Mice deficient in CD38 develop an attenuated form of collagen type II-induced arthritis

TM9SF1 expression correlates with autoimmune disease activity and regulates antibody production through mTOR-dependent autophagy

BACKGROUND

Transmembrane 9 superfamily member 1 (TM9SF1) is involved in inflammation. Since both inflammatory and autoimmune diseases are linked to immune cells regulation, this study investigated the association between TM9SF1 expression and autoimmune disease activity. As B cell differentiation and autoantibody production exacerbate autoimmune disease, the signaling pathways involved in these processes were explored.

METHODS

Tm9sf1-/- mouse rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) models were used to verify the relationship between gene expression and disease severity. Peripheral blood mononuclear cells (PBMCs) from 156 RA and 145 SLE patients were used to explore the relationship between TM9SF1 expression and disease activity. The effectiveness of TM9SF1 as a predictor of disease activity was assessed using multiple logistic regression and receiver operating characteristic (ROC) curves. The signaling pathways regulated by TM9SF1 in B cell maturation and antibody production were conducted by plasma cell induction experiment in vitro.

RESULTS

The Tm9sf1-/- RA and SLE model mice produced fewer autoantibodies and showed reduced disease severity relative to wild-type (WT) mice. TM9SF1 levels in PBMCs of patients were higher than those in healthy controls, and were reduced in patients with low disease activity relative to those with active RA and SLE. Furthermore, TM9SF1 levels were positively linked with autoantibody titers and pro-inflammatory cytokine levels in both diseases. ROC analyses indicated TM9SF1 outperformed several important clinical indicators in predicting disease activity (area under the curve (AUC) were 0.858 and 0.876 for RA and SLE, respectively). In vitro experiments demonstrated that Tm9sf1 knockout blocked differentiation of B cells into antibody-producing plasma cells by activating mTOR and inhibiting autophagy, and mTOR inhibitors such as rapamycin could reverse this effect.

CONCLUSIONS

The primary finding was the identification of the molecular mechanism underlying autophagy regulation in B cells, in which Tm9sf1 knockout was found to modulate mTOR-dependent autophagy to block B cell differentiation into antibody-secreting plasma cells. It was also found that TM9SF1 expression level in PBMCs was an accurate indicator of disease activity in patients with RA and SLE, suggesting its clinical potential for monitoring disease activity in these patients.

Human plasma cells engineered to secrete bispecifics drive effective in vivo leukemia killing

Bispecific antibodies are an important tool for the management and treatment of acute leukemias. As a next step toward clinical translation of engineered plasma cells, we describe approaches for secretion of bispecific antibodies by human plasma cells. We show that human plasma cells expressing either fragment crystallizable domain-deficient anti-CD19 × anti-CD3 (blinatumomab) or anti-CD33 × anti-CD3 bispecific antibodies mediate T cell activation and direct T cell killing of B acute lymphoblastic leukemia or acute myeloid leukemia cell lines in vitro. We demonstrate that knockout of the self-expressed antigen, CD19, boosts anti-CD19-bispecific secretion by plasma cells and prevents self-targeting. Plasma cells secreting anti-CD19-bispecific antibodies elicited in vivo control of acute lymphoblastic leukemia patient-derived xenografts in immunodeficient mice co-engrafted with autologous T cells. In these studies, we found that leukemic control elicited by engineered plasma cells was similar to CD19-targeted chimeric antigen receptor-expressing T cells. Finally, the steady-state concentration of anti-CD19 bispecifics in serum 1 month after cell delivery and tumor eradication was comparable with that observed in patients treated with a steady-state infusion of blinatumomab. These findings support further development of ePCs for use as a durable delivery system for the treatment of acute leukemias, and potentially other cancers.

Quantitative urinary proteome analysis reveals potential biomarkers for disease activity of Behcet's disease uveitis

PURPOSE

Behçet's disease-associated uveitis (BDU) is a severe, recurrent inflammatory condition affecting the eye and is part of a systemic vasculitis with unknown etiology, making biomarker discovery essential for disease management. In this study, we intend to investigate potential urinary biomarkers to monitor the disease activity of BDU.

METHODS

Firstly, label-free data-dependent acquisition (DDA) and tandem mass tag (TMT)-labeled quantitative proteomics methods were used to profile the proteomes of urine from active and quiescent BDU patients, respectively. For further exploration, the remaining fifty urine samples were analyzed by a data-independent acquisition (DIA) quantitative proteomics method.

RESULTS

Twenty-nine and 21 differential proteins were identified in the same urine from BDU patients by label-free DDA and TMT-labeled analyses, respectively. Seventy-nine differentially expressed proteins (DEPs) were significantly changed in other active BDU urine samples compared to those in quiescent BDU urine samples by IDA analysis. Gene Ontology (GO) and protein-protein interaction (PPI) analyses revealed that the DEPs were associated with multiple functions, including the immune and neutrophil activation responses. Finally, seven proteins were identified as candidate biomarkers for BDU monitoring and recurrence prediction, namely, CD38, KCRB, DPP4, FUCA2, MTPN, S100A8 and S100A9.

CONCLUSIONS

Our results showed that urine can be a good source of biomarkers for BDU. These dysregulated proteins provide potential urinary biomarkers for BDU activity monitoring and provide valuable clues for the analysis of the pathogenic mechanisms of BDU.

Human plasma cells engineered to secrete bispecifics drive effective in vivo leukemia killing

Bispecific antibodies are an important tool for the management and treatment of acute leukemias. Advances in genome-engineering have enabled the generation of human plasma cells that secrete therapeutic proteins and are capable of long-term in vivo engraftment in humanized mouse models. As a next step towards clinical translation of engineered plasma cells (ePCs) towards cancer therapy, here we describe approaches for the expression and secretion of bispecific antibodies by human plasma cells. We show that human ePCs expressing either fragment crystallizable domain deficient anti-CD19 × anti-CD3 (blinatumomab) or anti-CD33 × anti-CD3 bispecific antibodies mediate T cell activation and direct T cell killing of specific primary human cell subsets and B-acute lymphoblastic leukemia or acute myeloid leukemia cell lines in vitro. We demonstrate that knockout of the self-expressed antigen, CD19, boosts anti-CD19 bispecific secretion by ePCs and prevents self-targeting. Further, anti-CD19 bispecific-ePCs elicited tumor eradication in vivo following local delivery in flank-implanted Raji lymphoma cells. Finally, immunodeficient mice engrafted with anti-CD19 bispecific-ePCs and autologous T cells potently prevented in vivo growth of CD19+ acute lymphoblastic leukemia in patient-derived xenografts. Collectively, these findings support further development of ePCs for use as a durable, local delivery system for the treatment of acute leukemias, and potentially other cancers.

Molecular Determinants Underlying the Anti-Cancer Efficacy of CD38 Monoclonal Antibodies in Hematological Malignancies

CD38 was first discovered as a T-cell antigen and has since been found ubiquitously expressed in various hematopoietic cells, including plasma cells, NK cells, B cells, and granulocytes. More importantly, CD38 expression levels on malignant hematopoietic cells are significantly higher than counterpart healthy cells, thus presenting itself as a promising therapeutic target. In fact, for many aggressive hematological cancers, including CLL, DLBCL, T-ALL, and NKTL, CD38 expression is significantly associated with poorer prognosis and a hyperproliferative or metastatic phenotype. Studies have shown that, beyond being a biomarker, CD38 functionally mediates dysregulated survival, adhesion, and migration signaling pathways, as well as promotes an immunosuppressive microenvironment conducive for tumors to thrive. Thus, targeting CD38 is a rational approach to overcoming these malignancies. However, clinical trials have surprisingly shown that daratumumab monotherapy has not been very effective in these other blood malignancies. Furthermore, extensive use of daratumumab in MM is giving rise to a subset of patients now refractory to daratumumab treatment. Thus, it is important to consider factors modulating the determinants of response to CD38 targeting across different blood malignancies, encompassing both the transcriptional and post-transcriptional levels so that we can diversify the strategy to enhance daratumumab therapeutic efficacy, which can ultimately improve patient outcomes.

CD38 deficiency protects the retina from ischaemia/reperfusion injury partly via suppression of TLR4/MyD88/NF-κB signalling

PURPOSE

This study aimed to explore cellular localisation of CD38 in the retina and evaluate the role and potential mechanism of CD38 deficiency in retinal ischaemia/reperfusion (I/R) injury.

METHODS

Six-to eight-week-old male CD38 knockout (KO) and wild-type mice in C57BL/6 background were used. Immunostaining was performed to determine the cellular localisation of CD38 in the retina. Haematoxylin and eosin staining and immunostaining of Brn3a were used to evaluate the retinal I/R injury. Western blotting was performed to detect toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), p-p65, ionised calcium-binding adapter molecule 1, Sirtuin1 (Sirt1), Ac-p65, and pro-inflammatory cytokines protein expression.

RESULTS

CD38 was highly expressed in mouse retinal microglia and astrocytes/Müller cells. CD38 deficiency reduced I/R-induced retinal damage and retinal ganglion cell death. Following retinal I/R injury, TLR4, MyD88, nuclear factor-κB p-p65 (NF-κB p-p65), pro-inflammatory cytokines and CD38 protein levels were also upregulated. After I/R injury, retinal inflammation factors IL-1β, IL-6, and TNF-α mRNA and protein levels were increased. IL-1β, IL-6, and TNF-α were reduced in CD38 KO mice after I/R injury. Retinal I/R injury induced the activation of microglia, but this effect was also suppressed by KO of CD38. Additionally, retinal I/R induced a significant increase in Ac-p65 protein levels and decrease in Sirt1 protein levels, while this effect was greatly attenuated by KO of CD38.

CONCLUSION

CD38 deficiency protects the retina from I/R injury by suppressing microglial activation partly via activating Sirt1-mediated suppression of TLR4/MyD88/NF-κB signalling.

CD38 Deficiency Ameliorates Chronic Graft-Versus-Host Disease Murine Lupus via a B-Cell-Dependent Mechanism

The absence of the mouse cell surface receptor CD38 in Cd38^−/− mice suggests that this receptor acts as a positive regulator of inflammatory and autoimmune responses. Here, we report that, in the context of the chronic graft-versus-host disease (cGVHD) lupus inducible model, the transfer of B6.C-H2bm12/KhEg(bm12) spleen cells into co-isogenic Cd38^−/− B6 mice causes milder lupus-like autoimmunity with lower levels of anti-ssDNA autoantibodies than the transfer of bm12 spleen cells into WT B6 mice. In addition, significantly lower percentages of Tfh cells, as well as GC B cells, plasma cells, and T-bet⁺CD11c^hi B cells, were observed in Cd38^−/− mice than in WT mice, while the expansion of Treg cells and Tfr cells was normal, suggesting that the ability of Cd38^−/− B cells to respond to allogeneic help from bm12 CD4⁺ T cells is greatly diminished. The frequencies of T-bet⁺CD11c^hi B cells, which are considered the precursors of the autoantibody-secreting cells, correlate with anti-ssDNA autoantibody serum levels, IL-27, and sCD40L. Proteomics profiling of the spleens from WT cGVHD mice reflects a STAT1-driven type I IFN signature, which is absent in Cd38^−/− cGVHD mice. Kidney, spleen, and liver inflammation was mild and resolved faster in Cd38^−/− cGVHD mice than in WT cGVHD mice. We conclude that CD38 in B cells functions as a modulator receptor that controls autoimmune responses.

T-Cell Immune Imbalance in Rheumatoid Arthritis Is Associated with Alterations in NK Cells and NK-Like T Cells Expressing CD38

BACKGROUND

CD38+ NK (CD3- CD16+ CD38+ CD56+) cells were increased in rheumatoid arthritis (RA), which suppressed Treg cell differentiation. This study explored how CD38+ NK cells regulated CD4+ T-cell differentiation into Treg cells in RA.

METHODS

Proportions of CD38+ NK cells and their counterpart CD38+ NK-like T (CD3+ CD16+ CD38+ CD56+) cells were measured in RA and rats with collagen-induced arthritis (CIA). CD38+ NK cells and CD38+ NK-like T cells were cocultured with CD4+ T cells, respectively.

RESULTS

A significantly increased proportion of CD38+ NK cells and a decreased proportion of CD38+ NK-like T cells were detected in RA and CIA blood and synovial fluids. When CD4+ T cells were cocultured with CD38+ NK cells, mammalian target of rapamycin (mTOR) signaling was activated, and Th1/Th2 and Th17/Treg ratios were increased. When CD38+ NK cells were pretreated with anti-CD38 antibody, Treg cell proportion was increased, and Th1/Th2 and Th17/Treg ratios were decreased. CD38+ NK-like T cells showed the opposite results. CD38+ NK cells and CD38+ NK-like-T cells activated differential gene expressions and pathways in CD4+ T cells and initiated Th1 and Th2 cell differentiation by differential gene nodes.

CONCLUSIONS

This study suggest that the high CD38+ NK cell proportion and low CD38+ NK-like T cell proportion in RA suppress Treg cell differentiation by stimulating mTOR signaling in CD4+ T cells, which consequentially disturbs the immune tolerance.

20S-Hydroxyvitamin D3, a Secosteroid Produced in Humans, Is Anti-Inflammatory and Inhibits Murine Autoimmune Arthritis

The ability to use large doses of vitamin D3 (D3) to chronically treat autoimmune diseases such as rheumatoid arthritis (RA) is prohibitive due to its calcemic effect which can damage vital organs. Cytochrome P450scc (CYP11A1) is able to convert D3 into the noncalcemic analog 20S-hydroxyvitamin D3 [20S(OH)D3]. We demonstrate that 20S(OH)D3 markedly suppresses clinical signs of arthritis and joint damage in a mouse model of RA. Furthermore, treatment with 20S(OH)D3 reduces lymphocyte subsets such as CD4+ T cells and CD19+ B cells leading to a significant reduction in inflammatory cytokines. The ratio of T reg cells (CD4+CD25+Foxp3+ T cells) to CD3+CD4+ T cells is increased while there is a decrease in critical complement-fixing anti-CII antibodies. Since pro-inflammatory cytokines and antibodies against type II collagen ordinarily lead to destruction of cartilage and bone, their decline explains why arthritis is attenuated by 20(OH) D3. These results provide a basis for further consideration of 20S(OH)D3 as a potential treatment for RA and other autoimmune disorders.

Daratumumab induces mechanisms of immune activation through CD38+ NK cell targeting

Daratumumab (Dara), a multiple myeloma (MM) therapy, is an antibody against the surface receptor CD38, which is expressed not only on plasma cells but also on NK cells and monocytes. Correlative data have highlighted the immune-modulatory role of Dara, despite the paradoxical observation that Dara regimens decrease the frequency of total NK cells. Here we show that, despite this reduction, NK cells play a pivotal role in Dara anti-MM activity. CD38 on NK cells is essential for Dara-induced immune modulation, and its expression is restricted to NK cells with effector function. We also show that Dara induces rapid CD38 protein degradation associated with NK cell activation, leaving an activated CD38-negative NK cell population. CD38+ NK cell targeting by Dara also promotes monocyte activation, inducing an increase in T cell costimulatory molecules (CD86/80) and enhancing anti-MM phagocytosis activity ex-vivo and in vivo. In support of Dara’s immunomodulating role, we show that MM patients that discontinued Dara therapy because of progression maintain targetable unmutated surface CD38 expression on their MM cells, but retain effector cells with impaired cellular immune function. In summary, we report that CD38+ NK cells may be an unexplored therapeutic target for priming the immune system of MM patients.

Alterations in the Glycan Profile of Mouse Transferrin: New Insights in Collagen-Induced Arthritis

Transferrin purification from mice serum samples by immunoaffinity chromatography (IAC) was optimized in order to study the possible modifications occurring in its glycans in collagen-induced arthritis (CIA) samples. SDS-PAGE and nanoLC-MS/MS were used to monitor the IAC purification performance. Afterward, a relative quantification of mouse transferrin (mTf) glycan isomers using [¹²C₆]/[¹³C₆]-aniline was used to unequivocally detect alterations in the glycan profile of CIA mice. In addition, multivariate data analysis was applied to identify the most meaningful glycan isomers for the discrimination between control and pathological samples. Partial least-squares discriminant analysis (PLS-DA) revealed that five out of fifteen mTf glycan isomers could be potential biomarkers of CIA, most of them corresponding to highly sialylated structures (H6N5S3_2, H6N5S3_3, and H5N4S3_2). Moreover, some of these glycan isomers also seemed to be related with the progression of CIA, especially H6N5S2 and H6N5S3_2, as their overexpression increased with the clinical score of the pathology. Hence, the established methodology not only provides valuable information to find glycan-based biomarkers of CIA, but also leaves the door open to evaluate, in the future, glycosylation changes of many other inflammatory diseases, in which transferrin has been described to be altered.

The Good, the Bad and the Unknown of CD38 in the Metabolic Microenvironment and Immune Cell Functionality of Solid Tumors

The regulation of the immune microenvironment within solid tumors has received increasing attention with the development and clinical success of immune checkpoint blockade therapies, such as those that target the PD-1/PD-L1 axis. The metabolic microenvironment within solid tumors has proven to be an important regulator of both the natural suppression of immune cell functionality and the de novo or acquired resistance to immunotherapy. Enzymatic proteins that generate immunosuppressive metabolites like adenosine are thus attractive targets to couple with immunotherapies to improve clinical efficacy. CD38 is one such enzyme. While the role of CD38 in hematological malignancies has been extensively studied, the impact of CD38 expression within solid tumors is largely unknown, though most current data indicate an immunosuppressive role for CD38. However, CD38 is far from a simple enzyme, and there are several remaining questions that require further study. To effectively treat solid tumors, we must learn as much about this multifaceted protein as possible—i.e., which infiltrating immune cell types express CD38 for functional activities, the most effective CD38 inhibitor(s) to employ, and the influence of other similarly functioning enzymes that may also contribute towards an immunosuppressive microenvironment. Gathering knowledge such as this will allow for intelligent targeting of CD38, the reinvigoration of immune functionality and, ultimately, tumor elimination.

Potential therapeutic effects of cyanidin-3-O-glucoside on rheumatoid arthritis by relieving inhibition of CD38+ NK cells on Treg cell differentiation

Background

CD38+ NK cells are overabundant in rheumatoid arthritis (RA). Cyanidin-3-O-glucoside (C3G) is an inhibitor of CD38. This study investigated the pathogenic role of CD38+ NK cells and the effect of C3G on RA.

Methods

Rats with bovine type II collagen-induced arthritis (CIA) were injected with C3G. RA synovial fibroblasts (RASFs) or mononuclear cells (MNCs) were cultured with C3G. MNCs were also cocultured with CD38+ NK cells following C3G pretreatment.

Results

C3G injection significantly alleviated CIA. C3G also significantly increased the level of interleukin (IL)-10 and the regulatory T (Treg) cell proportion, and it decreased the interleukin (IL)-6 and interferon (IFN)-γ levels and CD38+ NK cell proportion in rat peripheral blood and synovial fluid. Additionally, C3G significantly increased RASF apoptosis and decreased RASF proliferation and IL-6 production in the culture medium. Furthermore, C3G stimulated MNCs to increase IL-2 and IL-10 production and the Treg cell proportion, and it caused MNCs to decrease IL-6 and IFN-γ production and the CD38+ NK cell proportion. Although CD38+ NK cells significantly decreased the Treg cell proportion and IL-10 level in MNCs, CD38+ NK cells that had been pretreated with C3G increased the proportion of Treg cells and IL-10 levels and decreased the IL-6 and IFN-γ levels in the coculture. In CD38+ NK cells, C3G significantly increased Sirtuin 6 (Sirt6) expression and the tumor necrosis factor (TNF)-α level, and it decreased natural killer group 2D (NKG2D) expression and the IFN-γ level. However, when CD38+ NK cells were treated with Sirt6 siRNA, C3G did not change the NKG2D expression, the TNF-α level sharply decreased, and the IFN-γ level increased. When MNCs were cocultured with C3G-pretreated CD38+ NK cells in the presence of TNF-α and an anti-IFN-γ antibody, the IL-10+ Treg cell proportion significantly increased. When MNCs were cocultured with C3G-pretreated CD38+ NK cells in the presence of IFN-γ and an anti-TNF-α antibody, the IL-10+ Treg cell proportion sharply decreased. When CIA rats were injected with both C3G and the Sirt6 inhibitor OSS_128167, the rats exhibited joint inflammation and a low Treg cell proportion, but the CD38+ NK proportion was still low.

Conclusion

C3G has therapeutic effects on CIA and RA. C3G decreased the proportion of CD38+ cells, RASF proliferation, and proinflammatory cytokine secretion, and it increased the Treg cell proportion. C3G also elevated Sirt6 expression to suppress NKG2D expression, increase TNF-α secretion, and decrease IFN-γ secretion in CD38+ NK cells, which stimulates MNCs to differentiate into Treg cells. This study also demonstrates that the inhibition of Treg cell differentiation in MNCs by CD38+ NK cells is a potential cause of the immune imbalance in RA and CIA.

Regulatory B cells: New players in inflammatory and autoimmune rheumatic diseases

OBJECTIVE

Regulatory B cells (Bregs) are a new subset of B cells with immunoregulatory functions, mainly through IL-10 production. Bregs suppress inflammatory Th1 and Th17 differentiation and induce Tregs suppressing autoimmune diseases. The aim of the study was to review the literature related to Bregs in autoimmune rheumatic diseases (ARDs).

METHODS

A literature review of publications in PUBMED published in English was performed using the relevant combinations of terms.

RESULTS

All relevant publications are discussed. Overall, recent studies in rheumatic diseases found Bregs to be decreased in ANCA-associated vasculitides (AAV) and in systemic sclerosis (SSc), particularly in SSc-associated lung fibrosis. In AAV Bregs levels are negatively correlated with autoantibody levels whereas in SSc this association is less clear but there is an inverse association with Th1 and Th17 cells. In rheumatoid arthritis (RA), Bregs were decreased, particularly in RA-associated lung fibrosis. In psoriatic arthritis IL-10 + Bregs are decreased and inversely associated with Th1 and Th17 cells. In systemic lupus erythematosus (SLE), the role of Bregs is unclear. In experimental diseases, when Bregs were expanded ex-vivo, they ameliorated established disease.

CONCLUSION

Bregs appear to be a new player in the pathogenesis of ARDs, and may offer a new strategy for therapeutic intervention.

The Role of CD38 on the Function of Regulatory B Cells in a Murine Model of Lupus

Previous work from our group has shown that Cd38^-/- mice develop a milder pristane-induced lupus disease than WT or Art2^-/- counterparts, demonstrating a new role for CD38 in promoting aberrant inflammation and lupus-like autoimmunity via a Transient Receptor Potential Melastatin 2 (TRPM2)-dependent apoptosis-driven mechanism. In this study we asked whether CD38 may play a role in the expression and function of regulatory B cells (IL-10-producing B cells or B10 cells). In pristane-treated mice the frequency of spleen CD19⁺CD1d^hiCD5⁺ B cells, which are highly enriched in B10 cells, was significantly increased in Cd38^-/- splenocytes compared to WT, while the frequency of peritoneal plasmacytoid dendritic cells (pDCs), which are major type I Interferon (IFN) producers, was greatly diminished. The low proportion of pDCs correlated with lower amounts of IFN-α in the peritoneal lavage fluids of the Cd38^-/- mice than of WT and Art2^-/- mice. Functional ex vivo assays showed increased frequencies of IL-10-producing B cells in Cd38^-/- splenocytes than in WT upon stimulation with an agonist anti-CD40 mAb. Overall these results strongly suggest that Cd38^-/- mice are better suited than WT mice to generate and expand regulatory B10 cells following the appropriate stimulation.

The Role of Nicotinamide Adenine Dinucleotide in the Pathogenesis of Rheumatoid Arthritis: Potential Implications for Treatment

Rheumatoid arthritis (RA) is a chronic, systemic, inflammatory, autoimmune disease characterised by small joint swelling, deformity, and dysfunction. Its exact aetiology is unclear. Current treatment approaches do not control harmful autoimmune attacks or prevent irreversible damage without considerable side effects. Nicotinamide adenine dinucleotide (NAD+), an important hydrogen carrier in mitochondrial respiration and oxidative phosphorylation, is the major determinant of redox state in the cell. NAD+ metabolites act as degradation substrates for a wide range of enzymes, such as sirtuins, poly-ADP-ribose polymerases, ADP-ribosyltransferases, and CD38. The roles of NAD+ have expanded beyond its role as a coenzyme, linking cellular metabolism to inflammation signalling and immune response. The aim of this review is to illustrate the role of NAD+-related enzymes in the pathogenesis of RA and highlight the potential therapeutic role of NAD+ in RA.

Control of Listeria monocytogenes infection requires classical IL-6 signaling in myeloid cells

IL-6 is required for the response of mice against Listeria monocytogenes. Control of infection depends on classical IL-6 signaling via membrane IL-6Rα, but IL-6 target cells and protective mechanisms remain unclear. We used mice with IL-6Rα-deficiency in T cells (Il6rafl/fl×CD4cre) or myeloid cells (Il6rafl/fl×LysMcre) to define the role of these cells in IL-6-mediated protection. Abrogation of IL-6Rα in T cells did not interfere with bacteria control and induction of TH1 and CD8+ T-cell responses. IL-6Rα-deficiency in myeloid cells caused significant defects in listeria control. This defect was not associated with reduced recruitment of granulocytes and inflammatory monocytes, and both cell populations were activated and not impaired in cytokine production. However, IL-6Rα-deficient inflammatory monocytes displayed diminished expression of IL-4Rα and of CD38, a protein required for phagocytosis and innate control of listeria. In vitro studies revealed that IL-4 and IL-6 cooperated in induction of CD38. In listeria-infected mice, phagocytic activity of inflammatory monocytes correlated with CD38 expression levels on cells and inflammatory monocytes of Il6rafl/fl×LysMcre mice were significantly impaired in phagocytosis. In conclusion, we demonstrate that inhibition of classical IL-6 signaling in myeloid cells causes alterations in differentiation and function of these cells, which subsequently prevent effective control of L. monocytogenes.

CD38 Is Robustly Induced in Human Macrophages and Monocytes in Inflammatory Conditions

Macrophages and their monocyte precursors mediate innate immune responses and can promote a spectrum of phenotypes from pro-inflammatory to pro-resolving. Currently, there are few markers that allow for robust dissection of macrophage phenotype. We recently identified CD38 as a marker of inflammatory macrophages in murine in vitro and in vivo models. However, it is unknown whether CD38 plays a similar marker and/or functional role in human macrophages and inflammatory diseases. Here, we establish that CD38 transcript and protein are robustly induced in human macrophages exposed to LPS (±IFN-γ) inflammatory stimuli, but not with the alternative stimulus, IL-4. Pharmacologic and/or genetic CD38 loss-of-function significantly reduced the secretion of inflammatory cytokines IL-6 and IL-12p40 and glycolytic activity in human primary macrophages. Finally, monocyte analyses in systemic lupus erythematosus patients revealed that, while all monocytes express CD38, high CD38 expression in the non-classical monocyte subpopulation is associated with disease. These data are consistent with an inflammatory marker role for CD38 in human macrophages and monocytes.

Ectonucleotidase-Mediated Suppression of Lupus Autoimmunity and Vascular Dysfunction

Objectives

CD39 and CD73 are surface enzymes that jut into the extracellular space where they mediate the step-wise phosphohydrolysis of the autocrine and paracrine danger signals ATP and ADP into anti-inflammatory adenosine. Given the role of vascular and immune cells' "purinergic halo" in maintaining homeostasis, we hypothesized that the ectonucleotidases CD39 and CD73 might play a protective role in lupus.

Methods

Lupus was modeled by intraperitoneal administration of pristane to three groups of mice: wild-type (WT), CD39^-/-, and CD73^-/-. After 36 weeks, autoantibodies, endothelial function, kidney disease, splenocyte activation/polarization, and neutrophil activation were characterized.

Results

As compared with WT mice, CD39^-/- mice developed exaggerated splenomegaly in response to pristane, while both groups of ectonucleotidase-deficient mice demonstrated heightened anti-ribonucleoprotein production. The administration of pristane to WT mice triggered only subtle dysfunction of the arterial endothelium; however, both CD39^-/- and CD73^-/- mice demonstrated striking endothelial dysfunction following induction of lupus, which could be reversed by superoxide dismutase. Activated B cells and plasma cells were expanded in CD73^-/- mice, while deficiency of either ectonucleotidase led to expansion of T_H17 cells. CD39^-/- and CD73^-/- mice demonstrated exaggerated neutrophil extracellular trap release, while CD73^-/- mice additionally had higher levels of plasma cell-free DNA.

Conclusion

These data are the first to link ectonucleotidases with lupus autoimmunity and vascular disease. New therapeutic strategies may harness purinergic nucleotide dissipation or signaling to limit the damage inflicted upon organs and blood vessels by lupus.

CD38 Deficiency Promotes Inflammatory Response through Activating Sirt1/NF-κB-Mediated Inhibition of TLR2 Expression in Macrophages

CD38 was first identified as a lymphocyte-specific antigen and then has been found to be widely expressed in a variety of cell types. The functions of CD38 are involved in numerous biological processes including immune responses. Here, we showed the downregulations of both TLR2 mRNA and protein in macrophages from CD38^−/− mice and in CD38 knockdown RAW264.7 cells. Several NF-κB-binding motifs in the promoter region of the TLR2 gene were identified by the bioinformatics analysis and were confirmed by the luciferase activity assay with the different truncated TLR2 promoters. CD38 deficiency resulted in the reduction of NF-κB p65 and acetyl-NF-κB p65 (Ac-p65) levels as determined by Western blot. The expression of Sirt1 did not change, but an increased activity of Sirt1 was observed in CD38-deficient macrophages. Inhibition of the Sirt1/NF-κB signaling pathway resulted in downregulation of TLR2 expression in RAW264.7 cells. However, re-expression of CD38 in the knockdown clones reversed the effect on Sirt1/NF-κB/TLR2 signaling, which is NAD-dependent. Moreover, the inflammatory cytokines including G-CSF, IL-1alpha, IL-6, MCP-1, MIP-1alpha, and RANTES were increased in CD38 knockdown RAW264.7 cells. Taken together, our data demonstrated that CD38 deficiency enhances inflammatory response in macrophages, and the mechanism may be partly associated with increased Sirt1 activity, which promoted NF-κB deacetylation and then inhibited expression of the TLR2 gene. Obviously, our study may provide an insight into the molecular mechanisms in CD38-mediated inflammation.

CD38 promotes pristane-induced chronic inflammation and increases susceptibility to experimental lupus by an apoptosis-driven and TRPM2-dependent mechanism

In this study, we investigated the role of CD38 in a pristane-induced murine model of lupus. CD38-deficient (Cd38-/-) but not ART2-deficient (Art2-/-) mice developed less severe lupus compared to wild type (WT) mice, and their protective phenotype consisted of (i) decreased IFN-I-stimulated gene expression, (ii) decreased numbers of peritoneal CCR2hiLy6Chi inflammatory monocytes, TNF-α-producing Ly6G+ neutrophils and Ly6Clo monocytes/macrophages, (iii) decreased production of anti-single-stranded DNA and anti-nRNP autoantibodies, and (iv) ameliorated glomerulonephritis. Cd38-/- pristane-elicited peritoneal exudate cells had defective CCL2 and TNF-α secretion following TLR7 stimulation. However, Tnf-α and Cxcl12 gene expression in Cd38-/- bone marrow (BM) cells was intact, suggesting a CD38-independent TLR7/TNF-α/CXCL12 axis in the BM. Chemotactic responses of Cd38-/- Ly6Chi monocytes and Ly6G+ neutrophils were not impaired. However, Cd38-/- Ly6Chi monocytes and Ly6Clo monocytes/macrophages had defective apoptosis-mediated cell death. Importantly, mice lacking the cation channel TRPM2 (Trpm2-/-) exhibited very similar protection, with decreased numbers of PECs, and apoptotic Ly6Chi monocytes and Ly6Clo monocytes/macrophages compared to WT mice. These findings reveal a new role for CD38 in promoting aberrant inflammation and lupus-like autoimmunity via an apoptosis-driven mechanism. Furthermore, given the implications of CD38 in the activation of TRPM2, our data suggest that CD38 modulation of pristane-induced apoptosis is TRPM2-dependent.

Evaluation of ion mobility for the separation of glycoconjugate isomers due to different types of sialic acid linkage, at the intact glycoprotein, glycopeptide and glycan level

The study of protein glycosylation can be regarded as an intricate but very important task, making glycomics one of the most challenging and interesting, albeit under-researched, type of "omics" science. Complexity escalates remarkably when considering that carbohydrates can form severely branched structures with many different constituents, which often leads to the formation of multiple isomers. In this regard, ion mobility (IM) spectrometry has recently demonstrated its power for the separation of isomeric compounds. In the present work, the potential of traveling wave IM (TWIMS) for the separation of isomeric glycoconjugates was evaluated, using mouse transferrin (mTf) as model glycoprotein. Particularly, we aim to assess the performance of this platform for the separation of isomeric glycoconjugates due to the type of sialic acid linkage, at the intact glycoprotein, glycopeptide and glycan level. Straightforward separation of isomers was achieved with the analysis of released glycans, as opposed to the glycopeptides which showed a more complex pattern. Finally, the developed methodology was applied to serum samples of mice, to investigate its robustness when analyzing real complex samples.

BIOLOGICAL SIGNIFICANCE

Ion mobility mass spectrometry is a promising analytical technique for the separation of glycoconjugate isomers due to type of sialic acid linkage. The impact of such a small modification in the glycan structure is more evident in smaller analytes, reason why the analysis of free glycans was easier compared to the intact protein or the glycopeptides. The established methodology could be regarded as starting point in the separation of highly decorated glycoconjugates. This is an important topic nowadays, as differences in the abundance of some glycan isomers could be the key for the early diagnosis, control or differentiation of certain diseases, such as inflammation or cancer.

Supporting data for the MS identification of distinct transferrin glycopeptide glycoforms and citrullinated peptides associated with inflammation or autoimmunity

This data article presents the results of all the statistical analyses applied to the relative intensities of the detected 2D-DiGE protein spots for each of the 3 performed DiGE experiments. The data reveals specific subsets of protein spots with significant differences between WT and CD38-deficient mice with either Collagen-induced arthritis (CIA), or with chronic inflammation induced by CFA, or under steady-state conditions. This article also shows the MS data analyses that allowed the identification of the protein species which serve to discriminate the different experimental groups used in this study. Moreover, the article presents MS data on the citrullinated peptides linked to specific protein species that were generated in CIA(+) or CFA-treated mice. Lastly, this data article provides MS data on the efficiency of the analyses of the transferrin (Tf) glycopeptide glycosylation pattern in spleen and serum from CIA(+) mice and normal controls. The data supplied in this work is related to the research article entitled "identification of multiple transferrin species in spleen and serum from mice with collagen-induced arthritis which may reflect changes in transferrin glycosylation associated with disease activity: the role of CD38" [1]. All mass spectrometry data have been deposited to the ProteomeXchange Consortium via the PRIDE partner repository with identifiers PRIDE: PXD002644, PRIDE: PXD002643, PRIDE: PXD003183 and PRIDE: PXD003163.

CD38 is expressed on inflammatory cells of the intestine and promotes intestinal inflammation

The enzyme CD38 is expressed on a variety of hematopoietic and non-hematopoietic cells and is involved in diverse processes such as generation of calcium-mobilizing metabolites, cell activation, and chemotaxis. Here, we show that under homeostatic conditions CD38 is highly expressed on immune cells of the colon mucosa of C57BL/6 mice. Myeloid cells recruited to this tissue upon inflammation also express enhanced levels of CD38. To determine the role of CD38 in intestinal inflammation, we applied the dextran sulfate sodium (DSS) colitis model. Whereas wild-type mice developed severe colitis, CD38-/- mice had only mild disease following DSS-treatment. Histologic examination of the colon mucosa revealed pronounced inflammatory damage with dense infiltrates containing numerous granulocytes and macrophages in wild-type animals, while these findings were significantly attenuated in CD38-/- mice. Despite attenuated histological findings, the mRNA expression of inflammatory cytokines and chemokines was only marginally lower in the colons of CD38-/- mice as compared to wild-type mice. In conclusion, our results identify a function for CD38 in the control of inflammatory processes in the colon.

Molecular bases of catalysis and ADP-ribose preference of human Mn2+-dependent ADP-ribose/CDP-alcohol diphosphatase and conversion by mutagenesis to a preferential cyclic ADP-ribose phosphohydrolase

Among metallo-dependent phosphatases, ADP-ribose/CDP-alcohol diphosphatases form a protein family (ADPRibase-Mn-like) mainly restricted, in eukaryotes, to vertebrates and plants, with preferential expression, at least in rodents, in immune cells. Rat and zebrafish ADPRibase-Mn, the only biochemically studied, are phosphohydrolases of ADP-ribose and, somewhat less efficiently, of CDP-alcohols and 2´,3´-cAMP. Furthermore, the rat but not the zebrafish enzyme displays a unique phosphohydrolytic activity on cyclic ADP-ribose. The molecular basis of such specificity is unknown. Human ADPRibase-Mn showed similar activities, including cyclic ADP-ribose phosphohydrolase, which seems thus common to mammalian ADPRibase-Mn. Substrate docking on a homology model of human ADPRibase-Mn suggested possible interactions of ADP-ribose with seven residues located, with one exception (Cys253), either within the metallo-dependent phosphatases signature (Gln27, Asn110, His111), or in unique structural regions of the ADPRibase-Mn family: s2s3 (Phe37 and Arg43) and h7h8 (Phe210), around the active site entrance. Mutants were constructed, and kinetic parameters for ADP-ribose, CDP-choline, 2´,3´-cAMP and cyclic ADP-ribose were determined. Phe37 was needed for ADP-ribose preference without catalytic effect, as indicated by the increased ADP-ribose Km and unchanged kcat of F37A-ADPRibase-Mn, while the Km values for the other substrates were little affected. Arg43 was essential for catalysis as indicated by the drastic efficiency loss shown by R43A-ADPRibase-Mn. Unexpectedly, Cys253 was hindering for cADPR phosphohydrolase, as indicated by the specific tenfold gain of efficiency of C253A-ADPRibase-Mn with cyclic ADP-ribose. This allowed the design of a triple mutant (F37A+L196F+C253A) for which cyclic ADP-ribose was the best substrate, with a catalytic efficiency of 3.5´104 M-1s-1 versus 4´103 M-1s-1 of the wild type.

Ectoenzymes in leukocyte migration and their therapeutic potential

Inflammation causes or accompanies a huge variety of diseases. Migration of leukocytes from the blood into the tissues, in the tissues, and from the tissues to lymphatic vasculature is crucial in the formation and resolution of inflammatory infiltrates. In addition to classical adhesion and activation molecules, several other molecules are known to contribute to the leukocyte traffic. Several of them belong to ectoenzymes, which are cell surface molecules having catalytically active sites outside the cell. We will review here how several ectoenzymes present on leukocytes or endothelial cell surface function as adhesins and/or modulate the extravasation cascade through their enzymatic activities. Moreover, their therapeutic potential as immune modulators in different experimental inflammation models and in clinical trials will be discussed.