CtIP fusion to Cas9 enhances transgene integration by homology-dependent repair

In genome editing with CRISPR-Cas9, transgene integration often remains challenging. Here, we present an approach for increasing the efficiency of transgene integration by homology-dependent repair (HDR). CtIP, a key protein in early steps of homologous recombination, is fused to Cas9 and stimulates transgene integration by HDR at the human AAVS1 safe harbor locus. A minimal N-terminal fragment of CtIP, designated HE for HDR enhancer, is sufficient to stimulate HDR and this depends on CDK phosphorylation sites and the multimerization domain essential for CtIP activity in homologous recombination. HDR stimulation by Cas9-HE, however, depends on the guide RNA used, a limitation that may be overcome by testing multiple guides to the locus of interest. The Cas9-HE fusion is simple to use and allows obtaining twofold or more efficient transgene integration than that with Cas9 in several experimental systems, including human cell lines, iPS cells, and rat zygotes.

Radiotherapy-exposed CD8+ and CD4+ neoantigens enhance tumor control

Neoantigens generated by somatic nonsynonymous mutations are key targets of tumor-specific T cells, but only a small number of mutations predicted to be immunogenic are presented by MHC molecules on cancer cells. Vaccination studies in mice and patients have shown that the majority of neoepitopes that elicit T cell responses fail to induce significant antitumor activity, for incompletely understood reasons. We report that radiotherapy upregulates the expression of genes containing immunogenic mutations in a poorly immunogenic mouse model of triple-negative breast cancer. Vaccination with neoepitopes encoded by these genes elicited CD8+ and CD4+ T cells that, whereas ineffective in preventing tumor growth, improved the therapeutic efficacy of radiotherapy. Mechanistically, neoantigen-specific CD8+ T cells preferentially killed irradiated tumor cells. Neoantigen-specific CD4+ T cells were required for the therapeutic efficacy of vaccination and acted by producing Th1 cytokines, killing irradiated tumor cells, and promoting epitope spread. Such a cytotoxic activity relied on the ability of radiation to upregulate class II MHC molecules as well as the death receptors FAS/CD95 and DR5 on the surface of tumor cells. These results provide proof-of-principle evidence that radiotherapy works in concert with neoantigen vaccination to improve tumor control.

Genetic diversity and reproductive success in mandrills (Mandrillus sphinx)

Recent studies of wild animal populations have shown that estimators of neutral genetic diversity, such as mean heterozygosity, are often correlated with various fitness traits, such as survival, disease susceptibility, or reproductive success. We used two estimators of genetic diversity to explore the relationship between heterozygosity and reproductive success in male and female mandrills (Mandrillus sphinx) living in a semifree ranging setting in Gabon. Because social rank is known to influence reproductive success in both sexes, we also examined the correlation between genetic diversity and social rank in females, and acquisition of alpha status in males, as well as length of alpha male tenure. We found that heterozygous individuals showed greater reproductive success, with both females and males producing more offspring. However, heterozygosity influenced reproductive success only in dominant males, not in subordinates. Neither the acquisition of alpha status in males, nor social rank in females, was significantly correlated with heterozygosity, although more heterozygous alpha males showed longer tenure than homozygous ones. We also tested whether the benefits of greater genetic diversity were due mainly to a genome-wide effect of inbreeding depression or to heterosis at one or a few loci. Multilocus effects best explained the correlation between heterozygosity and reproductive success and tenure, indicating the occurrence of inbreeding depression in this mandrill colony.

Correlates of care quality in long-term care facilities: a multilevel analysis

Hierarchical modeling was employed to explore correlates of the quality of care provided in long-term care facilities. For this purpose, a multilevel analysis offers two advantages over traditional analytical approaches. First, it accounts for the correlated nature of data recorded on multiple residents from the same facility. Second, it enables the investigators to study the influence of both resident and facility characteristics on care quality. The analysis was performed on data from 301 residents randomly sampled from 88 facilities located in the Province of Quebec, Canada. Results revealed that the presence of cognitive deficits was the strongest correlate of the quality of care provided to a resident. However, this relationship was found to vary significantly across facilities. Four facility-level variables were found to influence the relationship between cognitive functioning and care quality: the number of external collaborators the facility has, the type of training the facility manager has, the size of the facility, and the age distribution of its clientele. From these results, we suggest means to improve the quality of care provided to cognitively impaired older adults living in long-term care facilities.

Liquid chromatographic fractionation of small peptides from wine

Peptides are difficult to isolate from wine because they are present in a complex mixture together with non-peptidic compounds. A method for the isolation, separation and purity assessing of small peptides is proposed. Small peptides (Mr<3000) were isolated from wine by hollow fibre ultrafiltration followed by column chromatography using the gel matrix Sephadex LH20. Fractions obtained by gel filtration on Sephadex LH20 were subjected to HPLC on a porous graphitic carbon column in order to isolate small peptides. Peak purity was then analysed by capillary electrophoresis.

Purification method for the isolation of monophosphate nucleotides from Champagne wine and their identification by mass spectrometry

Monophosphate nucleotides are difficult to identify in Champagne wine because they are present in small concentrations in a complex mixture. A method for the isolation, separation and identification of reference compounds, which achieved on average 79% recovery (except for cytidine derivatives), was developed and applied to wine. Some monophosphate nucleotides were then isolated from a Champagne wine aged on lees for 8 years, by ultrafiltration followed by a semi-preparative HPLC step using a strong anion-exchange column. The fraction obtained was subjected to HPLC in a reversed-phase column to remove the salt previously introduced, before identification of compounds by HPLC coupled to a mass spectrometer. For the first time in wine, 5'-IMP, 5'-AMP, 5'-CMP, 5'-GMP, 5'-UMP and the 3'- and/or 2'-isomers of the four latter compounds were identified by comparing their HPLC and electrospray ionization mass spectrometry data with those of reference nucleotides.

Life history correlates of inbreeding depression in mandrills (Mandrillus sphinx)

Inbreeding depression reflects the negative consequences of increased homozygosity at genes that affect fitness. We investigate inbreeding depression in a semi-free-ranging colony of mandrills (Mandrillus sphinx), using high-quality pedigree data, comprising five maternal generations and 20 years of morphological and demographic data. We examine the relationship between inbreeding coefficients and four fitness correlates: two growth parameters (mass and height for age) and longevity in both sexes, and age at first conception in females. Inbreeding was correlated with both growth parameters, but only in females, with inbred females being smaller than noninbred females. Inbreeding was also correlated significantly with age at first conception, with inbred females giving birth earlier in life than noninbred females. We suggest that sex-biased maternal investment may explain this sex-differential response to inbreeding, although the lack of a significant association between inbreeding and growth in males may also be due to the provisioned nature of the colony. The surprising relationship between age at first conception and inbreeding may be related to smaller adult size in inbred females, or to their being less able to escape from male sexual coercion.

Radiotherapy Cooperates with IL15 to Induce Antitumor Immune Responses

Focal radiotherapy can promote cross-presentation of tumor antigens to T cells, but by itself, it is insufficient to induce therapeutically effective T-cell responses. The common gamma-chain cytokine IL15 promotes and sustains the proliferation and effector function of CD8⁺ T cells but has limited activity against poorly immunogenic tumors that do not elicit significant spontaneous T-cell responses. Here, we show that radiotherapy and subcutaneous IL15 had complementary effects and induced CD8⁺ T-cell-mediated tumor regression and long-term protective memory responses in two mouse carcinoma models unresponsive to IL15 alone. Mechanistically, radiotherapy-induced IFN type I production and Batf3-dependent conventional dendritic cells type 1 (cDC1) were required for priming of tumor-specific CD8⁺ T cells and for the therapeutic effect of the combination. IL15 cooperated with radiotherapy to activate and recruit cDC1s to the tumor. IL15 alone and in complex with a hybrid molecule containing the IL15α receptor have been tested in early-phase clinical trials in patients with cancer and demonstrated good tolerability, especially when given subcutaneously. Expansion of natural killer (NK) cells and CD8⁺ T cells was noted, without clear clinical activity, suggesting further testing of IL15 as a component of a combinatorial treatment with other agents. Our results provide the rationale for testing combinations of IL15 with radiotherapy in the clinic.

IRES-dependent translation of the long non coding RNA meloe in melanoma cells produces the most immunogenic MELOE antigens

MELOE-1 and MELOE-2, two highly specific melanoma antigens involved in T cell immunosurveillance are produced by IRES-dependent translation of the long « non coding » and polycistronic RNA, meloe. In the present study, we document the expression of an additional ORF, MELOE-3, located in the 5' region of meloe. Data from in vitro translation experiments and transfection of melanoma cells with bicistronic vectors documented that MELOE-3 is exclusively translated by the classical cap-dependent pathway. Using a sensitive tandem mass spectrometry technique, we detected the presence of MELOE-3 in total lysates of both melanoma cells and normal melanocytes. This contrasts with our previous observation of the melanoma-restricted expression of MELOE-1 and MELOE-2. Furthermore, in vitro stimulation of PBMC from 6 healthy donors with overlapping peptides from MELOE-1 or MELOE-3 revealed a very scarce MELOE-3 specific T cell repertoire as compared to the abundant repertoire observed against MELOE-1. The poor immunogenicity of MELOE-3 and its expression in melanocytes is consistent with an immune tolerance towards a physiologically expressed protein. In contrast, melanoma-restricted expression of IRES-dependent MELOE-1 may explain its high immunogenicity. In conclusion, within the MELOE family, IRES-dependent antigens represent the best T cell targets for immunotherapy of melanoma.

Cancer vaccines: designing artificial synthetic long peptides to improve presentation of class I and class II T cell epitopes by dendritic cells

There is now a consensus that efficient peptide vaccination against cancer requires that peptides should (i) be exclusively presented by professional APC and (ii) stimulate both CD4 and CD8-specific T cell responses. To this aim, in recent trials, patients were vaccinated with pools of synthetic long peptides (SLP) (15-30 aa long) composed of a potential class I epitope(s) elongated at both ends with native antigen sequences to also provide a potential class II epitope(s). Using MELOE-1 as a model antigen, we present an alternative strategy consisting in linking selected class I and class II epitopes with an artificial cathepsin-sensitive linker to improve epitope processing and presentation by DC. We provide evidence that some linker sequences used in our artificial SLPs (aSLPs) could increase up to 100-fold the cross-presentation of class I epitopes to CD8-specific T cell clones when compared to cross-presentation of the corresponding native long peptide. Presentation of class II epitopes were only slightly increased. We confirmed this increased cross-presentation after in vitro stimulation of PBMC from healthy donors with aSLP and assessment of CD8-specific responses and also in vivo following aSLP vaccination of HLA*A0201/HLA-DRB0101 transgenic mice. Finally, we provide some evidence that vaccination with aSLP could inhibit the growth of transplanted tumors in mice. Our data thus support the use of such aSLPs in future cancer vaccination trials to improve anti-tumor CD8 T cell responses and therapeutic efficacy.

Yeast adapted to wine: Nitrogen compounds released during induced autolysis in a model wine

As important as the blend of base wines before bottling, one of the most important steps in the champagne-making process is the long ageing on lees. Two yeast strains of Saccharomyces cerevisiae MC001 and MC002, used in champagne wine production, were allowed to autolyse. After 8 days of autolysis, active dry yeasts adapted to wine released 1.7- to 1.8-fold more nitrogen compounds than nonadapted active dry yeast. The nitrogen content (total, proteins, peptides and amino) present in autolysates was measured for yeasts adapted to wine. The composition of free amino acids and amino acids constituting peptides showed no difference between the two strains of yeast used. Studies of intracellular proteolytic activity and release of peptides showed no correlation between these two phenomena. These results indicate that yeasts adapted to wine give results similar to those that occur in wine during ageing.

The melanoma antigens MELOE-1 and MELOE-2 are translated from a bona fide polycistronic mRNA containing functional IRES sequences

Our previous studies on melanoma antigens identified two new polypeptides, named MELOE-1 and MELOE-2, that are involved in immunosurveillance. Intriguingly, these antigens are coded by distinct open reading frames (ORF) of the meloe mRNA which is significantly expressed only in the melanocytic lineage. In addition, MELOE-1 and -2 specific T cell clones recognized melanoma cells but very poorly normal melanocytes suggesting differential translation of meloe in normal vs tumor cells. This prompted us to elucidate the mechanisms of translation of these antigens in melanoma cells. We first demonstrated that no splicing event or cryptic promoter could generate shorter meloe transcripts containing only one of the two ORFs. Triggering meloe RNA degradation with a siRNA close to the ORF coding for MELOE-2 abrogated expression of both MELOE-1 and MELOE-2, thus confirming that the two ORFs are always associated. Next we showed, in a bicistronic reporter system, that IRES activities could be detected upstream of MELOE-1 and MELOE-2 and finally confirmed their translation from full length meloe cDNA in melanoma cells with eGFP constructs. In conclusion, meloe is a polycistronic mRNA that generates both MELOE-1 and MELOE-2 antigens through IRES-dependent translation in melanoma cells and that may explain their tumor specificity.

Atherosclerosis Associated with Pericardial Effusion in a Central Bearded Dragon (Pogona Vitticeps)

Atherosclerosis is a common disease in pet birds, particularly in psittacines, and is frequently found when performing postmortem examinations on adult and old dogs, in which it is mainly associated with endocrine diseases, such as hypothyroidism and diabetes mellitus. However, atherosclerosis is poorly documented in reptiles and consequently poorly understood. In the current case report, atherosclerosis and pericardial effusion were diagnosed in a 2-year-old male central bearded dragon ( Pogona vitticeps) based on ultrasound visualization, necropsy, and histologic examination.

The chitin-degrading enzyme system of a Streptomyces species

1. In the study of natural chitin metabolism by a strain of Streptomyces, we have separated by affinity chromatography the different extracellular chitinolytic enzymes synthetised by the microorganism. 2. N-acetylglucosaminidase (pHi = 3.6) with activity against the synthetic soluble derivatives from beta-D-N-acetylglucosamine, and against the chitobiose, with respectively pH optimum = 4.4-4.7 and 5.3 (mol. wt = 50,000). 3. N-acetylhexosaminidase (pHi = 8.5) with activity against M.U.G. 4. Chitinase (pHi = 4.25) with solubilizing activity against colloïdal chitin, and hydrolyzing activity against 3,4-dinitrophenylchitotetraoside, if the pH is 6 less than pH less than 10. (mol. wt 56,000). 5. Chitinases (pHi = 7.5 and 8.2) with activity against colloïdal chitin if the pH is 4.5 less than pH less than 9. (mol wt = 20,000).

hnRNP-A1 binds to the IRES of MELOE-1 antigen to promote MELOE-1 translation in stressed melanoma cells

The major challenge in antigen-specific immunotherapy of cancer is to select the most relevant tumor antigens to target. To this aim, understanding their mode of expression by tumor cells is critical. We previously identified a melanoma-specific antigen, melanoma-overexpressed antigen 1 (MELOE-1)-coded for by a long noncoding RNA-whose internal ribosomal entry sequence (IRES)-dependent translation is restricted to tumor cells. This restricted expression is associated with the presence of a broad-specific T-cell repertoire that is involved in tumor immunosurveillance in melanoma patients. In the present work, we explored the translation control of MELOE-1 and provide evidence that heterogeneous nuclear ribonucleoprotein A1 (hnRNP-A1) binds to the MELOE-1 IRES and acts as an IRES trans-activating factor (ITAF) to promote the translation of MELOE-1 in melanoma cells. In addition, we showed that endoplasmic reticulum (ER) stress induced by thapsigargin, which promotes hnRNP-A1 cytoplasmic translocation, enhances MELOE-1 translation and recognition of melanoma cells by a MELOE-1-specific T-cell clone. These findings suggest that pharmacological stimulation of stress pathways may enhance the efficacy of immunotherapies targeting stress-induced tumor antigens such as MELOE-1.

Immunotherapy targeting different immune compartments in combination with radiation therapy induces regression of resistant tumors

Radiation therapy (RT) increases tumor response to CTLA-4 inhibition (CTLA4i) in mice and in some patients, yet deep responses are rare. To identify rational combinations of immunotherapy to improve responses we use models of triple negative breast cancer highly resistant to immunotherapy in female mice. We find that CTLA4i promotes the expansion of CD4+ T helper cells, whereas RT enhances T cell clonality and enriches for CD8+ T cells with an exhausted phenotype. Combination therapy decreases regulatory CD4+ T cells and increases effector memory, early activation and precursor exhausted CD8+ T cells. A combined gene signature comprising these three CD8+ T cell clusters is associated with survival in patients. Here we show that targeting additional immune checkpoints expressed by intratumoral T cells, including PD1, is not effective, whereas CD40 agonist therapy recruits resistant tumors into responding to the combination of RT and CTLA4i, indicating the need to target different immune compartments.

IL15 synergizes with radiotherapy to reprogram the tumor immune contexture through a dendritic cell connection

IL15 is a key cytokine for the activation and survival of anti-tumor effectors CD8⁺ T and NK cells. Recently published preclinical studies demonstrate that the therapeutic activity of IL15 requires conventional dendritic cells type 1 (cDC1). Radiotherapy cooperates with IL15 by enhancing cDC1 tumor infiltration via interferon type 1 activation.

Abstract LB168: Blocking SIRPα on myeloid cells synergizes with radiation therapy in mouse breast cancer models

Focal tumor radiation therapy (RT) induces an immunogenic cell death associated with endogenous adjuvants that promote uptake of cancer antigens by conventional dendritic cells (cDCs). The expression of CD47 is markedly increased in a high proportion of breast cancers (BC) and correlates with poor-prognosis molecular subtypes. CD47 interaction with SIRPα expressed at the surface of cDCs and macrophages provides a negative signal that inhibits phagocytosis of dying cancer cells, hindering cross-presentation of tumor-derived antigens and activation of anti-tumor T cells. Thus, we hypothesized that the “don't-eat-me” signal mediated by CD47/SIRPα acts as a barrier to RT-induced anti-tumor immunity. Using two mouse BC models refractory to immune checkpoint blockade, we investigated the effects of RT combined with SIRPα; blockade on the development of anti-tumor immunity. BALB/c mice were inoculated subcutaneously in one or both flanks with the syngeneic TSA BC cells. RT was delivered to one tumor in 8 Gy doses on three consecutive days once tumor volume reached 60-80 mm3. SIRPα; blocking (MY1, OSAKA University [Garcia, et al. J Immunol. 2011;187:2268]) or isotype control antibodies (Abs) were given one day prior to RT and every 3 days thereafter. Some mice also received PD-L1 blocking Abs (BioXcell) every 3 days starting one day after RT completion. Mice were followed for tumor growth and splenic immune cells were analyzed by flow cytometry. Similar experiments were performed in the AT-3 mouse model of triple-negative BC (C57BL/6 background). SIRPα; blockade alone did not inhibit TSA tumor growth, but it significantly improved tumor response to RT (p&lt;0.05), leading to complete regression of the irradiated tumor in 50-60% of the mice. In addition, the combination of SIRPα; blockade with RT significantly inhibited the growth (p&lt;0.05) of a contralateral non-irradiated tumor (abscopal response), suggesting that it induced a systemic anti-tumor immune response. Consistent with systemic immune activation induced by SIRPα; blockade, the percentage of PD1+ CD4 T cells was increased in the spleen of mice treated with SIRPα; Abs compared to control Abs (p&lt;0.01), regardless of RT. In the myeloid compartment, SIRPα; blockade led to a reduction in PD-L1 expression on type 2 conventional DC (cDC2) whereas cDC1 and macrophages showed increased PD-L1 expression. However, addition of anti-PD-L1 to RT+anti-SIRPα; did not further improve abscopal responses. The ability of SIRPα; blockade to significantly improve tumor control induced by RT was also seen in the AT-3 model (p&lt;0.01).Overall, obtained results support the hypothesis that SIRPα; blockade potentiates the ability of RT to induce anti-tumor T cell responses and improve local and systemic tumor control. We are currently investigating the mechanisms of RT interaction with SIRPα; blockade to provide the rationale for translating these findings to the clinic.

Citation Format: Claire Lhuillier, Maud Charpentier, Sergio Trombetta, Sandra Demaria. Blocking SIRPα on myeloid cells synergizes with radiation therapy in mouse breast cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB168.

[Isolation and characterization of two strains of Streptomyces able to metabolize natural polysaccharides including mannan (author's transl)]

Two strains of aerobic and mesophilic microorganisms were isolated from palm-tree plantation sand. They grew on insoluble polysaccharides: mannan, cellulose, chitin as only source of carbon. This lytic activity was used for the purification of the two strains. The morphology of the organisms and the presence of LL-diaminopimetic acid in their cell-wall are characteristic of the genus Streptomyces. Investigations lead to: 1) the characterization of their specific polysaccharidase activity toward insoluble and natural beta-and alpha-glycans (mannan, cellulose, chitin, pectine and starch) and the formation of soluble saccharides (mannobiose, cellobiose, beta-D-N-acetylglucosamine, galacturonic acid, and maltose); 2) the research for antagonist, or synergic, effect on pathogenic bacteria and certain phytopathogenic microorganisms; only in the case of these latter was a weak lytic activity exerted by the two Streptomyces isolates, but one of them was shown to stimulate Colletotrichum lindemuthianum and Phialophora cinerescens; 3) a study of antibiotic sensitivity; the two strains were sensitive to tetracycline and streptomycin, but they had native resistance to other aminosides (gentamicin, kanamycin), to erythromycin and to the beta-lactam antibiotics (penicillin and cephalosporin); they possessed a beta-lactamase bound to the cell membrane.