Immune Depletion Research Articles

Oncolytic herpes virus G47Δ works synergistically with CTLA-4 inhibition via dynamic intratumoral immune modulation

Oncolytic virus therapy can increase the immunogenicity of tumors and remodel the immunosuppressive tumor microenvironment, leading to an increased antitumor response to immune-checkpoint inhibitors. Here, we investigated the therapeutic potential of G47Δ, a third-generation oncolytic herpes simplex virus type 1, in combination with immune-checkpoint inhibitors using various syngeneic murine subcutaneous tumor models. Intratumoral inoculations with G47Δ and systemic anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) antibody administration caused an enhanced antitumor activity when combined and worked synergistically. Conversely, the efficacy of G47Δ in combination with anti-programmed cell death protein-1 (PD-1) antibody was equivalent to that of the anti-PD-1 antibody alone in all murine models examined. The combination of intratumoral G47Δ and systemic anti-CTLA-4 antibody was shown to recruit effector T cells into the tumor efficiently while decreasing regulatory T cells. Furthermore, a wide range of gene signatures related to inflammation, lymphoid lineage, and T cell activation was highly upregulated with the combination therapy, suggesting the conversion of immune-insusceptible tumors to immune susceptible. The therapeutic effect proved tumor specific and long lasting. Immune cell subset depletion studies demonstrated that CD4+ T cells were required for synergistic curative activity. The results depict the dynamics of immune modulation of the tumor microenvironment and provide a clinical rationale for using G47Δ with immune checkpoint inhibitors.

Immune evasion in HPV− head and neck precancer–cancer transition is driven by an aneuploid switch involving chromosome 9p loss

An aneuploid-immune paradox encompasses somatic copy-number alterations (SCNAs), unleashing a cytotoxic response in experimental precancer systems, while conversely being associated with immune suppression and cytotoxic-cell depletion in human tumors, especially head and neck cancer (HNSC). We present evidence from patient samples and cell lines that alterations in chromosome dosage contribute to an immune hot-to-cold switch during human papillomavirus-negative (HPV-) head and neck tumorigenesis. Overall SCNA (aneuploidy) level was associated with increased CD3+ and CD8+ T cell microenvironments in precancer (mostly CD3+, linked to trisomy and aneuploidy), but with T cell-deficient tumors. Early lesions with 9p21.3 loss were associated with depletion of cytotoxic T cell infiltration in TP53 mutant tumors; and with aneuploidy were associated with increased NK-cell infiltration. The strongest driver of cytotoxic T cell and Immune Score depletion in oral cancer was 9p-arm level loss, promoting profound decreases of pivotal IFN-γ-related chemokines (e.g., CXCL9) and pathway genes. Chromosome 9p21.3 deletion contributed mainly to cell-intrinsic senescence suppression, but deletion of the entire arm was necessary to diminish levels of cytokine, JAK-STAT, and Hallmark NF-κB pathways. Finally, 9p arm-level loss and JAK2-PD-L1 codeletion (at 9p24) were predictive markers of poor survival in recurrent HPV- HNSC after anti-PD-1 therapy; likely amplified by independent aneuploidy-induced immune-cold microenvironments observed here. We hypothesize that 9p21.3 arm-loss expansion and epistatic interactions allow oral precancer cells to acquire properties to overcome a proimmunogenic aneuploid checkpoint, transform and invade. These findings enable distinct HNSC interception and precision-therapeutic approaches, concepts that may apply to other CN-driven neoplastic, immune or aneuploid diseases, and immunotherapies.

A DNA nanorobot targeted release aTIGIT improves the immunosuppressive state and synergizes the anti-tumor effect of aPD-1

Abstract Immune checkpoint inhibitor (ICIs) therapies have become the prominent breakthrough in the treatment of hepatocellular carcinoma (HCC). Dual blockade of TIGIT and PD-1 have promising results achieving synergistic antitumor effects for ICI-resistant HCC. However, immune-related adverse events (irAEs) and immune cell depletion in tumor microenvironment affect the clinical use of ICIs therapies. DNA nanobots have shown excellent potential as targeted release drug delivery systems in vivo. Here, using DNA origami we constructed an autonomous DNA robot to transport TIGIT antibodies to tumor site. The Pb (2+) dependent DNAzyme GR5 was used to achieve the aTIGIT free-loaded in DNA cargoes. The nucleolin-targeting aptamer serves both as a targeting domain and as a molecular trigger for the open of the DNA cargoes in tumor microenvironment. The CpG oligodeoxynucleotides (ODNs) responsible for immunostimulatory in tumor site by activation of TLR9, producing high-level secretion of various pro-inflammatory cytokines including tumor necrosis factor (TNF)-R, interleukin (IL)-6, and IL-12. DNA gel electrophoresis and TEM showing the structure of the nanobots. FRET efficiency verified the open of the cargoes regulated by nucleolin aptamer. Confocol microscopy showing the targeting of the nanobots to nucleolin-positive HCC cells. Cy5-modified oligonucleotides were conjugated to aTIGIT and the UV-Vis spectrometry results showed that aTIGIT was free-loaded and protected by the DNA cargoes. Tumor-bearing mouse model will be established to evaluate the synergistic antitumor effect of the DNA nanobots for aPD-1 in vivo. Our DNA nanorobot provide a safe and high efficient immunostimulatory delivery system for ICIs therapies.

Broad Severe Acute Respiratory Syndrome Coronavirus 2 Cell Tropism and Immunopathology in Lung Tissues From Fatal Coronavirus Disease 2019.

BackgroundCOVID-19 patients manifest with pulmonary symptoms reflected by diffuse alveolar damage (DAD), excessive inflammation, and thromboembolism. The mechanisms mediating these processes remain unclear.MethodsWe performed multicolor staining for SARS-CoV-2 proteins and lineage markers to define viral tropism and lung pathobiology in 5 autopsy cases.ResultsLung parenchyma showed severe DAD with thromboemboli. Viral infection was found in an extensive range of cells including pneumocyte type II, ciliated, goblet, club-like and endothelial cells. Over 90% infiltrating immune cells were positive for viral proteins including macrophages, monocytes, neutrophils, and natural killer (NK), B and T cells. Most but not all infected cells were ACE2-positive. The numbers of infected and ACE2-positive cells are associated with extensive tissue damage. Infected tissues exhibited high inflammatory cells including macrophages, monocytes, neutrophils and NK cells, and low B- but abundant T-cells consisting of mainly T helper cells, few cytotoxic T cells, and no T regulatory cell. Robust interleukin-6 expression was present in most cells, with or without infection.ConclusionsIn fatal COVID-19 lungs, there are broad SARS-CoV-2 cell tropisms, extensive infiltrated innate immune cells, and activation and depletion of adaptive immune cells, contributing to severe tissue damage, thromboemboli, excess inflammation and compromised immune responses.

Abstract LT016: Mechanosurveillance eliminates disseminated cancer cells by sensing their mechanical compliance

Abstract Metastatic dissemination of cancer cells to vital secondary organs pose a lifelong lethal threat unless they can successfully be eliminated by the immune system. Interestingly, despite their ability to evade immunity at primary organs, the vast majority of disseminated cancer cells are killed at secondary organs, suggesting that the process of dissemination renders cancer cells sensitive to immunity. Understanding how dissemination renders cancer cells sensitive to immunity would therefore provide exciting new opportunities to target metastases, but the relationship between dissemination and the immune response is not clear. In our effort to study this relationship, we manipulated cancer cells’ expression of myocardin related transcription factors A and B (MRTFA/B), which are central in regulation of actin cytoskeleton and are indispensable for metastatic invasion, dissemination and colonization. Surprisingly, despite MRTFA/B’s established roles in promoting metastasis, we found that MRTFA/B expression in cancer cells downregulated metastatic colonization in fully immuno-competent mouse models. MRTFA/B mediated decrease in colonization was completely reversed upon immune cell depletion suggesting that the immune cells exploit MRTFA/B expression in cancer cells for cytotoxicity. Among various cancer cell parameters involved in immune cell activation, T- and NK cell activation most prominently correlated with MRTFA/B driven mechanical compliance of cancer cells. Mechanical compliance, also known as stiffness, of antigen presenting cells and synthetic substrates are well-known to activate T- and NK cells through biophysical and mechano-chemical signal transduction. As such, perturbing cancer cells’ stiffness downregulated the immune response and cytotoxicity. Thus, we termed this process mechanosurveillance. Our work on mechanosurveillance will help us understand how disseminated cancer cells are targeted by immunity and how they evade it at secondary organs. Importantly the concept of mechanosurveillance will help guide the use of existing therapeutics that alter tissue stiffness and immune boosting therapies to combat metastases. Citation Format: Maria Tello-Lafoz, Katja Srpan, Jing Hu, Yevgeniy Romin, Annalisa Calò, Katharine C. Hsu, Joan Massagué, Morgan Huse, Ekrem Emrah Er. Mechanosurveillance eliminates disseminated cancer cells by sensing their mechanical compliance [abstract]. In: Proceedings of the AACR Virtual Special Conference on the Evolving Tumor Microenvironment in Cancer Progression: Mechanisms and Emerging Therapeutic Opportunities; in association with the Tumor Microenvironment (TME) Working Group; 2021 Jan 11-12. Philadelphia (PA): AACR; Cancer Res 2021;81(5 Suppl):Abstract nr LT016.

B16 melanoma control by anti-PD-L1 requires CD8+ T cells and NK cells: application of anti-PD-L1 Abs and Trp2 peptide vaccines

ABSTRACT Anti-programmed death ligand 1 (PD-L1) therapy has been beneficial in treating patients with certain cancers. Here, we tested whether anti-PD-L1 therapy is effective for controlling different types of tumors using animal models of TC-1, MC38 and B16. We found that, despite PD-L1 expression, anti-PD-L1 therapy showed little and some antitumor activity in the TC-1 and MC38 models. However, anti-PD-L1 therapy exhibited a more dramatic antitumor effect in the B16 model. This difference in antitumor responses was likely associated with the CD8 + T cell infiltration status of tumor tissues. In the B16 model, CD8 + T cells and to a lesser degree NK cells were found to be responsible for the antitumor response of anti-PD-L1 therapy, as determined by immune cell subset depletion. In particular, CD8 + T cells from B16-bearing mice produced an IFN-γ in response to B16 cells and citrate phosphate buffer-treated B16 cell peptide elutes but not to an immunodominant class I epitope, Trp2180-188, suggesting that CD8 + T cells that recognize neoantigens were induced in B16 tumor-bearing mice and then reactivated by anti-PD-L1 for tumor control. When B16 tumor-bearing mice were treated with anti-PD-L1 in combination with Trp2180-188 peptide vaccines, they displayed significantly more tumor control than either single therapy. Taken together, these studies show that B16 melanomas are more effectively controlled through reactivation of tumor-infiltrating lymphocytes by anti-PD-L1 therapy. Moreover, combined therapy using anti-PD-L1 and Trp2 peptide vaccines is more beneficial for controlling B16 melanomas through reactivation of neoantigen-specific CD8 + T cells and induction of Trp2-specific CD8 + T cells.

Clinical immunity and medical cost of COVID-19 patients under grey relational mathematical model

This study was to explore the performance of immune function and compositions of hospitalization cost for patients with COVID-19 as well as the application of a grey relational mathematical model (GRMM). A total of 100 COVID-19 patients diagnosed by nucleic acid test and chest CT examination in our hospital were collected in this study. They were divided into 2 groups: non-severe group (mild and moderate patients, n = 57 cases), and severe group (severe and critical patients, n = 43 cases) based on the Diagnosis and Treatment Protocol for Novel Coronavirus Pneumonia (Trial Version 7) published by the World Health Organization (WHO). The general clinical data, blood routine indexes, cellular immune and humoral immune function test indexes, and the composition of hospitalization costs of the two groups of patients were collected and analyzed. The results showed that the average age, proportion of males, smoking history, and the number and proportion of patients in the non-severe group were smaller than those in the severe group (P < 0.05); the severe group had significantly more shortness of breath patients than the non-severe group (P < 0.05). Compared with the non-severe group, the number of white blood cells (WBC), the number and proportion of neutrophils, and the count of neutrophils/lymphocytes in the severe group increased obviously (P < 0.05), and the number of lymphocytes and the proportion of monocytes decreased dramatically (P < 0.05); the number and proportion of CD3+, CD4+, CD8+, and CD19+ in the severe group were much lower in contrast to those in the non-severe group (P < 0.05), while the ratio of CD4+/CD8+ was greatly higher in contrast to that of non-severe patients (P < 0.05). Compared with the non-severe group, the bed fee, laboratory test fee, diagnosis fee, and medicine fee of the severe group were increased observably (P < 0.05). The changes in hospitalization cost of patients in the severe group was related to bed fees, laboratory fees, and expenses of proprietary Chinese medicines, while the hospitalization cost of patients in the severe group was related to bed fees, laboratory fees, and examination fees. The results revealed that elderly COVID-19 patients with basic diseases were prone to develop severe disease, immune cell depletion may be one of the reasons for the development of severe patients, and the medical insurance policy greatly reduced the hospitalization costs of COVID-19 patients.

A novel immune classification reveals distinct immune escape mechanism and genomic alterations: implications for immunotherapy in hepatocellular carcinoma

BackgroundThe tumor immunological microenvironment (TIME) has a prominent impact on prognosis and immunotherapy. However, the heterogeneous TIME and the mechanisms by which TIME affects immunotherapy have not been elucidated in hepatocellular carcinoma (HCC).MethodsA total of 2195 eligible HCC patients from TCGA and GEO database were collected. We comprehensively explored the different heterogeneous TIME phenotypes and its clinical significance. The potential immune escape mechanisms and what genomic alterations may drive the formation of different phenotypes were further investigated.ResultsWe identified three phenotypes in HCC: TIME-1, the “immune-deficiency” phenotype, with immune cell depletion and proliferation; TIME-2, the “immune-suppressed” phenotype, with enrichment of immunosuppressive cells; TIME-3, the “immune-activated phenotype”, with abundant leukocytes infiltration and immune activation. The prognosis and sensitivity to both sorafenib and immunotherapy differed among the three phenotypes. We also underlined the potential immune escape mechanisms: lack of leukocytes and defective tumor antigen presentation capacity in TIME-1, increased immunosuppressive cells in TIME-2, and rich in immunoinhibitory molecules in TIME-3. The different phenotypes also demonstrated specific genomic events: TIME-1 characterized by TP53, CDKN2A, CTNNB1, AXIN1 and FOXD4 alterations; TIME-2 characterized by significant alteration patterns in the PI3K pathway; TIME-3 characterized by ARID1A mutation. Besides, the TIME index (TI) was proposed to quantify TIME infiltration pattern, and it was a superior prognostic and immunotherapy predictor. A pipeline was developed to classify single patient into one of these three subtypes and calculated the TI.ConclusionsWe identified three TIME phenotypes with different clinical outcomes, immune escape mechanisms and genomic alterations in HCC, which could present strategies for improving the efficacy of immunotherapy. TI as a novel prognostic and immunotherapeutic signature that could guide personalized immunotherapy and clinical management of HCC.

Sult2b1 deficiency exacerbates ischemic stroke by promoting pro-inflammatory macrophage polarization in mice.

Rationale: Stroke is a leading causes of human death worldwide. Ischemic damage induces the sterile neuroinflammation, which directly determines the recovery of patients. Lipids, a major component of the brain, significantly altered after stroke. Cholesterol sulfate, a naturally occurring analog of cholesterol, can directly regulate immune cell activation, indicating the possible involvement of cholesterol metabolites in neuroinflammation. Sulfotransferase family 2b member 1 (Sult2b1) is the key enzyme that catalyzes the synthesis of cholesterol sulfate. This study aimed to investigate the function of Sult2b1 and cholesterol sulfate in the neuroinflammation after ischemic stroke.Methods and Results: Sult2b1-/- and wild-type mice were subjected to transient middle cerebral artery occlusion. Our data showed that Sult2b1-/- mice had larger infarction and worse neurological scores. To determine whether immune cells were involved in the worsening stroke outcome in Sult2b1-/- mice, bone marrow transplantation, immune cell depletion, and adoptive monocyte transfer were performed. Combined with CyTOF and immunofluorescence techniques, we demonstrated that after stroke, the peripheral monocyte-derived macrophages were the dominant cell type promoting the pro-inflammatory status in Sult2b1-/-mice. Using primary bone marrow-derived macrophages, we showed that cholesterol sulfate could attenuate the pro-inflammatory polarization of macrophages under both normal and oxygen-glucose deprivation conditions by regulating the levels of nicotinamide adenine dinucleotide phosphate (NADPH), reactive oxygen species (ROS), and activating the AMP-activated protein kinase (AMPK) - cAMP responsive element-binding protein (CREB) signaling pathway.Conclusions: Sult2b1-/- promoted the polarization of macrophages into pro-inflammatory status. This trend could be attenuated by adding cholesterol sulfate, which promotes the polarization of macrophages into anti-inflammatory status by metabolic regulation. In this study, we established an inflammation-metabolism axis during the macrophage polarization after ischemic stroke.

Urinary tract infection in HIV-positive women

Introduction: Urinary tract infections (UTI) are common in women and can cause systemic repercussions. In pregnant women, for example, the occurrence of UTI or asymptomatic bacteriuria (AB) can lead to premature birth and fetal death. The generalized immune depletion caused by HIV is related to the exacerbation of infections, and may be related to UTI. Objective: The objective of this review was to evaluate the characteristics of UTI in pregnant and non-pregnant HIV-positive women as well as the factors that interfere in its occurrence. Methods: By searching the databases PubMed, Web of Science, Scielo and Lilacs, we selected eleven articles that correlated UTI and HIV infection in women. Results: Our analysis showed that HIV-positive pregnant women have a higher predisposition to UTI than HIV-negative ones. The Viral Load (VL) is directly related to UTI and AB in HIV-positive non-pregnant women. TCD4 lymphocyte levels (TCD4) lower than 200 cells/mL and VL over 10,000 copies/mL are correlated with higher UTI and AB rates in HIV-positive pregnant women. There is a tendency for greater variability of pathogens in HIV-positive women and a predisposition to higher rates of antibiotic resistance in HIV-positive pregnant women. Conclusion: HIV-positive pregnant women have higher predisposition to urinary tract infection and its incidence is correlated with a high viral load and a low TCD4 count.

MDKN-01, a Novel Anti-DKK1 mAb, Enhances Innate Immune Responses in the Tumor Microenvironment.

Dickkopf-1 (DKK1), a secreted modulator of Wnt signaling, is overexpressed in many cancers, is often associated with worse clinical outcomes, and has been shown to have immunosuppressive effects. DKN-01 is an IgG4 clinical stage antibody that potently and specifically neutralizes human and murine DKK1 and has recently completed a promising study in combination with pembrolizumab in patients with gastric/gastroesophageal junction cancer. The purpose of this study is to characterize a murine version of DKN-01 (mDKN-01) and to better understand its mechanism of action. We examined the efficacy of mDKN-01 in both melanoma and metastatic breast cancer models. Immune depletion experiments revealed a requirement for natural killer (NK) but not B and T cells for tumor growth inhibition. mDKN-01 treatment promotes the induction of the NK-activating cytokines IL15 and IL33 as well as an enhanced recruitment of CD45+ cells. Other treatment-related changes include a reduction of Gr-1+CD11b+ myeloid-derived suppressor cells (MDSC) in the tumor and spleen and the upregulation of PD-L1 on MDSCs. In addition, mDKN-01 has a marked effect at reducing pulmonary metastases in the mouse 4T1 breast cancer model. Finally, the mDKN-01/anti-PD-1 combination was more effective at inhibiting melanoma growth than mDKN-01 alone. Taken together, our data demonstrate that mDKN-01 has efficacy by blocking the immunosuppressive effects of DKK1 in the tumor microenvironment (TME) and provides insight into the clinical activity observed with DKN-01-based treatment. IMPLICATIONS: mDKN-01 reverses a DKK1-mediated innate immune suppression in the TME and has additive efficacy with a PD-1 inhibitor.

Fighting Immune Cold and Reprogramming Immunosuppressive Tumor Microenvironment with Red Blood Cell Membrane-Camouflaged Nanobullets

Nanomedicine, acting as the magic bullet, is capable of combining immunotherapy with other treatments to reverse a cold tumor (immune depletion) into a hot tumor. However, how to comprehensively inhibit the immunosuppressive tumor microenvironment (TME) remains a major challenge for immunotherapy to achieve the maximum benefits. Thus, a strategy that can simultaneously increase the recruitment of tumor infiltrating lymphocytes (TILs) and comprehensively reprogram the immunosuppressive TME is still urgently needed. Herein, a thermal-sensitive nitric oxide (NO) donor S-nitrosothiols (SNO)-pendant copolymer (poly(acrylamide-co-acrylonitrile-co-vinylimidazole)-SNO copolymer, PAAV-SNO) with upper critical solution temperature (UCST) was synthesized and employed to fabricate an erythrocyte membrane-camouflaged nanobullet for codelivery of NIR II photothermal agent IR1061 and indoleamine 2,3-dioxygenase 1 (IDO-1) inhibitor 1-methyl-tryptophan (1-MT). This multifunctional nanobullet possessed long circulation in vivo, enhanced accumulation at the tumor site, and therapeutics-controlled release by NIR II laser, thereby it could avoid unspecific drug leakage while enhancing biosecurity. More importantly, the immunogenic cell death (ICD) induced by local hyperthermia from photothermal therapy (PTT) could be conducive for the increased recruitment of CD8+ cytotoxic T lymphocytes (CTLs) at the tumor site. Furthermore, through interfering in the IDO-1 activity by 1-MT and normalizing the tumor vessels by in situ generated NO, the immunosuppressive TME was comprehensively reprogrammed toward an immunostimulatory phenotype, achieving the excellent therapeutic efficacy against both primary breast cancer and metastases. Collectively, this multifunctional nanobullet described in this study developed an effective and promising strategy to comprehensively reprogram suppressive TME and treat "immune cold" tumors.

Ameli-01: Phase I, Open Label Dose-Escalation and Dose-Expansion Study to Evaluate the Safety, Expansion, Persistence and Clinical Activity of UCART123 (allogeneic engineered T-cells expressing anti-CD123 chimeric antigen receptor), Administered in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Ameli-01: Phase I, Open Label Dose-Escalation and Dose-Expansion Study to Evaluate the Safety, Expansion, Persistence and Clinical Activity of UCART123 (allogeneic engineered T-cells expressing anti-CD123 chimeric antigen receptor), Administered in Patients with Relapsed/Refractory Acute Myeloid Leukemia

Repositioning liothyronine for cancer immunotherapy by blocking the interaction of immune checkpoint TIGIT/PVR

BackgroundInhibitors targeting immune checkpoint were proved effective in cancer immunotherapy, such as PD-1/PD-L1 blockade. The novel immune checkpoint TIGIT/PVR plays critical roles in suppressing the anti-tumor effects of CD8+ T and NK cells, and dual blockade of TIGIT/PVR and PD-1/PD-L1 by antibody can elicit synergistic effects in tumor models and clinical trials. However, small molecules for TIGIT/PVR blockade have not been investigated.MethodsThe expression of PVR in tumors were analyzed by using TCGA, Oncomine and GEO database, and in cancer cell lines examined by flow cytometry. Natural product compounds were docked to PVR for virtual screening by using the software Molecular Operating Environment (MOE). Candidate compounds were further tested by biolayer interferometry-based binding assay, microscale thermophoresis assay and cell based blocking assay. The in vitro activity of the candidate compound was determined by MTT, peripheral blood mononuclear cells (PBMCs) activation assay and coculture assay. The anti-tumor effects and mechanism were also investigated by using MC38 tumor-bearing mice model and immune cell depletion tumor model.ResultsPVR was over-expressed in many tumor tissues and cancer cell lines, making it a promising therapeutic target. Through virtual screening, binding, and blocking assay, liothyronine was discovered to bind PVR and block the interaction of TIGIT/PVR. Liothyronine could enhance the function of CD4+ and CD8+ T cells in PBMCs. Besides, in the Jurkat-hTIGIT and CHOK1-hPVR coculture assay, liothyronine could reverse the IL-2 secretion inhibition resulted by TIGIT/PVR ligation. Although had no influence on the proliferation of tumor cells in vitro, liothyronine could significantly inhibit tumor growth when administrated in vivo, by enhancing CD8+ T cell infiltration and immune responses in the tumor bearing mice. The immune cell depletion model showed that the anti-tumor effects of liothyronine depends on CD4+ T cells, CD8+ T cells and NK cells.ConclusionsA small molecule liothyronine was discovered to serve as a potential candidate for cancer immunotherapy by blocking the immune checkpoint TIGIT/PVR.-Ev9Py5y6QZb5r8dVDwR9cVideo abstractGraphical abstract

Histopathological findings and viral tropism in UK patients with severe fatal COVID-19: a post-mortem study

BackgroundSevere COVID-19 has a high mortality rate. Comprehensive pathological descriptions of COVID-19 are scarce and limited in scope. We aimed to describe the histopathological findings and viral tropism in patients who died of severe COVID-19.MethodsIn this case series, patients were considered eligible if they were older than 18 years, with premortem diagnosis of severe acute respiratory syndrome coronavirus 2 infection and COVID-19 listed clinically as the direct cause of death. Between March 1 and April 30, 2020, full post-mortem examinations were done on nine patients with confirmed COVID-19, including sampling of all major organs. A limited autopsy was done on one additional patient. Histochemical and immunohistochemical analyses were done, and histopathological findings were reported by subspecialist pathologists. Viral quantitative RT-PCR analysis was done on tissue samples from a subset of patients.FindingsThe median age at death of our cohort of ten patients was 73 years (IQR 52–79). Thrombotic features were observed in at least one major organ in all full autopsies, predominantly in the lung (eight [89%] of nine patients), heart (five [56%]), and kidney (four [44%]). Diffuse alveolar damage was the most consistent lung finding (all ten patients); however, organisation was noted in patients with a longer clinical course. We documented lymphocyte depletion (particularly CD8-positive T cells) in haematological organs and haemophagocytosis. Evidence of acute tubular injury was noted in all nine patients examined. Major unexpected findings were acute pancreatitis (two [22%] of nine patients), adrenal micro-infarction (three [33%]), pericarditis (two [22%]), disseminated mucormycosis (one [10%] of ten patients), aortic dissection (one [11%] of nine patients), and marantic endocarditis (one [11%]). Viral genomes were detected outside of the respiratory tract in four of five patients. The presence of subgenomic viral RNA transcripts provided evidence of active viral replication outside the respiratory tract in three of five patients.InterpretationOur series supports clinical data showing that the four dominant interrelated pathological processes in severe COVID-19 are diffuse alveolar damage, thrombosis, haemophagocytosis, and immune cell depletion. Additionally, we report here several novel autopsy findings including pancreatitis, pericarditis, adrenal micro-infarction, secondary disseminated mucormycosis, and brain microglial activation, which require additional investigation to understand their role in COVID-19.FundingImperial Biomedical Research Centre, Wellcome Trust, Biotechnology and Biological Sciences Research Council.

Abstract 5511: Frontline therapy with anti-PD1 enhances the durability of combination targeted therapy in NRAS-mutant melanoma

Abstract Melanoma is one of the deadliest form of skin cancer. Although the activating NRAS mutations are present in 20% of melanoma patients, currently, there are no FDA-approved therapies for treating NRAS-mutant melanoma. In this project, our goal is to prime the immune system by immunotherapy and then improve the targeted therapy responses by suppressing recruitment of inhibitory immune cell populations and by increasing T cell infiltration, which would lead to enhanced responses in NRAS-mutant melanoma. We used a syngeneic C3H/HeNCrl mouse model of NRAS-mutant melanoma. The mice were treated with two doses of either anti-PD1 or IgG every 5 days followed by everyday treatment with either single agent or combination of ceritinib and trametinib for a total period of 40 days. Single cell RNA-seq platform was used to determine the impact of immunotherapy and targeted therapy upon each individual cell type. Flow cytometry experiments were carried out to assess the percentage of T cells and MDSCs recruitment. Altered signaling responses and chemokines/ cytokines responsible for MDSCs recruitment were determined from RPPA and RNA-seq data respectively. The in vivo studies demonstrated that the tumors in the mice treated with anti-PD1 followed by combination shrunk significantly over a period of 40 days without any relapse. Single cell RNA seq analysis and flow cytometry experiments revealed a 15- and 20-fold increase in T cell infiltration in these tumors. Immune cells depletion experiments showed that the cytotoxic effects of combination therapy was dependent upon CD8+ T cells only. Single cell RNA seq analysis also demonstrated that priming with immunotherapy increased IFN γ expression on T cells and subsequent treatment with ceritinib+trametinib increased melanoma antigen presentation by increased MHC class I expression. The RPPA data from tumors treated with anti-PD-1 followed by combination demonstrated inhibition of RTKs implicated in therapy escape such as c-MET, EGFR, IGF1R, HER2/3. Flow cytometric analysis also revealed around 60% decrease in Tregs and 80% decrease in MDSCs recruitment in the tumors treated with anti-PD1 followed by combination. RNA seq analysis revealed that ceritinib decreased mRNA expression of cytokines/ chemokines such as Cxcl5, Cxcl3, Cxcl2, Csf1, Cx3cl1, Cklf, that have been implicated in the recruitment and differentiation of MDSCs. Hence, we demonstrate that frontline immunotherapy primes the immune system, making the tumors more immunogenic with an increased accumulation of activated CD8+ T cells. Successive treatment with combination targeted therapy not only increases antigen presentation to T cells but also decreases recruitment of immunosuppressive MDSCs thus preventing immune escape and tumor progression. In summary, we have developed novel targeted therapy combinations that can be sequentially used with immunotherapy to maximize the durations of response in treatment of NRAS-mutant melanoma. Citation Format: Manali S. Phadke, Zhihua Chen, Eslam Mohamed, Michael Davies, Ann Chen, Uwe Rix, Paulo Rodriguez, Keiran Smalley. Frontline therapy with anti-PD1 enhances the durability of combination targeted therapy in NRAS-mutant melanoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5511.

When the Damage Is Done: Injury and Repair in Thymus Function.

Even though the thymus is exquisitely sensitive to acute insults like infection, shock, or common cancer therapies such as cytoreductive chemo- or radiation-therapy, it also has a remarkable capacity for repair. This phenomenon of endogenous thymic regeneration has been known for longer even than its primary function to generate T cells, however, the underlying mechanisms controlling the process have been largely unstudied. Although there is likely continual thymic involution and regeneration in response to stress and infection in otherwise healthy people, acute and profound thymic damage such as that caused by common cancer cytoreductive therapies or the conditioning regimes as part of hematopoietic cell transplantation (HCT), leads to prolonged T cell deficiency; precipitating high morbidity and mortality from opportunistic infections and may even facilitate cancer relapse. Furthermore, this capacity for regeneration declines with age as a function of thymic involution; which even at steady state leads to reduced capacity to respond to new pathogens, vaccines, and immunotherapy. Consequently, there is a real clinical need for strategies that can boost thymic function and enhance T cell immunity. One approach to the development of such therapies is to exploit the processes of endogenous thymic regeneration into novel pharmacologic strategies to boost T cell reconstitution in clinical settings of immune depletion such as HCT. In this review, we will highlight recent work that has revealed the mechanisms by which the thymus is capable of repairing itself and how this knowledge is being used to develop novel therapies to boost immune function.

Immunosuppression in Donation After Circulatory Death Liver Transplantation: Can Induction Modify Graft Survival?

Recipients of donation after circulatory death (DCD) LTs historically have an increased risk of graft failure. Antibody induction (AI) with antithymocyte globulin (ATG) or anti-interleukin 2 receptor (anti-IL2R) immunotherapy may decrease the incidence of graft failure by mitigating ischemia/reperfusion injury. A retrospective review of the United Network for Organ Sharing (UNOS) database for LTs between 2002 and 2015 was conducted to determine whether ATG or anti-IL2R AI was associated with graft survival in DCD. A secondary endpoint was postoperative renal function as measured by estimated glomerular filtration rate at 6 and 12 months. Among DCD recipients, ATG (hazard ratio [HR]=0.71; P=0.03), but not anti-IL2R (HR=0.82; P=0.10), was associated with a decrease in graft failure at 3 years when compared with recipients without AI. ATG (HR=0.90; P=0.02) and anti-IL2R (HR=0.94; P=0.03) were associated with a decreased risk of graft failure in donation after brain death (DBD) liver recipients at 3 years compared with no AI. When induction regimens were compared between DCD and DBD, only ATG (HR=1.19; P=0.19), and not anti-IL2R (HR=1.49; P<0.01) or no AI (HR=1.77; P<0.01), was associated with similar survival between DCD and DBD. In conclusion, AI therapy with ATG was associated with improved longterm liver allograft survival in DCD compared with no AI. ATG was associated with equivalent graft survival between DCD and DBD, suggesting a beneficial role of immune cell depletion in DCD outcomes.

MiR-199a-5p targeted regulation of MAGT1 expression in the functional depletion of CD8+T cells in HBV infection.

Magnesium transporter 1 (MAGT1) is a key protein that regulates the level of free Mg2+ in cells. Previous studies found that the downregulation of MAGT1 expression in CD8+T cells of HBV patients was correlated with the decrease of intracellular magnesium. However, the expression of MAGT1 mRNA in the CD8+T cells from HBV patients was not significantly altered, indicating that the change in MAGT1 expression was accomplished through posttranscriptional regulation. Through bioinformatics and qRT-PCR detection, miR-199a-5p was found to have a target gene relationship with MAGT1. The expression levels of miR-199a-5p and MAGT1 in HBV infection were evaluated. Lentivirus assays were used to analyze the effects of miR-199a-5p upregulation and downregulation on the MAGT1 expression level and the immune system. Results showed no significant change in the expression of MAGT1 mRNA in HBV-infected cell lines, but the expression of MAGT1 was downregulated. Additionally, the expression level of miR-199a-5p was significantly increased. To this end, we predicted a target relationship between miR-199a-5p and MAGT1 by using TargetScan and verified this relationship through a luciferase activity reporter gene assay. As a result, MAGT1 was found to be the direct target of miR-199a-5p. The targeted inhibition of MAGT1 induced by miR-199a-5p overexpression led to the immune function depletion of CD8+T cells in HBV patients. Downregulating the expression level of miR-199a-5p could effectively improve the functional depletion of CD8+T cells. These findings indicate that miR-199a-5p and MAGT1 could potentially be used as biomarkers for the diagnosis and treatment of chronic HBV infection.

HIV and SARS-Cov-2 the Dilemma

At a time when the COVID-19 pandemic is still at its peak with an expanding global activity, patients with HIV infection have always been a worrying population because, with a chronic disease causing immune system depletion, they are at high risk for serious diseases and poor prognosis. However, although there are no large studies directed at this population yet published both in terms of incidences and mortality that compare them with the non-HIV population.