TGF-β Signaling Prevents MHC Class II-Expressing Lymphatic Endothelial Cells from Reactivating Human Allogenic Memory CD4+ T Cells.

Lymphatic endothelial cells (LECs) express MHC class II (MHC-II) upon IFN-γ stimulation, yet recent evidence suggests that LECs cannot activate naive or memory CD4+ T cells. In this article, we show that IFN-γ-activated human dermal LECs can robustly reactivate allogeneic human memory CD4+ T cells (hCD4+ TMs), but only when TGF-β signaling is inhibited. We found that in addition to upregulating MHC-II, IFN-γ also induces LECs to upregulate glycoprotein A repetitions predominant, which anchors latent TGF-β to the membrane and potentially inhibits T cell activation.

Pro-lymphangiogenic VEGFR-3 signaling modulates memory T cell responses in allergic airway inflammation.

In allergic airway inflammation, VEGFR-3-mediated lymphangiogenesis occurs in humans and mouse models, yet its immunological roles, particularly in adaptive immunity, are poorly understood. Here, we explored how pro-lymphangiogenic signaling affects the allergic response to house dust mite (HDM). In the acute inflammatory phase, the lungs of mice treated with blocking antibodies against VEGFR-3 (mF4-31C1) displayed less inflammation overall, with dramatically reduced innate and T-cell numbers and reduced inflammatory chemokine levels.

Collagen-binding IL-12 enhances tumour inflammation and drives the complete remission of established immunologically cold mouse tumours.

Checkpoint-inhibitor (CPI) immunotherapy has achieved remarkable clinical success, yet its efficacy in 'immunologically cold' tumours has been modest. Interleukin-12 (IL-12) is a powerful cytokine that activates the innate and adaptive arms of the immune system; however, the administration of IL-12 has been associated with immune-related adverse events. Here we show that, after intravenous administration of a collagen-binding domain fused to IL-12 (CBD-IL-12) in mice bearing aggressive mouse tumours, CBD-IL-12 accumulates in the tumour stroma due to exposed collagen in the disordered tumour vasculature.

Recruitment of CD103 dendritic cells via tumor-targeted chemokine delivery enhances efficacy of checkpoint inhibitor immunotherapy.

Although a clinical breakthrough for cancer treatment, it remains that a minority of patients respond to checkpoint inhibitor (CPI) immunotherapy. The composition of tumor-infiltrating immune cells has been identified as a key factor influencing CPI therapy success. Thus, enhancing tumor immune cell infiltration is a critical challenge.

Tumor-associated factors are enriched in lymphatic exudate compared to plasma in metastatic melanoma patients.

Liquid biopsies allow monitoring of cancer progression and detection of relapse, but reliable biomarkers in melanoma are lacking. Because secreted factors preferentially drain to lymphatic vessels before dilution in the blood, we hypothesized that lymph should be vastly enriched in cancer biomarkers. We characterized postoperative lymphatic exudate and plasma of metastatic melanoma patients after lymphadenectomy and found a dramatic enrichment in lymphatic exudate of tumor-derived factors and especially extracellular vesicles containing melanoma-associated proteins and miRNAs, with unique protein signatures reflecting early versus advanced metastatic spread.

Targeted antibody and cytokine cancer immunotherapies through collagen affinity.

Cancer immunotherapy with immune checkpoint inhibitors (CPIs) and interleukin-2 (IL-2) has demonstrated clinical efficacy but is frequently accompanied with severe adverse events caused by excessive and systemic immune system activation. Here, we addressed this need by targeting both the CPI antibodies anti-cytotoxic T lymphocyte antigen 4 antibody (αCTLA4) + anti-programmed death ligand 1 antibody (αPD-L1) and the cytokine IL-2 to tumors via conjugation (for the antibodies) or recombinant fusion (for the cytokine) to a collagen-binding domain (CBD) derived from the blood protein von Willebrand factor (VWF) A3 domain, harnessing the exposure of tumor stroma collagen to blood components due to the leakiness of the tumor vasculature. We show that intravenously administered CBD protein accumulated mainly in tumors.

Improving Efficacy and Safety of Agonistic Anti-CD40 Antibody Through Extracellular Matrix Affinity.

CD40 is an immune costimulatory receptor expressed by antigen-presenting cells. Agonistic anti-CD40 antibodies have demonstrated considerable antitumor effects yet can also elicit serious treatment-related adverse events, such as liver toxicity, including in man. We engineered a variant that binds extracellular matrix through a super-affinity peptide derived from placenta growth factor-2 (PlGF-2) to enhance anti-CD40's effects when administered locally.

Matrix-binding checkpoint immunotherapies enhance antitumor efficacy and reduce adverse events.

Immune checkpoint blockade exhibits considerable antitumor activity, but previous studies have reported instances of severe treatment-related adverse events. We sought to explore local immune checkpoint blockade, with an antibody (Ab) form that would be retained intra- or peritumorally, limiting systemic exposure. To accomplish this, we conjugated the checkpoint blockade Abs to an extracellular matrix (ECM)-super-affinity peptide derived from placenta growth factor-2 (PlGF-2).

Tumor lymphangiogenesis promotes T cell infiltration and potentiates immunotherapy in melanoma.

In melanoma, vascular endothelial growth factor-C (VEGF-C) expression and consequent lymphangiogenesis correlate with metastasis and poor prognosis. VEGF-C also promotes tumor immunosuppression, suggesting that lymphangiogenesis inhibitors may be clinically useful in combination with immunotherapy. We addressed this concept in mouse melanoma models with VEGF receptor-3 (VEGFR-3)-blocking antibodies and unexpectedly found that VEGF-C signaling enhanced rather than suppressed the response to immunotherapy.

Exploiting lymphatic vessels for immunomodulation: Rationale, opportunities, and challenges.

Lymphatic vessels are the primary route of communication from peripheral tissues to the immune system; as such, they represent an important component of local immunity. In addition to their transport functions, new immunomodulatory roles for lymphatic vessels and lymphatic endothelial cells have come to light in recent years, demonstrating that lymphatic vessels help shape immune responses in a variety of ways: promoting tolerance to self-antigens, archiving antigen for later presentation, dampening effector immune responses, and resolving inflammation, among others. In addition to these new biological insights, the growing field of immunoengineering has begun to explore therapeutic approaches to utilize or exploit the lymphatic system for immunotherapy.

Lymph node stromal cells acquire peptide-MHCII complexes from dendritic cells and induce antigen-specific CD4⁺ T cell tolerance.

Dendritic cells (DCs), and more recently lymph node stromal cells (LNSCs), have been described to tolerize self-reactive CD8(+) T cells in LNs. Although LNSCs express MHCII, it is unknown whether they can also impact CD4(+) T cell functions. We show that the promoter IV (pIV) of class II transactivator (CIITA), the master regulator of MHCII expression, controls endogenous MHCII expression by LNSCs.

The number of Toll-like receptor 9-agonist motifs in the adenovirus genome correlates with induction of dendritic cell maturation by adenovirus immune complexes.

Adenovirus serotype 5 (Ad5) vectors and specific neutralizing antibodies (NAbs) generate immune complexes (ICs) which are potent inducers of dendritic cell (DC) maturation. Here we show that ICs generated with rare Ad vector serotypes, such as Ad26 and Ad35, which are lead candidates in HIV vaccine development, are poor inducers of DC maturation and that their potency in inducing DC maturation strongly correlated with the number of Toll-like receptor 9 (TLR9)-agonist motifs present in the Ad vector's genome. In addition, we showed that antihexon but not antifiber antibodies are responsible for the induction of Ad IC-mediated DC maturation.