignaling cell surface dimer that functions with high TME specificity.

Expression of CD40L by the ALVAC-Simian Immunodeficiency Virus Vector Abrogates T Cell Responses in Macaques

Immunization with recombinant ALVAC/gp120 alum vaccine provided modest protection from human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) acquisition in humans and macaques. Vaccine-mediated protection was associated with the elicitation of IgG against the envelope V2 loop and of envelope-specific CD4+ T cell responses. We hypothesized that the simultaneous expression of the costimulatory molecule CD40L (CD154) by the ALVAC-HIV vector could increase both protective humoral and cellular responses. We engineered an ALVAC-SIV coexpressing CD40L with SIVmac251 (ALVAC-SIV/CD40L) gag, pol, and env genes. We compared its immunogenicity in macaques with that of a canonical ALVAC-SIV, with both given as a vector-prime/gp120 in alum boost strategy. The ALVAC-SIV/CD40L was superior to the ALVAC-SIV regimen in inducing binding and tier 1 neutralizing antibodies against the gp120. The increase in humoral responses was associated with the expression of the membrane-bound form of the CD40L by CD4+ T cells in lymph nodes. Unexpectedly, the ALVAC-SIV/CD40L vector had a blunting effect on CD4+ Th1 helper responses and instead favored the induction of myeloid-derived suppressor cells, the immune-suppressive interleukin-10 (IL-10) cytokine, and the down-modulatory tryptophan catabolism. Ultimately, this strategy failed to protect macaques from SIV acquisition. Taken together, these results underlie the importance of balanced vaccine-induced activating versus suppressive immune responses in affording protection from HIV.IMPORTANCE CD40-CD40 ligand (CD40L) interaction is crucial for inducing effective cytotoxic and humoral responses against pathogens. Because of its immunomodulatory function, CD40L has been used to enhance immune responses to vaccines, including candidate vaccines for HIV. The only successful vaccine ever tested in humans utilized a strategy combining canarypox virus-based vector (ALVAC) together with an envelope protein (gp120) adjuvanted in alum. This strategy showed limited efficacy in preventing HIV-1/SIV acquisition in humans and macaques. In both species, protection was associated with vaccine-induced antibodies against the HIV envelope and CD4+ T cell responses, including type 1 antiviral responses. In this study, we tested whether augmenting CD40L expression by coexpressing it with the ALVAC vector could increase the protective immune responses. Although coexpression of CD40L did increase humoral responses, it blunted type 1 CD4+ T cell responses against the SIV envelope protein and failed to protect macaques from viral infection.

B cell checkpoints in autoimmune rheumatic diseases

B cells have important functions in the pathogenesis of autoimmune diseases, including autoimmune rheumatic diseases. In addition to producing autoantibodies, B cells contribute to autoimmunity by serving as professional antigen-presenting cells (APCs), producing cytokines, and through additional mechanisms. B cell activation and effector functions are regulated by immune checkpoints, including both activating and inhibitory checkpoint receptors that contribute to the regulation of B cell tolerance, activation, antigen presentation, T cell help, class switching, antibody production and cytokine production. The various activating checkpoint receptors include B cell activating receptors that engage with cognate receptors on T cells or other cells, as well as Toll-like receptors that can provide dual stimulation to B cells via co-engagement with the B cell receptor. Furthermore, various inhibitory checkpoint receptors, including B cell inhibitory receptors, have important functions in regulating B cell development, activation and effector functions. Therapeutically targeting B cell checkpoints represents a promising strategy for the treatment of a variety of autoimmune rheumatic diseases.

Decreased mRNA Expressions of CD40L in Patients with Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease that preferentially affects central nerve system. Herein, we evaluated changes of CD40L and CD40 mRNA expressions in NMOSD and controls to explore their potential roles in development of NMOSD. The expressions of CD40L and CD40 mRNA in peripheral blood mononuclear cells (PBMCs) from patients with NMOSD and healthy controls were detected by quantitative real-time PCR (qPCR). Kruskal-Wallis tests were used to compare expression levels of CD40L and CD40 mRNA between groups, and Spearman correlation analysis was performed to evaluate correlation between mRNA expression levels and annual relapse rate (ARR) of NMOSD. A total of 71 patients with NMOSD and 42 gender- and age-matched healthy volunteers were recruited in our study. Compared with healthy controls, expression of CD40L mRNA was significantly decreased in untreated patients with NMOSD, and similar trends were observed also in CD40 mRNA expression although the difference was not significant. Other than that, immunosuppressants not only successfully increased CD40L and CD40 mRNA levels during remission of NMOSD, but also corrected the negative correlation between CD40L mRNA expression and annual relapse rate (ARR) of patients NMOSD. These results favored the long-term prognosis of NMOSD patients. Our results suggest that decreased expressions of CD40L mRNA may be involved in developing of NMOSD and the proper CD40L mRNA levels benefit to prevent attacks of NMOSD. Nevertheless, the relationship between protein and mRNA expressions of CD40L and their underlying roles in the pathogenesis of NMOSD remains to be further studied.

Targeting the CD40-CD154 Signaling Pathway for Treatment of Autoimmune Arthritis

Full activation of T lymphocytes requires signals from both T cell receptors and costimulatory molecules. In addition to CD28, several T cell molecules could deliver costimulatory signals, including CD154, which primarily interacts with CD40 on B-cells. CD40 is a critical molecule regulating several B-cell functions, such as antibody production, germinal center formation and cellular proliferation. Upregulated expression of CD40 and CD154 occurs in immune effector cells and non-immune cells in different autoimmune diseases. In addition, therapeutic benefits have been observed by blocking the CD40-CD154 interaction in animals with collagen-induced arthritis. Given the therapeutic success of the biologics abatacept, which blocks CD28 costimulation, and rituximab, which deletes B cells in the treatment of autoimmune arthritis, the inhibition of the CD40-CD154 axis has two advantages, namely, attenuating CD154-mediated T cell costimulation and suppressing CD40-mediated B-cell stimulation. Furthermore, blockade of the CD40-CD154 interaction drives the conversion of CD4+ T cells to regulatory T cells that mediate immunosuppression. Currently, several biological products targeting the CD40-CD154 axis have been developed and are undergoing early phase clinical trials with encouraging success in several autoimmune disorders, including autoimmune arthritis. This review addresses the roles of the CD40-CD154 axis in the pathogenesis of autoimmune arthritis and its potential as a therapeutic target.

OMIP-060: 30-Parameter Flow Cytometry Panel to Assess T Cell Effector Functions and Regulatory T Cells

We developed this comprehensive 28-color flow cytometry panel with the aim to measure a variety of T cell effector functions in combination with T cell differentiation markers (CCR7, CD27, CD28, CD45RO, CD95) in γδ T cells and CD4⁺ and CD8⁺ αβ T cells (Table 1). The effector functions measured in this panel include activation and co-stimulatory molecules (CD69, CD137, and CD154), cytokines (IL-2, IL-13, IL-17A, IL-21, IL-22, TNF, and IFNγ), the chemokine IL-8, cytotoxic molecules (perforin and granzyme B), and the degranulation marker CD107a. In addition, Ki67 enables the identification and analysis of recently activated T cells. To characterize regulatory T cells (T_regs ), we included CD25, CD39, and the canonical T_regs transcription factor FoxP3. We developed and optimized this panel for cryopreserved human peripheral blood mononuclear cells (PBMC) and stimulation with phorbol 12-myristate 13-acetate (PMA) and ionomycin. However, we successfully tested other types of stimulation such as staphylococcus enterotoxin B (SEB) or a mix of immunodominant peptides (CEF peptide pool) from cytomegalovirus (CMV), Epstein-Barr virus (EBV) and influenza. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

Targeting CD40 enhances antibody- and CD8-mediated protection against respiratory syncytial virus infection

Respiratory Syncytial Virus (RSV) infects almost all children under the age of one and is the leading cause of hospitalization among infants. Despite several decades of research with dozens of candidate vaccines being vigorously evaluated in pre-clinical and clinical studies, there is no licensed vaccine available to date. Here, the RSV fusion protein (F) was fused with CD40 ligand and delivered by an adenoviral vector into BALB/c mice where the CD40 ligand serves two vital functions as a molecular adjuvant and an antigen-targeting molecule. In contrast to a formaldehyde-inactivated vaccine, the vectored vaccine effectively protected animals against RSV without inducing enhanced respiratory disease. This protection involved a robust induction of neutralizing antibodies and memory CD8 T cells, which were not observed in the inactivated vaccine group. Finally, the vectored vaccine was able to elicit long-lasting protection against RSV, one of the most challenging issues in RSV vaccine development. Further studies indicate that the long lasting protection elicited by the CD40 ligand targeted vaccine was mediated by increased levels of effector memory CD8 T cell 3 months post-vaccination.

Nonclinical Safety Assessment of CFZ533, a Fc-Silent Anti-CD40 Antibody, in Cynomolgus Monkeys

CFZ533 is a pathway blocking, nondepleting anti-CD40 antibody that is in clinical development for inhibition of transplant organ rejection and therapy for autoimmune diseases. A 26-week GLP toxicity study in sexually mature Cynomolgus monkeys was conducted in order to support chronic application of CFZ533. CFZ533 was subcutaneously administered at doses up to 150 mg/kg/week and was safe and generally well tolerated. CFZ533 showed no adverse effects for cardiovascular, respiratory, and neurobehavioral endpoints, and no changes were observed for blood lymphocyte and platelet counts or blood coagulation markers. In line with the nondepleting nature of CFZ533, CD20+ B cells in the blood were only marginally reduced. A complete suppression of germinal center (GC) development in lymph nodes and spleen was the most prominent result of post-mortem histological investigations. This was corroborated by an abrogated T-dependent antibody response (TDAR) to the antigen Keyhole Limpet Hemocyanin (KLH) as well as an absence of anti-drug antibodies (ADAs) in the absence of B cell depletion as seen with immunophenotyping and histology. When serum levels of CFZ533 in recovery animals dropped levels necessary for full CD40 occupancy on B cells, all animals were able to mount a TDAR to KLH. All histological changes also reverted to normal appearance after recovery. In summary, CFZ533 was shown to be well tolerated and safe in the 26-week toxicity study with a distinct pharmacodynamic profile in histology and immune function.

The Tumor Necrosis Factor Family: Family Conventions and Private Idiosyncrasies

The tumor necrosis factor (TNF) cytokine family and the TNF/nerve growth factor (NGF) family of their cognate receptors together control numerous immune functions, as well as tissue-homeostatic and embryonic-development processes. These diverse functions are dictated by both shared and distinct features of family members, and by interactions of some members with nonfamily ligands and coreceptors. The spectra of their activities are further expanded by the occurrence of the ligands and receptors in both membrane-anchored and soluble forms, by "re-anchoring" of soluble forms to extracellular matrix components, and by signaling initiation via intracellular domains (IDs) of both receptors and ligands. Much has been learned about shared features of the receptors as well as of the ligands; however, we still have only limited knowledge of the mechanistic basis for their functional heterogeneity and for the differences between their functions and those of similarly acting cytokines of other families.

TRAF3 as a Multifaceted Regulator of B Lymphocyte Survival and Activation

The adaptor protein TNF receptor-associated factor 3 (TRAF3) serves as a powerful negative regulator in multiple aspects of B cell biology. Early in vitro studies in transformed cell lines suggested the potential of TRAF3 to inhibit signaling by its first identified binding receptor, CD40. However, because the canonical TRAF3 binding site on many receptors also mediates binding of other TRAFs, and whole-mouse TRAF3 deficiency is neonatally lethal, an accurate understanding of TRAF3's specific functions was delayed until conditional TRAF3-deficient mice were produced. Studies of B cell-specific TRAF3-deficient mice, complemented by investigations in normal and malignant mouse and human B cells, reveal that TRAF3 has powerful regulatory roles that are unique to this TRAF, as well as functions context-specific to the B cell. This review summarizes the current state of knowledge of these roles and functions. These include inhibition of signaling by plasma membrane receptors, negative regulation of intracellular receptors, and restraint of cytoplasmic NF- κB pathways. TRAF3 is also now known to function as a resident nuclear protein, and to impact B cell metabolism. Through these and additional mechanisms TRAF3 exerts powerful restraint upon B cell survival and activation. It is thus perhaps not surprising that TRAF3 has been revealed as an important tumor suppressor in B cells. The many and varied functions of TRAF3 in B cells, and new directions to pursue in future studies, are summarized and discussed here.

B lymphocytes can be activated to act as antigen presenting cells to promote anti-tumor responses

Immune evasion by tumors includes several different mechanisms, including the inefficiency of antigen presenting cells (APCs) to trigger anti-tumor T cell responses. B lymphocytes may display a pro-tumoral role but can also be modulated to function as antigen presenting cells to T lymphocytes, capable of triggering anti-cancer immune responses. While dendritic cells, DCs, are the best APC population to activate naive T cells, DCs or their precursors, monocytes, are frequently modulated by tumors, displaying a tolerogenic phenotype in cancer patients. In patients with cervical cancer, we observed that monocyte derived DCs are tolerogenic, inhibiting allogeneic T cell activation compared to the same population obtained from patients with precursor lesions or cervicitis. In this work, we show that B lymphocytes from cervical cancer patients respond to treatment with sCD40L and IL-4 by increasing the CD80+CD86+ population, therefore potentially increasing their ability to activate T cells. To test if B lymphocytes could actually trigger anti-tumor T cell responses, we designed an experimental model where we harvested T and B lymphocytes, or dendritic cells, from tumor bearing donors, and after APC stimulation, transplanted them, together with T cells into RAG1-/- recipients, previously injected with tumor cells. We were able to show that anti-CD40 activated B lymphocytes could trigger secondary T cell responses, dependent on MHC-II expression. Moreover, we showed that dendritic cells were resistant to the anti-CD40 treatment and unable to stimulate anti-tumor responses. In summary, our results suggest that B lymphocytes may be used as a tool for immunotherapy against cancer.

Toward Small-Molecule Inhibition of Protein-Protein Interactions: General Aspects and Recent Progress in Targeting Costimulatory and Coinhibitory (Immune Checkpoint) Interactions

Protein-Protein Interactions (PPIs) that are part of the costimulatory and coinhibitory (immune checkpoint) signaling are critical for adequate T cell response and are important therapeutic targets for immunomodulation. Biologics targeting them have already achieved considerable clinical success in the treatment of autoimmune diseases or transplant recipients (e.g., abatacept, belatacept, and belimumab) as well as cancer (e.g., ipilimumab, nivolumab, pembrolizumab, atezolizumab, durvalumab, and avelumab). In view of such progress, there have been only relatively limited efforts toward developing small-molecule PPI inhibitors (SMPPIIs) targeting these cosignaling interactions, possibly because they, as all other PPIs, are difficult to target by small molecules and were not considered druggable. Nevertheless, substantial progress has been achieved during the last decade. SMPPIIs proving the feasibility of such approaches have been identified through various strategies for a number of cosignaling interactions including CD40-CD40L, OX40-OX40L, BAFFR-BAFF, CD80-CD28, and PD-1-PD-L1s. Here, after an overview of the general aspects and challenges of SMPPII-focused drug discovery, we review them briefly together with relevant structural, immune-signaling, physicochemical, and medicinal chemistry aspects. While so far only a few of these SMPPIIs have shown activity in animal models (DRI-C21045 for CD40-D40L, KR33426 for BAFFR-BAFF) or reached clinical development (RhuDex for CD80-CD28, CA-170 for PD-1-PD-L1), there is proof-of-principle evidence for the feasibility of such approaches in immunomodulation. They can result in products that are easier to develop/ manufacture and are less likely to be immunogenic or encounter postmarket safety events than corresponding biologics, and, contrary to them, can even become orally bioavailable.

Association Between Inflammatory Diet Pattern and Risk of Colorectal Carcinoma Subtypes Classified by Immune Responses to Tumor

BACKGROUND & AIMS

Dietary patterns affect systemic and local intestinal inflammation, which have been linked to colorectal carcinogenesis. Chronic inflammation can interfere with the adaptive immune response. We investigated whether the association of a diet that promotes intestinal inflammation with risk of colorectal carcinoma was stronger for tumors with lower lymphocytic reactions than tumors with higher lymphocytic reactions.

METHODS

We collected data from the molecular pathological epidemiology databases of 2 prospective cohort studies: the Nurses' Health Study (since 1976) and the Health Professionals Follow-Up Study (since 1986). We used duplication-method time-varying Cox proportional cause-specific hazards regression to assess the association of empirical dietary inflammatory pattern (EDIP) score (derived from food frequency questionnaire data) with colorectal carcinoma subtype. Foods that contribute to high EDIP scores include red and processed meats, refined grains, carbonated beverages, and some vegetables; foods that contribute to low EDIP scores include beer, wine, coffee, tea, yellow and leafy vegetables, and fruit juice. Colorectal tissue samples were analyzed histologically for patterns of lymphocytic reactions (Crohn's-like lymphoid reaction, peritumoral lymphocytic reaction, intratumoral periglandular reaction, and tumor-infiltrating lymphocytes).

RESULTS

During follow-up of 124,433 participants, we documented 1311 incident colon and rectal cancer cases with available tissue data. The association between the EDIP and colorectal cancer risk was significant (Ptrend = .02), and varied with degree of peritumoral lymphocytic reaction (Pheterogeneity < .001). Higher EDIP scores were associated with increased risk of colorectal cancer with an absent or low peritumoral lymphocytic reaction (highest vs lowest EDIP score quintile hazard ratio, 2.60; 95% confidence interval, 1.60-4.23; Ptrend < .001), but not risk of tumors with intermediate or high peritumoral lymphocytic reaction (Ptrend > .80).

CONCLUSIONS

In 2 prospective cohort studies, we associated inflammatory diets with a higher risk of colorectal cancer subtype that contains little or no peritumoral lymphocytic reaction. These findings suggest that diet-related inflammation might contribute to development of colorectal cancer, by suppressing the adaptive anti-tumor immune response.

Expression, purification, and functional analysis of an antigen-targeting fusion protein composed of CD40 ligand and the C-terminal fragment of ovalbumin

Delivering antigen via molecules specifically targeting receptors on the surface of antigen-presenting cells is a strategy to improve immune responses. In this study, an antigen-targeting fusion protein (OVA-CD40LS) composed of the C-terminal fragment of ovalbumin and the extracellular domain of mouse CD40 ligand was constructed by genetic fusion. The OVA-CD40LS and the control OVA (rOVA) genes were cloned in Escherichia coli and over-expressed as insoluble proteins. The rOVA protein was purified from the insoluble fraction of E. coli cell lysate by nickel affinity chromatography and refolded by step-wise dialysis to give a yield of 11.8 mg/L of culture. The OVA-CD40LS was purified by a 'two-round' nickel affinity and on-column protein-refolding chromatography. The yield was 528 μg/L of culture. The purified OVA-CD40LS, but not the rOVA, was able to simulate the production of pro-inflammatory cytokines and up-regulate cell surface marker proteins in mouse bone marrow-derived dendritic cells. The purified OVA-CD40LS elicited a robust immune response when injected submucosally in the oral cavity of mice. Collectively, the results indicate that the OVA-CD40LS fusion protein was biologically active, functioning as an antigen-targeting protein.

Association between CD40 rs1883832 and immune-related diseases susceptibility: A meta-analysis

Background/objective

It has been reported that CD40 rs1883832 might be associated with immune-related diseases susceptibility. Owing to mixed and inconclusive results, we conducted a meta-analysis of case–control studies to summarize and clarify this association.

Methods/main results

A systematic search of studies on the association between CD40 rs1883832 and immune-related diseases susceptibility was conducted in databases. Odds ratios and 95% confidence intervals were used to pool the effect size. 40 articles were included in our meta-analysis.

Conclusions

CD40 rs1883832 is associated with decreased risk of Graves’ disease, especially in Asian; CD40 rs1883832 is associated with increased risk of multiple sclerosis; CD40 -1C>T (rs1883832) is not associated with the susceptibility of Hashimoto's thyroiditis, systemic sclerosis or Asthma; there is insufficient data to fully confirm the association between CD40 rs1883832 and systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), Behçet's disease (BD), myasthenia gravis (MG), Crohn's disease (CD), ulcerative colitis (UC), Sarcoidosis, Fuch uveitis syndrome (FUS), Vogt-Koyanagi-Harada syndrome (VKH), Kawasaki disease (KD), giant cell arteritis (GCA) or Immune thrombocytopenia (ITP).

IL-21/anti-Tim1/CD40 ligand promotes B10 activity in vitro and alleviates bone loss in experimental periodontitis in vivo

IL-10-expressing regulatory B cells (B10) play an essential role in immune system balance by suppressing excessive inflammatory responses. In this study, we investigated induction of B 10 cell's IL-10 competency in vitro and its effect on ligature-induced experimental periodontitis in vivo. Spleen B cells were isolated from C57BL/6J mice and cultured for 48h under the following conditions: control, CD40L, IL-21, anti-Tim1, CD40L+IL-21, CD40L+anti-Tim1, CD40L+IL-21+anti-Tim1. Silk ligatures were tied around both maxillary second molars of C57BL/6J mice for two weeks. Optimized combination of CD40L, IL-21 and anti-Tim1 and vehicle were injected into contralateral side of palatal gingiva on days 3, 6 and 9. The palatal gingival tissues and maxillary bone were collected on day 14 to determine expressions of IL-10 and periodontal bone resorption respectively. Our results demonstrated that IL-10 expressions of cultured spleen B cells were significantly increased in the presence of CD40L, IL-21 and anti-Tim1 combination when compared with control groups. Gingival IL-10 mRNA and protein expressions were significantly increased after injection of CD40L, IL-21 and anti-Tim1 combination, when compared to the control side. The gingival RANKL expression and periodontal bone loss were significantly decreased on the combination treatment side, as compared to the control side. These results suggest that combination of IL-21, anti-Tim1 and CD40L treatment induced B10 cell's IL-10 competency in vitro and inhibited periodontal bone loss in ligature-induced experimental periodontitis.

CD40 Signaling in Graves Disease Is Mediated Through Canonical and Noncanonical Thyroidal Nuclear Factor κB Activation

CD40, a tumor necrosis factor receptor, is a major immune-modulating susceptibility gene for Graves disease (GD) as well as for a variety of other autoimmune diseases. Its broad association with autoimmunity underscores its paramount role in the development of a normal adaptive immune response, primarily in coordinating effective antigen presentation. The molecular pathways by which CD40 activation in the thyroid induces GD are unknown. In this study, we investigated whether NF-κB, a ubiquitious family of transcription factors, mediates the downstream effects of thyroid-specific CD40 activation. Cultured primary human thyrocytes, from patients with and without GD, underwent CD40 stimulation. Once stimulated, cytokines and transcription factors specific for either the canonical nuclear factor κB (NF-κB)1 pathway [interleukin (IL)-6, IL-8, tumor necrosis factor (TNF)-α], which primarily recruits cells for innate immunity, or the noncanonical NF-κB2 pathway [B cell-activating factor of the TNF family, CC chemokine ligand (CCL)21], which directs B cell viability, were analyzed. Significant upregulation in the messenger RNA and protein levels of both canonical and noncanonical pathway cytokines was observed. Western blot analyses of the specific transcription factors for the NF-κB1 and NF-κB2 pathways (p65 and p100/p52, respectively) demonstrated that p65 is constitutively expressed. In contrast, CD40 stimulation robustly increased the expression of the NF-κB2 p52 transcription factor, and the upregulation was significantly more profound in the GD tissue than in the normal thyroid tissue. Our data show that CD40 activity in thyrocytes is prominently mediated via NF-κB and furthermore suggest that the NF-κB1 and NF-κB2 pathways both contribute to the triggering and the progression of GD.

Potassium Channel-blockers as Therapeutic Agents to Interfere with Bone Resorption of Periodontal Disease

Inflammatory lesions of periodontal disease contain all the cellular components, including abundant activated/memory T- and B-cells, necessary to control immunological interactive networks and to accelerate bone resorption by RANKL-dependent and -independent mechanisms. Blockade of RANKL function has been shown to ameliorate periodontal bone resorption and other osteopenic disorders without affecting inflammation. Development of therapies aimed at decreasing the expression of RANKL and pro-inflammatory cytokines by T-cells constitutes a promising strategy to ameliorate not only bone resorption, but also inflammation. Several reports have demonstrated that the potassium channels Kv1.3 and IKCa1, through the use of selective blockers, play important roles in T-cell-mediated events, including T-cell proliferation and the production of pro-inflammatory cytokines. More recently, a potassium channel-blocker for Kv1.3 has been shown to down-regulate bone resorption by decreasing the ratio of RANKL-to-OPG expression by memory-activated T-cells. In this article, we first summarize the mechanisms by which chronically activated/memory T-cells, in concert with B-cells and macrophages, trigger inflammatory bone resorption. Then, we describe the main structural and functional characteristics of potassium channels Kv1.3 and IKCa1 in some of the cells implicated in periodontal disease progression. Finally, this review elucidates some recent advances in the use of potassium channel-blockers of Kv1.3 and IKCa1 to ameliorate the clinical signs or side-effects of several immunological disorders and to decrease inflammatory bone resorption in periodontal disease. ABBREVIATIONS: AICD, activation-induced cell death; APC, antigen-presenting cells; B(K), large conductance; CRAC, calcium release-activated calcium channels; DC, dendritic cell; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IFN-γ, interferon-γ; IP3, inositol (1,4,5)-triphosphate; (K)ir, inward rectifier; JNK, c-Jun N-terminal kinase; I(K), intermediate conductance; LPS, lipopolysaccharide; L, ligand; MCSF, macrophage colony-stimulating factor; MHC, major histocompatibility complex; NFAT, nuclear factor of activated T-cells; RANK, receptor activator of nuclear factor-κB; TCM, central memory T-cells; TEM, effector memory T-cells; TNF, tumor necrosis factor; TRAIL, TNF-related apoptosis-inducing ligand; OPG, osteoprotegerin; Omp29, 29-kDa outer membrane protein; PKC, protein kinase C; PLC, phospholipase C; RT-PCR, reverse-transcriptase polymerase chain-reaction; S(K), small conductance; TCR, T-cell receptor; and (K)v, voltage-gated.

CD40-Mediated NF-κB Activation in B Cells Is Increased in Multiple Sclerosis and Modulated by Therapeutics

CD40 interacts with CD40L and plays an essential role in immune regulation and homeostasis. Recent research findings, however, support a pathogenic role of CD40 in a number of autoimmune diseases. We previously showed that memory B cells from relapsing-remitting multiple sclerosis (RRMS) patients exhibited enhanced proliferation with CD40 stimulation compared with healthy donors. In this study, we used a multiparameter phosflow approach to analyze the phosphorylation status of NF-κB and three major MAPKs (P38, ERK, and JNK), the essential components of signaling pathways downstream of CD40 engagement in B cells from MS patients. We found that memory and naive B cells from RRMS and secondary progressive MS patients exhibited a significantly elevated level of phosphorylated NF-κB (p-P65) following CD40 stimulation compared with healthy donor controls. Combination therapy with IFN-β-1a (Avonex) and mycophenolate mofetil (Cellcept) modulated the hyperphosphorylation of P65 in B cells of RRMS patients at levels similar to healthy donor controls. Lower disease activity after the combination therapy correlated with the reduced phosphorylation of P65 following CD40 stimulation in treated patients. Additionally, glatiramer acetate treatment also significantly reduced CD40-mediated P65 phosphorylation in RRMS patients, suggesting that reducing CD40-mediated p-P65 induction may be a general mechanism by which some current therapies modulate MS disease.

TRAF3 as a powerful and multitalented regulator of lymphocyte functions

This review summarizes the current state of knowledge regarding the roles of the signaling adapter protein tumor necrosis factor receptor (TNFR)-associated factor 3 in regulating the functions of B and T lymphocytes. In B lymphocytes, TNFR-associated factor 3 inhibits signaling by TNFR superfamily receptors, Toll-like receptors, and interleukin-6R. In contrast, signaling to B cells by the virally encoded oncogenic protein latent membrane protein 1 is promoted by TNFR-associated factor 3. An important B cell-specific role for TNFR-associated factor 3 is the inhibition of homeostatic survival, directly relevant to the common occurrence of TNFR-associated factor 3 mutations in human B cell malignancies. TNFR-associated factor 3 was recently found to be a resident nuclear protein in B cells, where it interacts with and inhibits gene expression mediated by the cAMP response element-binding protein transcription complex, including expression of the prosurvival protein myeloid leukemia cell differentiation protein 1. In T lymphocytes, TNFR-associated factor 3 is required for normal signaling by the T cell antigen receptor, while inhibiting signaling by the interleukin-2 receptor. Cytoplasmic TNFR -associated factor 3 restrains nuclear factor-κB2 activation in both T and B cells. Clinical implications and future directions for the study of this context-dependent signaling regulator are discussed.

Association of CD40 Gene Polymorphisms with Susceptibility to Neuromyelitis Optica Spectrum Disorders

The CD40 gene is associated with many autoimmune diseases; however, there are few studies in literatures that investigate the association between CD40 and neuromyelitis optica spectrum disorders (NMOSD). This study aimed to estimate the potential association of CD40 gene polymorphisms with susceptibility to NMOSD. Four SNPs (rs1883832, rs3765459, rs4810485, and rs6074022) were selected and genotyped in a Chinese cohort comprising 162 patients with NMOSD and 237 healthy controls. P values, odds ratios (ORs), and 95 % confidential intervals (CI) for four test models (allelic, additive, dominant, and recessive) were used to assess relationships between CD40 and NMOSD. Results showed that the rs3765459 variant was significantly associated with increased risk of NMOSD in allelic model (OR = 1.48, 95 % CI 1.10-1.98, P = 0.009, P ^corr = 0.037), and similar results were detected in the additive and recessive models (OR = 1.47, 95 % CI 1.09-1.97, P = 0.010, P ^corr = 0.042; OR = 2.12, 95 % CI 1.18-3.8, P = 0.012, P ^corr = 0.048, respectively). Other three SNPs showed protections on NMOSD in dominant models (rs6074022, OR = 0.64, 95 % CI 0.42-0.95, P = 0.031; rs1883832, OR = 0.65, 95 % CI 0.43-0.97, P = 0.036; and rs4810485, OR = 0.63, 95 % CI 0.42-0.95, P = 0.029, respectively), but not significantly after Bonferroni corrections for multiple tests. In addition, haplotype analysis of these SNPs in tight linkage did not reveal significant association with NMOSD. This study indicates that the rs3765459 variant in CD40 gene is associated with susceptibility to NMOSD. Larger sample size studies in other ethnicities are needed to verify this association.

TRAF3, ubiquitination, and B-lymphocyte regulation

The signaling adapter protein tumor necrosis factor receptor (TNFR)-associated factor 3 (TRAF3) is both modified by and contributes to several types of ubiquitination events. TRAF3 plays a variety of context-dependent regulatory roles in all types of immune cells. In B lymphocytes, TRAF3 contributes to regulation of signaling by members of both the TNFR superfamily and innate immune receptors. TRAF3 also plays a unique cell type-specific and critical role in the restraint of B-cell homeostatic survival, a role with important implications for both B-cell differentiation and the pathogenesis of B-cell malignancies. This review focuses upon the relationship between ubiquitin and TRAF3, and how this contributes to multiple functions of TRAF3 in the regulation of signal transduction, transcriptional activation, and effector functions of B lymphocytes.

Progress on adenovirus-vectored universal influenza vaccines

Influenza virus (IFV) infection causes serious health problems and heavy financial burdens each year worldwide. The classical inactivated influenza virus vaccine (IIVV) and live attenuated influenza vaccine (LAIV) must be updated regularly to match the new strains that evolve due to antigenic drift and antigenic shift. However, with the discovery of broadly neutralizing antibodies that recognize conserved antigens, and the CD8(+) T cell responses targeting viral internal proteins nucleoprotein (NP), matrix protein 1 (M1) and polymerase basic 1 (PB1), it is possible to develop a universal influenza vaccine based on the conserved hemagglutinin (HA) stem, NP, and matrix proteins. Recombinant adenovirus (rAd) is an ideal influenza vaccine vector because it has an ideal stability and safety profile, induces balanced humoral and cell-mediated immune responses due to activation of innate immunity, provides 'self-adjuvanting' activity, can mimic natural IFV infection, and confers seamless protection against mucosal pathogens. Moreover, this vector can be developed as a low-cost, rapid-response vaccine that can be quickly manufactured. Therefore, an adenovirus vector encoding conserved influenza antigens holds promise in the development of a universal influenza vaccine. This review will summarize the progress in adenovirus-vectored universal flu vaccines and discuss future novel approaches.

Chimeric Vaccine Stimulation of Human Dendritic Cell Indoleamine 2, 3-Dioxygenase Occurs via the Non-Canonical NF-κB Pathway

A chimeric protein vaccine composed of the cholera toxin B subunit fused to proinsulin (CTB-INS) was shown to suppress type 1 diabetes onset in NOD mice and upregulate biosynthesis of the tryptophan catabolic enzyme indoleamine 2, 3-dioxygenase (IDO1) in human dendritic cells (DCs). Here we demonstrate siRNA inhibition of the NF-κB-inducing kinase (NIK) suppresses vaccine-induced IDO1 biosynthesis as well as IKKα phosphorylation. Chromatin immunoprecipitation (ChIP) analysis of CTB-INS inoculated DCs showed that RelB bound to NF-κB consensus sequences in the IDO1 promoter, suggesting vaccine stimulation of the non-canonical NF-κB pathway activates IDO1 expression in vivo. The addition of Tumor Necrosis Factor Associated Factors (TRAF) TRAF 2, 3 and TRAF6 blocking peptides to vaccine inoculated DCs was shown to inhibit IDO1 biosynthesis. This experimental outcome suggests vaccine activation of the TNFR super-family receptor pathway leads to upregulation of IDO1 biosynthesis in CTB-INS inoculated dendritic cells. Together, our experimental data suggest the CTB-INS vaccine uses a TNFR-dependent signaling pathway of the non-canonical NF-κB signaling pathway resulting in suppression of dendritic cell mediated type 1 diabetes autoimmunity.

Immunogenetics of autoimmune thyroid diseases: A comprehensive review

Both environmental and genetic triggers factor into the etiology of autoimmune thyroid disease (AITD), including Graves' disease (GD) and Hashimoto's thyroiditis (HT). Although the exact pathogenesis and causative interaction between environment and genes are unknown, GD and HT share similar immune-mediated mechanisms of disease. They both are characterized by the production of thyroid autoantibodies and by thyroidal lymphocytic infiltration, despite being clinically distinct entities with thyrotoxicosis in GD and hypothyroidism in HT. Family and population studies confirm the strong genetic influence and inheritability in the development of AITD. AITD susceptibility genes can be categorized as either thyroid specific (Tg, TSHR) or immune-modulating (FOXP3, CD25, CD40, CTLA-4, HLA), with HLA-DR3 carrying the highest risk. Of the AITD susceptibility genes, FOXP3 and CD25 play critical roles in the establishment of peripheral tolerance while CD40, CTLA-4, and the HLA genes are pivotal for T lymphocyte activation and antigen presentation. Polymorphisms in these immune-modulating genes, in particular, significantly contribute to the predisposition for GD, HT and, unsurprisingly, other autoimmune diseases. Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in the immunoregulatory genes may functionally hinder the proper development of central and peripheral tolerance and alter T cell interactions with antigen presenting cells (APCs) in the immunological synapse. Thus, susceptibility genes for AITD contribute directly to the key mechanism underlying the development of organ-specific autoimmunity, namely the breakdown in self-tolerance. Here we review the major immune-modulating genes that are associated with AITD and their potential functional effects on thyroidal immune dysregulation.

In vitro and in vivo imaging of initial B-T-cell interactions in the setting of B-cell based cancer immunotherapy

There has been a growing interest in the use of B cells for cancer vaccines, since they have yielded promising results in preclinical animal models. Contrary to dendritic cells (DCs), we know little about the migration behavior of B cells in vivo. Therefore, we investigated the interactions between CD40-activated B (CD40B) cells and cytotoxic T cells in vitro and the migration behavior of CD40B cells in vivo. Dynamic interactions of human antigen-presenting cells (APCs) and T cells were observed by time-lapse video microscopy. The migratory and chemoattractant potential of CD40B cells was analyzed in vitro and in vivo using flow cytometry, standard transwell migration assays, and imaging of fluorescently labeled murine CD40B cells. Murine CD40B cells show migratory features similar to human CD40B cells. They express important lymph node homing receptors which were functional and induced chemotaxis of T cells in vitro. Striking differences were observed with regard to interactions of human APCs with T cells. CD40B cells differ from DCs by displaying a rapid migratory pattern undergoing highly dynamic, short-lived and sequential interactions with T cells. In vivo, CD40B cells are home to the secondary lymphoid organs where they accumulate in the B cell zone before traveling to the B/T cell boundary. Moreover, intravenous (i.v.) administration of murine CD40B cells induced an antigen-specific cytotoxic T cell response. Taken together, this data show that CD40B cells home secondary lymphoid organs where they physically interact with T cells to induce antigen-specific T cell responses, thus underscoring their potential as cellular adjuvant for cancer immunotherapy.

Involvement of the cytoplasmic cysteine-238 of CD40 in its up-regulation of CD23 expression and its enhancement of TLR4-triggered responses

CD40, a member of the tumor necrosis factor receptor superfamily, plays a key role in both adaptive and innate immunity. Engagement of CD40 with its natural trimeric ligand or with cross-linked antibodies results in disulfide-linked CD40 (dl-CD40) homodimer formation, a process mediated by the cysteine-238 residues of the cytoplasmic tail of CD40. The present study was designed to elucidate the biological relevance of cysteine-238-mediated dl-CD40 homodimers to the expression of CD23 on B cells and to investigate its possible involvement in the innate response. Our results indicate that cysteine-238-mediated dl-CD40 homodimerization is required for CD40-induced activation of PI3-kinase/Akt signaling and the subsequent CD23 expression, as inhibition of dl-CD40 homodimer formation through a point mutation-approach specifically impairs these responses. Interestingly, cysteine-238-mediated dl-CD40 homodimers are also shown to play a crucial role in Toll-like receptor 4-induced CD23 expression, further validating the importance of this system in bridging innate and adaptive immune responses. This process also necessitates the activation of the PI3-kinase/Akt cascade. Thus, our results highlight new roles for CD40 and cysteine-238-mediated CD40 homodimers in cell biology and identify a potential new target for therapeutic strategies against CD40-associated chronic inflammatory diseases.

Roles of the NF-κB Pathway in B-Lymphocyte Biology

NF-κB was originally identified as a family of transcription factors that bind the enhancer of the immunoglobulin κ light-chain gene. Although its function in the regulation of immunoglobulin κ light-chain gene remains unclear, NF-κB plays critical roles in development, survival, and activation of B lymphocytes. In B cells, many receptors, including B-cell antigen receptor (BCR), activate NF-κB pathway, and the molecular mechanism of receptor-mediated activation of IκB kinase (IKK) complex has been partially revealed. In addition to normal B lymphocytes, NF-κB is also involved in the growth of some types of B-cell lymphomas, and many oncogenic mutations involved in constitutive activation of the NF-κB pathway were recently identified in such cancers. In this review, we first summarize the function of NF-κB in B-cell development and activation, and then describe recent progress in understanding the molecular mechanism of receptor-mediated activation of the IKK complex, focusing on the roles of the ubiquitin system. In the last section, we describe oncogenic mutations that induce NF-κB activation in B-cell lymphoma.

Targeting the HA2 subunit of influenza A virus hemagglutinin via CD40L provides universal protection against diverse subtypes

The influenza viral hemagglutinin (HA) is comprised of two subunits. Current influenza vaccine predominantly induces neutralizing antibodies (Abs) against the HA1 subunit, which is constantly evolving in unpredictable fashion. The other subunit, HA2, however, is highly conserved but largely shielded by the HA head domain. Thus, enhancing immune response against HA2 could potentially elicit broadly inhibitory Abs. We generated a recombinant adenovirus (rAd) encoding secreted fusion protein, consisting of codon-optimized HA2 subunit of influenza A/California/7/2009(H1N1) virus fused to a trimerized form of murine CD40L, and determined its ability of inducing protective immunity upon intranasal administration. We found that mice immunized with this recombinant viral vaccine were completely protected against lethal challenge with divergent influenza A virus subtypes including H1N1, H3N2, and H9N2. Codon-optimization of HA2 as well as the use of CD40L as a targeting ligand/molecular adjuvant were indispensable to enhance HA2-specific mucosal IgA and serum IgG levels. Moreover, induction of HA2-specific T-cell responses was dependent on CD40L, as rAd secreting HA2 subunit without CD40L failed to induce any significant levels of T-cell cytokines. Finally, sera obtained from immunized mice were capable of inhibiting 13 subtypes of influenza A viruses in vitro. These results provide proof of concept for a prototype HA2-based universal influenza vaccine.

TNF superfamily protein-protein interactions: feasibility of small- molecule modulation

The tumor necrosis factor (TNF) superfamily (TNFSF) contains about thirty structurally related receptors (TNFSFRs) and about twenty protein ligands that bind to one or more of these receptors. Almost all of these cell surface protein-protein interactions (PPIs) represent high-value therapeutic targets for inflammatory or immune modulation in autoimmune diseases, transplant recipients, or cancers, and there are several biologics including antibodies and fusion proteins targeting them that are in various phases of clinical development. Small-molecule inhibitors or activators could represent possible alternatives if the difficulties related to the targeting of protein-protein interactions by small molecules can be addressed. Compounds proving the feasibility of such approaches have been identified through different drug discovery approaches for a number of these TNFSFR-TNFSF type PPIs including CD40-CD40L, BAFFR-BAFF, TRAIL-DR5, and OX40-OX40L. Corresponding structural, signaling, and medicinal chemistry aspects are briefly reviewed here. While none of these small-molecule modulators identified so far seems promising enough to be pursued for clinical development, they provide proof-of-principle evidence that these interactions are susceptible to small-molecule modulation and can serve as starting points toward the identification of more potent and selective candidates.

In vivo targeted delivery of CD40 shRNA to mouse intestinal dendritic cells by oral administration of recombinant Sacchromyces cerevisiae

Short hairpin RNA (shRNA)-mediated gene regulation is a commonly used technique for gene manipulation. An efficient and safe delivery system is indispensable when shRNA is delivered into living organisms for gene therapy. Previous studies have proved that DNA and protein can be delivered into dendritic cells (DCs) by non-pathogenic Saccharomyces cerevisiae without being degraded. CD40 is closely related to apoptosis of tumor cells and some immune mechanisms. In this study, we demonstrated that recombinant yeast S. cerevisiae efficiently delivered the shRNA of immune-associated gene (CD40) into mouse intestinal DCs via oral administration. Western blot analysis of isolated intestinal DCs indicated that the inhibition of CD40 gene expression reached up to 56-91%. The secretion of cytokines such as interleukin-2 (IL-2), IL-6, IL-10, IL-12, tumor necrosis factor-α and interferon-γ in intestinal DCs had varying degrees of changes. In conclusion, we found that orally administered recombinant yeast can be used as an efficient shRNA delivery system for intestinal DC-specific gene silencing and immunomodulation in vivo.

Role of sphingosine kinase 1 and sphingosine-1-phosphate in CD40 signaling and IgE class switching

The tumor necrosis factor (TNF) receptor family member CD40 plays an essential role in the activation of antigen-presenting cells, B cell maturation, and immunoglobulin (Ig) class switching critical for adaptive immunity. Although the bioactive sphingolipid metabolite sphingosine-1-phosphate (S1P) and the kinase that produces it, sphingosine kinase 1 (SphK1), have long been implicated in the actions of TNF mediated by engagement of TNFR1, nothing is yet known of their role in CD40-mediated events. We have now found that ligation of CD40 activates and translocates SphK1 to the plasma membrane, leading to generation of S1P. SphK1 inhibition in human tonsil B cells, as well as inhibition or deletion of SphK1 in mouse splenic B cells, significantly reduced CD40-mediated Ig class switching and plasma cell differentiation ex vivo. Optimal activation of downstream CD40 signaling pathways, including NF-κB, p38, and JNK, also required SphK1. In mice treated with a SphK1 inhibitor or in SphK1(-/-) mice, isotype switching to antigen-specific IgE was decreased in vivo by 70 and 55%, respectively. Our results indicate that SphK1 is important for CD40-mediated B cell activation and regulation of humoral responses and suggest that targeting SphK1 might be a useful therapeutic approach to control antigen-specific IgE production.