Analysis Of Immune Cell Populations Research Articles

Flow cytometric analysis of immune cell populations in the bronchial and mesenteric lymph nodes of the dromedary camel.

Dromedary camel is an important livestock species with special economic value in arid and semi-arid regions of the world. Given the limited data on detailed immune cell composition and cell marker expression in the dromedary camel lymph node tissue, the present study was undertaken to investigate the immune cell composition of bronchial and mesenteric lymph nodes from healthy dromedary camels using flow cytometry. In this study, we applied flow cytometry and multicolor immuno-fluorescence to phenotype the main populations of immune cells in the bronchial and mesenteric camel lymph nodes and compared them with separated peripheral blood mononuclear cells and granulocytes. We used antibodies to detect several cell surface molecules associated with camel T cells (CD4, WC1), B cells (MHCII, BAQ44A), monocytes/macrophages (CD172a, CD14, CD163), in addition to the pan-leukocyte marker CD45 and the cell adhesion molecules CD44 and CD18. Compared to blood mononuclear cells, camel lymph node cells contained a higher percentage of lymphoid cells with only a minor fraction of myeloid cells. In addition, the lower expression of CD44 and CD18 on lymph node lymphocytes compared to lymphocytes from peripheral blood indicates higher frequency of naïve lymphocytes in the lymph nodes. The frequency of CD4+ T cells, B cells and γδ T cells within camel lymph node lymphocytes compared to blood indicates a similar tissue distribution pattern of lymphocyte subsets in camel and bovine and supports previous reports on the similarity between the camel immune system and the immune system of other ruminants. Lymph node neutrophils were identified as CD45++ CD172a++, CD14+, MHCIIlow, BAQ44A+, CD44++, CD18++ cells. In conclusion, the present study is describing the employment of flow cytometric single-cell analysis and immunostaining for the analysis of the immune cell composition in the camel lymph node.

Stimulator of Interferon Genes Pathway Activation through the Controlled Release of STINGel Mediates Analgesia and Anti-Cancer Effects in Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) presents significant treatment challenges due to its poor survival and intense pain at the primary cancer site. Cancer pain is debilitating, contributes to diminished quality of life, and causes opioid tolerance. The stimulator of interferon genes (STING) agonism has been investigated as an anti-cancer strategy. We have developed STINGel, an extended-release formulation that prolongs the availability of STING agonists, which has demonstrated an enhanced anti-tumor effect in OSCC compared to STING agonist injection. This study investigates the impact of intra-tumoral STINGel on OSCC-induced pain using two separate OSCC models and nociceptive behavioral assays. Intra-tumoral STINGel significantly reduced mechanical allodynia in the orofacial cancer model and alleviated thermal and mechanical hyperalgesia in the hind paw model. To determine the cellular signaling cascade contributing to the antinociceptive effect, we performed an in-depth analysis of immune cell populations via single-cell RNA-seq. We demonstrated an increase in M1-like macrophages and N1-like neutrophils after STINGel treatment. The identified regulatory pathways controlled immune response activation, myeloid cell differentiation, and cytoplasmic translation. Functional pathway analysis demonstrated the suppression of translation at neuron synapses and the negative regulation of neuron projection development in M2-like macrophages after STINGel treatment. Importantly, STINGel treatment upregulated TGF-β pathway signaling between various cell populations and peripheral nervous system (PNS) macrophages and enhanced TGF-β signaling within the PNS itself. Overall, this study sheds light on the mechanisms underlying STINGel-mediated antinociception and anti-tumorigenic impact.

Advances and Challenges in Sepsis Management: Modern Tools and Future Directions.

Sepsis, a critical condition marked by systemic inflammation, profoundly impacts both innate and adaptive immunity, often resulting in lymphopenia. This immune alteration can spare regulatory T cells (Tregs) but significantly affects other lymphocyte subsets, leading to diminished effector functions, altered cytokine profiles, and metabolic changes. The complexity of sepsis stems not only from its pathophysiology but also from the heterogeneity of patient responses, posing significant challenges in developing universally effective therapies. This review emphasizes the importance of phenotyping in sepsis to enhance patient-specific diagnostic and therapeutic strategies. Phenotyping immune cells, which categorizes patients based on clinical and immunological characteristics, is pivotal for tailoring treatment approaches. Flow cytometry emerges as a crucial tool in this endeavor, offering rapid, low cost and detailed analysis of immune cell populations and their functional states. Indeed, this technology facilitates the understanding of immune dysfunctions in sepsis and contributes to the identification of novel biomarkers. Our review underscores the potential of integrating flow cytometry with omics data, machine learning and clinical observations to refine sepsis management, highlighting the shift towards personalized medicine in critical care. This approach could lead to more precise interventions, improving outcomes in this heterogeneously affected patient population.

The “microbiome‐gut‐brain axis” in Alzheimer’s disease and its role in neurocognitive decline

AbstractBackgroundAlzheimer’s disease (AD) is a progressive neurocognitive disease characterized by amyloid beta plaques and neurofibrillary tangles in the brain along with inflammation both in the brain and systemically. This has led to the theory of microbial communities or infections as being causative in the development of neuroinflammation as well as immunosenescence and inflamm‐aging seen in AD. Our own research has demonstrated a decreased abundance of anti‐inflammatory taxa and an increased abundance of pro‐inflammatory taxa in the gut microbiome of AD patients. However, it is unclear how the AD microbiome exerts effects on the central nervous system.MethodWe have performed gut microbiome profiling, analysis of immune cell populations in serum, blood cytokine profiling, and cognitive assessments of AD older adults at 90‐day intervals.ResultIn our early data collected from this ongoing study we have observed changes in B‐cell populations with an increased abundance of class‐switched B‐cells in older adults with greater levels of cognitive impairment (Spearman R = 0.33, p = 0.001). We have further demonstrated that fecal transfer of the microbiome of older adults with AD into mice promotes B‐cell class‐switching when compared with cognitively impaired older adults without AD (Percent total B‐cells, AD 75.12 (SD 10.41) vs ND 50.02 (SD 11.90) p<0.016). Additionally, we have discovered a loss of phytoestrogen‐metabolizing bacteria such as Adlercreutzia equolifaciens among AD older adults with rapidly progressing dementia. Phytoestrogens have been previously identified in protecting the intestinal epithelium from oxidative stress and epithelial permeability. Our work suggests that that the phytoestrogen (s)‐equol, produced by A. equolifaciens, confers resistance to epithelial damage in the setting of oxidative stress and bacterial lipopolysaccharide.ConclusionWe propose that Adlercreutzia equolifaciens and similar phytoestrogen‐metabolizing bacteria will better maintain epithelial homeostasis in the setting of inflammation while a gain of pro‐inflammatory taxa in AD leads to intestinal barrier disruption. This leads to increased antigen presentation, immune cell dysregulation, and ultimately cognitive decline. This continuing work aims to further establish the connection between AD related neurocognitive decline, the microbiome, and immune system.

#4458 SINGLE CELL RNA SEQUENCING OF CIRCULATING LEUKOCYTES FROM IGA NEPHROPATHY PATIENTS IDENTIFIES AN IMPORTANT ROLE FOR INNATE IMMUNE CELLS

Abstract Background and Aims IgA-nephropathy (IgAN) is a slowly progressive disease characterized by mesangial deposition of IgA1 that causes kidney injury and can eventually lead to end stage renal disease. A key factor underlying the development of IgAN is the presence of galactose-deficient IgA1 (Gd-IgA1) in the circulation. The formation of IgA and IgG antibodies against Gd-IgA1 results in the formation of immune complexes which deposit in the kidney mesangium. Production of Gd-IgA1 hints to defects in B cell regulation. However, the exact immunological dysregulation leading to the formation of Gd-IgA1, and the subsequent antibody formation against it, remains elusive. Here we use single cell RNA sequencing (scRNA-seq) of circulating leukocytes for in depth analysis of immune cell populations in patients with active IgAN to gain a better understanding of the pathogenesis of this disease. Method Peripheral blood mononuclear cells were isolated for scRNA-seq from the blood of four patients with active IgAN, and four controls, matched for age and estimated glomerular filtration rate (eGFR). Cell hashing (Biolegend) of individual samples was performed before pooling samples for scRNA-seq. scRNA expression libraries were performed using the chromium X machine (10xgenomics) according to 10XGenomics single cell 5’ V2 user guide. Libraries were sequenced on an Illumina Nextseq500 and reads were mapped to GrCh38 using CellRanger. Differential gene expression analysis was performed for each immune cell type (FDR < 0.05). Reactome pathway enrichment analysis was performed on the differentially expressed genes. Results Identification of immune cell subtypes in IgAN patients and matched controls did not show a significant difference in cell numbers or ratios. B cells showed only minor changes in gene expression between IgAN patients and controls, and T cell populations showed changes in a limited set of genes, whereas interestingly, most differentially expressed genes were found in monocytes and NK cells (Figure 1A). Analysis of the differentially expressed genes showed enrichment for genes in interferon signaling pathways, mostly in monocytes and NK cells (Figure 1B). Gene enrichment analysis showed differential expression of type I IFN genes and antigen presentation genes, also mainly in monocytes and NK cells. Conclusion Our data shows the specific endotype of circulating immune cells from patients with active IgAN. While gene expression changes in T and B cells are discrete, changes in monocytes and NK cells appear especially prominent. In these cell types, we observed an important role for interferon signaling. Further analysis of scRNA-seq data in a larger patient cohort will follow, as well as analysis of T and B cell receptor clones in IgAN patients, with which we aim to gain new insights into immune dysregulation in IgAN.

Prostaglandin E2 signaling via its receptor EP4 on macrophages protects against acute colitis by preserving intestinal barrier function

Abstract The inflammatory bowel diseases are increasing in incidence and cause significant morbidity; however, disease pathogenesis is poorly understood. Prostaglandin E2 (PGE2) may protect against intestinal inflammation and its receptor EP4 is highly expressed on colon macrophages, cells essential for immune homeostasis, suggesting PGE2 signaling on macrophages may prevent gut inflammation. To address this, we induced DSS colitis in CX3CR1CRE/+EP4fl/fl (Cre+) mice, which lack EP4 on macrophages, and in their Cre- wildtype littermates. Cre+ mice developed worse colitis than the Cre- based on clinical scores, including increased rectal bleeding that implies major intestinal barrier disruption, a key mechanism of colitis. Cre+ mice have higher intestinal permeability early during inflammation, further supporting intestinal barrier disruption as a mechanism of increased disease severity in Cre+ mice. To address the protective mechanisms of PGE2, we performed scmRNA sequencing on colon cells of the Cre+ and Cre- mice following DSS treatment. We identified monocyte and macrophage populations, with macrophages (MPs) clustering into CD11c+ MPs expressing inflammatory cytokines, and CD169+ MPs associated with inflammation resolution and wound-healing. During colitis there was a progressive increase in the proportions of inflammatory monocytes and a loss of CD169+ MPs that was accelerated in Cre+ mice. Further, the proportion of CD11c+ MPs was increased in Cre+ mice. These data are the first detailed scmRNA analysis of immune cell populations in DSS colitis and suggest that PGE2 signaling through EP4 may protect non-inflammatory macrophage populations during inflammation, contributing to maintenance of the intestinal barrier.

The “microbiome-gut-brain axis” in Alzheimer's disease and its role in neurocognitive decline

Alzheimer’s disease (AD) is a progressive neurocognitive disease characterized by amyloid beta plaques and neurofibrillary tangles in the brain along with inflammation both in the brain and systemically. This has led to the theory of microbial communities or infections as being causative in the development of neuroinflammation as well as immunosenescence and inflamm-aging seen in AD. Our own research has demonstrated a decreased abundance of anti-inflammatory taxa and an increased abundance of pro-inflammatory taxa in the gut microbiome of AD patients. However, it is unclear how the AD microbiome exerts effects on the central nervous system. To address this gap in knowledge we have performed gut microbiome profiling, analysis of immune cell populations in serum, blood cytokine profiling, and cognitive assessments of AD older adults at 90-day intervals. In our early data collected from this ongoing study we have observed changes in B-cell populations with an increased abundance of class-switched B-cells in older adults with greater levels of cognitive impairment. We have further demonstrated that colonization of mice with the microbiome of AD older adults promotes B-cell class-switching when compared with cognitively impaired older adults without AD. Additionally, we have discovered a loss of phytoestrogen-metabolizing bacteria such as Adlercreutzia equolifaciens among AD older adults with rapidly progressing dementia. Phytoestrogens have been previously identified in protecting the intestinal epithelium from oxidative stress and epithelial permeability. Our preliminary studies have suggested that that the phytoestrogen (s)-equol, produced by A. equolifaciens, confers resistance to epithelial damage in the setting of bacterial lipopolysaccharide. Thus, we hypothesize that Adlercreutzia equolifaciens and similar phytoestrogen-metabolizing bacteria maintain epithelial homeostasis in the setting of inflammation while a gain of pro-inflammatory taxa in AD leads to intestinal barrier disruption, increased antigen presentation, immune cell dysregulation, and ultimately cognitive decline. This continuing work aims to further establish the connection between AD related neurocognitive decline, the microbiome, and immune system. This research was funded by grant numbers R01DK125407, R01AG067483, and 5T32A1007349-31 from the National Institutes of Health This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Poly(lactic acid)-based immunomodulatory nanoparticles promote survival in a polymicrobial mouse model of sepsis

Abstract Sepsis is a life-threatening multifactorial organ dysfunction caused by a dysregulated host response to infection. Despite being recognized as a global health priority, current therapeutic approaches for sepsis have yet to demonstrate significant improvements in patient outcomes. Our group previously demonstrated that cargo-less immunomodulatory nanoparticles (iNPs) could suppress innate immune cell proinflammatory responses and increase survival in an LPS-induced endotoxemia mouse model. In the present work, we examine the impact of poly(lactic acid)-based iNP delivery on survival and comprehensively characterize the host immune response using a clinically relevant and lethal mouse model of polymicrobial sepsis, cecal ligation and puncture (CLP). iNPs, when administered intraperitoneally in combination with broad spectrum antibiotics following CLP surgery, resulted in a significant improvement in disease symptoms and survival compared to CLP + antibiotics only. We also observed that iNP treatment reduced the levels of proinflammatory cytokines in the peritoneal fluid. Analysis of immune cell populations suggested that iNP treatment modulated macrophage, myeloid-derived suppressor cell, and inflammatory monocyte populations both locally and systemically. Our study demonstrates that local administration of iNPs promotes survival through a multimodal immunomodulatory mechanism to improve sepsis outcomes. This research was supported by startup funds from the University of Maryland School of Pharmacy, National Institute of General Medical Sciences of the National Institutes of Health under Award Number R35GM142752, and the Shock Society Faculty Research Award awarded to Ryan Pearson. Nhu Truong is supported by a PhRMA Foundation Pre-Doctoral Fellowship from Washington, DC. This publication was supported by funds through the National Cancer Institute - Cancer Center Support Grant (CCSG) - P30CA134274, and Maryland Department of Health's Cigarette Restitution Fund Program

Abstract CT196: A phase I clinical trial of oncolytic adenovirus mediated suicide and interleukin-12 gene therapy in patients with recurrent prostate cancer

Abstract Introduction: Men with locally recurrent prostate cancer, after definitive radiotherapy, have few therapeutic options. Oncolytic adenovirus-mediated cytotoxic gene therapy is an investigational cancer therapy. Delivery of the suicide gene to the tumor is by direct intratumoral or systemic injection of a viral vector containing the suicide gene. Our approach incorporates yeast cytosine deaminase (yCD) and herpes simplex virus thymidine kinase (HSV-1 TK), to confer sensitivity to 5-fluorocytosine (5-FC) and Valganciclovir (vGCV), respectively. The pro-drugs are converted into active drugs that inhibit DNA damage repair. Here we report the safety of oncolytic adenovirus-mediated suicide gene therapy that incorporates an interleukin-12 (IL12) gene for treatment of recurrent prostate cancer. Methods: In this phase I study, a replication-competent adenovirus (Ad5-yCD/mutTKSR39rep-hIL-12) expressing yCD/mutTKSR39 (yeast cytidine deaminase/mutant S39R HSV-1 thymidine kinase) and human IL-12 (IL12) was injected into tumors of 15 subjects with recurrent prostate cancer (T1c-T2) at escalating doses (1 × 1010, 3 × 1010, 1 × 1011, 3 × 1011, or 1 × 1012 viral particles). Subjects received 5-FC and vGCV for 7 days. The study endpoint was toxicity through day 30. Experimental endpoints included measurements of serum IL12, interferon gamma (IFNγ), and CXCL10 to assess immune system activation. Peripheral blood mononuclear cells (PBMC) and proliferation markers were analyzed by flow cytometry. Results and Conclusions: Fifteen patients received Ad5-yCD/mutTKSR39rep-hIL-12 and oral 5-FC and vGCV. Approximately 92% of the 115 adverse events observed were grade 1/2 requiring no medical intervention. Ad5-yCD/mutTKSR39rep-hIL-12 DNA was detected in the blood of only two patients. Elevated serum IL12, IFNγ, and CXCL10 levels were detected in 57%, 93%, and 79% of subjects, respectively. Serum cytokines demonstrated viral dose dependency, especially apparent in the highest-dose cohorts. Analysis of immune cell populations indicated activation after Ad5-yCD/mutTKSR39rep-hIL-12 administration in cohort 5. The study did not detect a significant difference in the PSA doubling time (PSADT) between pre and post treatment by paired Wilcoxon rank test (p=0.17). There was no correlation between adenoviral dose and PSADT in each cohort separately or pooled (cohorts1-3 and cohorts 4-5). The study maximum tolerated dose (MTD) was not reached indicating 1012 viral particles was safe. This trial confirmed that replication-competent Ad5-IL-12 adenovirus (Ad5-yCD/mutTKSR39 rep-hIL-12) was well tolerated when administered locally to prostate tumors. Citation Format: Shyam Nyati, Hans Stricker, Kenneth L. Barton, Piln Li, Mohamed Elshaikh, Haythem Ali, Stephen L. Brown, Clara Hwang, James Peabody, Svend O. Freytag, Benjamin Movsas, Farzan Siddiqui. A phase I clinical trial of oncolytic adenovirus mediated suicide and interleukin-12 gene therapy in patients with recurrent prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT196.

Abstract 3864: Cytometric analysis of immune cell populations in clinical tumor biopsy tissue microarrays for immuno-oncology

Abstract Over the past decade, a new focus on the interactions between the immune system and the development and progression of cancer has led to a wide array of research into medical treatments which leverage activation or modulation of the immune system to aid in treatment. Research in the field of immuno-oncology and elucidation of the biological mechanisms by which cancer cells suppress immunological function has led to new biological treatments for cancer, such as pembrolizumab, which have shown great clinical success since their advent. Population-level analysis of immune cell populations is critical for understanding the immune-component of disease progression, and flow cytometry is a commonly utilized technique for this purpose. However, flow cytometry requires dissolution of tissue specimens, and is incompatible with formalin-fixed paraffin-embedded (FFPE) samples, the gold standard in tissue archives. In order to allow for cytometric analysis of FFPE tissues, we have developed a digital pathology technique for the quantitative assessment of immune-cell populations within tissue microarrays prepared from archived FFPE clinical tissue specimens from patient biopsies. The technique involves a combination of HALO® image analysis using the Highplex FL, Spatial Analysis, and TMA modules, and custom scripting to develop imaging cytometry scatterplots. Bioinformatics techniques were utilized to assess features correlated with tumor progression from the quantitative data extracted from the tissue microarrays. Citation Format: Tom Villani, Jigar Patel, Kim Collins, Kate Lillard Tunstall, Bradley Krisanits. Cytometric analysis of immune cell populations in clinical tumor biopsy tissue microarrays for immuno-oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3864.

Abstract 629: Benefit of using a spectral flow analyzer for the analysis of immune cell populations in tumors

Abstract Flow cytometry is a widely applied approach for exploratory immune profiling and enables the identification of individual cells in a cell population, such as a tumor cell suspension, by staining cell markers with antibodies conjugated with a fluorophore. The markers allow for the differentiation of a large variety of immune cell populations, their change in frequency, and activation status upon treatment. Conventional flow cytometers, which use bandpass filters and need conventional compensation matrices, are limited by the number of parameters that can be simultaneously analyzed, restricting their utility. Spectral analysis technology promises a greater flexibility for panel design, a higher number of analyzed parameters, and more accurate visualization of results. Our standard all-in-one flow cytometry panel uses all possible fluorescent detectors of the flow analyzer BD Fortessa, which permits the differentiation of the main immune cell populations in the tumor, such as T cells (CD4+, CD8+, Treg), B and NK cells, macrophages (M1/M2), MDSCs (granulocytic and monocytic), and dendritic cells. However, in addition to immune cell frequency, it would also be interesting to investigate cell surface activation and memory markers like PD-1, CD40, CD44, or CD62L or intracellular activation markers like IFN-gamma, perforin, granzyme B, or Ki67. The 32-channel spectral flow analyzer SP6800 ZE from Sony allows the combination of both. Flow cytometry data of different tumor samples will be presented, as well as the comparison of the results and resolution of both flow analyzer systems. Auto-fluorescence of cells, which causes fluorescent signal contamination of other fluorescent markers in the conventional flow cytometer, can be subtracted using spectral technology to see the true fluorescent population, thereby allowing dim signal detection in rare populations. A comprehensive overview will be given regarding the pros and cons of the spectral analyzer system and difficulties switching from the one system to the other. Citation Format: Philipp Metzger, Muriel Malaisé, Cynthia Obodozie, Holger Weber. Benefit of using a spectral flow analyzer for the analysis of immune cell populations in tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 629.

Single-cell mRNA analysis of colon tissue during DSS colitis in CX3CR1cre/+EP4fl/fl mice suggests PGE2 signaling via EP4 promotes survival of protective macrophages

Abstract Prostaglandin E2 signaling through its receptor EP4 on macrophages (MPs) protects against DSS-induced colitis, however the mechanisms involved are not clear. Here we perform single cell RNA sequencing on the colons of CX3CR1cre/+EP4fl/fl(Cre+) mice and CX3CR1+/+EP4fl/fl(Cre−) littermate controls at days 0, 3 and 7 following DSS treatment. We identified monocyte (MO), MP, DC1, DC2 and pre-DC populations, with MPs clustering into Hes1hi, Mrc1hi Siglec1(CD169)hi, Retnlahi, and Il1r2hiCd80hi populations. With colitis there was a dramatic increase in the proportions of inflammatory MOs and a loss of all mature MPs, along with an increase in cDC2 but not cDC1 in both mouse strains. However, in Cre+ mice, which develop worse disease with universal GI bleeding, the loss of Mrc1hi Siglec1hi MPs was accelerated together with an increased proportion of Il1r2hiCd80hi MPs compared to Cre− littermates. Analysis of DEGs showed the Il1r2hiCd80hi MP cluster expresses high levels of leukocyte chemoattractants, suggesting that PGE2 may prevent leukocyte recruitment during inflammation. Cre+ mice also had fewer Retnlahi macrophages than Cre− mice both at days 0 and 7 post DSS. Genes highly expressed in the Retnlahi cluster are associated with wound healing and maintenance of vascular integrity indicating their loss could account for the enhanced GI bleeding in the inflamed Cre+ mice. This is the first detailed scmRNA analysis of immune cell populations involved in DSS colitis. While additional investigation is necessary, the data suggest a role for PGE2 signaling via EP4 on MPs in preventing excessive inflammatory cell infiltration, decreasing vascular permeability, and contributing to tissue repair by maintaining protective MP populations.

Evidence of islet CADM1-mediated immune cell interactions during human type 1 diabetes.

BACKGROUNDPathophysiology of type 1 diabetes (T1D) is illustrated by pancreatic islet infiltration of inflammatory lymphocytes, including CD8+ T cells; however, the molecular factors mediating their recruitment remain unknown. We hypothesized that single-cell RNA-sequencing (scRNA-Seq) analysis of immune cell populations isolated from islets of NOD mice captured gene expression dynamics providing critical insight into autoimmune diabetes pathogenesis.METHODSPancreatic sections from human donors were investigated, including individuals with T1D, autoantibody-positive (aAb+) individuals, and individuals without diabetes who served as controls. IHC was performed to assess islet hormones and both novel and canonical immune cell markers that were identified from unbiased, state-of-the-art workflows after reanalyzing murine scRNA-Seq data sets.RESULTSComputational workflows identified cell adhesion molecule 1–mediated (Cadm1-mediated) homotypic binding among the most important intercellular interactions among all cell clusters, as well as Cadm1 enrichment in macrophages and DCs from pancreata of NOD mice. Immunostaining of human pancreata revealed an increased number of CADM1+glucagon+ cells adjacent to CD8+ T cells in sections from T1D and aAb+ donors compared with individuals without diabetes. Numbers of CADM1+CD68+ peri-islet myeloid cells adjacent to CD8+ T cells were also increased in pancreatic sections from both T1D and aAb+ donors compared with individuals without diabetes.CONCLUSIONIncreased detection of CADM1+ cells adjacent to CD8+ T cells in pancreatic sections of individuals with T1D and those who were aAb+ validated workflows and indicated CADM1-mediated intercellular contact may facilitate islet infiltration of cytotoxic T lymphocytes and serve as a potential therapeutic target for preventing T1D pathogenesis.FUNDINGThe Johns Hopkins All Children’s Foundation Institutional Research Grant Program, the National Natural Science Foundation of China (grant 82071326), and the Deutsche Forschungsgemeinschaft (grants 431549029–SFB1451, EXC2030–390661388, and 411422114-GRK2550).

Abstract 1769: Study of innate immune responses during small cell lung cancer (SCLC) development

Abstract SCLC is a highly aggressive neuroendocrine tumor with dismal prognosis. Inability to detect SCLC early renders surgical resections a rare event, limiting investigation of the early stages of tumor development. We sought to address this challenge using a genetically engineered mouse model (GEMM) to investigate how the innate immune system responds to SCLC development. The RPM (Rb1fl/fl, p53fl/fl, MycLSL/LSL) SCLC GEMM was selected to characterize the local immune microenvironment throughout the process of tumor development. Following tumor induction using an intranasally installed Cre bearing adenovirus, lung tissue was collected and analyzed using multi-parametric flow cytometry to assess changes in innate immune cell populations. Induction of SCLC resulted in late stage disease being present in animals approximately 7 weeks after virus exposure. Flow cytometric analysis of immune cell populations of the whole lung showed no significant differences in the overall levels of immune cell types, although an upwards trend in the levels of neutrophils in tumor-bearing mice was observed. The most significant finding was a decrease in the expression levels of major histocompatibility complex class II (MHCII) in both alveolar and interstitial macrophage populations. Further characterization, including separate analysis of the two interstitial macrophage subpopulations described by Chakarov et al. (Science 2019), and Schyns et al. (Nature Communications 2019), showed significant drops in levels of MHCII in all populations as measured by median fluorescent intensity (MFI) (p=0.004 in alveolar macrophages, p=0.0148 in vascular supporting CD206+ve interstitial macrophages, and p=0.0027 in CD206-ve interstitial macrophages). The striking difference between the changes seen in these populations was that alveolar and CD206+ve interstitial macrophages both showed a downward shift in MHCII expression as a whole, while CD206-ve macrophages acquired a novel population completely negative for MHCII accounting for approx. half of the CD206-ve macrophage subpopulation. The development of SCLC has been found to result in all macrophage subtypes expressing lower levels of MHCII, pointing towards a more immunosuppressive immune environment. The population of CD206-ve MHCII-ve interstitial macrophages is of particular interest, as it is contrary to the currently described interstitial macrophage phenotypes. A more in-depth characterization of all macrophage populations in the mouse lung, including their precise phenotype and localization is currently underway using CyTOF and IHC approaches. The precise timings of the observed changes are being elucidated through analysis of a disease time-course ranging from very early stage to late stage disease, in order to better understand the process of SCLC development. Citation Format: Jakub Chudziak, Melanie Galvin, Antonia Banyard, Kathryn L. Simpson, Kristopher K. Frese, Elaine Kilgour, Tracy Hussell, Caroline Dive. Study of innate immune responses during small cell lung cancer (SCLC) development [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 1769.

Molecular subtypes based on CNVs related gene signatures identify candidate prognostic biomarkers in lung adenocarcinoma

The classical factors for predicting prognosis currently cannot meet the developing requirements of individualized and accurate prognostic evaluation in lung adenocarcinoma (LUAD). With the rapid development of high-throughput DNA sequencing technologies, genomic changes have been discovered. These sequencing data provide unprecedented opportunities for identifying cancer molecular subtypes. In this article, we classified LUAD into two distinct molecular subtypes (Cluster 1 and Cluster 2) based on Copy Number Variations (CNVs) and mRNA expression data from the Cancer Genome Atlas (TCGA) based on non-negative matrix factorization. Patients in Cluster 1 had worse outcomes than that in Cluster 2. Molecular features in subtypes were assessed to explain this phenomenon by analyzing differential expression genes expression pattern, which involved in cellular processes and environmental information processing. Analysis of immune cell populations suggested different distributions of CD4+ T cells, CD8+ T cells, and dendritic cells in the two subtypes. Subsequently, two novel genes, TROAP and RASGRF1, were discovered to be prognostic biomarkers in TCGA, which were confirmed in GSE31210 and Tianjin Medical University Cancer Institute and Hospital LUAD cohorts. We further proved their crucial roles in cancers by vitro experiments. TROAP mediates tumor cell proliferation, cycle, invasion, and migration, not apoptosis. RASGRF1 has a significant effect on tumor microenvironment. In conclusion, our study provides a novel insight into molecular classification based on CNVs related genes in LUAD, which may contribute to identify new molecular subtypes and target genes.

OP0083 INFECTIOUS AND AUTOINFLAMMATORY MODIC TYPE 1 CHANGES HAVE DIFFERENT PATHOMECHANISMS

Background:Modic type 1 changes (MC1) are vertebral bone marrow (BM) edema that associate with non-specific low back pain (LBP). Two etiologies have been described. In the infectious etiology the anaerobic aerotolerant Cutibacterium acnes (C. acnes) invades damaged intervertebral discs (IVDs) resulting in disc infection and endplate damage, which leads to the evocation of an immune response. In the autoinflammatory etiology disc and endplate damage lead to the exposure of immune privileged disc cells and matrix to leukocytes, thereby evoking an immune response in the BM. Different etiologies require different treatment strategies. However, it is unknown if etiology-specific pathological mechanisms exist.Objectives:The aim of this study was to identify etiology-specific dysregulated pathways of MC1 and to perform in-depth analysis of immune cell populations of the autoinflammatory etiology.Methods:BM aspirates and biopsies were obtained from LBP patients with MC1 undergoing spinal fusion. Aspirates/biopsies were taken prior screw insertion through the pedicle screw trajectory. From each patient, a MC1 and an intra-patient control aspiration/biopsy from the adjacent vertebral level was taken. If C. acnes in IVDs adjacent to MC1 were detected by anaerobic bacterial culture, patients were assigned to the infectious, otherwise to the autoinflammatory etiology.Total RNA was isolated from aspirates and sequenced (Novaseq) (infectious n=3 + 3, autoinflammatory n=5 + 5). Genes were considered as differentially expressed (DEG) if p-value < 0.01 and log2fc > ± 0.5. Gene ontology (GO) enrichment was performed in R (GOseq), gene set enrichment analysis (GSEA) with GSEA software.Changes in cell populations of the autoinflammatory etiology were analyzed with single cell RNA sequencing (scRNAseq): Control and MC1 biopsies (n=1 + 1) were digested, CD45+CD66b- mononuclear cells isolated with fluorescence activated cell sorting (FACS), and 10000 cells were sequenced (10x Genomics). Seurat R toolkit was used for quality-control, clustering, and differential expression analysis.Transcriptomic changes (n=5 + 5) of CD45+CD66b+ neutrophils isolated with flow cytometry from aspirates were analyzed as for total bulk RNAseq. Neutrophil activation (n=3 + 3) was measured as CD66b+ expression with flow cytometry. CD66bhigh and CD66blow fractions in MC1 and control neutrophils were compared with paired t-test.Results:Comparing MC1 to control in total bulk RNAseq, 204 DEG in the autoinflammatory and 444 DEG in the infectious etiology were identified with only 67 shared genes (Fig. 1a). GO enrichment revealed “T-cell activation” (p = 2.50E-03) in the autoinflammatory and “complement activation, classical pathway” (p=1.1E-25) in the infectious etiology as top enriched upregulated biological processes (BP) (Fig 1b). ScRNAseq of autoinflammatory MC1 showed an overrepresentation of T-cells (p= 1.00E-34, OR=1.54) and myelocytes (neutrophil progenitor cells) (p=4.00E-05, OR=2.27) indicating an increased demand of these cells (Fig. 1c). Bulk RNAseq analysis of neutrophils from the autoinflammatory etiology revealed an activated, pro-inflammatory phenotype (Fig 1d), which was confirmed with more CD66bhigh neutrophils in MC1 (+11.13 ± 2.71%, p=0.02) (Fig. 1e).Figure 1.(a) Venn diagram of DEG from total bulk RNAseq (b) Top enriched upregulated BP of autoinflammatory (left) and infectious (right) etiology (c) Cell clustering of autoinflammatory MC1 BM (d) Enrichment of “inflammatory response” gene set in autoinflammatory MC1 neutrophils (e) Representative histogram of CD66b+ expression in MC1 and control neutrophils.Conclusion:Autoinflammatory and infectious etiologies of MC1 have different pathological mechanisms. T-cell and neutrophil activation seem to be important in the autoinflammatory etiology. This has clinical implication as it could be explored for diagnostic approaches to distinguish the two MC1 etiologies and supports developing targeted treatments for both etiologies.Disclosure of Interests:None declared

Phase I trial of oncolytic adenovirus-mediated cytotoxic and interleukin-12 gene therapy for the treatment of metastatic pancreatic cancer

The safety of oncolytic adenovirus-mediated suicide and interleukin-12 (IL12) gene therapy was evaluated in metastatic pancreatic cancer patients. In this phase I study, a replication-competent adenovirus (Ad5-yCD/mutTKSR39rep-hIL-12) expressing yCD/mutTKSR39 (yeast cytidine deaminase/mutant S39R HSV-1 thymidine kinase) and human IL-12 (IL12) was injected into tumors of 12 subjects with metastatic pancreatic cancer (T2N0M1-T4N1M1) at escalating doses (1 × 1011, 3 × 1011, or 1 × 1012 viral particles). Subjects received 5-fluorocytosine (5-FC) therapy for 7 days followed by chemotherapy (FOLFIRINOX or gemcitabine/albumin-bound paclitaxel) starting 21 days after adenovirus injection. The study endpoint was toxicity through day 21. Experimental endpoints included measurements of serum IL12, interferon gamma (IFNG), and CXCL10 to assess immune system activation. Peripheral blood mononuclear cells and proliferation markers were analyzed by flow cytometry. Twelve patients received Ad5-yCD/mutTKSR39rep-hIL-12 and oral 5-FC. Approximately 94% of the 121 adverse events observed were grade 1/2 requiring no medical intervention. Ad5-yCD/mutTKSR39rep-hIL-12 DNA was detected in the blood of two patients. Elevated serum IL12, IFNG, and CXCL10 levels were detected in 42%, 75%, and 92% of subjects, respectively. Analysis of immune cell populations indicated activation after Ad5-yCD/mutTKSR39rep-hIL-12 administration. The median survival of patients in the third cohort is 18.1 (range, 3.5–20.0) months. The study maximum tolerated dose (MTD) was not reached.

Characterization of Surface Receptor Expression and Cytotoxicity of Human NK Cells and NK Cell Subsets in Overweight and Obese Humans.

Obesity is associated with an increased risk for several cancer types and an altered phenotype and functionality of natural killer (NK) cells. This study aimed to investigate the association of overweight and obesity with NK cell functions and receptor expression profiles in humans. Therefore, peripheral blood mononuclear cells were isolated from normal weight, overweight, and obese healthy blood donors. In depth analysis of immune cell populations and 23 different surface markers, including NK cell receptors, NK-cell-related markers as well as functional intracellular markers on total NK cells and NK subgroups were performed by multicolor flow cytometry. The data revealed a decreased expression of the activating NK cell receptors KIR2DS4 and NKp46 as well as an increased expression of the inhibitory NK cell receptors NKG2A and Siglec-7 in overweight and obese compared to normal weight individuals. Additionally, the expression of the adhesion molecule CD62L and the maturation and differentiation marker CD27 was downregulated in NK cells of overweight and obese subjects. Furthermore, the cytotoxicity of NK cells against colorectal cancer cells was decreased in overweight and obese subjects. Investigations on underlying killing mechanisms demonstrated a reduced TRAIL expression on NK cells of obese subjects suggesting an impaired death receptor pathway in obesity. The present study gives new insights into an impaired functionality and phenotype of NK cells and NK cell subsets in overweight and obesity. These phenotypic alterations and dysfunction of NK cells might be an explanation for the increased cancer risk in obesity.

Abstract 2665: Immune cell modulation of pulsed focused ultrasound in murine melanoma and breast cancer models

Abstract Major therapeutic advances in the field of tumor immunotherapy are hindered by the ability to overcome the immunosuppressive tumor microenvironment (TME), which prevents the immune system from mounting an efficient anti-tumor response. Pulsed focused ultrasound (pFUS) studies has shown some promise as an immunomodulatory strategy for altering TME. This study evaluated the temporal changes following non-ablative pFUS on TME immune cell profiles in spleen (Sp), lymph nodes (LN), and tumors (B16 melanoma and 4T1 mammary carcinoma). Murine B16 and 4T1 cells were subcutaneously, bilaterally implanted into C57BL/6J and BALB/c mice (n=10 tumors/time-point), respectively. Ultrasound guided pFUS (VIFU 2000, Alpinion) was administered at 1 MHz, at 6 MPa PNP to 5 mm tumors. Entire tumor volume was sonicated with a 2 mm spacing between points using a 10 ms pulse length, 10% duty cycle and a pulse repetition frequency of 10 Hz. At days 1, 3, and 5 post-sonication, Sp, LN and tumors were harvested, fixed and processed for flow cytometry (FACS) analysis of immune cell populations [cytotoxic (Tcyt), helper (Th), and regulatory (Treg) T cells, natural killer (NK), dendritic cells (DC), F4/80+ macrophages (M1 and M2), myeloid-derived suppressor cells (MDSC)] and immune checkpoint markers (CTLA-4, PD-1 and PD-L1). The immune response to pFUS differed between the B16 and 4T1 tumor bearing mice. B16 mice at days 1, 3 and 5 post-sonication revealed a 3-4 fold increase in Tcyt, Th, NK and M1 macrophage activity in tumor, which peaked at day 3, and decreased by day 5, compared to control tumors. At day 5, a shift of cell populations toward LN, with increased Treg, Tcyt, NK, F4/80, M1 and M2 activity was observed. 4T1 mice showed high levels of Tcyt in Sp on day 1, and NK cells on day 3 in LN. Interestingly, these cell populations decreased in Sp and LN by day 5, with 3-4 fold increase in 4T1 tumors, along with increasing macrophage and DC activity. Despite the differences in both tumor types, results suggest that pFUS altered the TME by inducing anti-tumor responses by activating both innate (macrophages, NK cells) and adaptive (Tcyt, Th cells) arms of immunity. This study reveals the differences in immune cell profiles following sonication between the two tumor types and underscores the importance of not generalizing the effect of pFUS on the TME. This analysis also suggests that the global changes to the immune cell profile represent a shift from anti-inflammatory, immunosuppressive TME towards an anti-tumor TME. Optimizing pFUS parameters to enhance immune cell infiltration, would presumably lead to slowing tumor growth rates and when coupled with immune checkpoint inhibits could serve as neoadjuvant approach in treating malignancy. Citation Format: Parwathy Chandran, Gadi Cohen, Scott R. Burks, Joseph A. Frank. Immune cell modulation of pulsed focused ultrasound in murine melanoma and breast cancer models [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 2665.

Molecular Pathways of Colon Inflammation Induced by Cancer Immunotherapy

Checkpoint blockade with antibodies specific for the PD-1 and CTLA-4 inhibitory receptors can induce durable responses in a wide range of human cancers. However, the immunological mechanisms responsible for severe inflammatory side effects remain poorly understood. Here we report a comprehensive single-cell analysis of immune cell populations in colitis, a common and severe side effect of checkpoint blockade. We observed a striking accumulation of CD8 Tcells with highly cytotoxic and proliferative states and no evidence of regulatory Tcell depletion. Tcell receptor (TCR) sequence analysis demonstrated that a substantial fraction of colitis-associated CD8 Tcells originated from tissue-resident populations, explaining the frequently early onset of colitis symptoms following treatment initiation. Our analysis also identified cytokines, chemokines, and surface receptors that could serve as therapeutic targets for colitis and potentially other inflammatory side effects of checkpoint blockade.