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

Mendelian randomization reveals association of gut microbiota with Henoch-Schönlein purpura and immune thrombocytopenia

Gut microbiota have been linked to immune thrombocytopenia (ITP) and Henoch-Schönlein purpura (HSP) in recent studies, but a cause-and-effect relationship is unclear. We used Mendelian randomization (MR) to assess causal relationships between gut microbiota and HSP/ITP using summary statistics from the GWAS dataset of the international MiBioGen and FinnGen consortium. The IVW method was used as the main evaluation indicator. MR analysis of 196 intestinal flora and HSP/ITP/sTP phenotypes showed that 12 flora were potentially causally associated with ITP, 6 with HSP, and 9 with sTP. The genes predicted that genus Coprococcus3 (p = 0.0264, OR = 2.05, 95% CI 1.09-3.88)and genus Gordonibacter (p = 0.0073, OR = 1.38; 95% CI 1.09-1.75) were linked to a higher likelihood of developing ITP. Additionally, family Actinomycetaceae (p = 0.02, OR = 0.51, 95% CI 0.28-0.90) and order Actinomycetales (p = 0.0199, OR = 0.50, 95% CI 0.28-0.90) linked to reduced HSP risk. Genus Ruminococcaceae UCG013 (p = 0.0426, OR = 0.44, 95% CI 0.20-0.97) negatively correlated with sTP risk. Our MR analyses offer evidence of a possible cause-and-effect connection between certain gut microbiota species and the likelihood of HSP/ITP.

Cholinergic signaling via the α7 nicotinic acetylcholine receptor regulates the migration of monocyte-derived macrophages during acute inflammation

BACKGROUND

The involvement of the autonomic nervous system in the regulation of inflammation is an emerging concept with significant potential for clinical applications. Recent studies demonstrate that stimulating the vagus nerve activates the cholinergic anti-inflammatory pathway that inhibits pro-inflammatory cytokines and controls inflammation. The α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages plays a key role in mediating cholinergic anti-inflammatory effects through a downstream intracellular mechanism involving inhibition of NF-κB signaling, which results in suppression of pro-inflammatory cytokine production. However, the role of the α7nAChR in the regulation of other aspects of the immune response, including the recruitment of monocytes/macrophages to the site of inflammation remained poorly understood.

RESULTS

We observed an increased mortality in α7nAChR-deficient mice (compared with wild-type controls) in mice with endotoxemia, which was paralleled with a significant reduction in the number of monocyte-derived macrophages in the lungs. Corroborating these results, fluorescently labeled α7nAChR-deficient monocytes adoptively transferred to WT mice showed significantly diminished recruitment to the inflamed tissue. α7nAChR deficiency did not affect monocyte 2D transmigration across an endothelial monolayer, but it significantly decreased the migration of macrophages in a 3D fibrin matrix. In vitro analysis of major adhesive receptors (L-selectin, β1 and β2 integrins) and chemokine receptors (CCR2 and CCR5) revealed reduced expression of integrin αM and αX on α7nAChR-deficient macrophages. Decreased expression of αMβ2 was confirmed on fluorescently labeled, adoptively transferred α7nAChR-deficient macrophages in the lungs of endotoxemic mice, indicating a potential mechanism for α7nAChR-mediated migration.

CONCLUSIONS

We demonstrate a novel role for the α7nAChR in mediating macrophage recruitment to inflamed tissue, which indicates an important new aspect of the cholinergic regulation of immune responses and inflammation.

Quercetin inhibits the activity and function of dendritic cells through the TLR4/IRAK4/NF-κB signalling pathway

Introduction

To investigate the inhibitory effect of quercetin (QUE) on dendritic cells (DCs) through the toll-like receptor 4/interleukin-1 receptor-associated kinase 4/nuclear factor kappa-B (TLR4/IRAK4/NF-κB) signalling pathway.

Material and methods

CCK-8 and apoptosis assays were performed to determine the optimal concentration and action time of QUE to inhibit DCs. Protein extracts from treated DCs were used for Western blotting experiments to determine the relative expression levels of TLR4, IRAK4, and NF-κB p65 proteins. Changes in the ratio of CD86 and CD11c positive cells on the DCs surface were detected using flow cytometry. The molecular docking technique was used to analyse the binding site and free energy of QUE and IRAK4.

Results

CCK-8 and apoptosis assays suggested that QUE inhibited the activity and function of DCs in a time-dose-dependent manner. The results of Western blotting suggested that the relative expression levels of TLR4, IRAK4, and NF-κB p65 proteins were increased in the lipopolysaccharide (LPS) group compared with the normal control group, and the relative expression of the above proteins was decreased after treatment with QUE and IRAK4-IN-4. The results of flow cytometry suggested that LPS increased the expression of CD86 and CD11c on the surface of DCs, and QUE and IRAK4-IN-4 decreased the expression of CD86 and CD11c induced by LPS. Molecular docking results showed that the binding sites of QUE and IRAK4 were stable, with the minimum binding energies comparable to that of IRAK4-IN-4.

Conclusions

Quercetin may inhibit the activity and function of DCs through the TLR4/IRAK4/NF-κB signalling pathway, and IRAK4 may be its target.

Gut microbiota and immune mediation: a Mendelian randomization study on granulomatosis with polyangiitis

Background

The gut microbiota plays a pivotal role in influencing various health outcomes, including immune-mediated conditions. Granulomatosis with Polyangiitis (GPA) is one such condition, and its potential associations with gut microbiota remain underexplored.

Method

Using a two-sample Mendelian randomization approach, we investigated the causal links between gut microbiota and GPA. We sourced our data from multiple cohorts and consortiums, including the MiBioGen consortium. Our study design incorporated both direct associations and mediation effects of immune traits on the relationship between gut microbiota and GPA.

Results

Our analysis revealed significant associations between 1 phylum, 1 family 9 genus microbiota taxa and GPA. Furthermore, we identified several immune cell traits that mediated the effects of gut microbiota on GPA. For instance, the family Defluviitaleaceae and genus Defluviitaleaceae UCG011 influenced GPA through CD11c in granulocytes. The mediation effect proportions further elucidated the complex dynamics between gut microbiota exposures, immune markers, and their combined influence on GPA.

Conclusion

Our findings underscore the intricate relationship between gut microbiota, immune markers, and GPA. The identified associations and mediation effects provide valuable insights into the potential therapeutic avenues targeting gut microbiota to manage GPA.

HEV-associated dendritic cells are observed in metastatic tumor-draining lymph nodes of cutaneous melanoma patients with longer distant metastasis-free survival after adjuvant immunotherapy

Introduction

Tissue biomarkers that aid in identifying cutaneous melanoma (CM) patients who will benefit from adjuvant immunotherapy are of crucial interest. Metastatic tumor-draining lymph nodes (mTDLN) are the first encounter site between the metastatic CM cells and an organized immune structure. Therefore, their study may reveal mechanisms that could influence patients´ outcomes.

Methods

Twenty-nine stage-III CM patients enrolled in clinical trials to study the vaccine VACCIMEL were included in this retrospective study. After radical mTDLN dissection, patients were treated with VACCIMEL (n=22) or IFNα-2b (n=6), unless rapid progression (n=1). Distant Metastasis-Free Survival (DMFS) was selected as an end-point. Two cohorts of patients were selected: one with a good outcome (GO) (n=17; median DMFS 130.0 months), and another with a bad outcome (BO) (n=12; median DMFS 8.5 months). We analyzed by immunohistochemistry and immunofluorescence the expression of relevant biomarkers to tumor-cell biology and immune cells and structures in mTDLN, both in the tumor and peritumoral areas.

Results

In BO patients, highly replicating Ki-67+ tumor cells, low tumor HLA-I expression and abundant FoxP3+ lymphocytes were found (p=0.037; p=0.056 and p=0.021). In GO patients, the most favorable biomarkers for prolonged DMFS were the abundance of peri- and intra-tumoral CD11c+ cells (p=0.0002 and p=0.001), peri-tumoral DC-LAMP+ dendritic cells (DCs) (p=0.001), and PNAd+ High Endothelial Venules (HEVs) (p=0.004). Most strikingly, we describe in GO patients a peculiar, heterogeneous structure that we named FAPS (Favoring Antigen-Presenting Structure), a triad composed of DC, HEV and CD62L+ naïve lymphocytes, whose postulated role would be to favor tumor antigen (Ag) priming of incoming naïve lymphocytes. We also found in GO patients a preferential tumor infiltration of CD8+ and CD20+ lymphocytes (p=0.004 and p=0.027), as well as peritumoral CD20+ aggregates, with no CD21+ follicular dendritic cells detected (p=0.023). Heterogeneous infiltration with CD64+CD68-CD163-, CD64+CD68+CD163- and CD64+CD68+CD163+ macrophages were observed in both cohorts.

Discussion

The analysis of mTDLN in GO and BO patients revealed marked differences. This work highlights the importance of analyzing resected mTDLN from CM patients and suggests a correlation between tumor and immune characteristics that may be associated with a spontaneous or vaccine-induced long DMFS. These results should be confirmed in prospective studies.

Upconversion Nanoplatform Enables Multimodal Imaging and Combinatorial Immunotherapy for Synergistic Tumor Treatment and Monitoring

Designing a novel nanoplatform that integrates multimodal imaging and synergistic therapy for precision tumor nanomedicines is challenging. Herein, we prepared rare-earth ion-doped upconversion hydroxyapatite (FYH) nanoparticles as nanocarriers coated and loaded respectively with polydopamine (PDA) and doxorubicin (DOX), i.e., FYH-PDA-DOX, for tumor theranostics. The developed FYH-PDA-DOX complexes exhibited desirable photothermal conversion, pH/near-infrared-irradiation-responsive DOX release, and multimodal upconversion luminescence/computed tomography/magnetic resonance imaging performance and helped monitor the metabolic distribution process of the complexes and provided feedback to the therapeutic effect. Upon 808 nm laser irradiation, the fast release of DOX facilitated the photothermal-chemotherapy effect, immunogenic cell death, and antitumor immune response. On combining with the anti-programmed cell death 1 ligand 1 antibody, an enhanced tri-mode photothermal-chemo-immunotherapy synergistic treatment against tumors can be realized. Thus, this treatment elicited potent antitumor immunity, producing appreciable T-cell cytotoxicity against tumors, amplifying tumor suppression, and extending the survival of mice. Therefore, the FYH-PDA-DOX complexes are promising as a smart nanoplatform for imaging-guided synergistic cancer treatment.

Anticipation of Relapse and Acute Graft-Versus-Host Disease after Allogeneic Peripheral Blood Stem Cell Transplantation: The Fundamental Role of Antigen-Presenting (Dendritic) Cells

Background

Dendritic cells (DCs) are antigen-presenting cells. In humans two distinct lineages of DCs exist: DC1 and DC2. Efforts to explore the role of DCs in acute graft-versus-host disease (aGVHD) after allogeneic peripheral blood stem-cell transplantation (PBSCT) are gaining traction. However, further research is needed to identify particular lineages and their values in terms of developing an evidence-based aGVHD- or relapse-prevention strategy. We monitored DC counts and subsets in PBSC grafts while harvesting stem cells in recipients to elucidate their value in anticipating disease relapse or aGVHD.

Methods

We enrolled 29 participants. Using fluorescence-activated cell sorting, total counts/kg of CD34⁺, DCs, and DC subsets were analyzed in 29 PBSC-graft components using CMRF44, CD11c, and CD4 monoclonal antibodies (MoAbs).

Results

In the 29 grafts, we detected a significant positive correlation (P<0.01) between DCs and both DC1 and DC2. Significantly higher counts (P<0.01) of DCs and DC1 in those who had developed aGVHD (nine cases) were also observed. Relapsed cases (two) were also associated with higher counts of DCs and DC2. A significant positive correlation (P<0.05), was recorded between DCs and DC1 counts and the day of myeloid engraftment, while this was not detected on the day of platelet engraftment. Myeloid engraftment transpired earlier in patients without aGVHD. Increased DC-graft numbers, particularly DC1 measured by CD11c Moabs, were associated with aGVHD. Recipients of higher numbers of CD4^bright DCs had an increased risk of relapse after allogeneic PBSCT.

Conclusion

This study analyzed DCs in PBSC grafts, using novel specific MoAbs and flow cytometry. Our data showed that higher donor DC1 counts were linked to the incidence of aGVHD and DC2 with relapse. We propose a fundamental role for DC-graft monitoring in anticipating aGVHD and disease relapse.