CD11c+ macrophages are proangiogenic and necessary for experimental choroidal neovascularization.

Patients with neovascular AMD (nAMD) suffer vision loss from destructive angiogenesis, termed choroidal neovascularization (CNV). Macrophages are found in CNV lesions from patients with nAMD. Additionally, Ccr2-/- mice, which lack classical monocyte-derived macrophages, show reduced CNV size. However, macrophages are highly diverse cells that can perform multiple functions. We performed single-cell RNA-Seq on immune cells from WT and Ccr2-/- eyes to uncover macrophage heterogeneity during the laser-induced CNV mouse model of nAMD. We identified 12 macrophage clusters, including Spp1+ macrophages. Spp1+ macrophages were enriched from WT lasered eyes and expressed a proangiogenic transcriptome via multiple pathways, including vascular endothelial growth factor signaling, endothelial cell sprouting, cytokine signaling, and fibrosis. Additionally, Spp1+ macrophages expressed the marker CD11c, and CD11c+ macrophages were increased by laser and present in CNV lesions. Finally, CD11c+ macrophage depletion reduced CNV size by 40%. These findings broaden our understanding of ocular macrophage heterogeneity and implicate CD11c+ macrophages as potential therapeutic targets for treatment-resistant patients with nAMD.

Post-endotoxin exposure-induced lung inflammation and resolution consequences beneficially impacted by lung-delivered IL-10 therapy.

Although lung diseases typically result from long-term exposures, even a robust, one-time exposure can result in long-lasting consequences. Endotoxin is a ubiquitous environmental/occupational inflammatory agent often used to model airway inflammation. Using a murine model, the return to lung homeostasis following high dose inhalant lipopolysaccharide (LPS, 10-100 µg) exposure were delineated over 2 weeks. LPS-induced rapid weight loss, release of proinflammatory mediators, and inflammatory cell influx with prolonged persistence of activated macrophages CD11c+CD11b+ and recruited/transitioning CD11cintCD11b+ monocyte-macrophages out to 2 weeks. Next, lung-delivered recombinant (r) interleukin (IL)-10 was intratracheally administered for 3 doses initiated 5 h following LPS (10 µg) exposure for 2 days. IL-10 therapy reduced LPS-induced weight loss and increased blood glucose levels. Whereas there was no difference in LPS-induced bronchoalveolar lavage airway fluid cellular influx, total lung cell infiltrates were reduced (37%) with rIL-10 treatment. Post-LPS exposure treatment with rIL-10 strikingly reduced lavage fluid and lung homogenate levels of tumor necrosis factor-α (88% and 93% reduction, respectively), IL-6 (98% and 94% reduction), CXCL1 (66% and 75% reduction), and CXCL2 (47% and 67% reduction). LPS-induced recruited monocyte-macrophages (CD11cintCD11b+) were reduced (68%) with rIL-10. Correspondingly, LPS-induced lung tissue CCR2+ inflammatory monocyte-macrophage were reduced with rIL-10. There were also reductions in LPS-induced lung neutrophils, lymphocyte subpopulations, collagen content, and vimentin expression. These findings support the importance of studying resolution processes for the development of treatment after unintended environmental/occupational biohazard exposures. Short-term, lung-delivered rIL-10 favorably hastened inflammatory recovery processes following acute, high dose inhalant LPS exposure.

Economical and Efficient Protocol for Isolating and Culturing Bone Marrow-derived Dendritic Cells from Mice.

The demand for dendritic cells (DCs) is gradually increasing as immunology research advances. However, DCs are rare in all tissues. The traditional method for isolating DCs primarily involves inducing bone marrow (BM) differentiation into DCs by injecting large doses (>10 ng/mL) of granulocyte-macrophage colony-stimulating factor/interleukin-4 (GM-CSF/IL-4), making the procedure complex and expensive. In this protocol, using all BM cells cultured in 10 ng/mL GM-CSF/IL-4 medium, after 3-4 half-culture exchanges, up to 2.7 x 107 CD11c+ cells (DCs) per mouse (two femurs) were harvested with a purity of 80%-95%. After 10 days in culture, the expression of CD11c, CD80, and MHC II increased, whereas the number of cells decreased. The number of cells peaked after 7 days of culture. Moreover, this method only took 10 min to harvest all bone marrow cells, and a high number of DCs were obtained after 1 week of culture.

Conditional knockout of oestrogen receptor alpha in CD11c+ cells impacts female survival and inflammatory cytokine profile in murine lupus.

Oestrogen and oestrogen receptor alpha (ERα) have been implicated in systemic lupus erythematosus pathogenesis. ERα signalling influences dendritic cell (DC) development and function, as well as inflammation and downstream immune responses. We previously reported that ERα modulates multiple Toll-like receptor-stimulated pathways in both conventional and plasmacytoid DCs in lupus-prone mice. For example, CD11chi MHCII+ cell numbers are reduced in mice with global ERα deficiency or when expressing a short variant of ERα. Herein, RNA-seq analysis of CD11chi cells from bone marrow of NZM2410 mice expressing WT ERα versus ERα short versus ERα null revealed differentially expressed complement genes, interferon-related genes and cytokine signalling (e.g., IL-17 and Th17 pathways). To better understand the role of ERα in CD11c+ cells, lupus prone NZM2410 mice with selective deletion of the Esr1 gene in CD11c+ cells were generated. Phenotype and survival of these mice were similar with the exception of Cre positive (CrePos) female mice. CrePos females, but not males, all died unexpectedly prior to 35 weeks. DC subsets were not significantly different between groups. Since ERα is necessary for robust development of DCs, this result suggests that DC fate was determined prior to CD11c expression and subsequent ERα deletion (i.e., proximally in DC ontogeny). Overall, findings point to a clear functional role for ERα in regulating cytokine signalling and inflammation, suggesting that further study into ERα-mediated regulatory mechanisms in DCs and other immune cell types is warranted.

The Effect of Age and Cell Culture Parameters on the Quantity and Function of Bone Marrow-derived Dendritic Cells.

Dendritic cells (DCs) are a group of bone marrow-derived cells that play a crucial role in innate and acquired immune responses. Bone marrow-derived dendritic cells (BMDC) are used in many studies, so the efficiency and purity of the differentiated cells are essential. This study aimed to investigate the effect of several parameters, including the age of mice, cell culture medium, and swirling of the culture plate, to increase the efficiency of the induced cells, considering the standard protocols. Bone marrow-derived dendritic cells were induced from both juvenile and adult mice bone marrow cells. Then, the purity of CD11c+ cells was compared between juvenile mice BMDCs and adult mice BMDCs. Cells were cultured in an enriched and non-enriched medium, and some wells were swirled when changing the medium on the 3rd day. Then the effect of enriched medium and swirling before medium replacement were evaluated based on the expression of the CD11c marker. The efficiency of DCs differentiation (CD11c+ cells) was higher when juvenile mouse bone marrow precursors were used compared to adult mice; using the enriched media with supplements and swirling the well before media replacement significantly affected the purity of immature CD11c+ cells. Due to our results, using juvenile mice, an enriched culture medium, and physical removal of granulocyte cells could significantly improve the purity and efficiency of CD11c+ cells. Therefore, considering these three items in the production protocol of these cells can probably reduce the use of lymphocyte-removing antibodies and purification methods.

Decreased CD11c-positive dendritic cells in the tumor microenvironment predict double-hit/triple-hit genotype and survival in diffuse large B-cell lymphoma.

Diffuse large B-cell lymphoma (DLBCL) is the most common type of non-Hodgkin lymphoma and is a potentially curable disease. However, it is heterogenous, and the prognosis is poor if the tumor cells harbor fusions involving MYC and BCL2 or MYC and BCL6 (double-hit [DH] lymphoma), or fusions involving all three genes (triple-hit [TH] lymphoma). Fluorescence in situ hybridization is currently the gold standard for confirming the presence of DH/TH genotypes. However, the test is laborious and not readily available in some laboratories. Germinal center B (GCB) signatures and dual expression of MYC and BCL2 are commonly used as initial screening markers (traditional model) in clinical practice. Our study proposes immunohistochemical markers for more conveniently and accessibly screening DH/TH genotypes in DLBCL. We retrospectively reviewed the clinical and pathological parameters of patients with DLBCL. We assessed the proliferative index, apoptotic index, and tumor microenvironment (TME), with regard to T cells and CD11c(+) dendritic cells, in formalin-fixed paraffin-embedded tissue. We then generated a decision tree as a screening algorithm to predict DH/TH genotypes and employed decision curve analysis to demonstrate the superiority of this new model in prediction. We also assessed the prognostic significance of related parameters. Our study revealed that GCB subtypes, a Ki67 proliferative index higher than 70%, and BCL2 expression were significantly associated with DH/TH genotypes. Decreased CD11c(+) dendritic cells in the TME indicated additional risk. Our proposed screening algorithm outperformed a traditional model in screening for the DH/TH genotypes. In addition, decreased CD11c(+) dendritic cells in the DLBCL TME were an independent unfavorable prognosticator. In conclusion, we provide a convenient, well-performing model that predicts DH/TH genotypes in DLBCL. The prognostic significance of CD11c(+) dendritic cells in the TME might influence the classification and development of immunotherapy for DLBCL in the future.

Splenic Dendritic Cells and Macrophages Drive B Cells to Adopt a Plasmablast Cell Fate.

Upon encountering cognate antigen, B cells can differentiate into short-lived plasmablasts, early memory B cells or germinal center B cells. The factors that determine this fate decision are unclear. Past studies have addressed the role of B cell receptor affinity in this process, but the interplay with other cellular compartments for fate determination is less well understood. Moreover, B cell fate decisions have primarily been studied using model antigens rather than complex pathogen systems, which potentially ignore multifaceted interactions from other cells subsets during infection. Here we address this question using a Plasmodium infection model, examining the response of B cells specific for the immunodominant circumsporozoite protein (CSP). We show that B cell fate is determined in part by the organ environment in which priming occurs, with the majority of the CSP-specific B cell response being derived from splenic plasmablasts. This plasmablast response could occur independent of T cell help, though gamma-delta T cells were required to help with the early isotype switching from IgM to IgG. Interestingly, selective ablation of CD11c+ dendritic cells and macrophages significantly reduced the splenic plasmablast response in a manner independent of the presence of CD4 T cell help. Conversely, immunization approaches that targeted CSP-antigen to dendritic cells enhanced the magnitude of the plasmablast response. Altogether, these data indicate that the early CSP-specific response is predominately primed within the spleen and the plasmablast fate of CSP-specific B cells is driven by macrophages and CD11c+ dendritic cells.

Rituximab in Systemic Lupus Erythematosus: Transient Effects on Autoimmunity Associated Lymphocyte Phenotypes and Implications for Immunogenicity.

B cell abnormalities are common in systemic lupus erythematosus (SLE), and include expansion of double negative (DN) and age-associated-like B cells (ABC-like). We aimed to investigate rituximab (RTX) effects on DN and ABC-like B-cell subsets and, when possible, also secondary effects on T cells. Fifteen SLE patients, fulfilling the ACR 1982 criteria, starting RTX and followed longitudinally up to two years, were analyzed for B- and T- lymphocyte subsets using multicolor flow cytometry. DN were defined as IgD-CD27- and ABC-like as CD11c+CD21- within the DN gate. Additional phenotyping was performed adding CXCR5 in the B-cell panel. Cellular changes were further analyzed in the context of the generation of anti-drug antibodies (ADA) against RTX and clinical information. The SLE patients were mainly females (86.6%), of median age 36.7 (29.8-49.4) years and disease duration of 6.1 (1.6-11.8) years. Within the DN subset, ABC-like (IgD-CD27-CD11c+CD21-) B cell frequency reduced from baseline median level of 20.4% to 11.3% (p=0.03), at early follow-up. The DN B cells were further subdivided based on CXCR5 expression. Significant shifts were observed at the early follow-up in the DN2 sub-cluster (CD11c+CXCR5-), which reduced significantly (-15.4 percentage points, p=0.02) and in the recently described DN3 (CD11c-CXCR5-) which increased (+13 percentage points, p=0.03). SLE patients treated with RTX are at high risk of developing ADA. In our cohort, the presence of ADA at 6 months was associated with lower frequencies of DN cells and to a more pronounced expansion of plasmablasts at early follow-up. The frequency of follicular helper T cells (TFH, CD4+PD-1+CXCR5+) and of peripheral helper T cells (TPH, CD4+PD-1+CXCR5-) did not change after RTX. A sub-cluster of PD-1highCD4+ T cells showed a significant decrease at later follow-up compared to early follow-up (p=0.0039). It is well appreciated that RTX transiently influences B cells. Here, we extend these observations to cell phenotypes which are believed to directly contribute to autoimmunity in SLE. We show early transient effects of RTX on ABC-like memory B cells, later effects on PD-1high CD4+ cells, and possible implications for RTX immunogenicity. Further insight in such effects and their monitoring may be of clinical relevance.

BMPR1a Is Required for the Optimal TGFß1-Dependent CD207+ Langerhans Cell Differentiation and Limits Skin Inflammation through CD11c+ Cells.

The cytokine TGFß1 induces epidermal Langerhans cell (LC) differentiation from human precursors, an effect mediated through BMPR1a/ALK3 signaling, as revealed from ectopic expression and receptor inhibition studies. Whether TGFß1‒BMPR1a signaling is required for LC differentiation in vivo remained incompletely understood. We found that TGFß1-deficient mice show defective perinatal expansion and differentiation of LCs. LCs can be identified within the normal healthy human epidermis by anti-BMPR1a immunohistology staining. Deletion of BMPR1a in all (vav+) hematopoietic cells revealed that BMPR1a is required for the efficient TGFß1-dependent generation of CD207+ LC-like cells from CD11c+ intermediates in vitro. Similarly, BMPR1a was required for the optimal induction of CD207 by preformed major histocompatibility complex II‒positive epidermal resident LC precursors in the steady state. BMPR1a expression is strongly upregulated in epidermal cells in psoriatic lesions, and BMPR1aΔCD11c mice showed a defect in the resolution phase of allergic and psoriatic skin inflammation. Moreover, whereas LCs from these mice expressed CD207, BMPR1a counteracted LC activation and migration from skin explant cultures. Therefore, TGFß1‒BMPR1a signaling seems to be required for the efficient induction of CD207 during LC differentiation in the steady state, and bone marrow‒derived lesional CD11c+ cells may limit established skin inflammation through enhanced BMPR1a signaling.

Characterization of Recruited Mononuclear Phagocytes following Corneal Chemical Injury.

Mononuclear phagocytes (MP) have central importance in innate immunity, inflammation, and fibrosis. Recruited MPs, such as macrophages, are plastic cells and can switch from an inflammatory to a restorative phenotype during the healing process. However, the role of the MPs in corneal wound healing is not completely understood. The purpose of this study is to characterize the kinetics of recruited MPs and evaluate the role of macrophage metalloelastase (MMP12) in the healing process, using an in vivo corneal chemical injury model. Unwounded and wounded corneas of wild-type (WT) and Mmp12-/- mice were collected at 1, 3, and 6 days after chemical injury and processed for flow cytometry analysis. Corneal MP phenotype significantly changed over time with recruited Ly6Chigh (proinflammatory) cells being most abundant at 1 day post-injury. Ly6Cint cells were highly expressed at 3 days post-injury and Ly6Cneg (patrolling) cells became the predominant cell type at 6 days post-injury. CD11c+ dendritic cells were abundant in corneas from Mmp12-/- mice at 6 days post-injury. These findings show the temporal phenotypic plasticity of recruited MPs and provide valuable insight into the role of the MPs in the corneal repair response, which may help guide the future development of MP-targeted therapies.

Differential expression of CD11c defines two types of tissue-resident macrophages with different origins in steady-state salivary glands.

Gland macrophages are primed for gland development and functions through interactions within their niche. However, the phenotype, ontogeny, and function of steady-state salivary gland (SG) macrophages remain unclear. We herein identified CD11c+ and CD11c- subsets among CD64+ macrophages in steady-state murine SGs. CD11c- macrophages were predominant in the SGs of embryonic and newborn mice and decreased with advancing age. CD11c+ macrophages were rarely detected in the embryonic period, but rapidly expanded after birth. CD11c+, but not CD11c-, macrophage numbers decreased in mice treated with a CCR2 antagonist, suggesting that CD11c+ macrophages accumulate from bone marrow-derived progenitors in a CCR2-dependent manner, whereas CD11c- macrophages were derived from embryonic progenitors in SGs. CD11c+ and CD11c- macrophages strongly expressed colony-stimulating factor (CSF)-1 receptor, the injection of an anti-CSF-1 receptor blocking antibody markedly reduced both subsets, and SGs strongly expressed CSF-1, indicating the dependency of SG resident macrophage development on CSF-1. The phagocytic activity of SG macrophages was extremely weak; however, the gene expression profile of SG macrophages indicated that SG macrophages regulate gland development and functions in SGs. These results suggest that SG CD11c+ and CD11c- macrophages are developed and instructed to perform SG-specific functions in steady-state SGs.

Adenosine receptor 2a agonists target mouse CD11c+T-bet+ B cells in infection and autoimmunity.

CD11c+T-bet+ B cells are recognized as an important component of humoral immunity and autoimmunity. These cells can be distinguished from other B cells by their higher expression of the adenosine receptor 2a. Here we address whether A2A receptor activation can affect CD11c+T-bet+ B cells. We show that administration of the A2A receptor agonist CGS-21680 depletes established CD11c+T-bet+ B cells in ehrlichial-infected mice, in a B cell-intrinsic manner. Agonist treatment similarly depletes CD11c+T-bet+ B cells and CD138+ B cells and reduces anti-nuclear antibodies in lupus-prone mice. Agonist treatment is also associated with reduced kidney pathology and lymphadenopathy. Moreover, A2A receptor stimulation depletes pathogenic lymphocytes and ameliorates disease even after disease onset, highlighting the therapeutic potential of this treatment. This study suggests that targeting the adenosine signaling pathway may provide a method for the treatment of lupus and other autoimmune diseases mediated by T-bet+ B cells.

Inflammatory macrophages exploit unconventional pro-phagocytic integrins for phagocytosis and anti-tumor immunity.

Blockade of the inhibitory checkpoint SIRPα-CD47 promotes phagocytosis of cancer cells by macrophages and is a promising avenue in anti-cancer therapy. Productive phagocytosis is strictly predicated on co-engagement of pro-phagocytic receptors-namely, Fc receptors (FcRs), integrin CD11b, or SLAMF7-by their ligands on cancer cells. Here, we examine whether additional pro-phagocytic receptors could be harnessed to broaden the scope of phagocytosis. Inflammatory stimuli, including multiple cytokines and Toll-like receptor (TLR) ligands, augment phagocytosis efficiency and fully alleviate the requirement of FcRs, CD11b, and SLAMF7 for phagocytosis. These effects are mediated by the unconventional pro-phagocytic integrins CD11a and CD11c, which act with CD18 to initiate actin polarization, leading to phagocytosis. Some inflammatory stimuli enable phagocytosis even in the absence of SIRPα-CD47 blockade. Higher CD11c expression in macrophage-enriched tumors correlates with improved survival in clinical studies. Thus, inflammatory macrophages exploit unconventional pro-phagocytic integrins for improved phagocytosis and anti-tumor immunity.

Targeting glycan sulfation in a CD11c+ myeloid population inhibits early KRAS-mutant lung neoplasia.

Early lung carcinoma development may be modulated by innate host cellular mechanisms that promote tumor growth and invasion. We recently identified how a loss-of-function mutation in the glycan sulfating enzyme N-deacetylase/N-sulfotransferase-1 (Ndst1; involved in heparan sulfate biosynthesis) targeted to antigen presenting cells (APCs) may augment acquired anti-tumor T cell immune mechanisms. Crossing this mutation (Ndst1f/f CD11cCre+) onto a model of inducible spontaneous Kras mutant lung cancer [CCSP-rtTA; (tetO7) CMV-Kras-G12D] allowed us to examine how the APC mutation affects the formation and growth of early lung carcinoma. We examined early bronchocentric adenoma formation in the model, and the frequency of such events was significantly reduced on the mutant background. This was associated with significant reductions in tumor associated FOXP3+ cellular infiltration and CD163+ M2-type macrophage infiltration. The findings evolved prior to effector CD8+ T cell infiltration into tumors. The impact of this unique glycan under-sulfating mutation on inhibiting early Kras G12D mutant bronchocentric adenoma formation along with a cellular phenotype of inhibited tumor infiltration by cells involved in suppressive T-regulatory cell signaling (FOXP3+ cells) or tumor-permissive M2 macrophage functions (CD163+ cells) provides insight on how glycan targeting may modulate innate cellular mechanisms during early lung tumor development. The findings may also impact the future design of host-centered immunologic anti-tumor therapeutic strategies.

Biologia Futura: stories about the functions of ß2-integrins in human phagocytes.

Integrins are essential membrane proteins that provide a tightly regulated link between the extracellular matrix and the intracellular cytoskeletal network. These cell surface proteins are composed of a non-covalently bound α chain and ß chain. The leukocyte-specific complement receptor 3 (CR3, αMß2, CD11b/CD18) and complement receptor 4 (CR4, αXß2, CD11c/CD18) belong to the family of ß2-integrins. These receptors bind multiple ligands like iC3b, ICAMs, fibrinogen or LPS, thus allowing them to partake in phagocytosis, cellular adhesion, extracellular matrix rearrangement and migration. CR3 and CR4 were generally expected to mediate identical functions due to their structural homology, overlapping ligand specificity and parallel expression on human phagocytes. Despite their similarities, the expression level and function of these receptors differ in a cell-type-specific manner, both under physiological and inflammatory conditions.We investigated comprehensively the individual role of CR3 and CR4 in various functions of human phagocytes, and we proved that there is a "division of labour" between these two receptors. In this review, I will summarize our current knowledge about this area.

Posttranslational modifications by ADAM10 shape myeloid antigen-presenting cell homeostasis in the splenic marginal zone.

The spleen contains phenotypically and functionally distinct conventional dendritic cell (cDC) subpopulations, termed cDC1 and cDC2, which each can be divided into several smaller and less well-characterized subsets. Despite advances in understanding the complexity of cDC ontogeny by transcriptional programming, the significance of posttranslational modifications in controlling tissue-specific cDC subset immunobiology remains elusive. Here, we identified the cell-surface-expressed A-disintegrin-and-metalloproteinase 10 (ADAM10) as an essential regulator of cDC1 and cDC2 homeostasis in the splenic marginal zone (MZ). Mice with a CD11c-specific deletion of ADAM10 (ADAM10ΔCD11c) exhibited a complete loss of splenic ESAMhi cDC2A because ADAM10 regulated the commitment, differentiation, and survival of these cells. The major pathways controlled by ADAM10 in ESAMhi cDC2A are Notch, signaling pathways involved in cell proliferation and survival (e.g., mTOR, PI3K/AKT, and EIF2 signaling), and EBI2-mediated localization within the MZ. In addition, we discovered that ADAM10 is a molecular switch regulating cDC2 subset heterogeneity in the spleen, as the disappearance of ESAMhi cDC2A in ADAM10ΔCD11c mice was compensated for by the emergence of a Clec12a+ cDC2B subset closely resembling cDC2 generally found in peripheral lymph nodes. Moreover, in ADAM10ΔCD11c mice, terminal differentiation of cDC1 was abrogated, resulting in severely reduced splenic Langerin+ cDC1 numbers. Next to the disturbed splenic cDC compartment, ADAM10 deficiency on CD11c+ cells led to an increase in marginal metallophilic macrophage (MMM) numbers. In conclusion, our data identify ADAM10 as a molecular hub on both cDC and MMM regulating their transcriptional programming, turnover, homeostasis, and ability to shape the anatomical niche of the MZ.

BCR activated CLL B cells use both CR3 (CD11b/CD18) and CR4 (CD11c/CD18) for adhesion while CR4 has a dominant role in migration towards SDF-1.

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in the western world. In previous studies, various proportion of patients was found to carry CD11b+ or CD11c+ B cells whose presence was an unfavourable prognostic factor. The exact mechanism however, how these receptors contribute to the pathogenesis of CLL has not been revealed so far. Here we analysed the role of CD11b and CD11c on B cells of CLL patients in the adhesion to fibrinogen and in the migration towards stromal cell derived factor-1 (SDF-1) and studied the role of CR4 in the adherence of the CD11c+ B cell line BJAB. We observed that both CR3 and CR4 mediate adhesion of the malignant B cells. Moreover, we found, that CR4 was strongly involved in the migration of the leukemic cells towards the chemoattractant SDF-1. Our data suggest that CR3 and CR4 are not only passive markers on CLL B cells, but they might contribute to the progression of the disease. Since the role of SDF-1 is prominent in the migration of CLL cells into the bone marrow where their survival is supported, our findings help to understand how the presence of CD11c on leukemic B cells can worsen the prognosis of chronic lymphocytic leukaemia.

CD11c participates in triggering acute graft-versus-host disease during bone marrow transplantation.

CD11c is a canonical dendritic cell (DC) marker with poorly defined functions in the immune system. Here, we found that blocking CD11c on human peripheral blood mononuclear cell-derived DCs (MoDCs) inhibited the proliferation of CD4+ T cells and the differentiation into IFN-γ-producing T helper 1 (Th1) cells, which were critical in acute graft-versus-host disease (aGVHD) pathogenesis. Using allogeneic bone marrow transplantation (allo-BMT) murine models, we consistently found that CD11c-deficient recipient mice had alleviated aGVHD symptoms for the decreased IFN-γ-expressing CD4+ Th1 cells and CD8+ T cells. Transcriptional analysis showed that CD11c participated in several immune regulation functions including maintaining antigen presentation of APCs. CD11c-deficient bone marrow-derived DCs (BMDCs) impaired the antigen presentation function in coculture assay. Mechanistically, CD11c interacted with MHCII and Hsp90 and participated in the phosphorylation of Akt and Erk1/2 in DCs after multiple inflammatory stimulations. Therefore, CD11c played crucial roles in triggering aGVHD and might serve as a potential target for the prevention and treatment of aGVHD.

Transcriptome and IgH Repertoire Analyses Show That CD11chi B Cells Are a Distinct Population With Similarity to B Cells Arising in Autoimmunity and Infection.

A distinct B cell population marked by elevated CD11c expression is found in patients with systemic lupus erythematosus (SLE). Cells with a similar phenotype have been described during chronic infection, but variable gating strategies and nomenclature have led to uncertainty of their relationship to each other. We isolated CD11chi cells from peripheral blood and characterized them using transcriptome and IgH repertoire analyses. Gene expression data revealed the CD11chi IgD+ and IgD- subsets were highly similar to each other, but distinct from naive, memory, and plasma cell subsets. Although CD11chi B cells were enriched in some germinal center (GC) transcripts and expressed numerous negative regulators of B cell receptor (BCR) activation, they were distinct from GC B cells. Gene expression patterns from SLE CD11chi B cells were shared with other human diseases, but not with mouse age-associated B cells. IgH V-gene sequencing analysis showed IgD+ and IgD- CD11chi B cells had somatic hypermutation and were clonally related to each other and to conventional memory and plasma cells. However, the IgH repertoires expressed by the different subsets suggested that defects in negative selection during GC transit could contribute to autoimmunity. The results portray a pervasive B cell population that accumulates during autoimmunity and chronic infection and is refractory to BCR signaling.

Prognostic Relevance of Macrophage Phenotypes in High-grade Oral Tongue Squamous Cell Carcinomas.

Tumor-associated macrophages (TAMs) are part of the tumor microenvironment, broadly divided into M1 and M2 phenotypes. M1 macrophages, commonly identified by staining the CD11c antigen, have an antitumour immunity role, while M2 macrophages, expressing the CD163 antigen, are involved in tumor progression. Little is known about M1 and M2 phenotypes in the context of the oral tongue squamous cell carcinomas (OTSCC), a subgroup of oral cancer with peculiar clinical behavior. This study evaluated the macrophage polarization in OTSCC specimens to examine their prognostic relevance. To this end, specimens from 71 OTSCC patients graded as G1 or G3 were investigated for CD11c and CD163 expression. Immunohistochemical staining of TAMs was evaluated in tumor nests, tumor inflammation area (TIA), and tumor stroma. To analyze the expression of CD11c and CD163, the percentage of positive cells was scored as 0 (negative), 1 (<10%), 2 (11% to 50%), 3 (51% to 80%), and 4 (>80%). The staining intensity was scored as 0 (negative), 1 (weak), 2 (moderate), and 3 (intense). Higher expression of both CD163+ and CD11c+ macrophages in inflammation area positively correlated with G3 grade, both in extension and intensity. Focusing on G3 tumors, survival curves showed better disease-free survival in patients with high CD11c expression in the TIA. Presence of CD163 expression in TIA was associated with worse disease-free survival. This study evaluated, for the first time, the distribution of M1 and M2 macrophages in relation to the pathologic grade in OTSCC, highlighting the prognostic relevance of analyzing the localization of TAMs.