The rate of light delivery (fluence rate) plays a critical role in photodynamic therapy (PDT) through its control of tumor oxygenation. This study tests the hypothesis that fluence rate also influences the inflammatory responses associated with PDT. PDT regimens of two different fluences (48 and 128 J/cm 2 ) were designed for the Colo 26 murine tumor that either conserved or depleted tissue oxygen during PDT using two fluence rates (

Photodynamic therapy (PDT) is a Food and Drug Administration-approved local cancer treatment that can be curative of early disease and palliative in advanced disease. PDT of murine tumors results in regimen-dependent induction of an acute local inflammatory reaction, characterized in part by rapid neutrophil infiltration into the treated tumor bed. In this study, we show that a PDT regimen that induced a high level of neutrophilic infiltrate generated tumor-specific primary and memory CD8 + T-cell responses. In contrast, immune cells isolated from mice treated with a PDT regimen that induced little or no neutrophilic infiltrate exhibited minimal antitumor immunity. Mice defective in neutrophil homing to peripheral tissues (CXCR2 À/À mice) or mice depleted of neutrophils were unable to mount strong antitumor CD8 + T-cell responses following PDT. Neutrophils seemed to be directly affecting T-cell proliferation and/or survival rather than dendritic cell maturation or T-cell migration. These novel findings indicate that by augmenting T-cell proliferation and/or survival, tumor-infiltrating neutrophils play an essential role in establishment of antitumor immunity following PDT. Furthermore, our results may suggest a mechanism by which neutrophils might affect antitumor immunity following other inflammation-inducing cancer therapies. Our findings lay the foundation for the rational design of PDT regimens that lead to optimal enhancement of antitumor immunity in a clinical setting. Immune-enhancing PDT regimens may then be combined with treatments that result in optimal ablation of primary tumors, thus inhibiting growth of primary tumor and controlling disseminated disease. [Cancer Res 2007;67(21):10501-10]

Mammalian genomes encode up to four Notch receptors (Notch1-4) and five Notch ligands of the DSL (Delta/Serrate/Lag-2) family, and Notch signaling controls a wide spectrum of developmental processes. Intrathymic Notch1 signaling is essential for several distinct aspects of early T cell development. Notch signaling has also been implicated as a key regulator of peripheral T cell activation and effector cell differentiation, but its functions in these processes remain poorly understood. Notch signaling is dispensable for B cell development in the bone marrow, but it is required to generate the innate-like marginal zone B cell subset in the spleen and may also regulate plasma cell functions. Modification of Notch receptors by fringe glycosyltransferases influences many Notch-dependent aspects of hematopoiesis by altering Notch responsiveness to Delta-like versus Jagged DSL ligands. Here we review recent advances in general aspects of Notch signaling, as well as studies probing Notch functions in these immunological processes.

SUMMARY Basal-like breast cancers (BLBC) express a luminal progenitor gene signature. Notch receptor signaling promotes luminal cell fate specification in the mammary gland, while suppressing stem cell self-renewal. Here we show that deletion of Lfng, a sugar transferase that prevents Notch activation by Jagged ligands, enhances stem/progenitor cell proliferation. Mammary-specific deletion of Lfng induces basal-like and claudin-low tumors with accumulation of Notch intracellular domain fragments, increased expression of proliferation-associated Notch targets, amplification of the Met/Caveolin locus, and elevated Met and Igf-1R signaling. Human BL breast tumors, commonly associated with JAGGED expression, elevated MET signaling, and CAVEOLIN accumulation, express low levels of LFNG. Thus, reduced LFNG expression facilitates JAG/NOTCH luminal progenitor signaling and cooperates with MET/CAVEOLIN basal-type signaling to promote BLBC.

No abstract

The ability of NK cells to mediate Ab-dependent cellular cytotoxicity (ADCC) largely contributes to the clinical success of antitumor Abs, including trastuzumab, which is approved for the treatment of breast cancer with HER2/neu overexpression. Notably, only ∼25% of breast cancer patients overexpress HER2/neu. Moreover, HER2/neu is expressed on healthy cells, and trastuzumab application is associated with side effects. In contrast, the ligands of the activating immunoreceptor NKG2D (NKG2DL) are selectively expressed on malignant cells. In this study, we took advantage of the tumor-associated expression of NKG2DL by using them as target Ags for NKG2D-IgG1 fusion proteins optimized by amino acid exchange S239D/I332E in their Fc part. Compared to constructs with wild-type Fc parts, fusion proteins carrying the S239D/I332E modification (NKG2D–Fc–ADCC) mediated highly enhanced degranulation, ADCC, and IFN-γ production of NK cells in response to breast cancer cells. NKG2D–Fc–ADCC substantially enhanced NK reactivity also against HER2/neu-low targets that were unaffected by trastuzumab, as both compounds mediated their immunostimulatory effects in strict dependence of target Ag expression levels. Thus, in line with the hierarchically organized potential of the various activating receptors governing NK reactivity and due to its highly increased affinity to CD16, NKG2D–Fc–ADCC potently enhances NK cell reactivity despite the inevitable reduction of activating signals upon binding to NKG2DL. Due to the tumor-restricted expression of NKG2DL, NKG2D–Fc–ADCC may constitute an attractive means for immunotherapy especially of HER2/neu-low or -negative breast cancer.

Notch activation plays an important role in T cell development and mature T cell differentiation. In this study we investigated the role of Notch activation in a mouse model of Respiratory Syncytial Virus (RSV)-exacerbated allergic airway disease. During RSV exacerbation, in vivo neutralization of a specific Notch ligand, Delta-like 4 (Dll4) significantly decreased airway hyperreactivity (AHR), mucus production and Th2 cytokines. Lunatic Fringe (Lfng) a glycosyltransferase that enhances Notch activation by Dll4 was increased during RSV exacerbation. Lfng loss of function in Th2 skewed cells inhibited Dll4-Notch activation and subsequent IL-4 production. Further knockdown of Lfng in T cells in CD4Cre+Lfngfl/fl mice showed reduced Th2 response and disease pathology during RSV exacerbation. Finally, we identified STAT5-binding cis-acting regulatory element activation as a critical driver of Lfng transcriptional activation. These data demonstrate that STAT5-dependent amplification of Notch modifying Lfng augments Th2 response via Dll4 and is critical for amplifying viral exacerbation during allergic airway disease.

Notch1 (N1) signaling induced by intrathymic Delta-like (DL) ligands is required for T cell lineage commitment as well as self-renewal during “β-selection” of TCRβ+ CD4−CD8− double negative 3 (DN3) T cell progenitors. However, over-expression of the N1 intracellular domain (ICN1) renders N1 activation ligand-independent and drives leukemic transformation during β-selection. DN3 progenitors also express Notch3 (N3) mRNA, and over-expression of ligand-independent mutant N3 (ICN3) influences β-selection and drives T cell leukemogenesis. However, the importance of ligand-activated N3 in promoting β-selection and ICN1-induced T cell leukemogenesis has not been examined. To address these questions we generated mice lacking functional N3. We confirmed that DN3 progenitors express N3 protein using a N3-specific antibody. Surprisingly however, N3-deficient DN3 thymocytes were not defective in generating DP thymocytes under steady state conditions or in more stringent competition assays. To determine if N3 co-operates with N1 to regulate β-selection, we generated N1;N3 compound mutants. However, N3 deficiency did not exacerbate the competitive defect of N1+/− DN3 progenitors, demonstrating that N3 does not compensate for limiting N1 during T cell development. Finally, N3 deficiency did not attenuate T cell leukemogenesis induced by conditional expression of ICN1 in DN3 thymocytes. Importantly, we showed that in contrast to N1, N3 has a low binding affinity for DL4, the most abundant intrathymic DL ligand. Thus, despite the profound effects of ectopic ligand-independent N3 activation on T cell development and leukemogenesis, physiologically activated N3 is dispensable for both processes, likely because N3 interacts poorly with intrathymic DL4.