InVivoMAb anti-mouse CD16/CD32

The TP53 gene (encoding the human p53 protein) is mutated in about 50% of non-small cell lung cancer (NSCLC). Loss of p53 is closely related to tumor metastasis and immune regulation, contributing to malignant progression and poor prognosis. However, therapeutic strategies for p53-loss NSCLC are still relatively limited. We found that DPEP2 is a diagnostic marker and predicts better outcome and prognosis in NSCLC with mutant TP53, but not with wild-type TP53. Loss of p53 induced DPEP2 downregulation at cellular and tissue levels. Functionally, DPEP2 inhibited the invasion and migration abilities, and decreased F-actin fibers. Mechanistically, DPEP2 impeded epithelial-mesenchymal transition (EMT) via the MAP3K7-mediated NF-κB signaling. Immunological analysis suggested that low level of DPEP2 and high level of M1 macrophages led to poor prognosis, whereas patients with high level of DPEP2 and low level of M2 had the best survival. Subsequently, a co-culture system was established to verify the effect of DPEP2 on M2 macrophages. The results showed that DPEP2 inhibited M2 macrophages polarization in a NF-κB-dependent manner. In addition, we found that DPEP2 antagonized the tumor-promoting effects of M2 macrophages by depleting LTD4. In vivo experiments indicated that high DPEP2 levels resulted in fewer lung metastases and less M2 macrophage infiltration. Overall, our studies suggest that DPEP2 might be a promising therapeutic target for highly metastatic p53-loss NSCLC by inhibiting tumor metastasis and M2 macrophage capacity.

Loss of function mutations of ORAI1 suppress store-operated Ca2+ entry (SOCE) and cause an immunodeficiency disorder called Ca2+ release-activated Ca2+ (CRAC) channelopathy. Here we report an infant patient who is compound heterozygous for p.His134Pro and p.Leu194Pro mutations in ORAI1 and whose T cells have strongly reduced SOCE. Whereas the p.Leu194Pro mutant ORAI1 protein is not expressed at the plasma membrane, the p.His134Pro mutation results in a constitutively open channel that is unresponsive to activation by stromal interaction molecule 1 (STIM1). The patient suffered from a severe form of combined immunodeficiency (CID), hemophagocytic lymphohistiocytosis (HLH) and fatal chronic cytomegalovirus infection. His immunodeficiency was characterized by an altered composition of T and NK cell compartments, impaired stimulation-induced cytokine production and signs of CD4+ T cell and NK cell activation but attenuated CD8+ T effector memory cell function. Our findings demonstrate that small constitutive SOCE through a mutant ORAI1 channel is not sufficient to provide immunity to viral infection.

In the non-obese diabetic (NOD) mouse model of autoimmune diabetes, interleukin (IL)-27 stimulates interferon γ (IFNγ) production by CD4 and CD8 T cells and is essential for disease development. Here, we tested the role of IL-27 in cellular communication. Single-cell RNA sequencing and T cell adoptive transfer showed that IL-27 intrinsically controlled the differentiation of islet-infiltrating CD4 T cells by driving them toward an IL-21+ Th1 phenotype. Consequently, IL-27 signaling in CD4 T cells was important for BATF and granzyme B expression in islet CD8 T effectors. BATF overexpression increased the diabetogenic potential of β cell autoreactive CD8 T cells lacking help from CD4 T cell-derived IL-21. Macrophages were the main source of IL-27 in the islets, whose expression correlated with T cell infiltration. IFNγ and CD40 signaling conferred by activated T cells induced macrophage IL-27 production. Collectively, our findings reveal a role for IL-27 in orchestrating interconnected positive feedback loops involving CD4 T cells, CD8 T cells, and macrophages in autoimmune diabetes.

Collective cell migration (CCM) is characterized by the coordinated movement of cell groups while maintaining cell-to-cell cohesion. Despite extensive research on CCM, the collective migration of mature epithelial cells over the extracellular matrix in response to external stimuli has not been reported. Using intravital imaging in mice, we identified urothelial CCM (UCCM) triggered by immunogenic substances, including bladder cancer cells (MB49) and uropathogenic Escherichia coli (UPEC). Integrin signaling inhibitors suppress UCCM, significantly enhancing MB49 tumor growth and UPEC bladder infection. UCCM initiation involves Toll-like receptor 4 (TLR4), we designated this TLR4-associated UCCM as the urothelial collective-gliding response (UCGR). Downstream of integrin signaling, urothelial matrix metalloproteinases (MMP)-8 and MMP-9 mediate UCGR. Intravesical instillation of these factors accelerates UCCM and inhibits tumor growth and infection. UCGR may represent a TLR4-associated defense mechanism, offering potential therapeutic strategies for bladder disorders such as refractory cystitis and recurrent non-muscle invasive bladder cancer after endoscopic resection.

LC3-associated phagocytosis (LAP) represents a non-canonical function of autophagy proteins in which ATG8-family proteins (LC3 and GABARAP proteins) are lipidated onto single-membrane phagosomes as particles are engulfed by phagocytic cells. LAP plays roles in innate immunity, inflammation and anticancer responses, and is initiated following phagocytosis of particles that stimulate Toll-like receptors (TLR) and Fc receptors as well as following engulfment of dying cells. However, how this molecular process is initiated remains elusive. Here we report that receptors that engage LAP enrich phosphatidylserine (PS) in the phagosome membrane via membrane-proximal domains that are necessary and sufficient for LAP to proceed. Subsequently, PS recruits the Rubicon-containing PI3-kinase complex to initiate the enzymatic cascade leading to LAP. Manipulation of plasma membrane PS content, PS binding by Rubicon or the PS-clustering domains of receptors prevents LAP and delays phagosome maturation. Therefore, the initiation of LAP represents a novel mechanism of PS-mediated signal transduction following ligation of surface receptors.

Glioblastoma (GBM) is an aggressive and highly therapy-resistant brain tumour1,2. Although advanced disease has been intensely investigated, the mechanisms that underpin the earlier, likely more tractable, stages of GBM development remain poorly understood. Here we identify axonal injury as a key driver of GBM progression, which we find is induced in white matter by early tumour cells preferentially expanding in this region. Mechanistically, axonal injury promotes gliomagenesis by triggering Wallerian degeneration, a targetable active programme of axonal death3, which we show increases neuroinflammation and tumour proliferation. Inactivation of SARM1, the key enzyme activated in response to injury that mediates Wallerian degeneration4, was sufficient to break this tumour-promoting feedforward loop, leading to the development of less advanced terminal tumours and prolonged survival in mice. Thus, targeting the tumour-induced injury microenvironment may supress progression from latent to advanced disease, thereby providing a potential strategy for GBM interception and control.

Small interfering RNA (siRNA) therapeutics are a new class of drugs that is rapidly expanding to tackle various diseases. Extrahepatic delivery of siRNAs, especially to the parenchyma of solid tumors, is challenging with multiple strategies being explored such as lipid nanoparticle based delivery and ligand conjugation strategies. Here, we report that an albumin-binding dendritic siRNA (D-siRNA) boosts blood circulation time following systemic administration, leading to improved delivery and silencing activity in a melanoma tumor model, in comparison to non-albumin binding lipophilic siRNAs. D-siRNAs increased the tumor-to-liver delivery ratio, including both immune and non-immune cell types within the tumor parenchyma. Using D-siRNAs to target JAK1 expression as an adjuvant to immune checkpoint inhibitors, we found that D-siRNAs was able to enhance PD1 antibody treatment and slow tumor progression of melanoma. Thus, this work demonstrates the utility of D-siRNAs as a systemically administered tumor delivery strategy, enabling the use of siRNAs as chemotherapeutic agents. Further mechanistic studies into the role of JAK1 in melanoma pathology and progression may expand this into additional targets as potential treatments.

Durable serological protection is maintained through the persistence of antigen-specific plasma cells (PCs), but key factors regulating the survival of nascent PCs remain unclear. Previously, we reported that bone marrow (BM) PCs partially organize into clusters that are enriched for long-lived PCs, suggesting that clusters are survival niches. Here, we report that acute blockade of a proliferation-inducing ligand (APRIL) and B cell activating factor (BAFF) using transmembrane activator and CAML interactor (TACI)-Fc rapidly disrupts clusters and mobilizes BM PCs. CD138, a surface co-receptor that is abundant on PCs and binds APRIL but not BAFF, regulates PC retention in the BM and adhesion and motility on fibronectin. Cell-intrinsic CD138 levels control competition for survival between nascent CD138low PCs and mature CD138high PCs, and enhanced survival of CD138high PCs correlates with retention in clusters. Collectively, these results indicate that PC clusters are survival niches and that dynamic competition between new and pre-existing PCs regulates the survival of new PCs and the durability of antibody responses.

Allergic reactions to foods are primarily driven by allergen-binding immunoglobulin (Ig)E antibodies. IgE-expressing cells can be generated through direct switching from IgM to IgE or a sequential class switching pathway where activated B cells first switch to an intermediary isotype, most frequently IgG1, and then to IgE. It has been proposed that sequential class switch recombination is involved in augmenting the severity of allergic reactions, generating high affinity IgE, differentiation of IgE plasma cells, and in holding the memory of IgE responses. We directly tested these possibilities by comparing the allergic immunity of wild-type and IgG1-deficient (hMT) mice. We found that sequential switching through IgG1 was not required to maintain the binding capacity of IgE nor for its ability to promote degranulation and elicit anaphylaxis against bona fide food allergens. Furthermore, the absence of sequential switching modestly impacted IgE affinity and clinical reactivity against hapten antigens, suggesting that the nature of the antigen impacts the requirement for sequential switching. At a cellular level, the capacity to undergo sequential switching through IgG1 provided no competitive advantage for subsequent IgE expression among germinal center B cells or plasma cells. Furthermore, the recall of allergic immunity at memory timepoints was preserved in the absence of sequential switching through IgG1, a finding that corresponded with intact type 2 memory B cell polarization. Together, these data demonstrate that sequential switching through IgG1 is redundant in sensitization, anaphylaxis, and the persistence of allergy, ultimately revealing that IgE derived from any switching source should be targeted by novel therapeutics seeking to ameliorate allergic diseases.

Despite the success of fructose as a low-cost food additive, epidemiological evidence suggests that high fructose consumption during pregnancy or adolescence is associated with disrupted neurodevelopment1-3. An essential step in appropriate mammalian neurodevelopment is the phagocytic elimination of newly formed neurons by microglia, the resident professional phagocyte of the central nervous system4. Whether high fructose consumption in early life affects microglial phagocytosis and whether this directly affects neurodevelopment remains unknown. Here we show that offspring born to female mice fed a high-fructose diet and neonates exposed to high fructose exhibit decreased phagocytic activity in vivo. Notably, deletion of the high-affinity fructose transporter GLUT5 (also known as SLC2A5) in neonatal microglia completely reversed microglia phagocytic dysfunction, suggesting that high fructose directly affects neonatal development by suppressing microglial phagocytosis. Mechanistically, we found that high-fructose treatment of mouse and human microglia suppresses phagocytosis capacity, which is rescued in GLUT5-deficient microglia. Additionally, we found that high fructose drives significant GLUT5-dependent fructose uptake and catabolism to fructose 6-phosphate, rewiring microglial metabolism towards a hypo-phagocytic state in part by enforcing mitochondrial localization of the enzyme hexokinase 2. Mice exposed to high fructose as neonates develop anxiety-like behaviour as adolescents-an effect that is rescued in GLUT5-deficient mice. Our findings provide a mechanistic explanation for the epidemiological observation that high-fructose exposure during early life is associated with increased prevalence of adolescent anxiety disorders.

Acute myeloid leukemia (AML) is a malignancy of immature myeloid blast cells with stem-like and chemoresistant cells being retained in the bone marrow through CXCL12-CXCR4 signaling. Current CXCR4 inhibitors that mobilize AML cells into the bloodstream have failed to improve patient survival, likely reflecting persistent chemokine receptor localization on target cells. Here we characterize the signaling properties of CXCL12-locked dimer (CXCL12-LD), a bioengineered variant of the naturally occurring oligomer of CXCL12. CXCL12-LD, in contrast to wild-type or locked monomer variants, was unable to induce chemotaxis in AML cells. CXCL12-LD binding to CXCR4 decreased G protein, β-arrestin, and intracellular calcium mobilization signaling pathways, and indicated the locked dimer is a partial agonist of CXCR4. Despite these partial agonist properties, CXCL12-LD increased CXCR4 internalization compared to wild-type and monomeric CXCL12. Analysis of a previously published AML transcriptomic data showed CXCR4 positive AML cells co-express genes involved in survival, proliferation, and maintenance of a blast-like state. The CXCL12-LD partial agonist effectively mobilized stem cells into the bloodstream in mice suggesting a potential role for their use in targeting CXCR4. Together, our results suggest that enhanced internalization by CXCL12-LD partial agonist can avoid pharmacodynamic tolerance and may identify new avenues to better target GPCRs.

Interferon-γ (IFN-γ) is an immunoregulatory cytokine essential for cellular immunity against intracellular pathogens, including Chlamydia. Interferon-stimulated gene (ISG) 15, a member of the ubiquitin family, contributes to host resistance to viral and bacterial infections. ISG15 can exist either in an unconjugated form or covalently attached to host proteins through a process known as ISGylation. Here, we show that infection with Chlamydia trachomatis (Ct) induces the expression and secretion of ISG15 in human primary cells and mouse female genital tract (FGT) organoids. ISG15 secretion by genital tract epithelial cells resulted in increased IFN-γ release from natural killer (NK) cells. The production of IFN-γ by NK cells in response to ISG15 was completely abolished in NK cells lacking the interleukin-18 receptor alpha (IL-18Ra), demonstrating a co-stimulatory effect of ISG15 with IL-18 in enhancing IFN-γ release. ISG15 was secreted into the FGT and was involved in controlling bacterial load in a murine infection model. Furthermore, ISG15 reduced macrophage responsiveness to IFN-γ as an M1-polarizing signal for pro-inflammatory responses, potentially "shielding" macrophages from excessive IFN-γ. Evidence of uterine horn pathology and reduced IL-10 levels in the FGT of infected ISG15-/- mice further supports a critical dual function of ISG15 in controlling chlamydial infection and modulating the resulting inflammatory responses.

Hematopoietic stem cell (HSC) transplantation offers a cure for a variety of blood disorders, predominantly affecting the elderly; however, its application, especially in this demographic, is limited by treatment toxicity. In response, we employ a murine transplantation model based on low-intensity conditioning protocols using antibody-mediated HSC depletion. While aging presents a significant barrier to effective HSC engraftment, optimizing HSC doses and non-genotoxic targeting methods greatly enhance the long-term multilineage activity of the transplanted cells. We demonstrate that young HSCs, once effectively engrafted in aged hosts, improve hematopoietic output and ameliorate age-compromised lymphopoiesis. This culminated in a strategy that robustly mitigates disease progression in a genetic model of myelodysplastic syndrome. These results suggest that non-genotoxic HSC transplantation could fundamentally change the clinical management of age-associated hematological disorders, offering a prophylactic tool to delay or even prevent their onset in elderly patients.

Tissue-resident macrophages (TRM) are critical for mammalian organismal development and homeostasis. Here we report that with-no-lysine 1 (WNK1) controls myeloid progenitor fate, with Csf1riCre-mediated Wnk1 deletion in mice (WNK1-deficient mice) resulting in loss of TRMs and causing perinatal mortality. Mechanistically, absence of WNK1 or inhibition of WNK kinase activity disrupts macrophage colony-stimulating factor (M-CSF)-stimulated macropinocytosis, thereby blocking mouse and human progenitor and monocyte differentiation into macrophages and skewing progenitor differentiation into neutrophils. Treatment with PMA rescues macropinocytosis but not macrophage differentiation of WNK-inhibited progenitors, implicating that M-CSF-stimulated, macropinocytosis-induced activation of WNK1 is required for macrophage differentiation. Finally, M-CSF-stimulated macropinocytosis triggers WNK1 nuclear translocation and concomitant increased protein expression of interferon regulatory factor (IRF)8, whereas inhibition of macropinocytosis or WNK kinase activity suppresses IRF8 expression. Our results thus suggest that WNK1 and downstream IRF8-regulated genes are important for M-CSF/macropinocytosis-mediated regulation of myeloid cell lineage commitment during TRM development and homeostasis.

The growing demand for advanced analytical techniques to explore complex cellular targets of nanotherapeutics has driven the development of innovative methodologies. This protocol presents a refined approach for fluorescent labeling and flow cytometric analysis of colonic cells following oral lipid nanoparticle (LNP) treatment, focusing on LNP uptake in colonic cell subpopulations in a DSS-induced colitis mouse model. By integrating optimized fluorochrome selection and gating strategies with advanced t-distributed stochastic neighbor embedding (t-SNE) analysis, this method enables precise identification and multidimensional visualization of LNP-targeted epithelial and macrophage populations under the complex conditions of inflamed colon tissue. Building on our previous studies demonstrating the effectiveness of nanoparticles in targeted drug delivery, this approach highlights the utility of flow cytometry for assessing uptake efficiency and cellular targeting. Unlike conventional protocols, it incorporates t-SNE for enhanced multidimensional analysis, allowing for the detection of subtle cellular patterns and the delineation of intricate clusters. By addressing gaps in traditional methodologies, this protocol provides a robust and reproducible framework for investigating in vivo cellular targets and optimizing drug delivery strategies for nanomedicines. Key features • This protocol is optimized for investigating nanoparticle uptake in inflamed colonic tissues from DSS-induced colitis models. • This protocol integrates flow cytometry with t-SNE for high-dimensional data analysis, enabling detailed characterization of cellular populations.

Neuronal hyperexcitability precedes synapse loss in certain neurodegenerative diseases, yet the synaptic membrane interactions and downstream signaling events remain unclear. The disordered amino terminus of the prion protein (PrPC) has been implicated in aberrant signaling in prion and Alzheimer's disease. To disrupt neuronal interactions and signaling linked to the amino terminus, we CRISPR-engineered a knockin mouse expressing mutant PrPC (G92N), generating an N-linked glycosylation site between 2 functional motifs. Mice developed seizures and necrosis of hippocampal pyramidal neurons, similar to prion-infected mice and consistent with excitotoxicity. Phosphoproteomics analysis revealed phosphorylated glutamate receptors and calcium-sensitive kinases, including protein kinase C (PKC). Additionally, 92N-PrPC-expressing neurons showed persistent calcium influx as well as dendritic beading, which was rescued by an N-methyl-d-aspartate receptor (NMDAR) antagonist. Finally, survival of Prnp92N mice was prolonged by blocking active NMDAR channels. We propose that dysregulated PrPC-NMDAR-induced signaling can trigger an excitatory-inhibitory imbalance, spongiform degeneration, and neurotoxicity and that calcium dysregulation is central to PrPC-linked neurodegeneration.

The lack of targetable antigens poses a significant challenge in developing effective cancer-targeted therapies. Cell surface translocation of endoplasmic reticulum (ER) chaperones, such as glucose-regulated protein 78 (GRP78), during malignancy, drug resistance, and ER stress induced by therapies, offers a promising pan-cancer target. To target GRP78, nanobody C5, identified from a phage library and exhibiting high affinity for human and mouse GRP78, is utilized to develop the Pseudomonas exotoxin (PE) immunotoxin C5-PE38. C5-PE38 induced ER stress, apoptosis and immunogenic cell death in targeted cells and showed antitumor efficacy against colorectal cancer and melanoma models without obvious toxicity. Mechanistically, transcriptome profiling showed that C5-PE38 reshaped the tumor immune microenvironment with enhanced innate and adaptive immune response and response to interferon beta. Moreover, C5-PE38-induced cell death could trans-activate STING pathway in dendritic cells and macrophages, promoting CD8+ T cell infiltration. It also sensitizes both primary and metastatic melanomas to anti-PD1 therapy, partly through STING activation. Overall, this study unveils a feasible GRP78 nanobody-directed therapy strategy for single or combinatorial cancer intervention. This work finds that C5-PE38-induced cell death stimulates STING-dependent cytosolic DNA release to promote antitumor immunity, a mechanism not previously reported for PE38, providing valuable insights for its clinical use.

Gastrointestinal (GI) cancers are a leading cause of cancer morbidity and mortality worldwide. Despite advances in treatment, cancer relapse remains a significant challenge, necessitating novel therapeutic strategies. In this study, we engineered nanobody-based chimeric antigen receptor (CAR) natural killer (NK) cells targeting cadherin 17 (CDH17) for the treatment of GI tumors. In addition, to enhance the efficacy of CAR-NK cells, we also incorporated CV1, a CD47-SIRPα axis inhibitor, to evaluate the anti-tumor effect of this combination. We found that CDH17-CAR-NK cells effectively eliminated GI cancers cells in a CDH17-dependent manner. CDH17-CAR-NK cells also exhibit potent in vivo anti-tumor effects in cancer cell-derived xenograft and patient-derived xenograft mouse models. Additionally, the anti-tumor activity of CDH17-CAR-NK cells is synergistically enhanced by CD47-signal regulatory protein α (SIRPα) axis inhibitor CV1, likely through augmented macrophages activation and an increase in M1-phenotype macrophages in the tumor microenvironment. Collectively, our findings suggest that CDH17-targeting CAR-NK cells are a promising strategy for GI cancers. The combination of CDH17-CAR-NK cells with CV1 emerges as a potential combinatorial approach to overcome the limitations of CAR-NK therapy. Further investigations are warranted to speed up the clinical translation of these findings.