Erin Murphy

Involvement of chemokine receptors in breast cancer metastasis

Breast cancer is characterized by a distinct metastatic pattern involving the regional lymph nodes, bone marrow, lung and liver. Tumour cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokines and their receptors. Here we report that the chemokine receptors CXCR4 and CCR7 are highly expressed in human breast cancer cells, malignant breast tumours and metastases. Their respective ligands CXCL12/SDF-1α and CCL21/6Ckine exhibit peak levels of expression in organs representing the first destinations of breast cancer metastasis. In breast cancer cells, signalling through CXCR4 or CCR7 mediates actin polymerization and pseudopodia formation, and subsequently induces chemotactic and invasive responses. In vivo, neutralizing the interactions of CXCL12/CXCR4 significantly impairs metastasis of breast cancer cells to regional lymph nodes and lung. Malignant melanoma, which has a similar metastatic pattern as breast cancer but also a high incidence of skin metastases, shows high expression levels of CCR10 in addition to CXCR4 and CCR7. Our findings indicate that chemokines and their receptors have a critical role in determining the metastatic destination of tumour cells.

IL-23 is essential for T cell–mediated colitis and promotes inflammation via IL-17 and IL-6

Uncontrolled mucosal immunity in the gastrointestinal tract of humans results in chronic inflammatory bowel disease (IBD), such as Crohn disease and ulcerative colitis. In early clinical trials as well as in animal models, IL-12 has been implicated as a major mediator of these diseases based on the ability of anti-p40 mAb treatment to reverse intestinal inflammation. The cytokine IL-23 shares the same p40 subunit with IL-12, and the anti-p40 mAbs used in human and mouse IBD studies neutralized the activities of both IL-12 and IL-23. IL-10-deficient mice spontaneously develop enterocolitis. To determine how IL-23 contributes to intestinal inflammation, we studied the disease susceptibility in the absence of either IL-23 or IL-12 in this model, as well as the ability of recombinant IL-23 to exacerbate IBD induced by T cell transfer. Our study shows that in these models, IL-23 is essential for manifestation of chronic intestinal inflammation, whereas IL-12 is not. A critical target of IL-23 is a unique subset of tissue-homing memory T cells, which are specifically activated by IL-23 to produce the proinflammatory mediators IL-17 and IL-6. This pathway may be responsible for chronic intestinal inflammation as well as other chronic autoimmune inflammatory diseases.

IGIF Does Not Drive Th1 Development but Synergizes with IL-12 for Interferon-γ Production and Activates IRAK and NFκB

Abstract In these studies, IFNγ-inducing factor (IGIF), unlike IL-12, did not drive Th1 development in BALB/c or C57BL/6 mice, but like IL-1α, potentiated IL-12–driven Th1 development in BALB/c mice. IGIF and IL-12 synergized for IFNγ production from Th1 cells. Unlike IL-1α, IGIF had no effect on Th2 cells. IGIF signaled through IRAK, IL-1 receptor–associated kinase, to induce nuclear translocation of p65/p50 NFκB in Th1 cells. IL-1α had no effect on proliferation, cytokine production, or NFκB activation in Th1 cells but activated NFκB and proliferation in Th2 cells. Thus, Th1 and Th2 cells may differ in responsiveness and receptor expression for IL-1 family molecules. IGIF and IL-1α may differentially amplify Th1 and Th2 effector responses, respectively.

TGF-β1 down-regulates Th2 development and results in decreased IL-4-induced STAT6 activation and GATA-3 expression

TGF‐β plays an important role in immune regulation in vivo and affects T cell differentiation in vitro. Here we describe how TGF‐β modulates Th2 development in vitro and investigate its mechanisms of action. TGF‐β down‐regulated Th2 development of naive CD4+ Mel‐14high T cells derived from the DO11.10 ovalbumin‐specific TCR‐transgenic mouse, and this was observed both in cultures driven with anti‐CD3 and anti‐CD28 and with splenic APC and antigen. TGF‐β down‐regulated GATA‐3 expression in developing Th2 and these cells showed a diminished IL‐4‐induced STAT6 activation. We found, however, that naive cells driven in Th2 conditions with TGF‐β did not show a significantly decreased STAT6 activation, suggesting that TGF‐β inhibits Th2 development via a STAT6‐independent mechanism.

IL-10 Elicits IFNγ-Dependent Tumor Immune Surveillance

Tumor immune surveillance and cancer immunotherapies are thought to depend on the intratumoral infiltration of activated CD8(+) Txa0cells. Intratumoral CD8(+) Txa0cells are rare and lack activity. IL-10 is thought to contribute to the underlying immune suppressive microenvironment. Defying those expectations we demonstrate that IL-10 induces several essential mechanisms for effective antitumor immune surveillance: infiltration and activation of intratumoral tumor-specific cytotoxic CD8(+) Txa0cells, expression of the Th1 cytokine interferon-γ (IFNγ) and granzymes in CD8(+) Txa0cells, and intratumoral antigen presentation molecules. Consequently, tumor immune surveillance is weakened in mice deficient for IL-10 whereas transgenic overexpression of IL-10 protects mice from carcinogenesis. Treatment with pegylated IL-10 restores tumor-specific intratumoral CD8(+) Txa0cell function and controls tumor growth.

IFN-γ–related mRNA profile predicts clinical response to PD-1 blockade

Programmed death-1–directed (PD-1–directed) immune checkpoint blockade results in durable antitumor activity in many advanced malignancies. Recent studies suggest that IFN-&ggr; is a critical driver of programmed death ligand-1 (PD-L1) expression in cancer and host cells, and baseline intratumoral T cell infiltration may improve response likelihood to anti–PD-1 therapies, including pembrolizumab. However, whether quantifying T cell–inflamed microenvironment is a useful pan-tumor determinant of PD-1–directed therapy response has not been rigorously evaluated. Here, we analyzed gene expression profiles (GEPs) using RNA from baseline tumor samples of pembrolizumab-treated patients. We identified immune-related signatures correlating with clinical benefit using a learn-and-confirm paradigm based on data from different clinical studies of pembrolizumab, starting with a small pilot of 19 melanoma patients and eventually defining a pan-tumor T cell–inflamed GEP in 220 patients with 9 cancers. Predictive value was independently confirmed and compared with that of PD-L1 immunohistochemistry in 96 patients with head and neck squamous cell carcinoma. The T cell–inflamed GEP contained IFN-&ggr;–responsive genes related to antigen presentation, chemokine expression, cytotoxic activity, and adaptive immune resistance, and these features were necessary, but not always sufficient, for clinical benefit. The T cell–inflamed GEP has been developed into a clinical-grade assay that is currently being evaluated in ongoing pembrolizumab trials.

Detection of in vivo expression of interleukin-10 using a semi-quantitative polymerase chain reaction method in Schistosoma mansoni infected mice

A modified polymerase chain reaction (PCR) assay for analysis of cytokine gene expression from reverse-transcribed (R/T) RNA obtained from small numbers of cells is described in detail. This method employs a previously described dot-blot format and utilizes a target specific radioactive oligonucleotide probe which hybridizes to the PCR amplified product, thus increasing both specificity and sensitivity. This obviates the need for repeated electrophoresis gels and easily accommodates large experiments (e.g., numerous samples or kinetic studies), using small amounts of RNA from low cell numbers. Manipulation of many samples is further enhanced with the use of a PCR thermocycler, which like the dot-blot apparatus is designed in a 96-well format. We describe the use of the house-keeping enzyme hypoxanthine phosphoribosyltransferase (HPRT) as an internal standard, which is especially suitable since its range of detectability of expression is similar to that of the cytokines under test. This enables one to obtain an accurate measure of losses or degradation of RNA, as well as controlling for efficiency of the R/T and PCR reactions. These reactions are further controlled by inclusion of a standard curve consisting of a titration of a known amount of RNA from a cell line expressing the cytokine under test. As well as controlling for the R/T-PCR, this standard curve also enables one to obtain a semi-quantitative measure of cytokine expression by different cell populations during an immune response. We show that this method can be used successfully for studying differential expression of IL-10 in different microenvironments during infection of mice with Schistosoma mansoni.

Early expression of cytokines in lymph nodes after treatment in vivo with Staphylococcus enterotoxin B.

Excessive cytokine expression induced by superantigen may be one aspect of the pathophysiology associated with Gram positive bacteremia. We have undertaken a study of the kinetics of cytokine production in lymph nodes obtained from in vivo Staphylococcus enterotoxin B (SEB) treated animals. This study was designed to evaluate the short term cytokine profile observed using immunohistochemistry (IHC) in BALB/c mice injected intraperitoneally (i.p.). The observed immunohistochemical kinetic profiles were corroborated using reverse transcription-polymerase chain reaction (RT-PCR) RNA analysis. We report here that TNF, IL-2, and IFN-gamma are the principal cytokines which were detected within hours of SEB administration, and that other cytokines such as IL-3, IL-4, IL-5, IL-6, IL-10, GM-CSF and M-CSF were undetectable. TNF and IL-2 appeared very early following SEB priming, and were observed by 1 h. IFN-gamma which appeared later (maximally at 14 h) was produced predominantly by CD8+ cells. In contrast, the TNF and IL-2 were produced primarily by CD4+ cells. Identical results were obtained by IHC and RT-PCR; the kinetics of mRNA expression slightly preceded the appearance of protein. The TNF and IFN-gamma staining patterns observed in lymph node sections were indicative of Golgi-localized cytokine. The IL-2 staining pattern observed in lymph node sections was distinctive, covering a significant local area of cells. This local regional concentration of IL-2, which may result from cytokine attached to extracellular binding components, may be an important aspect of the activation phase of a developing immune response. Rapid induction and excessive cytokine production elicited by superantigen in vivo, may ultimately help to explain the shock and death associated with SEB.

Characterization of a novel subset of CD8(+) T cells that expands in patients receiving interleukin-12.

IL-12 has significant antitumor activity in mice that may be mediated by CD8(+) T cells. We show in this report that repeated subcutaneous injections of IL-12 in patients with cancer resulted in the selective expansion of a subset of peripheral blood CD8(+) T cells. This T cell subset expressed high levels of CD18 and upregulated IL-12 receptor expression after IL-12 treatment in vivo. In normal subjects, these CD3(+)CD8(+)CD18(bright) T cells expressed IL-12 and IL-2 receptors and adhesion/costimulatory molecules to a greater degree than other CD8(+) and CD4(+) T cells. They appeared morphologically as large granular lymphocytes, although they did not express NK cell markers such as CD56. In addition, CD8(+)CD18(bright) T cells were almost exclusively T cell receptor (TCR) alphabeta+, and exhibited a TCR Vbeta repertoire that was strikingly oligoclonal, whereas the Vbeta repertoire of CD18(dim) T cells was polyclonal. Although CD8+CD18(bright) T cells demonstrated little functional responsiveness to IL-12 or IL-2 alone in vitro, they responded to the combination of IL-12+IL-2 with strong IFN-gamma production and proliferation and enhanced non-MHC-restricted cytolytic activity. In contrast, CD18(dim) T cells were not activated by IL-12 or IL-2, alone or in combination. These findings demonstrate that CD8+CD18(bright) T cells are a unique population of peripheral blood lymphocytes with features of both memory and effector cells that are capable of TCR-independent activation through combined stimulation with IL-12+IL-2. As this activation results in IFN-gamma production and enhanced cytolytic activity, these T cells may play a role in innate as well as acquired immunity to tumors and infectious pathogens. Additional studies will be necessary to determine whether CD8+CD18(bright) T cells mediate the antitumor effect of IL-12 or IL-2 administered to cancer patients, and if so, whether maximal activation of these T cells with the combination of IL-12+IL-2 in vivo can augment the clinical effectiveness of these cytokines.

PD-L2 Expression in Human Tumors: Relevance to Anti-PD-1 Therapy in Cancer

Purpose: Tumor-associated PD-L1 expression is predictive of clinical response to PD-1–directed immunotherapy. However, PD-L1–negative patients may also respond to PD-1 checkpoint blockade, suggesting that other PD-1 ligands may be relevant to the clinical activity of these therapies. The prevalence of PD-L2, the other known ligand of PD-1, and its relationship to response to anti-PD-1 therapy were evaluated. Experimental Design: PD-L2 expression was assessed in archival tumor tissue from seven indications using a novel immunohistochemical assay. In addition, relationships between clinical response and PD-L2 status were evaluated in tumor tissues from patients with head and neck squamous cell carcinoma (HNSCC) with recurrent or metastatic disease, treated with pembrolizumab. Results: PD-L2 expression was observed in all tumor types and present in stromal, tumor, and endothelial cells. The prevalence and distribution of PD-L2 correlated significantly with PD-L1 (P = 0.0012–<0.0001); however, PD-L2 was detected in the absence of PD-L1 in some tumor types. Both PD-L1 and PD-L2 positivity significantly predicted clinical response to pembrolizumab on combined tumor, stromal and immune cells, with PD-L2 predictive independent of PD-L1. Response was greater in patients positive for both PD-L1 and PD-L2 (27.5%) than those positive only for PD-L1 (11.4%). PD-L2 status was also a significant predictor of progression-free survival (PFS) with pembrolizumab independent of PD-L1 status. Longer median times for PFS and overall survival were observed for PD-L2–positive than PD-L2–negative patients. Conclusions: Clinical response to pembrolizumab in patients with HNSCC may be related partly to blockade of PD-1/PD-L2 interactions. Therapy targeting both PD-1 ligands may provide clinical benefit in these patients. Clin Cancer Res; 23(12); 3158–67. ©2017 AACR.