Dendritic Cells In Response Research Articles

Obesity drives dysregulation in DC responses to viral infection

Abstract Introduction Obesity is a worldwide epidemic, with over 1 billion people worldwide living with obesity. It is associated with an increased risk of over 200 chronic co-morbidities, including an increased susceptibility to infection. Numerous studies have highlighted the dysfunction caused by obesity on a wide range of immune cell subsets, including dendritic cells (DCs). DCs are innate immune sentinels which bridge the innate and adaptive immune systems. DCs provide critical signals which instruct and shape the immune response. Our group has previously reported that DCs from people with obesity (PWO) display defective cytokine production, however the mechanisms underpinning these defects are unclear. Methods We investigated the functional responses of DCs using a murine-specific single-stranded RNA virus, Sendai virus (SeV), in mice on a standard diet and in a model of diet-induced obesity (DIO). Results Here, we demonstrate that GM-CSF cultured bone marrow-derived DCs (GM-DCs) from mice on a high fat diet (HFD) have reduced cytokine production following viral challenge. This was associated with a dysfunctional metabolism through reduced translation in the HFD GM-DCs. Conclusion We propose that obesity-mediated effects on DCs have downstream consequences on their ability to effectively mediate subsequent immune responses, especially during viral infection.

Dual-Targeting AIE Polymer Micelles Mediate Immunogenic Sonodynamic Therapy for Tumor Cell Growth Inhibition and Macrophage Reprogramming.

Sonodynamic therapy (SDT) is a promising cancer treatment known for its deep tumor penetration and high efficacy. However, developing highly efficient sonosensitizers remains a significant challenge. Reports on SDT using aggregation-induced emission luminogens (AIEgens) are rare, highlighting the urgent need for novel AIE-active sonosensitizers. For the first time, we have developed tumor- and macrophage-targeting nano micelles, AIE/Biotin/Mannose-M (ABM-M), utilizing aggregation-induced emission polymers. The ABM-M mediate immunogenic cell death through SDT. By reprogramming tumor-associated macrophages (TAMs), they promote the conversion of M2 macrophages into M1 macrophages, reversing the tumor's immunosuppressive environment. We optimized the ratio of functional molecules to achieve maximum fluorescence intensity and reactive oxygen species (ROS) generation. The multi-targeting nature of ABM-M enables them to bind to relevant antibodies or other molecules, enhancing the capture and presentation of tumor antigens. This, in turn, activates the immune responses of dendritic cells and T cells while inhibiting angiogenesis, creating a more favorable microenvironment for antitumor therapy. Furthermore, ABM-M can be combined with immune checkpoint inhibitors, such as anti-PD-L1 antibodies, to achieve promising outcomes in cancer immunotherapy. The ABM-M nanomaterials offer multi-layered and multi-targeting immune regulation. This study provides a blueprint for developing next-generation cancer diagnostic and therapeutic strategies. STATEMENT OF SIGNIFICANCE: Our research pioneers the use of nanomicelles to simultaneously target both tumor cells and tumor-associated macrophages (TAMs), integrated with sonodynamic therapy. Through precise ratio adjustments, we engineered nanomicelles capable of multi-target regulation. These micelles uniquely induce immunogenic cell death (ICD) and repolarize macrophages from an immunosuppressive M2 phenotype to an immunostimulatory M1 phenotype, reversing the tumor's immunosuppressive microenvironment. This dual mechanism can be enhanced by combining with immune checkpoint inhibitors, such as anti-PD-L1 antibodies, offering a promising strategy to treat refractory cancers. Extensive in vitro and in vivo validation confirms their therapeutic potential, providing a solid foundation for clinical application. This innovative approach shows significant promise for revolutionizing cancer treatment and improving patient outcomes.

DOP027 Caudovirales may trigger molecular mimicry mechanisms in Crohn’s Disease

Abstract Background Inflammatory Bowel Disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), has been increasingly associated with imbalances in the gut microbiota. Dysregulation within the gut virome has been linked to CD pathogenesis, with elevated levels of Caudovirales observed in CD patients1. Among them, we found the Proteus virus Isfahan species as considerably abundant in CD but absent in UC. We hypothesized that this virus can induce a potential molecular mimicry mechanism, causing a CD’s autoimmune response. This project aims to investigate whether Proteus virus Isfahan proteins exhibit homology with human proteins, potentially triggering an autoimmune response. Methods To assess Proteus virus Isfahan's correlation with CD, we utilized the IBD Transcriptome and Metatranscriptome Meta-Analysis (TaMMA) framework2, analyzing immune and non-immune cell populations from intestinal biopsies of CD patients and healthy controls. Cells, including CD4 and CD8 T cells, B cells, macrophages, dendritic cells, fibroblasts, and epithelial cells, were isolated using flow cytometry (FACS) and subjected to transcriptomic analysis. Furthermore, to investigate Proteus virus Isfahan’s role in CD, viral proteins were assessed for homology to human proteins using in silico tools such as NCBI BLAST and iPBA. Additionally, in vitro experiments coculturing T cells with immune cells overexpressing Proteus virus Isfahan proteins are underway to explore immune responses. Results Our analyses confirmed increased levels of Caudovirales, especially Proteus virus Isfahan, in cells from CD patients compared to controls, particularly in dendritic cells and macrophages. Gene ontology (GO) analysis indicated compromised responses in dendritic cells, while CD macrophages displayed upregulated viral-response pathways. Viral proteins gp16 and gp82 showed structural homology with human thymidylate synthase and dCMP deaminase, supporting the hypothesis of molecular mimicry. Results highlighted Proteus virus Isfahan as an activator of autoreactive T cells, contributing to CD-associated autoimmunity and disruption of intestinal cells. Conclusion These findings suggest that gut virome-associated Proteus virus Isfahan species play a role in CD pathogenesis through molecular mimicry. The viral proteins’ similarity to human proteins could lead to immune misrecognition, triggering autoimmunity and sustaining the inflammatory environment in CD patients. Ongoing experiments aim to validate these interactions and clarify the immune response, potentially identifying Proteus virus Isfahan as a target for novel therapeutic interventions.

Personalized Nanovaccine Based on STING-Activating Nanocarrier for Robust Cancer Immunotherapy.

Tumor-specific T cells play a vital role in potent antitumor immunity. However, their efficacy is severely affected by the spatiotemporal orchestration of antigen-presentation as well as the innate immune response in dendritic cells (DCs). Herein, we develop a minimalist nanovaccine that exploits a dual immunofunctional polymeric nanoplatform (DIPNP) to encapsulate ovalbumin (OVA) via electrostatic interaction when the nanocarrier serves as both STING agonist and immune adjuvant in DCs. In vitro results reveal that the nanocarrier induces STING activation via facilitating interferon regulatory factor 3 phosphorylation by block poly 18-crown-6-yl methacrylate (P18C6MA) mediated K+ perturbation cascade with endoplasmic reticulum stress, and stimulates DC maturation via the Toll-like receptor 4 activation by primary amine. In vivo studies indicate that the smart nanovaccine dramatically inhibits tumor growth with a long-term immune memory response in both the B16-OVA and EG7-OVA tumor models. After combination with programmed death ligand-1 antibody (aPD-L1), mice survival rate is notably prolonged. In addition, DIPNP forms a personalized nanovaccine after resected autologous primary tumor cell membranes decoration with a high antitumor activity in a homologous distant tumor model. The rational design provides inspiration for personalized nanovaccine construction via immunofunctional nanocarriers.

S100A8/A9 Promotes Dendritic Cell-Mediated Th17 Cell Response in Sjögren's Dry Eye Disease by Regulating the Acod1/STAT3 Pathway.

To investigate the role of S100A8/A9 in the pathogenesis of Sjögren's dry eye disease (SjDED) and explore its potential mechanism of action. S100A8/A9 expression was determined by western blot and quantitative real-time polymerase chain reaction (qRT-PCR). Tear secretion, corneal fluorescein staining, and hematoxylin and eosin staining were used to evaluate the effect of paquinimod, a S100A8/A9 inhibitor, on dry eye disease in nonobese diabetic (NOD) mice. Immune cell infiltration and percentage were assessed by immunofluorescence and flow cytometry. Proinflammatory cytokine levels were examined by qRT-PCR or ELISA. The mechanism of action was analyzed using western blot, immunofluorescence, and chromatin immunoprecipitation. S100A8/A9 was upregulated in peripheral blood mononuclear cells of patients with SjDED and lacrimal glands (LGs) of SjDED mice. The upregulation of S100A8/A9 was correlated with the dry eye severity and inflammatory infiltration levels in LGs. Administration of paquinimod ameliorated clinical and histopathological phenotypes of SjDED mice and reduced the proportion of Th17 cells in LGs, lymph nodes, and spleens. Further experiments revealed that S100A8/A9 did not directly affect Th17 generation and function but upregulated the expression of major histocompatibility complex Ⅱ (MHC Ⅱ) and Th17-polarizing cytokines in dendritic cells (DCs) to augment Th17 cell response. Mechanistically, S100A8/A9 induced the expression of Acod1 and thereby promoted the activation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3), resulting in increased Il23a transcription. STAT3 activator reversed the therapeutic effect of paquinimod on SjDED mice. S100A8/A9 activated the Acod1/STAT3 pathway to promote DC-driven Th17 cell responses in SjDED. The S100A8/A9/Acod1/STAT3 pathway may represent a promising therapeutic target for SjDED.

Molecular Mechanism of VSV-Vectored ASFV Vaccine Activating Immune Response in DCs.

The vesicular stomatitis virus (VSV)-vectored African swine fever virus (ASFV) vaccine can induce efficient immune response, but the potential mechanism remains unsolved. In order to investigate the efficacy of recombinant viruses (VSV-p35, VSV-p72)-mediated dendritic cells (DCs) maturation and the mechanism of inducing T-cell immune response, the functional effects of recombinant viruses on DC activation and target antigens presentation were explored in this study. The results showed that surface-marked molecules (CD80, CD86, CD40, and MHC-II) and secreted cytokines (IL-4, TNF-α, IFN-γ) were highly expressed in the recombinant virus-infected DCs. In addition, the co-culture results of recombinant virus-treated DCs with naive T cells showed that the Th1- and Th17-type responses were effectively activated. Taken together, the study indicated that the VSV-vectored ASFV vaccine activated the maturation of DCs and the Th1- and Th17-type immune response, which provided a theoretical basis for the development of novel ASF vaccines.

Bovine Lactoferrin Enhances Toll-like Receptor 7 Response in Plasmacytoid Dendritic Cells and Modulates Cellular Immunity.

Plasmacytoid dendritic cells (pDCs) express Toll-like receptor 7 (TLR7) in the endosomes, recognize viral single-stranded RNA (ssRNA), and produce significant amounts of interferon (IFN)-α. Bovine lactoferrin (LF) enhances the response of IFN regulatory factors followed by the activation of IFN-sensitive response elements located in the promoter regions of the IFN-α gene and IFN-stimulated genes in the TLR7 reporter THP-1 cells in the presence of R-848, a TLR7 agonist. In ex vivo experiments using human peripheral blood mononuclear cells, LF enhances IFN-α levels in the supernatant in the presence of R-848. Additionally, it increases the expression of IFN-α, human leukocyte antigen (HLA)-DR, and CD86 in pDCs; HLA-DR and CD86 in myeloid dendritic cells; CD69 in CD56 dim natural killer and T killer cells; and IFN-γ in T helper type 1 and B cells in the presence of R-848. The inhibition of phagocytosis or neutralization of nucleolin, a receptor of LF, suppresses LF incorporation into pDCs. These results suggest that pDCs incorporate LF through phagocytosis or nucleolin-mediated endocytosis, and LF enhances TLR7 response in the endosome and subsequent IFN signaling pathway and activates innate and adaptive immune cells. We anticipate that LF modulates antiviral immunity against environmental ssRNA viruses and contributes to homeostasis.

Engineered GM-CSF polarizes protumorigenic tumor-associated macrophages to an antitumorigenic phenotype and potently synergizes with IL-12 immunotherapy

BackgroundThe use of immune checkpoint inhibitors (CPIs) has become a dominant regimen in modern cancer therapy, however immune resistance induced by tumor-associated macrophages (TAMs) with immune suppressive and evasion properties...

Schistosoma heamatobium tetraspanins TSP-2 and TSP-6 induce Dendritic Cells maturation, cytokine production and T helper cells differentiation in vitro

Urogenital schistosomiasis caused by Schistosoma haematobium is a major cause of disability in endemic areas. Despite its socio-economic burden, no vaccine exists and the parasite's immunobiology remains underexplored. Genome annotation has revealed over 40 different genes encoding tetraspanins, transmembrane proteins with known immunomodulatory properties in other plathelminthes. This study investigated the role of Sh-TSP-2, Sh-TSP-6 and Sh-TSP-23, which are expressed in the parasite's tegument and extracellular vesicles (EVs). Immature dendritic cells (DCs) from unexposed healthy donors were stimulated with these proteins to evaluate maturation maker expression and cytokine production. Also, pre-activated T CD4+ cells were stimulated with the DCs supernatant to assess cytokine gene expression. Sh-TSP-2 and Sh-TSP-6 induced maturation markers and cytokine production in DCs: Sh-TSP-2 increased CD80 and CD83 levels and the concentration of both pro-inflammatory (IL-6, TNF) and regulatory (IL-10) cytokines, while Sh-TSP-6 increased the production of IL-6. Moreover, supernatants from Sh-TSP-2 stimulated DCs induced the expression of Th1 (IFNɣ) and regulatory (IL-10) cytokines in CD4+ T cells, while Sh-TSP-6 induced Th2 (IL-4, IL-13) cytokine expression. These results provide evidence that S. haematobium tetraspanins modulate the response of human DCs and CD4+ T cells in vitro, and support Sh-TSP-2 as a promising vaccine candidate.

Vitamin D3 alleviates intestinal injury in necrotizing enterocolitis and lipopolysaccharide-induced inflammatory response in dendritic cells in rats.

Necrotizing enterocolitis (NEC) is a serious condition that predominantly affects premature infants and involves an aberrant immune response and inflammatory cytokine release resulting in intestinal epithelial damage. The current study investigated the immunoregulatory effects of vitamin D3 on the maturation and activation of dendritic cells (DCs) and the antiinflammatory impact on the intestines in a neonatal rat model of NEC.Materials and methods: Inflammatory damage to intestinal tissue was assessed via morphological changes and apoptosis and DC expression of costimulatory molecules, inflammatory factors, and immunoregulatory factors by immunohistochemical staining, quantitative real-time PCR, and immunofluorescence. The fluorescein isothiocyanate-ovalbumin (FITC-OVA) uptake assay was used to analyze DC endocytosis. Vitamin D3 administration attenuated intestinal damage and apoptosis, inhibiting CD86 and increasing CD80 expression. Lipopolysaccharide (LPS)-challenged DC2.4 cells in vitro showed upregulated CD86, tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), and indoleamine 2,3-dioxygenase 1 (IDO-1) expression, which were all reduced by vitamin D3, except for IDO-1. LPS inhibited CD80 expression, which was restored by vitamin D3 treatment, and endocytic capacity was improved. Vitamin D3 ameliorated intestinal damage in neonatal rats with NEC and exerted antiinflammatory and immunomodulatory effects on DCs. Vitamin D3 has potential as a supplementary treatment for NEC patients.

Toll-like receptor 7 protects against intestinal inflammation and restricts the development of colonic tissue-resident memory CD8+ T cells.

The maintenance of intestinal homeostasis depends on a complex interaction between the immune system, intestinal epithelial barrier, and microbiota. Alteration in one of these components could lead to the development of inflammatory bowel diseases (IBD). Variants within the autophagy gene ATG16L1 have been implicated in susceptibility and severity of Crohn's disease (CD). Individuals carrying the risk ATG16L1 T300A variant have higher caspase 3-dependent degradation of ATG16L1 resulting in impaired autophagy and increased cellular stress. ATG16L1-deficiency induces enhanced IL-1β secretion in dendritic cells in response to bacterial infection. Infection of ATG16L1-deficient mice with a persistent strain of murine norovirus renders these mice highly susceptible to dextran sulfate sodium colitis. Moreover, persistent norovirus infection leads to intestinal virus specific CD8+ T cells responses. Both Toll-like receptor 7 (TLR7), which recognizes single-stranded RNA viruses, and ATG16L1, which facilitates the delivery of viral nucleic acids to the autolysosome endosome, are required for anti-viral immune responses. However, the role of the enteric virome in IBD is still poorly understood. Here, we investigate the role of TLR7 and ATG16L1 in intestinal homeostasis and inflammation. At steady state, Tlr7-/- mice have a significant increase in large intestinal lamina propria (LP) granzyme B+ tissue-resident memory CD8+ T (TRM) cells compared to WT mice, reminiscent of persistent norovirus infection. Deletion of Atg16l1 in myeloid (Atg16l1ΔLyz2 ) or dendritic cells (Atg16l1ΔCd11c ) leads to a similar increase of LP TRM. Furthermore, Tlr7-/- and Atg16l1ΔCd11c mice were more susceptible to dextran sulfate sodium colitis with an increase in disease activity index, histoscore, and increased secretion of IFN-γ and TNF-α. Treatment of Atg16l1ΔCd11c mice with the TLR7 agonist Imiquimod attenuated colonic inflammation in these mice. Our data demonstrate that ATG16L1-deficiency in myeloid and dendritic cells leads to an increase in LP TRM and consequently to increased susceptibility to colitis by impairing the recognition of enteric viruses by TLR7. In conclusion, the convergence of ATG16L1 and TLR7 signaling pathways plays an important role in the immune response to intestinal viruses. Our data suggest that activation of the TLR7 signaling pathway could be an attractive therapeutic target for CD patients with ATG16L1 risk variants.

Ebola Virus Infection of Flt3-Dependent, Conventional Dendritic Cells and Antigen Cross-presentation Leads to High Levels of T-Cell Activation.

Previous studies have described that Ebola virus (EBOV) infection of human monocyte-derived dendritic cells (moDCs) inhibits dendritic cell (DC) maturation, resulting in poor T-cell activation. However, it is unknown how other DC subsets distinct from moDCs respond to EBOV infection. To better understand how DCs initiate T-cell activation during EBOV infection, we assessed the response of conventional mouse DCs (cDCs) to EBOV infection utilizing a recombinant EBOV expressing the model antigen ovalbumin. In contrast to moDCs, mouse cDC2s and cDC1s were poorly infected with EBOV but were highly activated. DCs were able to prime CD8 T cells via cross-presentation of antigens obtained from cell debris of EBOV-infected cells. EBOV infection further enhanced DC cross-presentation. Our findings indicate that EBOV infection of cDCs results in activation rather than inhibition, leading to high levels of T-cell activation. With that we propose a mechanistic explanation for the excess T-cell activation observed in human Ebola virus disease.

Comparative Analysis of the Aspergillus fumigatus Cell Wall Modification and Ensuing Human Dendritic Cell Responses by β-(1,3)-Glucan Synthase Inhibitors-Caspofungin and Enfumafungin.

Caspofungin, a lipopeptide, is an antifungal drug that belong to the class of echinocandin. It inhibits fungal cell wall β-(1,3)-glucan synthase activity and is the second-line of drug for invasive aspergillosis, a fatal infection caused mainly by Aspergillus fumigatus. On the other hand, Enfumafungin is a natural triterpene glycoside also with a β-(1,3)-glucan synthase inhibitory activity and reported to have antifungal potential. In the present study, we compared the growth as well as modifications in the A. fumigatus cell wall upon treatment with Caspofungin or Enfumafungin, consequentially their immunomodulatory capacity on human dendritic cells. Caspofungin initially inhibited the growth of A. fumigatus, but the effect was lost over time. By contrast, Enfumafungin inhibited this fungal growth for the duration investigated. Both Caspofungin and Enfumafungin caused a decrease in the cell wall β-(1,3)-glucan content with a compensatory increase in the chitin, and to a minor extent they also affected cell wall galactose content. Treatment with these two antifungals did not result in the exposure of β-(1,3)-glucan on A. fumigatus mycelial surface. Enzymatic digestion suggested a modification of β-(1,3)-glucan structure, specifically its branching, upon Enfumafungin treatment. While there was no difference in the immunostimulatory capacity of antifungal treated A. fumigatus conidia, alkali soluble-fractions from Caspofungin treated mycelia weakly stimulated the dendritic cells, possibly due to an increased content of immunosuppressive polysaccharide galactosaminogalactan. Overall, we demonstrate a novel mechanism that Enfumafungin not only inhibits β-(1,3)-glucan synthase activity, but also causes modifications in the structure of β-(1,3)-glucan in the A. fumigatus cell wall.

Tissue Kallikrein-1 Suppresses Type I Interferon Responses and Reduces Depressive-Like Behavior in the MRL/lpr Lupus-Prone Mouse Model.

Excessive production and response to Type I interferons (IFNs) is a hallmark of systemic lupus erythematosus (SLE). Neuropsychiatric lupus (NPSLE) is a common manifestation of human SLE, with major depression as the most common presentation. Clinical studies have demonstrated that IFNα can cause depressive symptoms. We have shown that the kallikrein-kinin system (KKS) [comprised of kallikreins (Klks) and bradykinins] and angiotensin-converting enzyme inhibitors suppressed Type I IFN responses in dendritic cells from lupus-prone mice and human peripheral blood mononuclear cells. Tissue Klk genes are decreased in patients with lupus, and giving exogenous Klk1 ameliorated kidney pathology in mice. We retro-orbitally administered mouse klk1 gene-carrying adenovirus in the Murphy Roths Large lymphoproliferative (MRL/lpr) lupus-prone mice at early disease onset and analyzed immune responses and depressive-like behavior. Klk1 improved depressive-like behavior, suppressed interferon-responsive genes and neuroinflammation, and reduced plasma IFNα levels and proinflammatory cytokines. Klk1 also reduced IFNAR1 and JAK1 protein expression, important upstream molecules in Type I IFN signaling. Klk1 reduced bradykinin B1 receptor expression, which is known to induce proinflammatory response. Together, these findings suggest that Klk1 may be a potential therapeutic candidate to control IFNα production/responses and other inflammatory responses in SLE and NPSLE.

Peculiar transcriptional reprogramming with functional impairment of dendritic cells upon exposure to transformed HTLV-1-infected cells.

Manipulation of immune cell functions, independently of direct infection of these cells, emerges as a key process in viral pathophysiology. Chronic infection by Human T-cell Leukemia Virus type 1 (HTLV-1) is associated with immune dysfunctions, including misdirected responses of dendritic cells (DCs). Here, we interrogate the ability of transformed HTLV-1-infected T cells to manipulate human DC functions. We show that exposure to transformed HTLV-1-infected T cells induces a biased and peculiar transcriptional signature in monocyte-derived DCs, associated with an inefficient maturation and a poor responsiveness to subsequent stimulation by a TLR4 agonist. This poor responsiveness is also associated with a unique transcriptional landscape characterized by a set of genes whose expression is either conferred, impaired or abolished by HTLV-1 pre-exposure. Induction of this functional impairment requires several hours of coculture with transformed HTLV-1-infected cells, and associated mechanisms driven by viral capture, cell-cell contacts, and soluble mediators. Altogether, this cross-talk between infected T cells and DCs illustrate how HTLV-1 might co-opt communications between cells to induce a unique local tolerogenic immune microenvironment suitable for its own persistence.

Targeting Specific Kinase Substrates Rescues Increased Colitis Severity Induced by the Crohn's Disease-Linked LRRK2-N2081D Variant.

LRRK2 contains a kinase domain where both the N2081D Crohn's disease (CD) risk and the G2019S Parkinson's disease (PD)-pathogenic variants are located. The mechanisms by which the N2081D variant increase CD risk, and how these adjacent mutations result in distinct diseases, remain unclear. To investigate the pathophysiology of the CD-linked LRRK2 N2081D variant, we generated a knock-in (KI) mouse model and compared its effects to those of the LRRK2-G2019S mutation. We find that Lrrk2 N 2081 D KI mice demonstrate heightened sensitivity to induced colitis, resulting in more severe inflammation and intestinal damage than Lrrk2 G2019S KI and wild-type mice. Analysis of Colon tissue revealed distinct mutation-dependent LRRK2 RAB substrate phosphorylation, with significantly elevated phosphorylated RAB10 levels in Lrrk2 N2081D mice. In cells, we demonstrate that the N2081D mutation activates LRRK2 through a mechanism distinct from that of LRRK2-G2019S. We further find that proinflammatory stimulation enhances LRRK2 kinase activity, leading to mutation-dependent differences in RAB phosphorylation and inflammatory responses in dendritic cells. Finally, we show that genetic knockout of Rab12 , but not pharmacological LRRK2 kinase inhibition, significantly reduced colitis severity in Lrrk2 N2081D mice. Our study characterizes the pathogenic mechanisms of LRRK2-linked CD, highlights important structural and functional differences between disease-associated LRRK2 variants, and suggests RAB proteins as promising therapeutic targets for modulating LRRK2 activity in CD treatment.

Immune system adaptation during gender-affirming testosterone treatment

Infectious, inflammatory and autoimmune conditions present differently in males and females. SARS-CoV-2 infection in naive males is associated with increased risk of death, whereas females are at increased risk of long COVID1, similar to observations in other infections2. Females respond more strongly to vaccines, and adverse reactions are more frequent3, like most autoimmune diseases4. Immunological sex differences stem from genetic, hormonal and behavioural factors5 but their relative importance is only partially understood6–8. In individuals assigned female sex at birth and undergoing gender-affirming testosterone therapy (trans men), hormone concentrations change markedly but the immunological consequences are poorly understood. Here we performed longitudinal systems-level analyses in 23 trans men and found that testosterone modulates a cross-regulated axis between type-I interferon and tumour necrosis factor. This is mediated by functional attenuation of type-I interferon responses in both plasmacytoid dendritic cells and monocytes. Conversely, testosterone potentiates monocyte responses leading to increased tumour necrosis factor, interleukin-6 and interleukin-15 production and downstream activation of nuclear factor kappa B-regulated genes and potentiation of interferon-γ responses, primarily in natural killer cells. These findings in trans men are corroborated by sex-divergent responses in public datasets and illustrate the dynamic regulation of human immunity by sex hormones, with implications for the health of individuals undergoing hormone therapy and our understanding of sex-divergent immune responses in cisgender individuals.

TLR10 (CD290) Is a Regulator of Immune Responses in Human Plasmacytoid Dendritic Cells.

TLRs are the most thoroughly studied group of pattern-recognition receptors that play a central role in innate immunity. Among them, TLR10 (CD290) remains the only TLR family member without a known ligand and clearly defined functions. One major impediment to studying TLR10 is its absence in mice. A recent study on TLR10 knock-in mice demonstrated its intrinsic inhibitory role in B cells, indicating that TLR10 is a potential drug target in autoimmune diseases. In this study, we interrogated the expression and function of TLR10 in human plasmacytoid dendritic cells (pDCs). We have seen that primary human pDCs, B cells, and monocytes constitutively express TLR10. Upon preincubation with an anti-TLR10 Ab, production of cytokines in pDCs was downregulated in response to stimulation with DNA and RNA viruses. Upon further investigation into the possible mechanism, we documented phosphorylation of STAT3 upon Ab-mediated engagement of TLR10. This leads to the induction of inhibitory molecule suppressor of cytokine signaling 3 (SOCS3) expression. We have also documented the inhibition of nuclear translocation of transcription factor IFN regulatory factor 7 (IRF7) in pDCs following TLR10 engagement. Our data provide the (to our knowledge) first evidence that TLR10 is constitutively expressed on the surface of human pDCs and works as a regulator of their innate response. Our findings indicate the potential of harnessing the function of pDCs by Ab-mediated targeting of TLR10 that may open a new therapeutic avenue for autoimmune disorders.

Indirubin induces tolerogenic dendritic cells via aryl hydrocarbon receptor activation and ameliorates allergic asthma in a murine model by expanding Foxp3-expressing regulatory T cells

BackgroundAllergic asthma is a chronic bronchial inflammatory disease closely associated with abnormal immune responses of dendritic cells (DCs) and allergen-specific type 2 T helper (Th2) cells. Indirubin (IR), a natural aryl hydrocarbon receptor (AhR) ligand, exerts anti-inflammatory and immunomodulatory properties. PurposeIn this study, we aimed to clarify whether IR exhibits immunomodulatory action on DCs via AhR activation and investigated the antiallergic effects of IR in a mouse model of allergic asthma. MethodsLipopolysaccharide (LPS)-activated bone marrow-derived DCs were treated with IR. Their mRNA expressions, cytokine production, and phenotype patterns were determined by a quantitative real-time PCR, ELISA, flow cytometry, and RNA sequencing. The mixed lymphocyte reaction was utilized to evaluate the regulatory function of IR-treated DCs on T-cell differentiation. Moreover, mice with ovalbumin (OVA)-induced allergic asthma were treated with IR. Thereafter, the airway hyperresponsiveness (AHR), allergen-specific IgE production, cytokine levels, airway inflammation, and T-cell responses were evaluated. ResultsTreatment of LPS-stimulated DCs with 20 μM IR significantly reduced IL-12 and TNF-α production while increasing IL-10 secretion. Meanwhile, these DCs expressed decreased levels of CD80 but increased levels of Jagged 1 surface molecules. However, the effects of IR on DCs were reversed by pretreatment with the AhR antagonist, CH223191. Additionally, the coculture of these tolerogenic-like DCs with allogeneic CD4+T cells promoted the generation of Foxp3+ regulatory T (Treg) cells. A transcriptomic analysis identified several downregulated genes that are involved in regulating cell migration, cytokine secretion, and inflammatory responses in DCs after IR treatment. In an asthmatic murine model, oral administration of 25 mg kg-1 body weight of IR efficiently alleviated the development of AHR, OVA-specific IgE production, and levels of Th2-type cytokines (IL-4, IL-5, and IL-13) and the CCL11 chemokine. IR treatment also attenuated inflammatory cell recruitment and mucus production in the lungs. Notably, an enhanced frequency of Foxp3+ Treg cells and reduced effector T-cell proliferation associated with increased levels of IL-10 and TGF-β were observed in IR-treated mice. ConclusionIR can induce tolerogenic-like BMDCs which promote the differentiation of Treg cells. Importantly, the expansion of Foxp3+ Treg cells contributed to the therapeutic efficacy of IR against allergic asthma.

Lymph node-targeted STING agonist nanovaccine against chronic HBV infection

Chronic hepatitis B virus (HBV) infection is a global health problem that substantially increases the risk of developing liver disease. The development of a novel strategy to induce anti-HB seroconversion and achieve a long-lasting immune response against chronic HBV infection remains challenging. Here, we found that chronic HBV infection affected the signaling pathway involved in STING-mediated induction of host immune responses in dendritic cells (DCs) and then generated a lymph node-targeted nanovaccine that co-delivered hepatitis B surface antigen (HBsAg) and cyclic diguanylate monophosphate (c-di-GMP) (named the PP-SG nanovaccine). The feasibility and efficiency of the PP-SG nanovaccine for CHB treatment were evaluated in HBV-carrier mice. Serum samples were analyzed for HBsAg, anti-HBs, HBV DNA, and alanine aminotransferase levels, and liver samples were evaluated for HBV DNA and RNA and HBcAg, accompanied by an analysis of HBV-specific cellular and humoral immune responses during PP-SG nanovaccine treatment. The PP-SG nanovaccine increased antigen phagocytosis and DC maturation, efficiently and safely eliminated HBV, achieved a long-lasting immune response against HBV reinjection, and disrupted chronic HBV infection-induced immune tolerance, as characterized by the generation and multifunctionality of HBV-specific CD8+ T and CD4+ T cells and the downregulation of immune checkpoint molecules. HBV-carrier mice immunized with the PP-SG nanovaccine achieved partial anti-HBs seroconversion. The PP-SG nanovaccine can induce sufficient and persistent viral suppression and achieve anti-HBs seroconversion, rendering it a promising vaccine candidate for clinical chronic hepatitis B therapy.