InVivoMAb mouse IgG1 isotype control, unknown specificity

Cutaneous leishmaniasis, caused by protozoan parasites of the Leishmania genus, remains a significant health concern in endemic regions such as the Middle-East, Asia, Latin America, and North Africa. The disease affects millions of people worldwide, with over one million new infections reported annually. Despite its health impact, there is currently no approved vaccine largely due to limited understanding of immunological mechanisms underlying protective immunity and disease pathogenesis. We previously reported that long pentraxin 3 (PTX3), a pattern recognition molecule involved in inflammation, tissue repair, and wound healing, is a negative regulator of immunity in primary Leishmania major infection. Specifically, we showed that PTX3 exacerbates disease by suppressing protective Th17 responses. Here, we extend these findings by showing that PTX3 also influences secondary (memory) immunity to L. major. PTX3-deficient (PTX3-/-) mice which had resolved a primary infection exhibited enhanced resistance to secondary challenge compared to their wild-type (WT) controls. This enhanced resistance correlated with higher frequencies of effector memory CD4+ T cells in the spleens and draining lymph nodes. Upon re-infection, healed PTX3-/- mice produced significantly more IL-17A, while levels of IFN-γ, TNF-α, and IL-10 were similar. In vivo BrdU incorporation assays further revealed increased proliferation of IL-17+ CD4+ T cells in PTX3-/- mice. Importantly, neutralization of IL-17A during secondary challenge abolished the enhanced resistance observed in PTX3-/- mice, confirming a central role of IL-17 in PTX3-regulated secondary immunity. Collectively, our findings identify PTX3 as a key regulator of secondary immunity in cutaneous leishmaniasis and underscores the importance of IL-17 in this process.

Prostate cancer (PCa) is a malignancy with high heterogeneity arising from tumor microenvironment and histological subtypes. Identifying conserved progression drivers within such heterogeneity is essential for improving clinical outcomes. Using imaging mass cytometry, this study analyzes 38 proteins across paracancerous tissue and four histological subtypes: low-grade prostate acinar adenocarcinoma (LgPAC), high-grade PAC (HgPAC), intraductal carcinoma (IDC), and ductal adenocarcinoma (DAC). Results reveal that eIF1A is overexpressed in high-risk subtypes including HgPAC, IDC, and DAC and correlates with poor prognosis. In luminal cells, EIF1A knockdown and the translation inhibitor homoharringtonine (HHT) both suppress HIF-1α translation and tumor growth, while promoting infiltration of anticancer immune cells including PD-1- T cells and CD163- macrophages. Clinically, neoadjuvant HHT combined with androgen deprivation therapy reduces hypoxia and enhances immune cell infiltration, as shown by single-cell RNA sequencing. Collectively, this work defines conserved molecular features across PCa subtypes, providing promising insights for clinical management. This study was registered at Clinicaltrials.gov (NCT06834321).

The protective correlates of Mycobacterium tuberculosis (Mtb) infection-elicited host immune responses are incompletely understood. Here, we report pro-pathogenic crosstalk involving Ly6G+ granulocytes (Ly6G+Gra), IL-17, and COX2. We show that in the lungs of Mtb-infected wild-type mice, either BCG-vaccinated or not, most intracellular bacilli are Ly6G+Gra-resident 4 weeks post-infection onwards. In the genetically susceptible ifng-/- mice, excessive Ly6G+Gra infiltration correlates with severe bacteremia. Neutralizing IL-17 (anti-IL17mAb) and COX2 inhibition by celecoxib reverse Ly6G+Gra infiltration, associated pathology, and death in ifng-/- mice. Surprisingly, Ly6G+Gra also serves as the major source of IL-17 in the lungs of Mtb-infected WT or ifng-/- mice. The IL-17-COX2-Ly6G+Gra interplay also operates in WT mice. Inhibiting RORγt, the key transcription factor for IL-17 production or COX2, reduces the bacterial burden in Ly6G+Gra, leading to reduced bacterial burden and pathology in the lungs of WT mice. In the Mtb-infected WT mice, COX2 inhibition abrogates IL-17 levels in the lung homogenates and significantly enhances BCG's protective efficacy, mainly by targeting the Ly6G+Gra-resident Mtb pool, a phenotype also observed when IL-17 is blocked by RORγt inhibitor. Furthermore, in pulmonary TB patients, high neutrophil count and IL-17 correlated with adverse treatment outcomes. Together, our results suggest that IL-17 and PGE2 are the negative correlates of protection, and we propose targeting the pro-pathogenic IL-17-COX2-Ly6G+Gra axis for TB prevention and therapy.

Tumor-draining lymph nodes are a pivotal site for antitumor T-cell priming. However, their mechanistic roles in cancer immune surveillance and immunotherapy response remain poorly defined. Intratumor (IT) virotherapy generates antitumor T-cell immunity through multifaceted engagement of innate antiviral inflammation. In this study, we identify type-I interferon (IFNI) signaling in glioma-draining cervical lymph nodes as a mediator of IT polio virotherapy. Transient IFNI signaling after IT administration was rescued by cervical perilymphatic infusion (CPLI) virotherapy, targeting cervical lymph nodes directly. Dual-site (IT plus CPLI) virotherapy induced profound inflammatory reprogramming of cervical lymph nodes, enhanced viral RNA replication and IFNI signaling in dendritic cells and high endothelial venules, augmented antiglioma efficacy in mice, and was associated with T-cell activation in patients with recurrent glioblastoma. A phase II clinical trial of IT plus CPLI polio virotherapy is ongoing (NCT06177964). This study implicates the lymphatic system as a virotherapy target and demonstrates that CPLI virotherapy has the potential to complement brain tumor immunotherapy. See related Spotlight by Kaufman, p. 182.

Background: The switch to endothelial-to-mesenchymal transition (EndMT) in endothelial cells (ECs) induced by disturbed flow (d-flow) has been identified as the critical driver of the pathogenesis of inflammatory vascular disorders. We aimed to investigate the role of EndMT in abdominal aortic aneurysms (AAA) and the underlying mechanism. Methods: Immunoblotting, immunofluorescence and transmission electron microscope were used to assess d-flow-induced EndMT in human and mouse AAA models (Ang II/PPE). An Ibidi pump system was used to produce d-flow on human aortic endothelial cells (HAECs), and the expression of galectin-7 was enhanced and weakened using an adeno-associated virus. Furthermore, single-cell RNA sequencing was performed to explore the underlying mechanism of galectin-7-mediated EndMT. Results: EndMT induced by d-flow, which suppressed galectin-7 expression, was positively correlated with AAA. Enhanced galectin-7 expression inhibited d-flow-induced EndMT and AAA progression, whereas reduced galectin-7 expression resulted in the opposite effect. Mechanistically, we found a EndMT-related cluster in HAECs by single-cell RNA sequencing, and the SRGN gene in this cluster was considered the core gene. Galectin-7 bound competitively to the transcription factor CREB, resulting in the inhibition of SRGN transcription, which in turn prevented TGFβ/smad pathway activation, thereby restoring EndMT progression. Conclusions: EndMT transformation in ECs exposed to d-flow was the critical driver of AAA development. Furthermore, endothelium-enriched galectin-7 suppressed the EndMT process induced by d-flow and prevent AAA progression by transcriptionally inhibiting SRGN via competitive binding with CREB to restrict TGFβ/smad pathway.

Women diagnosed with metastatic triple negative breast cancer (mTNBC) have limited treatment options, are more prone to develop resistance and are associated with high mortality. A cold tumor immune microenvironment (TIME) characterized by low T cells and high tumor associated macrophages (TAMs) in mTNBC is associated with the failure of standard-of-care chemotherapy and immune checkpoint blockade (ICB) treatment. We demonstrate that the combination of immunomodulatory low-dose Cyclophosphamide (CTX) coupled with anti-CSF-1R antibody targeted therapy (SNDX-ms6352) and anti-PD-1 (ICB), was highly effective against aggressive metastatic Trp53 null TNBC transplantable syngeneic models that present with high macrophage infiltration. Mechanistically, CSF-1R inhibition along with CTX disrupted the M-CSF/CSF-1R axis which upregulated IL-17, IL-5 and type II interferon resulting in elevated B- and T cell infiltration. Addition of an anti-PD-1 maintenance dose helped overcome de novo PD-L1 intra-tumoral heterogeneity (ITH) associated recurrence in lung and liver mTNBC.

Neutrophil extracellular traps (NETs) are associated with cancer progression; however, the functional role and clinical importance of NET-DNA in therapeutic resistance remain unclear. Here, we show that chemotherapy and radiotherapy provoke NET-DNA formation in primary tumor and metastatic organs in breast cancer patients and mouse models, and the level of NET-DNA correlates with treatment resistance. Mechanistically, the cathepsin C in tumor debris generated by anticancer therapy is phagocytosed by macrophages and drives CXCL1/2 and complement factor B production via activating the TLR4/NF-κB signaling pathway, subsequently promoting NETosis and impairing therapeutic efficacy. Importantly, we demonstrate that NET-DNA sensor CCDC25 is indispensable in NET-mediated treatment resistance by inducing cancer cell epithelial-mesenchymal transition via pyruvate kinase isoform M2-mediated STAT3 phosphorylation. Clinically, tumoral CCDC25 abundance is closely associated with poor prognosis in patients who underwent chemotherapy. Overall, our data reveal the mechanism of NET formation and elucidate the interaction of NET-CCDC25 in therapy resistance, highlighting CCDC25 as an appealing target for anticancer interventions.

Head and neck squamous cell carcinoma (HNSCC) demonstrates suboptimal responses to current immune checkpoint inhibitors (ICIs), with objective response rates (ORRs) of merely 15-20%. The molecular mechanisms underlying these low ORRs remain incompletely defined. Here, two functionally distinct CD8⁺ T cell subsets are identified within the tumor microenvironment: precursor exhausted T (Texprog) cells and terminally exhausted T (Texterm) cells. Notably, although anti-PD-1 therapy reduced Texprog cell frequencies, it failed to reverse Texterm cells. Elevated Texterm cell infiltration correlated with advanced tumor-node-metastasis (TNM) staging and poor prognosis. Furthermore, non-responders exhibited significantly higher baseline Texterm proportions than responders before immunotherapy. Multivariate analysis established stromal Texterm cell density as both an independent prognostic factor and predictor of ICIs resistance. Mechanistically, Texterm cell infiltration strongly correlated with PD-L1 on tumor-derived extracellular vesicles (PD-L1+EVs). Most importantly, it is demonstrated that PD-L1+EVs drive Texterm cell differentiation by upregulating the basic leucine zipper transcription factor, ATF-like (BATF) in CD8⁺ T cells. Knocking out PD-L1 on EVs reduced Texterm cell infiltration and BATF expression. These findings elucidate an EV-mediated immune evasion axis and reveal actionable targets to overcome immunotherapy resistance.

The olfactory epithelium (OE) undergoes life-long renewal and regeneration. This process is supported by the globose basal cells (GBC) during the homeostatic state, as well as horizontal basal cells (HBC) during severe damage. Inflamm-aging refers to the low-grade, chronic and progressive state of heightened pro-inflammation associated with aging. However, the impact of inflamm-aging on OE homeostasis, regeneration, and the inflammatory microenvironment is not fully understood. In this study using mouse models, we elucidate the role of interleukin-17a (IL-17a) in OE regeneration and olfactory function. Our findings implicate that inflamm-aging in aged OE promotes the recruitment and activation of immune cells, accompanied by crosstalk between HBC and T cells. Elevated expression of IL-17a in aged OE triggers inflammatory signals and impairs olfactory function. Administration of IL-17a inhibitor Y-320 or neutralizing antibody promotes sensory neuronal regeneration and reverses age-related respiratory metaplasia in OE. Co-culturing mouse OE organoids with Th17 cells impairs neuronal generation and enhances the transformation towards respiratory cells, while neutralizing antibody against IL-17a alleviates neuronal loss and respiratory transformation. Additionally, conditional knockout of IL-17a in T cells facilitates OE regeneration by promoting HBC recruitment and differentiation into GBC. Collectively, our study identifies a function of IL-17a in OE regeneration and age-related deficits in olfactory function, providing evidence for further investigation of IL-17a as a possible therapeutic target against presbyosmia.

The management of bronchiectasis-asthma overlap (BAO) is an important clinical issue to be addressed. Little is known regarding the endotype of BAO. Here we recruit patients with a primary diagnosis of bronchiectasis and co-existing asthma. The levels of interleukin (IL)-17C are positively correlated with the levels of IL-17A or group 3 innate lymphoid cells (ILC3s) in peripheral blood samples from patients with BAO. An in vivo mouse model of Pseudomonas aeruginosa chronic lower respiratory tract infection followed by ovalbumin-induced asthma shows that IL-17C potentiates IL-17A expression via interacting with IL-17 receptor E in ILC3s. Additionally, ablation of Il17re in mice attenuates ILC3 responses and IL-17A-mediated asthma endotype switching towards neutrophilic asthma driven by P. aeruginosa chronic lower respiratory tract infection. Lastly, impaired epithelial barrier integrity by P. aeruginosa exposure is associated with IL-17C production in vitro. Collectively, our study implicates evidence for IL-17C governing IL-17A pathogenicity and promoting asthma endotype switching in bronchiectasis, implicating IL-17C as a potential therapeutic target for individuals with BAO.

We recently showed that cell surface translocation of the endoplasmic reticulum-resident protein GRP78, when bound by activated α 2-macroglobulin (α2M*), induces pro-fibrotic responses in glomerular mesangial cells in response to high glucose and regulates activation of the pro-fibrotic cytokine transforming growth factor-β1 (TGF-β1), implicating a pathogenic role in glomerulosclerosis. Interstitial fibrosis, largely mediated by proximal tubular epithelial cells (PTEC) and renal fibroblasts, develops later in kidney disease and correlates with functional decline. Here we investigated whether interstitial fibrosis was mediated by cell surface GRP78 (csGRP78)/α2M*. High glucose and TGF-β1 increased csGRP78 and α2M* in PTEC and renal fibroblasts, and their inhibition prevented fibrotic protein production. Interestingly, for TGF-β1, this depended on inhibition of noncanonical signaling through YAP/TAZ, with Smad3 activation unaffected. In vivo, type 1 diabetic Akita mice overexpressing TGF-β1 were treated with either a neutralizing antibody for csGRP78 (C38) or α2M* (Fα2M) or an inhibitory peptide blocking csGRP78/α2M* interaction, and mice with unilateral ureteral obstruction were treated with Fα2M or inhibitory peptide. Consistently, inhibition by antibody or peptide attenuated fibrosis and pro-fibrotic signaling. These findings show an important role for csGRP78/α2M* in mediating tubulointerstitial fibrosis in both diabetic and nondiabetic kidney disease and support their inhibition as a potential antifibrotic therapeutic intervention.

The microenvironment of distant organs affects the colonization and growth of disseminated tumor cells. It remains unclear how tumor-associated neutrophils are influenced by the microenvironment of distant organs. Here, we demonstrate that mature low-density neutrophils in colorectal cancer patients abnormally accumulate neutral lipids and induce the reactivation of dormant tumor cells, a process regulated by hepatic stellate cells. Mechanistically, activated hepatic stellate cells increased DGAT1/2-dependent lipid droplet synthesis in low-density neutrophils through the secretion of IL33, thereby maintaining the survival and immunosuppressive function of these neutrophils. The uptake of lipids from lipid-laden low-density neutrophils drives dormant tumor cell reactivation through the potentiation of β-oxidation and the stimulation of protumorigenic eicosanoid synthesis. In mouse models, targeting IL33 blocked neutrophil lipid synthesis, decreased the colonization of colorectal cancer cells in the liver, and enhanced the efficacy of immunotherapy. Overall, our study revealed that lipid accumulation in mature low-density neutrophils regulates the growth of dormant tumor cells and antitumor immunity to facilitate colorectal cancer liver metastasis. Targeting IL33 could be a promising therapeutic approach for colorectal cancer liver metastases.

Immune checkpoint blockade (ICB) therapy, especially in combination regimens, has significantly increased survival of renal cell carcinoma (RCC) patients. However, the ICB-resistant mechanisms remain largely unclear and require further investigation. Here, an immunosuppressive ecosystem in ICB-resistant tumors is identified, featured by preferential infiltration of MARCO+ tumor-associated macrophages (TAMs) and restrained cytotoxicity of CD8+ cytotoxic T lymphocytes (CTLs). The infiltrated MARCO+ TAMs can obstruct the development of CD8+ CTLs by impairing MHC-I-mediated neoantigen cross-presentation. Mechanistically, MARCO up-regulates the expression of SOCS1, which obstructs the kinase activity of JAK1, thereby downregulating MHC-I expression through the inhibition of the JAK1-STAT1-NLRC5 signaling cascade. Further, MARCO blockade significantly facilitates ICB therapy in in vivo models by recovering tumor recognition and priming anti-tumor CD8+ T cell responses. Taken together, these findings highlight MARCO as a highly desirable target in ICB-refractory individuals for immunorecognition reignition and immunotherapy modulation.

KRASG12C inhibitors (G12Ci) have produced encouraging, albeit modest and transient, clinical benefit in pancreatic ductal adenocarcinoma (PDAC). Identifying and targeting resistance mechanisms to G12Ci treatment are therefore crucial. To better understand the function of KRASG12C and possible G12Ci bypass mechanisms, we developed an autochthonous KRASG12C-driven PDAC model. Compared with the classical KRASG12D PDAC model, the G12C model exhibits slower tumor growth, yet similar histopathologic and molecular features. Aligned with clinical experience, G12Ci treatment of KRASG12C tumors produced modest impact despite stimulating a "hot" tumor immune microenvironment. Immunoprofiling revealed that CD24, a "do not eat me" signal, is significantly upregulated on cancer cells upon G12Ci treatment. Blocking CD24 enhanced macrophage phagocytosis of cancer cells and significantly sensitized tumors to G12Ci treatment. Similar findings were observed in KRASG12D-driven PDAC. Together, this study reveals common and distinct oncogenic KRAS allele-specific biology and identifies a clinically actionable adaptive mechanism that may improve the efficacy of oncogenic KRAS inhibitor therapy in PDAC.

Smoldering multiple myeloma (SMM), which is in principle curable, may develop into life-threatening MM. Intestinal microbiota and gut-born T helper-17 (Th17) lymphocytes may contribute to this development, but the mechanisms are unclear. Here we demonstrate that administering the human commensal Prevotella melaninogenica to transgenic Vk*MYC mice that exhibit SMM-like phenotypes delays the evolution to full-blown MM. Mechanistically, P. melaninogenica increases the production of short-chain fatty acids (SCFA), thereby preventing the skewing of dendritic cells towards a pro-Th17 phenotype and subsequently accumulation of Th17 cells in the bone marrow of treated mice. P. melaninogenica or butyrate synergizes with anti-PD-L1 or anti-TIGIT to suppress myeloma progression by restraining Th17 cell expansion while inducing effector CD8+ T cells. P. melaninogenica also attenuates IL-17-mediated skin lesions that mimic anti-PD-L1-induced adverse events. Our results thus suggest that gut microbiota modulation or SCFAs administration may represent treatment options for patients affected by plasma cell dyscrasias.

Cytomegalovirus is the leading viral cause of congenital infection with neurological sequelae. Effective medical treatments are limited due to an inadequate understanding of the underlying pathogenesis. Here, we applied single-cell transcriptomics to analyze neonatal mouse brains with congenital cytomegalovirus infection (cCMV). We profiled cCMV in 22 cell types and identified neural progenitor cells (NPCs) and monocyte-derived macrophages (MDMs) as the most commonly infected cells. Infected NPCs exhibited dysregulated neurodevelopment-associated signaling pathways, correlating with viral transcript levels that indicate viral replication levels. Genes associated with phagocytosis and antigen presentation were downregulated exclusively in infected MDMs but remained largely unaffected in microglia and barrier-associated macrophages regardless of infection status. Analysis of intrinsic and induced interferon-stimulated gene expression revealed great heterogeneity across cell types but no direct correlation with cCMV susceptibility. Furthermore, our findings indicate that interferon type II is crucial for the control of cCMV and consequent cortical damage and calcification in the neonatal brain. This study advances our understanding of cCMV tropism and the molecular details of cCMV-induced neurodevelopmental impairment, cerebral immune response, and brain pathology.

Cancer metastasis to sentinel lymph nodes (LNs) is often the first marker of potential disease progression. Although it is recognized that tumor-induced lymphangiogenesis facilitates metastasis into LNs in murine models, tumor-induced alterations in human lymphatic vessels remain obscure. Here we use single-cell RNA sequencing and high-resolution spatial transcriptomics to profile lymphatic endothelial cell (LEC) subsets in paired metastatic and non-metastatic LNs obtained from female patients with treatment-naïve breast cancer. Tumor metastasis decreases immunoregulatory LEC subsets, such as PD-L1+ subcapsular sinus LECs, while inducing an increase in capillary-like CD200+ HEY1+ LECs. Matrix Gla protein (MGP) is the most upregulated gene in metastatic LN LECs, and its expression on LECs is TGF-β and VEGF dependent. Upregulated MGP promotes cancer cell adhesion to LN lymphatics. Thus, breast cancer cell metastasis to LNs remodels LEC subsets in human LNs and escalates MGP expression, potentially facilitating cancer cell dissemination through the lymphatic system.

CD16a triggers antibody-dependent cellular cytotoxicity (ADCC) and phagocytosis by natural killer (NK) cells and macrophages in anti-tumor immunity. However, CD16a undergoes cleavage by ADAM17 that dampens its anti-tumor immunity. We here develop a monoclonal antibody (F9H4) that binds to CD16a and inhibits its cleavage. F9H4 retains CD16a on the surface of NK cells and macrophages, without triggering or blocking CD16a. F9H4 also binds to and inhibits shedding of CD16b by neutrophils, and inhibits CD16a/b shedding by leukocytes in tumor samples from lung cancer patients. F9H4 promotes ADCC against lung cancer cells that are opsonized by cetuximab, an epidermal growth factor receptor antibody that engages CD16a. F9H4 synergizes with cetuximab to inhibit human lung adenocarcinoma development in immunodeficient mice reconstituted with human NK cells. F9H4 combining with cetuximab also inhibits murine lung carcinoma growth in Fc gamma receptor-humanized mice, and such effect is mediated by NK cells and macrophages. The efficacy of F9H4+cetuximab in lung cancer models is the proof-of-concept for this new approach that promotes anti-tumor functions of Fc-enabled antibodies.