Radiotherapy Both Promotes and Inhibits Myeloid-Derived Suppressor Cell Function: Novel Strategies for Preventing the Tumor-Protective Effects of Radiotherapy

Cancer immunotherapies aimed at neutralizing the programmed death-1 (PD-1) immune suppressive pathway have yielded significant therapeutic efficacy in a subset of cancer patients. However, only a subset of patients responds to antibody therapy with either anti-PD-1 or anti-PD-L1 antibodies. These patients appear to have so-called “hot” tumors containing tumor-reactive T cells. Therefore, checkpoint blockade therapy may be effective in a larger percentage of cancer patients if combined with therapeutics that also activate tumor-reactive T cells. Radiotherapy (RT) is a prime candidate for combination therapy because it facilitates activation of both local antitumor immunity and antitumor immunity at non-radiated, distant sites (abscopal response). However, RT also promotes tumor cell expression of PD-L1 and facilitates the development of myeloid-derived suppressor cells (MDSC), a population of immune suppressive cells that also suppress through PD-L1. This article will review how RT induces MDSC, and then describe two novel therapeutics that are designed to simultaneously activate tumor-reactive T cells and neutralize PD-1-mediated immune suppression. One therapeutic, a CD3xPD-L1 bispecific T cell engager (BiTE), activates and targets cytotoxic T and NKT cells to kill PD-L1+ tumor cells, despite the presence of MDSC. The BiTE significantly extends the survival time of humanized NSG mice reconstituted with human PBMC and carrying established metastatic human melanoma tumors. The second therapeutic is a soluble form of the costimulatory molecule CD80 (sCD80). In addition to costimulating through CD28, sCD80 inhibits PD-1 suppression by binding to PD-L1 and sterically blocking PD-L1/PD-1 signaling. sCD80 increases tumor-infiltrating T cells and significantly extends survival time of mice carrying established, syngeneic tumors. sCD80 does not suppress T cell function via CTLA-4. These studies suggest that the CD3xPD-L1 BiTE and sCD80 may be efficacious therapeutics either as monotherapies or in combination with other therapies such as radiation therapy for the treatment of cancer

Myeloid-Derived Suppressor Cells: Not Only in Tumor Immunity

Since the realization that immature myeloid cells are powerful modulators of the immune response, many studies on “myeloid-derived suppressor cells” (MDSCs) have documented their ability to promote tumor progression in melanoma and other cancers. Whether MDSCs are induced solely pathologically in tumorigenesis, or whether they also represent physiological immune control mechanisms, is not well-understood, but is particularly important in the light of ongoing attempts to block their activities in order to enhance anti-tumor immunity. Here, we briefly review studies which explore (1) how best to identify MDSCs in the context of cancer and how this compares to other conditions in humans; (2) what the suppressive mechanisms of MDSCs are and how to target them pharmacologically; (3) whether levels of MDSCs with various phenotypes are informative for clinical outcome not only in cancer but also other diseases, and (4) whether MDSCs are only found under pathological conditions or whether they also represent a physiological regulatory mechanism for the feedback control of immunity. Studies unequivocally document that MDSCs strongly influence cancer outcomes, but are less informative regarding their relevance to infection, autoimmunity, transplantation and aging, especially in humans. So far, the results of clinical interventions to reverse their negative effects in cancer have been disappointing; thus, developing differential approaches to modulate MSDCs in cancer and other diseases without unduly comprising any normal physiological function requires further exploration

A nonclassical non-Vα14Jα18 CD1d-restricted (type II) NKT cell is sufficient for down-regulation of tumor immunosurveillance

The importance of immunoregulatory T cells has become increasingly apparent. Both CD4+CD25+ T cells and CD1d-restricted NKT cells have been reported to down-regulate tumor immunity in mouse tumor models. However, the relative roles of both T cell populations have rarely been clearly distinguished in the same tumor models. In addition, CD1d-restricted NKT cells have been reported to play a critical role not only in the down-regulation of tumor immunity but also in the promotion of the immunity. However, the explanation for these apparently opposite roles in different tumor models remains unclear. We show that in four mouse tumor models in which CD1d-restricted NKT cells play a role in suppression of tumor immunity, depletion of CD4+CD25+ T cells did not induce enhancement of immunosurveillance. Surprisingly, among the two subpopulations of CD1d-restricted NKT cells, Vα14Jα18+ (type I) and Vα14Jα18− (type II) NKT cells, type I NKT cells were not necessary for the immune suppression. These unexpected results may now resolve the paradox in the role of CD1d-restricted NKT cells in the regulation of tumor immunity, in that type II NKT cells may be sufficient for negative regulation, whereas protection has been found to be mediated by α-galactosylceramide–responsive type I NKT cells

Recommendations for myeloid-derived suppressor cell nomenclature and characterization standards

Myeloid-derived suppressor cells (MDSCs) have emerged as major regulators of immune responses in cancer and other pathological conditions. In recent years, ample evidence supports key contributions of MDSC to tumour progression through both immune-mediated mechanisms and those not directly associated with immune suppression. MDSC are the subject of intensive research with >500 papers published in 2015 alone. However, the phenotypic, morphological and functional heterogeneity of these cells generates confusion in investigation and analysis of their roles in inflammatory responses. The purpose of this communication is to suggest characterization standards in the burgeoning field of MDSC research

The adaptor protein TRAF3 is an immune checkpoint that inhibits myeloid-derived suppressor cell expansion

Myeloid-derived suppressor cells (MDSCs) are aberrantly expanded in cancer patients and under other pathological conditions. These cells orchestrate the immunosuppressive and inflammatory network to facilitate cancer metastasis and mediate patient resistance to therapies, and thus are recognized as a prime therapeutic target of human cancers. Here we report the identification of the adaptor protein TRAF3 as a novel immune checkpoint that critically restrains MDSC expansion. We found that myeloid cell-specific Traf3-deficient (M-Traf3-/-) mice exhibited MDSC hyperexpansion during chronic inflammation. Interestingly, MDSC hyperexpansion in M-Traf3-/- mice led to accelerated growth and metastasis of transplanted tumors associated with an altered phenotype of T cells and NK cells. Using mixed bone marrow chimeras, we demonstrated that TRAF3 inhibited MDSC expansion via both cell-intrinsic and cell-extrinsic mechanisms. Furthermore, we elucidated a GM-CSF-STAT3-TRAF3-PTP1B signaling axis in MDSCs and a novel TLR4-TRAF3-CCL22-CCR4-G-CSF axis acting in inflammatory macrophages and monocytes that coordinately control MDSC expansion during chronic inflammation. Taken together, our findings provide novel insights into the complex regulatory mechanisms of MDSC expansion and open up unique perspectives for the design of new therapeutic strategies that aim to target MDSCs in cancer patients

Alternative Ii-independent antigen-processing pathway in leukemic blasts involves TAP-dependent peptide loading of HLA class II complexes

During HLA class II synthesis in antigen-presenting cells, the invariant chain (Ii) not only stabilizes HLA class II complexes in the endoplasmic reticulum, but also mediates their transport to specialized lysosomal antigen-loading compartments termed MIICs. This study explores an alternative HLA class II presentation pathway in leukemic blasts that involves proteasome and transporter associated with antigen processing (TAP)-dependent peptide loading. Although HLA-DR did associate with Ii, Ii silencing in the human class II-associated invariant chain peptide (CLIP)-negative KG-1 myeloid leukemic cell line did not affect total and plasma membrane expression levels of HLA-DR, as determined by western blotting and flow cytometry. Since HLA-DR expression does require peptide binding, we examined the role of endogenous antigen-processing machinery in HLA-DR presentation by CLIP− leukemic blasts. The suppression of proteasome and TAP function using various inhibitors resulted in decreased HLA-DR levels in both CLIP− KG-1 and ME-1 blasts. Simultaneous inhibition of TAP and Ii completely down-modulated the expression of HLA-DR, demonstrating that together these molecules form the key mediators of HLA class II antigen presentation in leukemic blasts. By the use of a proteasome- and TAP-dependent pathway for HLA class II antigen presentation, CLIP− leukemic blasts might be able to present a broad range of endogenous leukemia-associated peptides via HLA class II to activate leukemia-specific CD4+ T cells

Marianne Steinberg Ostrand Collection 1926-1990

The Marianne Steinberg Ostrand Collection documents the education, emigration, and early professional life of the physician Marianne Steinberg Ostrand as well as the lives of members of her family, especially her husband Arnold Ostrand and her mother and siblings.The collection holds letters to and from Marianne Steinberg Ostrand from the early 1920's through 1948. The letters from late 1938 through November 1941 are predominantly correspondence between her and her mother and other relatives in Germany. The letters from 1941 through the end of the war are mostly letters between Dr. Ostrand and her brother and sister in Palestine. Also included are some letters after the war (through 1948) since they shed light on the fate of the siblings’ mother and aunt.In addition, the collection contains educational certificates, official documents, diaries, notebooks, notes, and a friendship album, travel memorabilia, as well as newspaper clippings.A spread sheet listing all of the letters (dates, addressees, etc.) is available in hard copy, as well as an e-copy in the Digital Archive. In addition to Dr. Ostrand’s letters, the spreadsheet also lists the letters held by nieces/nephews in Chile (Alicia Frohman) and in Israel.The letters were part of the basis for Rebecca Boehling's and Uta Larkey's book "Life and Loss in the Shadow of the Holocaust” (Cambridge University Press).Marianne Steinberg was born February 2, 1911, in Altenessen, a borough of the city of Essen, to Alex and Selma (née Kaufmann) Steinberg. She had two elder siblings: Kurt (born 1906) and Charlotte (called Lotti, born 1908). In their household lived also Selma's sister Henriette (called Henny) and Alex's brother Hermann. Alex Steinberg was a grain wholesaler, and Selma and Henny had a manufactured goods store. The family's large apartment was located above this store. After attending the Jewish primary school, Marianne Steinberg attended the Luisenschule (Städtisches Lyzeum und Oberlyzeum, a girls' high school), where she was elected prefect for several years and graduated with honors. She competed in several sports while in school and traveled frequently as a young woman.In summer of 1930 Marianne began her medical studies at the university in Freiburg im Breisgau, and continued at the universities of Kiel, Würzburg and Düsseldorf. After her father’s death in June of 1933, she spent some time in England, where she worked as a cook and nanny. When she was not allowed to complete her medical studies in Germany, she matriculated at the University of Bern, financing her studies there with the assistance of a scholarship from the International Student Service. In February of 1936 she passed the Swiss medical exams and began work on her doctoral thesis. In August 1936 she returned to Essen, interning at the Israelitisches Asyl für Kranke und Altersschwache. After completing her thesis, titled "Letzte Aufzeichnungen von Selbstmordern nebst kurzer Selbstmordstatistik der Stadt Bern 1929 bis und mit 1935" (Last notes of suicides including brief suicide statistics of the city of Bern from 1929 until and including 1935), she received her medical degree in Bern in June of 1938 and that same month left for the United States, assisted by distant relatives who had previously emigrated.Marianne Steinberg spent her first months in the United States studying to pass the New York State medical exams in order to practice as a physician, which she did in September 1939. After working as a nurse and submitting numerous applications for internships, she was accepted at the Tewksbury State Hospital and Infirmary, where she had a rotating internship from December 1939 to January 1941. In the meantime, Marianne’s sister Charlotte had married her first husband Hans Kaiser Blüth and they had emigrated to Tel Aviv by 1935, where Charlotte opened a dental practice. On November 8, 1938 their brother Kurt was arrested and taken to the concentration camp at Buchenwald. His fiancée Hanna Levy eventually was able to free him at the end of the month; they joined Charlotte in Tel Aviv in February of 1939.Marianne and her siblings tried to get their mother, aunt Henny, and aunt Emma Kaufmann out of Germany: after American consulates were closed in Germany, Marianne pursued Cuban visas. In February 1942 Selma and Henny were sent to the Müngersdorf ghetto outside of Cologne. In September of 1942 they were sent to the Theresienstadt concentration camp and were later deported to Auschwitz.By December 1939 Marianne Steinberg had met Arnold Oestreicher in Massachusetts. Arnold was a fellow immigrant born in Leipzig in 1911, who had studied structural engineering at the Technische Hochschule (technical university) of Berlin and later changed his surname to Ostrand. The couple married in March 1941 and would later have two children. Marianne established a medical practice in their apartment in the Washington Heights neighborhood of Manhattan, where their living room doubled as a patients' waiting room, and the bedroom as her office. In 1955 she was granted her German medical degree, retroactively to March 1938.In 1957 the Ostrands moved to Englewood, New Jersey, where Marianne opened her own practice and also worked as an attending physician at the Englewood Hospital until her retirement in 1981. Marianne passed away on May 28, 2002; Arnold passed away in 2004.The final series of the collection was previously a separate archival collection of the same name, with the call number AR 5823.Finding aid available onlineProcesse

Studies of bovine blood cell surfaces

The cell surface expression of genetically defined bovine red cell antigens has been studied by electron microscopic and serological techniques. Electron microscopic cell surface localization of specific antigens on bovine red cells has been achieved with the use of an indirect labeling reagent: hemocyanin glutaraldehyde coupled to rabbit-antibovineimmunoglobulin (Hcy-RABI). When the specific antigenic sites on the cell surface are combined with their corresponding antibodies, the secondary application of Hcy-RABI serves to visualize these sites for electron microscopy. Serological dosage reagents for the Z antigen are known to differentiate Z homozygotes (Z/Z) from heterozygotes (Z/-) in terms of the kinetics of complement mediated hemolysis. In the present study, cells homozygous for the Z antigen and saturated with anti-Z antibody were found to take up approximately twice as much Hcy-RABI as cells heterozygous for Z; cells negative for Z showed only background labeling values. Cells possessing the J antigen, a soluble serum substance secondarily absorbed to the red cell surface, were also examined for their quantitative uptake of hemocyanin. Many intergrades of J positive cells exist, ranging from cells which require large amounts of anti-J antibody for complement mediated lysis to cells which are lysed by minute quantities of specific antibody. The quantity of label taken up by a sampling of cells was found to be inversely related to the amount of antibody necessary to lyse those cells. Sequential double labeling studies were conducted to characterize the cell surface steric configurations of antigens whose genes reside in 1) the same blood group system; 2) different blood group systems; and 3) cis versus trans conformations within a system. In no case was steric hindrance found. This result indicates that each antigenic determinant examined is spacially distant from others; it suggests that the determinants may be coded for by distinct genes, and that the antigens labeled are not a series of determinants on a common backbone macromolecule. Sequential double labeling of one set of antigens gave a value which was twice the sum of the two single label values. This phenomenon was noted only for one particular pair of antigens, and only on cells treated initially with one of the antisera. The increased uptake of the second antibody was highly specific. This observation suggests that new antigenic sites are revealed in the presence of bound antibody directed against another specificity, on cells labeled for this particular pair of antigens. Concanavalin A (Con A) binding experiments on trypsinized and nontrypsinized cells strongly indicate that the Con A receptor and the A antigen are molecular unique cell surface entities. Trypsinization of A positive cells caused increased binding of anti-A, accompanied by clustering of the A antigen sites and of the intramembranous particles seen in freeze-fracture experiments. These phenomena were accompanied by cell agglutination. Using bovine red cell blood typing reagents in a leukocyte microcytotoxicity system, bovine leukocytes were found to have specific surface antigens. In this preliminary study there is no obvious association between leukocyte antigens and red cell antigens of any individual animal. The leukocyte and erythrocyte antigenic systems appear to be distinct from each other