Human Granzyme K Is a Feature of Innate T Cells in Blood, Tissues, and Tumors, Responding to Cytokines Rather than TCR Stimulation

NK cells and CD8 T cells use cytotoxic molecules to kill virally infected and tumor cell targets. While perforin and granzyme B (GzmB) are the most commonly studied lytic molecules, less is known about granzyme K (GzmK). However, this granzyme has been recently associated with improved prognosis in solid tumors. In this study, we show that, in humans, GzmK is predominantly expressed by innate-like lymphocytes, as well as a newly identified population of GzmK+CD8+ non- mucosal-associated invariant T cells with innate-like characteristics. We found that GzmK+ T cells are KLRG1+EOMES+IL-7R+CD62L-Tcf7int, suggesting that they are central memory T and effector memory T cells. Furthermore, GzmK+ cells are absent/low in cord blood, suggesting that GzmK is upregulated with immune experience. Surprisingly, GzmK+ cells respond to cytokine stimuli alone, whereas TCR stimulation downregulates GzmK expression, coinciding with GzmB upregulation. GzmK+ cells have reduced IFN-γ production compared with GzmB+ cells in each T cell lineage. Collectively, this suggests that GzmK+ cells are not naive, and they may be an intermediate memory-like or preterminally differentiated population. GzmK+ cells are enriched in nonlymphoid tissues such as the liver and adipose. In colorectal cancer, GzmK+ cells are enriched in the tumor and can produce IFN-γ, but GzmK+ expression is mutually exclusive with IL-17a production. Thus, in humans, GzmK+ cells are innate memory-like cells that respond to cytokine stimulation alone and may be important effector cells in the tumor.

γδ T cell dichotomy with opposing cytotoxic and wound healing functions in human solid tumors

γδ T cells are important tissue-resident, innate T cells that are critical for tissue homeostasis. γδ cells are associated with positive prognosis in most tumors; however, little is known about their heterogeneity in human cancers. Here, we phenotyped innate and adaptive cells in human colorectal (CRC) and endometrial cancer. We found striking differences in γδ subsets and function in tumors compared to normal tissue, and in the γδ subsets present in tumor types. In CRC, an amphiregulin (AREG)-producing subset emerges, while endometrial cancer is infiltrated by cytotoxic cells. In humanized CRC models, tumors induced this AREG phenotype in Vδ1 cells after adoptive transfer. To exploit the beneficial roles of γδ cells for cell therapy, we developed an expansion method that enhanced cytotoxic function and boosted metabolic flexibility, while eliminating AREG production, achieving greater tumor infiltration and tumor clearance. This method has broad applications in cellular therapy as an 'off-the-shelf' treatment option.

Human Hepatic CD56bright NK Cells Display a Tissue-Resident Transcriptional Profile and Enhanced Ability to Kill Allogenic CD8+ T Cells

Liver-resident CD56^brightCD16^- natural killer (NK) cells are enriched in the human liver and are phenotypically distinct from their blood counterparts. Although these cells are capable of rapid cytotoxic effector activity, their functional role remains unclear. We hypothesise that they may contribute to immune tolerance in the liver during transplantation. RNA sequencing was carried out on FACS sorted NK cell subpopulations from liver perfusates (n=5) and healthy blood controls (n=5). Liver-resident CD56^brightCD16^+/- NK cells upregulate genes associated with tissue residency. They also upregulate expression of CD160 and LY9, both of which encode immune receptors capable of activating NK cells. Co-expression of CD160 and Ly9 on liver-resident NK cells was validated using flow cytometry. Hepatic NK cell cytotoxicity against allogenic T cells was tested using an in vitro co-culture system of liver perfusate-derived NK cells and blood T cells (n=10-13). In co-culture experiments, hepatic NK cells but not blood NK cells induced significant allogenic T cell death (p=0.0306). Allogenic CD8⁺ T cells were more susceptible to hepatic NK cytotoxicity than CD4⁺ T cells (p<0.0001). Stimulation of hepatic CD56^bright NK cells with an anti-CD160 agonist mAb enhanced this cytotoxic response (p=0.0382). Our results highlight a role for donor liver NK cells in regulating allogenic CD8⁺ T cell activation, which may be important in controlling recipient CD8⁺ T cell-mediated rejection post liver-transplant.

Cysteine 253 of UCP1 regulates energy expenditure and sex-dependent adipose tissue inflammation

Uncoupling protein 1 (UCP1) is a major regulator of brown and beige adipocyte energy expenditure and metabolic homeostasis. However, the widely employed UCP1 loss-of-function model has recently been shown to have a severe deficiency in the entire electron transport chain of thermogenic fat. As such, the role of UCP1 in metabolic regulation in vivo remains unclear. We recently identified cysteine-253 as a regulatory site on UCP1 that elevates protein activity upon covalent modification. Here, we examine the physiological importance of this site through the generation of a UCP1 cysteine-253-null (UCP1 C253A) mouse, a precise genetic model for selective disruption of UCP1 in vivo. UCP1 C253A mice exhibit significantly compromised thermogenic responses in both males and females but display no measurable effect on fat accumulation in an obesogenic environment. Unexpectedly, we find that a lack of C253 results in adipose tissue redox stress, which drives substantial immune cell infiltration and systemic inflammatory pathology in adipose tissues and liver of male, but not female, mice. Elevation of systemic estrogen reverses this male-specific pathology, providing a basis for protection from inflammation due to loss of UCP1 C253 in females. Together, our results establish the UCP1 C253 activation site as a regulator of acute thermogenesis and sex-dependent tissue inflammation.

UCP1 governs liver extracellular succinate and inflammatory pathogenesis

Non-alcoholic fatty liver disease (NAFLD), the most prevalent liver pathology worldwide, is intimately linked with obesity and type 2 diabetes. Liver inflammation is a hallmark of NAFLD and is thought to contribute to tissue fibrosis and disease pathogenesis. Uncoupling protein 1 (UCP1) is exclusively expressed in brown and beige adipocytes, and has been extensively studied for its capacity to elevate thermogenesis and reverse obesity. Here we identify an endocrine pathway regulated by UCP1 that antagonizes liver inflammation and pathology, independent of effects on obesity. We show that, without UCP1, brown and beige fat exhibit a diminished capacity to clear succinate from the circulation. Moreover, UCP1KO mice exhibit elevated extracellular succinate in liver tissue that drives inflammation through ligation of its cognate receptor succinate receptor 1 (SUCNR1) in liver-resident stellate cell and macrophage populations. Conversely, increasing brown and beige adipocyte content in mice antagonizes SUCNR1-dependent inflammatory signalling in the liver. We show that this UCP1-succinate-SUCNR1 axis is necessary to regulate liver immune cell infiltration and pathology, and systemic glucose intolerance in an obesogenic environment. As such, the therapeutic use of brown and beige adipocytes and UCP1 extends beyond thermogenesis and may be leveraged to antagonize NAFLD and SUCNR1-dependent liver inflammation.

O66: FLOW CYTOMETRIC AND RNA SEQUENCED UNCOUPLING OF TUMOUR-INFILTRATING LYMPHOCYTE CHECKPOINT EXPRESSION AND MISMATCH REPAIR STATUS IN COLORECTAL CANCER

Introduction

Selection criteria for immunotherapy with checkpoint blockade in colorectal cancer are currently based on mismatch repair status. However, intra-tumoral T cell response varies among patients with the same MMR status. Inhibitory checkpoint expression on tumour-infiltrating lymphocytes in microsatellite stable and unstable CRC is unknown.

Method

Flow cytometric analysis and single-cell RNA sequencing, using the 10x genomic platform, were performed ex vivo on tumour and uninvolved colonic tissue samples from patients undergoing surgical resection for colorectal cancer. Inhibitory checkpoint expression (PD-1) and functional status of isolated populations of TILs were analysed.

Result

Conventional and unconventional tissue-resident T cells were enriched in tumour samples compared to uninvolved healthy colonic tissue. Upregulation of PD-1 expression on TILs was observed in all patients, however the % upregulation varied among those with the same MMR status. A proportion of MSS tumours were found to have high levels of PD-1 expression, while a subset of MSI tumours had low PD-1 expression. Functional studies of cytotoxicity demonstrated varying TIL production of IFNg, TNFa and amphiregulin in patients with the same MMR status.

Conclusion

TIL profile (infiltration pattern, checkpoint expression and functional status) differs among patients with the same MMR status. A subset of ‘hot’ immunogenic MSS tumours exist that may respond to checkpoint blockade. Characterisation of TIL profile represents a more accurate method of selecting patients likely to derive benefit. Abbrev. CRC Colorectal cancer, MMR Mismatch repair, TIL Tumour-infiltrating lymphocytes, MSS Microsatellite stable, MSI Microsatellite unstable, IFNg Interferon-gamma, TNFa Tumour necrosis factor alpha

Take-home message

A subset of immunogenic microsatellite stable colorectal tumours exist that may respond to checkpoint blockade. Mismatch repair status alone does not accurately predict response to immunotherapy.

The Immune Checkpoint Kick Start: Optimization of Neoadjuvant Combination Therapy Using Game Theory

PURPOSE

In an upcoming clinical trial at the Moffitt Cancer Center for women with stage 2/3 estrogen receptor-positive breast cancer, treatment with an aromatase inhibitor and a PD-L1 checkpoint inhibitor combination will be investigated to lower a preoperative endocrine prognostic index (PEPI) that correlates with relapse-free survival. PEPI is fundamentally a static index, measured at the end of neoadjuvant therapy before surgery. We have developed a mathematical model of the essential components of the PEPI score to identify successful combination therapy regimens that minimize tumor burden and metastatic potential, on the basis of time-dependent trade-offs in the system.

METHODS

We considered two molecular traits, CCR7 and PD-L1, which correlate with treatment response and increased metastatic risk. We used a matrix game model with the four phenotypic strategies to examine the frequency-dependent interactions of cancer cells. This game was embedded in an ecological model of tumor population-growth dynamics. The resulting model predicts evolutionary and ecological dynamics that track with changes in the PEPI score.

RESULTS

We considered various treatment regimens on the basis of combinations of the two therapies with drug holidays. By considering the trade off between tumor burden and metastatic potential, the optimal therapy plan was a 1-month kick start of the immune checkpoint inhibitor followed by 5 months of continuous combination therapy. Relative to a protocol giving both therapeutics together from the start, this delayed regimen resulted in transient suboptimal tumor regression while maintaining a phenotypic constitution that is more amenable to fast tumor regression for the final 5 months of therapy.

CONCLUSION

The mathematical model provides a useful abstraction of clinical intuition, enabling hypothesis generation and testing of clinical assumptions.

Abstract A47: scRNA-seq reveals functionally distinct gd T cells in human colorectal tumors

Colorectal cancer is the third most common malignancy worldwide, with increasing numbers due to the spreading obesity epidemic and Western diet. Colorectal tumors are subclassed by mutational burden, caused by microsatellite instability (MSI). MSI-high tumors tend to induce robust T-cell responses and respond well to immunotherapy. However, microsatellite-stable (MSS) tumors lack high mutational burden and conventional T-cell recognition. While these tumors have therefore been considered immunologically “cold,”, MSS tumors are infiltrated by innate lymphocytes, including gd T cells, natural killer (NK) cells, and mucosal associated invariant T (MAIT) cells. We therefore focused on the innate antitumor response in these patients. Colon tumor and uninvolved tissue were sampled from 6 patients undergoing surgical resection for MSS tumors. Using the 10x genomics platform, single-cell RNAseq was performed on isolated populations of gd T cells, NK cells, MAIT cells, and conventional T cells. Single-cell analysis of these tumors revealed significant heterogeneity in all cell subsets analyzed, revealing phenotypic and functional changes not previously observed in bulk sequencing data. A subset of gdT cells adopted a wound healing phenotype in all colorectal cancer samples. These soluble factors are involved in the tissue repair response and barrier integrity, providing mitogenic signals to epithelial cells. In addition, they are associated with immune suppression and induction of regulatory T cells. In humans, this phenotype can be induced in Vd1 T cells in response to proinflammatory cytokine stimulation. In the murine gut, resident gd T cells adopt this phenotype basally and increase production in response to inflammatory cytokine production. The combination of pro-tissue growth and immune suppression, by gd T cells, likely contributes to the poor immunogenicity of MSS tumors. Depleting or converting these cells represents a novel immunotherapeutic target in colorectal cancer.

Citation Format: Cathal Harmon, Alex Zaborowski, Harry Kane, Stephen Cunningham, Leandro Agudelo, Manolis Kellis, Des Winter, Lydia Lynch. scRNA-seq reveals functionally distinct gd T cells in human colorectal tumors [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr A47.

The Immune Consequences of Lactate in the Tumor Microenvironment

The tumor microenvironment consists of complex and dynamic networks of cytokines, growth factors, and metabolic products. These contribute to significant alterations in tissue architecture, cell growth, immune cell phenotype, and function. Increased glycolytic flux is commonly observed in solid tumors and is associated with significant changes in metabolites, generating high levels of lactate. While elevated glycolytic flux is a characteristic metabolic adaption of tumor cells, glycolysis is also a key metabolic program utilized by a variety of inflammatory immune cells. As such lactate and the pH changes associated with lactate transport affect not only tumor cells but also immune cells. Here we provide an overview of lactate metabolic pathways and the effects lactate has on tumor growth and immune cell function. This knowledge provides opportunities for synergistic therapeutic approaches that combine metabolic drugs, which limit tumor growth and support immune cell function, together with immunotherapies to enhance tumor eradication.

γδ T cells in cancer: a small population of lymphocytes with big implications

γδ T cells are a small population of mostly tissue‐resident lymphocytes, with both innate and adaptive properties. These unique features make them particularly attractive candidates for the development of new cellular therapy targeted against tumor development. Nevertheless, γδ T cells may play dual roles in cancer, promoting cancer development on the one hand, while participating in antitumor immunity on the other hand. In mice, γδ T‐cell subsets preferentially produce IL‐17 or IFN‐γ. While antitumor functions of murine γδ T cells can be attributed to IFN‐γ⁺ γδ T cells, recent studies have implicated IL‐17⁺ γδ T cells in tumor growth and metastasis. However, in humans, IL‐17‐producing γδ T cells are rare and most studies have attributed a protective role to γδ T cells against cancer. In this review, we will present the current knowledge and most recent findings on γδ T‐cell functions in mouse models of tumor development and human cancers. We will also discuss their potential as cellular immunotherapy against cancer.

Hepatic Tumor Microenvironments and Effects on NK Cell Phenotype and Function

The liver is a complex organ with critical physiological functions including metabolism, glucose storage, and drug detoxification. Its unique immune profile with large numbers of cytotoxic CD8+ T cells and significant innate lymphoid population, including natural killer cells, γ δ T cells, MAIT cells, and iNKTcells, suggests an important anti-tumor surveillance role. Despite significant immune surveillance in the liver, in particular large NK cell populations, hepatic cell carcinoma (HCC) is a relatively common outcome of chronic liver infection or inflammation. The liver is also the second most common site of metastatic disease. This discordance suggests immune suppression by the environments of primary and secondary liver cancers. Classic tumor microenvironments (TME) are poorly perfused, leading to accumulation of tumor cell metabolites, diminished O2, and decreased nutrient levels, all of which impact immune cell phenotype and function. Here, we focus on changes in the liver microenvironment associated with tumor presence and how they affect NK function and phenotype.

Liver-Derived TGF-β Maintains the EomeshiTbetlo Phenotype of Liver Resident Natural Killer Cells

The adult human liver hosts a complex repertoire of liver resident and transient natural killer (NK) cell populations with diverse phenotypes and functions. Liver resident NK cells are CD56^bright NK cells defined by a unique expression profile of transcription factors and cell surface markers (Eomes^hiTbet^loTIGIT⁺CD69⁺CXCR6⁺CD49e⁻). Despite extensive characterization of the phenotype of liver resident NK cells, it remains unclear how factors within the liver microenvironment induce and maintain this unique phenotype. In this study, we have explored the factors regulating the phenotype of liver resident NK cells. Isolation of healthy liver resident NK cells from donor liver perfusate and in vitro culture results in the gradual loss of the characteristic Tbet^lo phenotype, with the cells increasing Tbet expression significantly at day 7. This phenotypic loss could be halted through the dose-dependent addition of liver conditioned media (LCM), generated from the ex vivo culture of liver biopsies from healthy organ donors. TGF-β, but not IL-10, replicated the Tbet suppressive effects of LCM in both liver resident and peripheral blood NK cells. Furthermore, blocking TGF-β receptor signaling using the inhibitor SB431542, reversed the effect of LCM treatment on liver resident NK cells, causing the loss of tissue resident Eomes^hi Tbet^lo phenotype. Our findings identify liver-derived TGF-β as an important component of the liver microenvironment, which acts to regulate and maintain the phenotype of liver resident NK cells.

Lactate-Mediated Acidification of Tumor Microenvironment Induces Apoptosis of Liver-Resident NK Cells in Colorectal Liver Metastasis

Colorectal cancer is the third most common malignancy worldwide, with 1.3 million new cases annually. Metastasis to the liver is a leading cause of mortality in these patients. In human liver, metastatic cancer cells must evade populations of liver-resident natural killer (NK) cells with potent cytotoxic capabilities. Here, we investigated how these tumors evade liver NK-cell surveillance. Tissue biopsies were obtained from patients undergoing resection of colorectal liver metastasis (CRLM, n = 18), from the tumor, adjacent tissue, and distal resection margin. The number and phenotype of liver-resident NK cells, at each site, were analyzed by flow cytometry. Tumor-conditioned media (TCM) was generated for cytokine and metabolite quantification and used to treat healthy liver-resident NK cells, isolated from donor liver perfusate during transplantation. Liver-resident NK cells were significantly depleted from CRLM tumors. Healthy liver-resident NK cells exposed to TCM underwent apoptosis in vitro, associated with elevated lactate. Tumor-infiltrating liver-resident NK cells showed signs of mitochondrial stress, which was recapitulated in vitro by treating liver-resident NK cells with lactic acid. Lactic acid induced apoptosis by decreasing the intracellular pH of NK cells, resulting in mitochondrial dysfunction that could be prevented by blocking mitochondrial ROS accumulation. CRLM tumors produced lactate, thus decreasing the pH of the tumor microenvironment. Liver-resident NK cells migrating toward the tumor were unable to regulate intracellular pH resulting in mitochondrial stress and apoptosis. Targeting CRLM metabolism provides a promising therapeutic approach to restoring local NK-cell activity and preventing tumor growth.

Depleted polymorphonuclear leukocytes in human metastatic liver reflect an altered immune microenvironment associated with recurrent metastasis

BACKGROUND

Hepatic immunity, normally protective against neoplasia, is subverted in colorectal liver metastasis (CRLM). Here, we compare the inflammatory microenvironment of CRLM-bearing liver tissue to donor liver.

METHODS

Twenty-five patients undergoing resection for CRLM were recruited, 13 of whom developed intrahepatic recurrence within 18 months. Biopsies were obtained from tumour and normal liver tissue adjacent to and distal from, the tumour. Donor liver biopsies were obtained during transplantation. Biopsies were cultured and conditioned media (CM) screened for 102 inflammatory mediators. Twelve of these were validated by Luminex assay. Transwell assays measured cancer cell chemotaxis. Polymorphonuclear leukocytes (PMN) and lymphocytes were quantified in H&E sections.

RESULTS

Fewer periportal tissue-resident PMN were present in metastatic liver compared to donor liver. Patients with the fewest PMN in liver tissue distal to their tumour had a shorter time to intrahepatic recurrence (P < 0.001). IL-6, CXCL1, CXCL5, G-CSF, GM-CSF, VEGF, LIF, and CCL3 were higher in liver-bearing CRLM compared to donor tissue. Consequently, cancer cells migrated equally towards CM of all regions of metastatic liver but not towards donor liver CM.

CONCLUSIONS

The local inflammatory environment may affect both immune cell infiltration and cancer cell migration contributing to recurrence following resection for CRLM.

Uterine natural killer cell progenitor populations predict successful implantation in women with endometriosis-associated infertility

PROBLEM

Uterine natural killer (uNK) cells play a critical role early in gestation. As we previously identified altered uNK cell development in endometriosis-associated infertility, we herein sought to characterize natural killer (NK) cell profiles in endometriosis that may predict embryo implantation.

METHOD OF STUDY

Study participants had a surgical diagnosis of endometriosis-associated infertility. Endometrial tissue and peripheral blood were obtained from 58 women. Thirty-three patients underwent artificial reproductive technology (IVF, ICSI, or IUI) within a mean of 9.5 months of surgery. NK and hematopoietic progenitor cells from endometrium and blood were analyzed by flow cytometry. Successful implantation was defined as a positive pregnancy test.

RESULTS

In successful implantation, populations of endometrial CD34⁺ hematopoietic stem cells were higher (3.97% vs 0.69%; P < .0004), and coexpression of NK cell marker CD56 was increased (81.1% vs 60.9%; P < .034) compared with patients who had failed implantation. In contrast, levels of blood NK progenitors were similar in both groups.

CONCLUSION

Our study revealed that uterine NK progenitor cell populations are markedly different in patients with endometriosis who proceed to successful or failed embryo implantation and may define a novel predictor of implantation success. Our findings also highlight the fundamental differences inherent in NK cell repertoires between blood and uterine compartments.

Tissue-resident Eomes(hi) T-bet(lo) CD56(bright) NK cells with reduced proinflammatory potential are enriched in the adult human liver

The adult human liver is enriched with natural killer (NK) cells, accounting for 30-50% of hepatic lymphocytes, which include tissue-resident hepatic NK-cell subpopulations, distinct from peripheral blood NK cells. In murine liver, a subset of liver-resident hepatic NK cells have altered expression of the two highly related T-box transcription factors, T-bet and eomesodermin (Eomes). Here, we investigate the heterogeneity of T-bet and Eomes expression in NK cells from healthy adult human liver with a view to identifying human liver-resident populations. Hepatic NK cells were isolated from donor liver perfusates and biopsies obtained during orthotopic liver transplantation (N = 28). Hepatic CD56(bright) NK cells were Eomes(hi) T-bet(lo) , a phenotype virtually absent from peripheral blood. These NK cells express the chemokine receptor CXCR6 (chemokine (C-X-C motif) receptor 6), a marker of tissue residency, which is absent from hepatic CD56(dim) and blood NK cells. Compared to blood populations, these hepatic CD56(bright) NK cells have increased expression of activatory receptors (NKp44, NKp46, and NKG2D). They show reduced ability to produce IFN-γ but enhanced degranulation in response to challenge with target cells. This functionally distinct population of hepatic NK cells constitutes 20-30% of the total hepatic lymphocyte repertoire and represents a tissue-resident immune cell population adapted to the tolerogenic liver microenvironment.

Myeloid Engraftment in Humanized Mice: Impact of Granulocyte-Colony Stimulating Factor Treatment and Transgenic Mouse Strain

Poor myeloid engraftment remains a barrier to experimental use of humanized mice. Focusing primarily on peripheral blood cells, we compared the engraftment profile of NOD-scid-IL2Rγc(-/-) (NSG) mice with that of NSG mice transgenic for human membrane stem cell factor (hu-mSCF mice), NSG mice transgenic for human interleukin (IL)-3, granulocyte-macrophage-colony stimulating factor (GM-CSF), and stem cell factor (SGM3 mice). hu-mSCF and SGM3 mice showed enhanced engraftment of human leukocytes compared to NSG mice, and this was reflected in the number of human neutrophils and monocytes present in these strains. Importantly, discrete classical, intermediate, and nonclassical monocyte populations were identifiable in the blood of NSG and hu-mSCF mice, while the nonclassical population was absent in the blood of SGM3 mice. Granulocyte-colony stimulating factor (GCSF) treatment increased the number of blood monocytes in NSG and hu-mSCF mice, and neutrophils in NSG and SGM3 mice; however, this effect appeared to be at least partially dependent on the stem cell donor used to engraft the mice. Furthermore, GCSF treatment resulted in a preferential expansion of nonclassical monocytes in both NSG and hu-mSCF mice. Human tubulointerstitial CD11c(+) cells were present in the kidneys of hu-mSCF mice, while monocytes and neutrophils were identified in the liver of all strains. Bone marrow-derived macrophages prepared from NSG mice were most effective at phagocytosing polystyrene beads. In conclusion, hu-mSCF mice provide the best environment for the generation of human myeloid cells, with GCSF treatment further enhancing peripheral blood human monocyte cell numbers in this strain.

Liver immunology and its role in inflammation and homeostasis

The human liver is usually perceived as a non-immunological organ engaged primarily in metabolic, nutrient storage and detoxification activities. However, we now know that the healthy liver is also a site of complex immunological activity mediated by a diverse immune cell repertoire as well as non-hematopoietic cell populations. In the non-diseased liver, metabolic and tissue remodeling functions require elements of inflammation. This inflammation, in combination with regular exposure to dietary and microbial products, creates the potential for excessive immune activation. In this complex microenvironment, the hepatic immune system tolerates harmless molecules while at the same time remaining alert to possible infectious agents, malignant cells or tissue damage. Upon appropriate immune activation to challenge by pathogens or tissue damage, mechanisms to resolve inflammation are essential to maintain liver homeostasis. Failure to clear ‘dangerous' stimuli or regulate appropriately activated immune mechanisms leads to pathological inflammation and disrupted tissue homeostasis characterized by the progressive development of fibrosis, cirrhosis and eventual liver failure. Hepatic inflammatory mechanisms therefore have a spectrum of roles in the healthy adult liver; they are essential to maintain tissue and organ homeostasis and, when dysregulated, are key drivers of the liver pathology associated with chronic infection, autoimmunity and malignancy. In this review, we explore the changing perception of inflammation and inflammatory mediators in normal liver homeostasis and propose targeting of liver-specific immune regulation pathways as a therapeutic approach to treat liver disease.

Natural Killer Cells and Liver Transplantation: Orchestrators of Rejection or Tolerance?

Natural killer (NK) cells are highly heterogeneous innate lymphocytes with a diverse repertoire of phenotypes and functions. Their role in organ transplantation has been poorly defined due to conflicting clinical and experimental data. There is evidence that NK cells can contribute to graft rejection and also to tolerance induction. In most solid organ transplantation settings, the role of NK cells is only considered from the perspective of the recipient immune system. In contrast to other organs, the liver contains major resident populations of immune cells, particularly enriched with innate lymphocytes such as NK cells, NKT cells, and gamma-delta T cells. Liver transplantation therefore results in a unique meeting of donor and recipient immune systems. The unusual immune repertoire and tolerogenic environment of the liver may explain why this potentially inflammatory "meeting" often results in attenuated immune responses and reduced requirement for immunosuppression. Recent trials of immunosuppression withdrawal in liver transplant patients have identified NK cell features as possible predictors of tolerance. Here we propose that hepatic NK cells play a key role in the induction of tolerance post-liver transplant and examine potential mechanisms by which these cells influence liver transplant outcome.

A randomized, double-blind, phase II study of erlotinib with or without sunitinib for the second-line treatment of metastatic non-small-cell lung cancer (NSCLC)

BACKGROUND

Combined inhibition of vascular, platelet-derived, and epidermal growth factor receptor (EGFR) pathways may overcome refractoriness to single agents in platinum-pretreated non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

This randomized, double-blind, multicenter, phase II trial evaluated sunitinib 37.5 mg/day plus erlotinib 150 mg/day versus placebo plus erlotinib continuously in 4-week cycles. Eligible patients had histologically confirmed stage IIIB or IV NSCLC previously treated with one or two chemotherapy regimens, including one platinum-based regimen. The primary end point was progression-free survival (PFS) by an independent central review.

RESULTS

One hundred and thirty-two patients were randomly assigned, and the median duration of follow-up was 17.7 months. The median PFS was 2.8 versus 2.0 months for the combination versus erlotinib alone (HR 0.898, P = 0.321). The median overall survival (OS) was 8.2 versus 7.6 months (HR 1.066, P = 0.617). Objective response rates (ORRs) were 4.6% and 3.0%, respectively. Sunitinib plus erlotinib was fairly well tolerated although most treatment-related adverse events (AEs) were more frequent than with erlotinib alone: diarrhea (55% versus 33%), rash (41% versus 30%), fatigue (31% versus 25%), decreased appetite (30% versus 13%), nausea (28% versus 14%), and thrombocytopenia (13% versus 0%).

CONCLUSIONS

The addition of sunitinib to erlotinib did not significantly improve PFS in patients with advanced, platinum-pretreated NSCLC.

Extension plant pathology: strengthening resources to continue serving the public interest

Extension plant pathologists deliver science-based information that protects the economic value of agricultural and horticultural crops in the United States by educating growers and the general public about plant diseases. Extension plant pathologists diagnose plant diseases and disorders, provide advice, and conduct applied research on local and regional plant disease problems. During the last century, extension plant pathology programs have adjusted to demographic shifts in the U.S. population and to changes in program funding. Extension programs are now more collaborative and more specialized in response to a highly educated clientele. Changes in federal and state budgets and policies have also reduced funding and shifted the source of funding of extension plant pathologists from formula funds towards specialized competitive grants. These competitive grants often favor national over local and regional plant disease issues and typically require a long lead time to secure funding. These changes coupled with a reduction in personnel pose a threat to extension plant pathology programs. Increasing demand for high-quality, unbiased information and the continued reduction in local, state, and federal funds is unsustainable and, if not abated, will lead to a delay in response to emerging diseases, reduce crop yields, increase economic losses, and place U.S. agriculture at a global competitive disadvantage. In this letter, we outline four recommendations to strengthen the role and resources of extension plant pathologists as they guide our nation's food, feed, fuel, fiber, and ornamental producers into an era of increasing technological complexity and global competitiveness.

Health insurance and health services utilization in Ireland

The numbers buying private health insurance in Ireland have continued to grow, despite a broadening in entitlement to public care. About 40% of the population now have insurance, although everyone has entitlement to public hospital care. In this paper, we examine in detail the growth in insurance coverage and the factors underlying the demand for insurance. Attitudinal responses reveal the importance of perceptions about waiting times for public care, as well as some concerns about the quality of that care. Individual characteristics, such as education, age, gender, marital status, family composition and income all influence the probability of purchasing private insurance. We also examine the relationship between insurance and utilization of hospital in-patient services. The positive effect of private insurance appears less than that of entitlement to full free health care from the state, although the latter is means-tested, and may partly represent health status.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

Membrane transport of long-chain fatty acids: evidence for a facilitated process

In mammalian cells, membrane uptake of long-chain fatty acids is mediated by two separate components; a passive component that is a linear function of the concentration of free fatty acid in the extracellular medium and a saturable component that exhibits the characteristics of a protein-facilitated process. This review summarizes the body of work that has accumulated related to the mechanism of fatty acid transport. Evidence in support of a facilitated uptake process is presented with relation to the different cell types or membrane systems where it was collected. The evidence includes saturation kinetics, competition between different substrates, and sensitivity to a variety of inhibitors. Recent knowledge related to membrane proteins thought to be implicated in the uptake process is reviewed. Factors that may modulate uptake or alter the relative contribution of passive versus facilitated components are briefly discussed. These include the molar ratio of fatty acid to its physiological carrier, plasma albumin and the metabolic or hormonal milieu.

Protection against cyclophosphamide-induced alopecia and inhibition of mammary tumor growth by topical 1,25-dihydroxyvitamin D3 in mice

Twenty-one-day-old BALB/c mice were shaved on the back to synchronize hair growth. On day 30 or 31, when at least 90% of mice exhibited hair regrowth in the shaved area, 1,25(OH)2D3 was applied topically to the shaved area daily for 5 days. On the 6th day, cyclophosphamide (Cytoxan, CTX) was injected i.p. to induce hair loss in the shaved area. Alopecia was induced in a dose-dependent manner by CTX treatment within 1 to 2 weeks. This effect was reduced significantly if mice were pre-treated with 1,25(OH)2D3, though only slight protection was observed in female mice. Interestingly, this 1,25(OH)2D3-mediated protection against hair loss was attenuated in male mice but became more significant in female mice when they were inoculated with the EMT-6 murine mammary tumor prior to treatment. More importantly, topical treatment with 1,25(OH)2D3 alone was able to inhibit EMT-6 tumor growth in both male and female BALB/c mice. Furthermore, 1,25(OH)2D3 pre-treatment also augmented the anti-tumor effect of CTX. Our results demonstrate that topical application of 1,25(OH)2D3 can protect against CTX-induced alopecia both in tumor-free and in tumor-bearing mice in a sex-dependent manner. Moreover, 1,25(OH)2D3 was shown, either alone or in combination with CTX, to inhibit tumor growth.

A 1.1-Mb transcript map of the hereditary hemochromatosis locus

In the process of positionally cloning a candidate gene responsible for hereditary hemochromatosis (HH), we constructed a 1.1-Mb transcript map of the region of human chromosome 6p that lies 4.5 Mb telomeric to HLA-A. A combination of three gene-finding techniques, direct cDNA selection, exon trapping, and sample sequencing, were used initially for a saturation screening of the 1.1-Mb region for expressed sequence fragments. As genetic analysis further narrowed the HH candidate locus, we sequenced completely 0.25 Mb of genomic DNA as a final measure to identify all genes. Besides the novel MHC class 1-like HH candidate gene HLA-H, we identified a family of five butyrophilin-related sequences, two genes with structural similarity to a type 1 sodium phosphate transporter, 12 novel histone genes, and a gene we named RoRet based on its strong similarity to the 52-kD Ro/SSA lupus and Sjogren's syndrome auto-antigen and the RET finger protein. Several members of the butyrophilin family and the RoRet gene share an exon of common evolutionary origin called B30-2. The B30-2 exon was originally isolated from the HLA class 1 region, yet has apparently "shuffled" into several genes along the chromosome telomeric to the MHC. The conservation of the B30-2 exon in several novel genes and the previously described amino acid homology of HLA-H to MHC class 1 molecules provide further support that this gene-rich region of 6p21.3 is related to the MHC. Finally, we performed an analysis of the four approaches for gene finding and conclude that direct selection provides the most effective probes for cDNA screening, and that as much as 30% of ESTs in this 1.1-Mb region may be derived from noncoding genomic DNA.

Role of tyrosine kinases, protein kinase C, and protein kinase A in the regulation of interferon-alpha production induced by herpes simplex virus type 1

Herpes simplex virus 1 (HSV-1) is able to induce interferon-alpha production by natural IFN-alpha-producing cells. In this study, signal transduction in this process was examined. It was found that sequestering of calcium by EGTA abolished IFN-alpha induction by HSV-infected cells. Stimulation of human PBMC by HSV-1-infected fibroblasts resulted in the production of inositol triphosphate (InsP3) and tyrosine phosphorylation of cellular proteins. The protein kinase C inhibitor, H7, and the tyrosine kinase inhibitor, herbimycin A, were able to suppress IFN-alpha gene expression as determined by IFN bioassay and RT-PCR. An IFN-alpha-specific ELISpot assay revealed that herbimycin A and H7 remarkably decreased the number of IFN-alpha-producing cells. PMA or calcium ionophore A23187 alone did not increase IFN-alpha production. However, PMA in conjugation with ionophores increased IFN-alpha production as early as 2 h. HA1004 and 2',5'-dideoxyadenosine, which are potent inhibitors of PKA pathway, had no effect on IFN-alpha production. In contrast, BrcAMP, a specific PKA activator, inhibited the IFN-alpha secretion and number of IFN-alpha-producing cells and to a lesser extent reduced the level of IFN-alpha mRNA. Our results indicate that protein kinase C, tyrosine kinases, and protein kinase A are involved in the regulation of IFN-alpha production in response to HSV-1.

Reliability of three clinical measures of muscle tone in the shoulders and wrists of poststroke patients

Muscle tone was tested at the shoulders and wrists of 49 randomly selected poststroke patients with the use of resting joint position (SJP and WJP), resistance to passive movement or stiffness (SRM and WRM), and angle of appearance of resistance (SAR and WAR). Subjects were tested while seated with their arm supported in a suspension sling adapted for free movement. Five of the first and immediately repeated measurement pairs showed strong correlations and interrater reliability (SJP, .839; WJP, .900; SRM, .886; WRM, .904; SAR, .884 [p less than .05]). The sixth (WAR) showed moderate reliability (.618, p less than .05). Resting joint position measurements were most reliable among subjects with higher tone. The joint first measured had a slight order effect on SRM among subjects with higher muscle tone. Its second measurements were slightly increased over the first among those subjects whose shoulders were measured first and slightly reduced when measured immediately after the wrist. Reliable means of clinical evaluation of muscle tone at the shoulder and wrist are available if the influence of level of tone and the mutual influence of muscles tested are prudently considered.

Toxicity of coumarin (1,2-benzopyrone) on human peripheral blood mononuclear cells and human and murine bone marrow progenitor stem cells

Coumarin (1,2-benzopyrone), in combination with cimetidine, has been subjected to separate clinical trials for the treatment of advanced renal cell carcinoma, malignant melanoma, and non-small cell lung cancer. While objective tumor regressions were observed only in renal carcinoma, no symptomatic or organ dysfunction toxicity was observed in any of the trials. The purpose of the present in vitro study was to determine the concentrations of coumarin and 7-hydroxycoumarin (7-HC) that would be toxic to human peripheral blood mononuclear cells (PB-MNC) and human and murine bone marrow (GM) progenitor stem cells. Coumarin was nontoxic for PB-MNC in concentrations up to 100 micrograms/ml. Concentrations of coumarin or 7-HC greater than or equal to 200 micrograms/ml produced significant suppression of human marrow GM stem cell activity. Coumarin greater than or equal to 25 micrograms/ml produced suppression of murine marrow GM stem cell activity. Differences in human and murine marrow sensitivity probably reflect interspecies differences in metabolism of coumarin. Correlations between toxic concentrations in vitro and maximally achievable serum concentration in vivo in humans await the results of further clinical trials.

Ro/SSA antigen in human epidermis

It has been shown previously by an immunofluorescence technique, that whole serum from patients who have anti-Ro/SSA autoantibodies reacts with a component or components of the epidermis. We have now demonstrated by immunoblotting that the antigen identified in human epidermis by anti-Ro/SSA sera is Ro/SSA antigen, and that Ro/SSA antigen is present both in adult and in neonatal epidermis. The presence of this antigen in tissues which are injured in the anti-Ro/SSA-associated syndromes subacute cutaneous lupus erythematosus and neonatal lupus erythematosus supports the hypothesis that anti-Ro/SSA antibodies react with Ro/SSA antigen in the skin and are important in the initiation of tissue damage.

Characterization of immune response to oral administration of Streptococcus sobrinus ribosomal preparations in liposomes

Gnotobiotic rats gastrically intubated with a total of 12.5 micrograms of Streptococcus sobrinus ribosomal protein incorporated into cholesterol-based liposomes had significantly (P less than or equal to 0.01) fewer carious lesions on their molar surfaces than did nonimmunized infected controls after challenge with a virulent organism. The immunized animals had significantly (P less than or equal to 0.01) lower numbers of molar-adherent S. sobrinus cells and higher levels of salivary immunoglobulin A antibodies to S. sobrinus whole cells and ribosomes than did the control group. Dose-response studies indicated that 12.5 micrograms of S. sobrinus ribosomal protein in liposomes induced slightly higher immune responses than did 62.5, 125.0, and 250.0 micrograms of ribosomal protein incorporated into liposomes. Intubation of rats with up to 250.0 micrograms of S. sobrinus ribosomal protein alone was no more effective in reducing the numbers of molar-adherent S. sobrinus cells than were nonimmunized infected controls, establishing that insertion of ribosomes into liposomes was required for inducing an effective immune response. These results indicate that oral administration of as little as 12.5 micrograms of S. sobrinus ribosomal protein incorporated into liposomes can protect rats from caries formation after challenge with the virulent organism by inducing specific salivary immunoglobulin A antibodies which can inhibit colonization by the challenged S. sobrinus.

Autoantibodies to SS-A/Ro in infants with congenital heart block

Antibodies to SS-A/Ro have been proposed to be a serologic marker for the neonatal lupus syndrome, which is characterized by congenital heart block or cutaneous lupus or both. The antibodies occur in the mother and are transiently found in the child's serum. We examined an unselected series of 12 children with idiopathic CHB, isolated in 10 children and with cutaneous lupus lesions in two. Six of these children and their mothers were studied during the child's neonatal period, and six were studied retrospectively. All six neonates had SS-A/Ro autoantibodies. Nine of 12 mothers had SS-A/Ro autoantibodies. Of the seropositive mothers, one had systemic lupus erythematosus, two had sicca syndrome, one had photosensitivity, one had arthralgias, and four were asymptomatic. We propose that congenital heart block may be related to transplacental passage of maternal SS-A/Ro antibodies and that neonatal lupus may be the most common cause.

Immunogenetics of the neonatal lupus syndrome

Infants with neonatal lupus erythematosus have congenital heart block, transient cutaneous lesions, or both. Mothers of these infants have SSA/Ro autoantibodies that are passed across the placenta to the fetus and that have been temporarily associated with the syndrome. Six families with neonatal lupus were studied by HLA typing. All seven infants had transient cutaneous lesions, congenital heart block, or both. Five of six mothers were asymptomatic and one had Sjögren's syndrome. Six of seven infants and all six mothers had antibodies to SSA/Ro in their sera. The infants became seronegative by age 8 months. Five mothers were positive for HLA-DR3, five for HLA-MB2, six for HLA-MT2, and six for HLA-B8. No HLA associations were seen in infants. Gene products of the DR or similar regions may be associated with autoantibody production but not with other events in tissue injury.

Allergic reaction to allopurinol with cross-reactivity to oxypurinol

A 25-year-old white man with gout and nephropathy and with a previous reaction to allopurinol was given a trial dose of oxypurinol. He developed malaise, a generalized erythematous reaction with edema, pruritus, and emesis; this was clinically identical to the reaction he experienced with allopurinol. When the patient's lymphocytes were exposed in vitro to oxypurinol and allopurinol, increased DNA synthesis was observed, suggesting an immunologic basis for the reaction. This patient indicates that clinical cross reactivity to allopurinol and oxypurinol does occur and may be of an immunologic basis. There is a need for additional xanthine oxidase inhibitors for such patients.