The Untold Story of Granzymes in Oncoimmunology: Novel Opportunities with Old Acquaintances

Selective Detection of Active Extracellular Granzyme A by Using a Novel Fluorescent Immunoprobe with Application to Inflammatory Diseases

Granzymes (Gzms), a family of serine proteases, expressed by immune and nonimmune cells, present perforin-dependent and independent intracellular and extracellular functions. When released in the extracellular space, GzmA, with trypsin-like activity, is involved in the pathophysiology of different inflammatory diseases. However, there are no validated specific systems to detect active forms of extracellular GzmA, making it difficult to assess its biological relevance and potential use as a biomarker. Here, we have developed fluorescence-energy resonance-transfer (FRET)-based peptide probes (FAM-peptide-DABCYL) to specifically detect GzmA activity in tissue samples and biological fluids in both mouse and human samples during inflammatory diseases. An initial probe was developed and incubated with GzmA and different proteases like GzmB and others with similar cleavage specificity as GzmA like GzmK, thrombin, trypsin, kallikrein, or plasmin. After measuring fluorescence, the probe showed very good specificity and sensitivity for human and mouse GzmA when compared to GzmB, its closest homologue GzmK, and with thrombin. The specificity of this probe was further refined by incubating the samples in a coated plate with a GzmA-specific antibody before adding the probe. The results show a high specific detection of soluble GzmA even when compared with other soluble proteases with very similar cleavage specificity like thrombin, GzmK, trypsin, kallikrein, or plasmin, which shows nearly no fluorescence signal. The high specific detection of GzmA was validated, showing that using pure proteins and serum and tissue samples from GzmA-deficient mice presented a significant reduction in the signal compared with WT mice. The utility of this system in humans was confirmed, showing that GzmA activity was significantly higher in serum samples from septic patients in comparison with healthy donors. Our results present a new immunoprobe with utility to detect extracellular GzmA activity in different biological fluids, confirming the presence of active forms of the soluble protease in vivo during inflammatory and infectious diseases.

Exploring the cross-cancer effect of circulating proteins and discovering potential intervention targets for 13 site-specific cancers

BACKGROUND

The proteome is an important reservoir of potential therapeutic targets for cancer. This study aimed to examine the causal associations between plasma proteins and cancer risk and to identify proteins with cross-cancer effects.

METHODS

Genetic instruments for 3991 plasma proteins were extracted from a large-scale proteomic study. Summary-level data of 13 site-specific cancers were derived from publicly available datasets. Proteome-wide Mendelian randomization and colocalization analyses were used to investigate the causal effect of circulating proteins on cancers. Protein-protein interactions and druggability assessment were conducted to prioritize potential therapeutic targets. Finally, systematical Mendelian randomization analysis between healthy lifestyle factors and cancer-related proteins was conducted to identify which proteins could act as interventional targets by lifestyle changes.

RESULTS

Genetically determined circulating levels of 58 proteins were statistically significantly associated with 7 site-specific cancers. A total of 39 proteins were prioritized by colocalization, of them, 11 proteins (ADPGK, CD86, CLSTN3, CSF2RA, CXCL10, GZMM, IL6R, NCR3, SIGLEC5, SIGLEC14, and TAPBP) were observed to have cross-cancer effects. Notably, 5 of these identified proteins (CD86, CSF2RA, CXCL10, IL6R, and TAPBP) have been targeted for drug development in cancer therapy; 8 proteins (ADPGK, CD86, CXCL10, GZMM, IL6R, SIGLEC5, SIGLEC14, TAPBP) could be modulated by healthy lifestyles.

CONCLUSION

Our study identified 39 circulating protein biomarkers with convincing causal evidence for 7 site-specific cancers, with 11 proteins demonstrating cross-cancer effects, and prioritized the proteins as potential intervention targets by either drugs or lifestyle changes, which provided new insights into the etiology, prevention, and treatment of cancers.

Heterogeneity of T cells in periapical lesions and in vitro validation of the proangiogenic effect of GZMA on HUVECs

AIM

T cells are key immunomodulatory cells in periapical lesions. This study aimed to explore the roles of T cells in chronic apical periodontitis (CAP) using single-cell RNA sequencing and to further investigate Granzyme A (GZMA) in angiogenesis regulation.

METHODOLOGY

A total of five CAP samples were collected for single-cell RNA sequencing. We performed subcluster and lineage-tracing analyses for T cells. According to differential gene expression, distinct biological functions enriched in T cells of CAP were presented by gene set enrichment analysis (GSEA) and compared with healthy gingiva (data obtained from the GEO database). CellChat was used to explore potential ligand-receptor interactions between T cells and endothelial cells in CAP. The coculture of primary human umbilical vein endothelial cells (HUVECs) and Jurkat T cells, as well as the addition of GZMA recombinant protein, was used to validate the predicted pair of GZMA and coagulation factor II thrombin receptor (F2R) by RT-PCR, angiogenesis and migration assays.

RESULTS

A transcriptomic atlas of 44 746 individual cells was constructed from the periapical lesions of five patients with CAP by single-cell RNA-seq, and eight cell types were identified. We identified nine subsets of T cells and deciphered the cellular heterogeneity of T cells in CAP at the functional level by subclustering and GSEA. Lineage tracing revealed a distinct lineage of T cells in CAP and predicted the transition of the T cellular state upon CAP. GSEA revealed multiple biological processes and relevant angiogenesis genes upregulated in CAP T cells. GZMA-F2R pairs were predicted by cell-cell interactions in CAP. High expression of GZMA and F2R was observed in the coculture of HUVECs and Jurkat T cells, and the proangiogenic capacity of the GZMA recombinant protein was emphasized by in vitro experiments.

CONCLUSIONS

Our study provides novel insights into the heterogeneity of T cells in periapical lesions and reveals the potential role of GZMA in T cells in regulating angiogenesis in HUVECs.

Long noncoding RNA MIAT regulates TP53 ubiquitination and expedites prostate adenocarcinoma progression by recruiting TBL1X

Despite recent advances in cancer immunotherapy, their efficacy for treating patients with prostate adenocarcinoma (PRAD) is low due to complex immune evasion mechanisms. However, the function of long non-coding RNA (lncRNAs) in immune evasion has not been fully clarified. This study aimed to expound the role of myocardial infarction-associated transcript (MIAT), a lncRNA significantly upregulated in three PRAD-associated datasets, in immune evasion and try to reveal the potential mechanism. MIAT was highly expressed in PRAD tissues and predicted poor prognosis, and suppression of MIAT inhibited the malignant biological behavior of PRAD cells. Moreover, the depletion of MIAT promoted the immune response of CD8+ T cells and hampered the immune evasion of PRAD cells. In addition, MIAT downregulated TP53 protein expression by recruiting transducin beta-like protein 1X (TBL1X) for ubiquitination modification. Silencing of TP53 or overexpression of TBL1X was enough to abate the tumor suppressive effects of MIAT knockdown in vitro and in vivo. Our results provide evidence for a novel regulation mechanism of CD8+ T cells in PRAD and MIAT may serve as a potential therapeutic target in PRAD.

Murine regulatory T cells utilize granzyme B to promote tumor metastasis

Regulatory T cells (Tregs) possess a wide range of mechanisms for immune suppression. Among them, Granzyme B (GzmB) and perforin expressed by Tregs were shown to inhibit tumor clearance in previous reports, which contradicted the canonical roles of these cytotoxic molecules expressed by cytotoxic T cells and NK cells in antitumor immune responses. Given the ability of the tumor to manipulate the microenvironment, Treg-derived GzmB function may represent an important approach to aid in tumor growth as well as facilitating tumor metastasis. In this study, we utilized Treg-specific GzmB knockout (Foxp3creGzmBfl/fl) mice to test whether Treg-derived GzmB can aid in tumor progression and metastasis. Using an IL-2 complex to activate GzmB expression in the non-immunogenic B16-F10 tumor model, we provide evidence to show that GzmB produced by Tregs is important for spontaneous metastasis to the lungs. In addition, we depleted CD8 + T cells to selectively measure the impact of Treg-derived GzmB in an experimental lung metastasis model by intravenous injection of B16-F10 tumor cells; our results demonstrate that Treg-derived GzmB plays an important role in increasing the metastatic burden to the lungs.

Multifunctional Redox-Responsive Nanoplatform with Dual Activation of Macrophages and T Cells for Antitumor Immunotherapy

High expression of programmed death ligand 1 (PD-L1) and strong immune evasion ability of the tumor microenvironment (TME) are maintained through mutual regulation between different immune and stromal cells, which causes obstructions for cancer immunotherapy, especially immunosuppressive M2-like phenotype tumor-associated macrophages (TAMs). Repolarization of TAMs to the M1-like phenotype could secrete proinflammatory cytokines and reverse the immunosuppressive state of the TME. However, we found that reactive oxygen species (ROS) generated by repolarized TAMs could be a double-edged sword: ROS cause a stronger suppressive effect on CD8 T cells through an increased proportion of apoptotic regulatory T (Treg) cells. Thus, simply repolarizing TAMs while ignoring the suppressed function of T cells is insufficient for generating adequate antitumor immunity. Accordingly, we engineered multifunctional redox-responsive nanoplatform NPs (M+C+siPD-L1) with Toll-like receptor agonist (M), catalase (C), and siPD-L1 encased for coregulation of both TAMs and T cells to maximize cancer immunotherapy. Our results demonstrated that NPs (M+C+siPD-L1) showed superior biocompatibility and intratumor accumulation. For in vitro experiments, NPs (M+C+siPD-L1) simultaneously repolarized TAMs to the M1-like phenotype, hydrolyzed extra ROS, knocked down the expression of PD-L1 on tumor cells, and rescued the function of CD8 T cells suppressed by Treg cells. In both orthotopic Hepa1-6 and 4T1 tumor-bearing mouse models, NPs (M+C+siPD-L1) could effectively evoke active systemic antitumor immunity and inhibit tumor growth. The combination of repolarizing TAMs, hydrolyzing extra ROS, and knocking down the expression of PD-L1 proves to be a synergistic approach in cancer immunotherapy.

Aging modifies endometrial dendritic cell function and unconventional double negative T cells in the human genital mucosa

BACKGROUND

Immune function in the genital mucosa balances reproduction with protection against pathogens. As women age, genital infections, and gynecological cancer risk increase, however, the mechanisms that regulate cell-mediated immune protection in the female genital tract and how they change with aging remain poorly understood. Unconventional double negative (DN) T cells (TCRαβ + CD4-CD8-) are thought to play important roles in reproduction in mice but have yet to be characterized in the human female genital tract. Using genital tissues from women (27-77 years old), here we investigated the impact of aging on the induction, distribution, and function of DN T cells throughout the female genital tract.

RESULTS

We discovered a novel site-specific regulation of dendritic cells (DCs) and unconventional DN T cells in the genital tract that changes with age. Human genital DCs, particularly CD1a + DCs, induced proliferation of DN T cells in a TFGβ dependent manner. Importantly, induction of DN T cell proliferation, as well as specific changes in cytokine production, was enhanced in DCs from older women, indicating subset-specific regulation of DC function with increasing age. In human genital tissues, DN T cells represented a discrete T cell subset with distinct phenotypical and transcriptional profiles compared to CD4 + and CD8 + T cells. Single-cell RNA and oligo-tag antibody sequencing studies revealed that DN T cells represented a heterogeneous population with unique homeostatic, regulatory, cytotoxic, and antiviral functions. DN T cells showed relative to CD4 + and CD8 + T cells, enhanced expression of inhibitory checkpoint molecules and genes related to immune regulatory as well as innate-like anti-viral pathways. Flow cytometry analysis demonstrated that DN T cells express tissue residency markers and intracellular content of cytotoxic molecules. Interestingly, we demonstrate age-dependent and site-dependent redistribution and functional changes of genital DN T cells, with increased cytotoxic potential of endometrial DN T cells, but decreased cytotoxicity in the ectocervix as women age, with implications for reproductive failure and enhanced susceptibility to infections respectively.

CONCLUSIONS

Our deep characterization of DN T cell induction and function in the female genital tract provides novel mechanistic avenues to improve reproductive outcomes, protection against infections and gynecological cancers as women age.

Trichosanthin Promotes Anti-Tumor Immunity through Mediating Chemokines and Granzyme B Secretion in Hepatocellular Carcinoma

Trichosanthin (TCS) is a type I ribosome-inactivating protein extracted from the tuberous root of the plant Trichosanthes. TCS shows promising potential in clinical drug abortion, anti-tumor and immunological regulation. However, the molecular mechanisms of its anti-tumor and immune regulation properties are still not well discovered. In the present study, we investigated the anti-tumor activity of TCS in hepatocellular carcinoma (HCC), both in vitro and in vivo. Both HCC cell lines and xenograft tumor tissues showed considerable growth inhibition after they were treated with TCS. TCS provoked caspase-mediated apoptosis in HCC cells and xenograft tumor tissues. The recruitment of CD8⁺ T cells to HCC tissues and the expression of chemokines, CCL2 and CCL22, were promoted upon TCS treatment. In addition, TCS induced an upregulation of Granzyme B (GrzB), TNF-α and IFN-γ in HCC tissues, which are the major cytotoxic mediators produced by T cells. Furthermore, TCS also resulted in an increase of mannose-6-phosphate receptor (M6PR), the major receptor of GrzB, in HCC tissues. In summary, these results suggest that TCS perhaps increases T-cell immunity via promoting the secretion of chemokines and accelerating the entry of GrzB to HCC cells, which highlights the potential role of TCS in anti-tumor immunotherapy.

A Subset of PD-1-Expressing CD56bright NK Cells Identifies Patients with Good Response to Immune Checkpoint Inhibitors in Lung Cancer

(1) Despite the effectiveness of immune checkpoint inhibitors (ICIs) in lung cancer, there is a lack of knowledge about predictive biomarkers. The objective of our study is to analyze different subsets of T-lymphocytes and natural killer (NK) cells as predictive biomarkers in a cohort of patients with nonsmall cell lung cancer (NSCLC) treated with ICI. (2) This is an observational, prospective study with 55 NSCLC patients treated with ICI. A total of 43 T and NK cell subsets are analyzed in peripheral blood, including the main markers of exhaustion, differentiation, memory, activation, and inhibition. (3) Regarding the descriptive data, Granzyme B+CD4+ Treg lymphocytes stand out (median 17.4%), and within the NK populations, most patients presented cytotoxic NK cells (CD56+CD3-CD16+GranzymeB+; median 94.8%), and about half of them have highly differentiated adaptive-like NK cells (CD56+CD3-CD16+CD57+ (mean 59.8%). A statistically significant difference was observed between the expression of PD1 within the CD56^bright NK cell subpopulation (CD56+CD3-CD16-PD-1+) (p = 0.047) and a better OS. (4) Circulating immune cell subpopulations are promising prognostic biomarkers for ICI. Pending on validation with a larger sample, here we provide an analysis of the major circulating T and NK cell subsets involved in cancer immunity, with promising results despite a small sample size.

Granzymes expression patterns predict immunotherapy response and identify the heterogeneity of CD8+ T cell subsets

BACKGROUND

Recent studies illustrated the effects of granzymes (GZMs) gene alterations on immunotherapy response of cancer patients. Thus, we aimed to systematically analyze the expression and prognostic value of GZMs for immunotherapy in different cancers, and identified heterogeneity of the GZMs expression-based CD8+ T cell subsets.

METHODS

First, we analyzed GZMs expression and prognostic value at pan-cancer level. Meanwhile, we established a GZMs score by using the single-sample gene set enrichment analysis (ssGSEA) algorithm to calculate the enrichment scores (ES) based on a gene set of five GZMs. The potential value of GZMs score for predicting survival and immunotherapy response was evaluated using the tumor immune dysfunction and exclusion (TIDE) and immunophenoscore (IPS) algorithm, and we validated it in immunotherapy cohorts. CellChat, scMetabolism, and SCENIC R packages were used for intercellular communication networks, quantifying metabolism activity, and regulatory network reconstruction, respectively.

RESULTS

The GZMs score was significantly associated with IPS, TIDE score. Patients with high GZMs score tended to have higher objective response rates of immunotherapy in melanoma and urothelial carcinoma. GZMs expression-based CD8+ T cell subsets presented heterogeneity in functions, metabolism, intercellular communications, and the tissue-resident memory programs in lung adenocarcinoma (LUAD). The transcription factors RUNX3 and ETS1, which may regulate the expression of GZMs, was found to be positively correlated with the tissue-resident memory T cells-related marker genes.

CONCLUSIONS

The higher GZMs score may indicate better response and overall survival (OS) outcome for immunotherapy in melanoma and urothelial carcinoma but worse OS in renal cell carcinoma (RCC). The GZMs score is a potential prognostic biomarker of diverse cancers. RUNX3 and ETS1 may be the potential targets to regulate the infiltration of GZMs expression-based CD8+ T cell subsets and affect the tissue-resident memory programs in LUAD, which may affect the prognosis of LUAD patients and the response to immunotherapy.

IL-33 induces granzyme C expression in murine mast cells via an MSK1/2-CREB-dependent pathway

Granzymes comprise a group of proteases involved in the killing of infected or cancerous cells by the immune system. Although best studied in T cells and natural killer (NK) cells, they are also expressed in some innate immune cells. Granzymes B and C are encoded in the mouse chymase locus that also encodes a number of mast cell-specific proteases. In line with this, mast cells can express granzyme B, although how this is regulated and their ability to express other granzymes is less well studied. We therefore examined how IL-33, a cytokine able to activate mast cells but not induce degranulation, regulated granzyme B and C levels in mast cells. Granzyme C, but not B, mRNA was strongly up-regulated in bone marrow-derived mast cells following IL-33 stimulation and there was a corresponding increase in granzyme C protein. These increases in both granzyme C mRNA and protein were blocked by a combination of the p38α/β MAPK inhibitor VX745 and the MEK1/2 inhibitor PD184352, which blocks the activation of ERK1/2. ERK1/2 and p38α activate the downstream kinases, mitogen and stress-activated kinases (MSK) 1 and 2, and IL-33 stimulated the phosphorylation of MSK1 and its substrate CREB in an ERK1/2 and p38-dependent manner. The promoter for granzyme C contains a potential CREB-binding site. Bone marrow-derived mast cells from either MSK1/2 double knockout or CREB Ser133Ala knockin mice were unable to up-regulate granzyme C. Together these results indicate that IL-33-induced granzyme C expression in mast cells is regulated by an MSK1/2-CREB-dependent pathway.

Hemizygous Granzyme A Mice Expressing the hSOD1G93A Transgene Show Slightly Extended Lifespan

Granzyme A (gzmA), a serine protease involved in the modulation of the inflammatory immune response, is found at an elevated level in the serum from ALS patients. However, the influence of gzmA on the progression of ALS remains unclear. The aim of our work was to assess whether the absence of gzmA in an ALS murine model could help slow down the progression of the disease. Homozygous and hemizygous gzmA-deficient mice expressing the hSOD1G93A transgene were generated, and survival of these mice was monitored. Subsequently, gene and protein expression of inflammatory and oxidative stress markers was measured in the spinal cord and quadriceps of these mice. We observed the longest lifespan in gzmA+/- mice. GzmA gene and protein expression was downregulated in the spinal cord and serum from gmzA+/- mice, confirming that the increased survival of hemizygous mice is correlated with lower levels of gzmA. In addition, mRNA and protein levels of glutathione reductase (GSR), involved in oxidative stress, were found downregulated in the spinal cord and quadriceps of gmzA+/- mice, together with lower IL-1β and IL-6 mRNA levels in hemyzigous mice. In summary, our findings indicate for the first time that reduced levels, but not the absence, of gzmA could slightly ameliorate the disease progression in this animal model.

Noncytotoxic Roles of Granzymes in Health and Disease

Granzymes are serine proteases previously believed to play exclusive and somewhat redundant roles in lymphocyte-mediated target cell death. However, recent studies have challenged this paradigm. Distinct substrate profiles and functions have since emerged for each granzyme while their dysregulated proteolytic activities have been linked to diverse pathologies.

Systematic analysis of prognostic and immunologic characteristics associated with coronavirus disease 2019 regulators in acute myeloid leukemia

The coronavirus disease 2019 (COVID-19) pandemic has so far damaged the health of millions and has made the treatment of cancer patients more complicated, and so did acute myeloid leukemia (AML). The current problem is the lack of understanding of their interactions and suggestions of evidence-based guidelines or historical experience for the treatment of such patients. Here, we first identified the COVID-19-related differentially expressed genes (C-DEGs) in AML patients by analyzing RNA-seq from public databases and explored their enrichment pathways and candidate drugs. A total of 76 C-DEGs associated with the progress of AML and COVID-19 infection were ultimately identified, and the functional analysis suggested that there are some shared links between them. Their protein–protein interactions (PPIs) and protein–drug interactions were then recognized by multiple bioinformatics algorithms. Moreover, a COVID-19 gene-associated prognostic model (C-GPM) with riskScore was constructed, patients with a high riskScore had poor survival and apparently immune-activated phenotypes, such as stronger monocyte and neutrophil cell infiltrations and higher immunosuppressants targeting expressions, meaning which may be one of the common denominators between COVID-19 and AML and the reason what complicates the treatment of the latter. Among the study’s drawbacks is that these results relied heavily on publicly available datasets rather than being clinically confirmed. Yet, these findings visualized those C-DEGs’ enrichment pathways and inner associations, and the C-GPM based on them could accurately predict survival outcomes in AML patients, which will be helpful for further optimizing therapies for AML patients with COVID-19 infections.

Bioinformatics analysis of lncRNAs in the occurrence and development of osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a disease with high mortality in children and adolescents, and metastasis is one of its important clinical features. However, the molecular mechanism of OS occurrence is not completely clear. Thus, we screened potential biomarkers of OS and analyze their prognostic value.

METHODS

The Cancer Genome Atlas (TCGA) datasets were used to analyze the differential lncRNAs in patients with OS of different immune score and the lncRNAs expressed by immune cells. Cox regression was used to develop the prognosis prediction model and specify the prognosis outcomes. Risk-proportional regression model was constructed, and the samples were divided into high and low groups based on the risk scores for the survival analysis. The areas under the receiver operating characteristic (ROC) curve were calculated and the risk-score model was verified. Finally, using 4 gene sets (comprising chemokines, immune checkpoint blockades, immune activity-related genes, and immune cells), and 4 analysis tools (CIBERSORT, TIMER, XCELL and MCP) to evaluated tumor immune infiltration.

RESULTS

Twenty-nine long non-coding ribonucleic acids (lncRNAs) were obtained from the intersection of the screened lncRNAs. Caspase recruitment domain-containing protein 8-antisense RNA 1 (CARD8-AS1), lncRNA five prime to Xist (FTX), KAT8 regulatory NSL complex unit 1-antisense RNA 1 (KANSL1-AS1), Neuroplastin Intronic Transcript 1 (NPTN-IT1), oligodendrocyte maturation-associated long intervening non-coding RNA (OLMALINC) and RPARP Antisense RNA 1 (RPARP-AS1) were found to be correlated with survival. Univariate and multivariate regression analysis showed risk score [HR (hazard ratio) 3.5, P value 0.0043; HR 3.7, P value 0.0033] and metastasis (HR 4.7, P value 6.60E-05; HR 4.8, P value 8.36E-05) were the key factors of patients with OS. The areas under curves (AUCs) of the 1-, 3-, and 5-year ROC curves of the prognostic model were 0.715, 0.729, and 0.771. The low-risk patients tended to have a high abundance of immune cells.

CONCLUSIONS

This study showed that a risk score based on 6 lncRNAs has potential value in the prognosis of OS, and patients with low-risk scores have high immune cell infiltration and good prognosis. This study may enrich understandings of underlying mechanisms related to the occurrence and development of OS.

All About (NK Cell-Mediated) Death in Two Acts and an Unexpected Encore: Initiation, Execution and Activation of Adaptive Immunity

NK cells are key mediators of immune cell-mediated cytotoxicity toward infected and transformed cells, being one of the main executors of cell death in the immune system. NK cells recognize target cells through an array of inhibitory and activating receptors for endogenous or exogenous pathogen-derived ligands, which together with adhesion molecules form a structure known as immunological synapse that regulates NK cell effector functions. The main and best characterized mechanisms involved in NK cell-mediated cytotoxicity are the granule exocytosis pathway (perforin/granzymes) and the expression of death ligands. These pathways are recognized as activators of different cell death programmes on the target cells leading to their destruction. However, most studies analyzing these pathways have used pure recombinant or native proteins instead of intact NK cells and, thus, extrapolation of the results to NK cell-mediated cell death might be difficult. Specially, since the activation of granule exocytosis and/or death ligands during NK cell-mediated elimination of target cells might be influenced by the stimulus received from target cells and other microenvironment components, which might affect the cell death pathways activated on target cells. Here we will review and discuss the available experimental evidence on how NK cells kill target cells, with a special focus on the different cell death modalities that have been found to be activated during NK cell-mediated cytotoxicity; including apoptosis and more inflammatory pathways like necroptosis and pyroptosis. In light of this new evidence, we will develop the new concept of cell death induced by NK cells as a new regulatory mechanism linking innate immune response with the activation of tumour adaptive T cell responses, which might be the initiating stimulus that trigger the cancer-immunity cycle. The use of the different cell death pathways and the modulation of the tumour cell molecular machinery regulating them might affect not only tumour cell elimination by NK cells but, in addition, the generation of T cell responses against the tumour that would contribute to efficient tumour elimination and generate cancer immune memory preventing potential recurrences.

A Potential Diagnostic and Prognostic Biomarker TMEM176B and Its Relationship With Immune Infiltration in Skin Cutaneous Melanoma

Background: Melanoma is a highly malignant and aggressive tumor. The search for new and effective biomarkers facilitates early diagnosis and treatment, ultimately improving the prognosis of melanoma patients. Although the transmembrane protein TMEM176B has been linked to a number of cancers, its role in cancer immunity remains unknown.

Methods: Expression levels of TMEM176B in normal tissues and several cancers, including Skin Cutaneous Melanoma (SKCM), were collected from TCGA and GTEx. We used Receiver operating characteristic and Kaplan–Meier survival curves and performed regression analysis to elucidate the link between TMEM176B and clinicopathological features of SKCM in order to determine the prognostic significance of TMEM176B in SKCM. We then used the GEPIA and STRING websites to search for proteins and associated top genes that may interact with TMEM176B and enriched them for analysis. The link between TMEM176B and immune cells infiltration was then investigated using TIMER, CIBERSORT algorithm and GSVA package of R (v3.6.3). Finally, animal tests were conducted to confirm the expression of Tmem176b and its influence on T-cell immune infiltration.

Results:TMEM176B expression was considerably elevated in SKCM compared to normal tissues. Particularly, TMEM176B expression was also linked to pathological stage, tumor ulceration and radiation therapy. Patients with elevated TMEM176B expression had a better prognosis, according to the survival analysis. The majority of tumor infiltrating lymphocytes (TILs) especially T cells in SKCM was positively linked with TMEM176B expression. Our animal experiments also verified that the T-cell infiltration was significantly inhibited in local melanoma tissue of Tmem176b knockout mice. At the same time deleting Tmem176b accelerated tumor progress and impaired T cells effector function.

Conclusion: Upregulated expression of TMEM176B in SKCM is associated with a better prognosis and it has the potential to serve as a diagnostic and prognostic marker for the disease. It may serve as a target for SKCM immunotherapy by regulating CD8⁺ T cells although it requires more evidence.

The prognostic effect of PNN in digestive tract cancers and its correlation with the tumor immune landscape in colon adenocarcinoma

Background

The present study investigated the expression, mutation, and methylation profile of PNN and its prognostic value in digestive tract cancers. The disparities in signaling pathways and the immune landscape in colon adenocarcinoma (COAD) based on PNN expression were specifically explored.

Methods

The expression, mutation, methylation levels of PNN, and survival data in esophageal cancer, gastric adenocarcinoma, COAD, and rectal adenocarcinoma were evaluated using several bioinformatic databases. Gene Ontology (GO) enrichment analysis and gene set enrichment analysis (GSEA) were performed to investigate the enriched biological functions and pathways in COAD. Several acknowledged bioinformatic algorithms were employed to assess the correlation between PNN expression and the tumor immune landscape in COAD.

Results

PNN was upregulated and remarkably related to tumor stage in digestive tract cancers. High expression of PNN was positively associated with poor progression‐free survival and overall survival time, specifically in COAD. PNN expression was identified as an independent prognostic factor in COAD. GO and GSEA analyses revealed that PNN participates in multiple biological processes underlying carcinogenicity in COAD. Further investigation showed that PNN expression was significantly associated with tumor‐infiltrating immune cells, immune cell functions, and several immune checkpoints in COAD. The PNN low expression group had a lower tumor immune dysfunction and exclusion (TIDE) score and a higher immunophenoscore (IPS), indicating a better response to immunotherapy.

Conclusion

PNN was highly expressed in digestive tract cancers and could act as an independent prognostic factor and a response predictor for immunotherapy in COAD.

Heterogeneity induced GZMA-F2R communication inefficient impairs antitumor immunotherapy of PD-1 mAb through JAK2/STAT1 signal suppression in hepatocellular carcinoma

Tumor heterogeneity has been associated with immunotherapy and targeted drug resistance in hepatocellular carcinoma (HCC). However, communications between tumor and cytotoxic cells are poorly understood to date. In the present study, thirty-one clusters of cells were discovered in the tumor tissues and adjacent tissues through single-cell sequencing. Moreover, the quantity and function exhaustion of cytotoxic cells was observed to be induced in tumors by the TCR and apoptosis signal pathways. Furthermore, granzyme failure of cytotoxic cells was observed in HCC patients. Importantly, the GZMA secreted by cytotoxic cells was demonstrated to interact with the F2R expressed by the tumor cells both in vivo and in vitro. This interaction induced tumor suppression and T cell-mediated killing of tumor cells via the activation of the JAK2/STAT1 signaling pathway. Mechanistically, the activation of JAK2/STAT1 signaling promoted apoptosis under the mediating effect of the LDPRSFLL motif at the N-terminus of F2R, which interacted with GZMA. In addition, GZMA and F2R were positively correlated with PD-1 and PD-L1 in tumor tissues, while the expressions of F2R and GZMA promoted PD-1 mAb-induced tumor suppression in both mouse model and HCC patients. Finally, in HCC patients, a low expression of GZMA and F2R in the tumor tissues was correlated with aggressive clinicopathological characteristics and poor prognosis. Collectively, GZMA-F2R communication inefficient induces deficient PD-1 mAb therapy and provide a completely novel immunotherapy strategy for tumor suppression in HCC patients.

ATG16L1 is a Potential Prognostic Biomarker and Immune Signature for Osteosarcoma: A Study Based on Bulk RNA and Single-Cell RNA-Sequencing

Background

Osteosarcoma is a common solid malignancy of the bone in children and adolescents, and its metastasis and recurrence are the principal causes of poor treatment outcomes.

Methods

Autophagy-related genes were used to cluster osteosarcoma patients by consensus clustering analysis using the GSE21257 database. Differentially expressed genes (DEGs) were identified by limma package. Multiple-gene risk signature was constructed using least absolute shrinkage and selection operator (LASSO) analysis and Cox regression analyses. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to determine gene expression levels. Then, single-cell RNA-sequencing dataset GSE152048 were used to identify the correlation between the DEGs and effector molecules expressed in specific tumor-infiltrating immune cells.

Results

Two clusters were identified in the consensus clustering analysis, which were confirmed by principal component analysis. Limma analysis revealed that 15 genes were related, and 9 genes were screened using protein-protein interaction network and LASSO regression analysis. Cox regression analyses identified 5 genes. Combined with survival analysis, only the autophagy related 16 like 1 gene (ATG16L1) was significant. The results of qRT-PCR showed low expression levels of ATG16L1 in tumor cells group. Immune infiltration analysis revealed significantly lower expression of CD8⁺ T cells in the high ATG16L1 gene expression group. ScRNA-seq revealed that in the ATG16L1⁺CD8⁺ T cell group, the expression of GZMB was lower, whereas the expression of ITGA1 was higher. These results showed that ATG16L1 is an immune-related gene, which is associated with poor prognosis in patients with osteosarcoma.

Conclusion

ATG16L1 is a potential prognostic biomarker and immune signature and may be a therapeutic target for osteosarcoma.

Positive Correlation Between LTA Expression and Overall Immune Activity Suggests an Increased Probability of Survival in Uterine Corpus Endometrial Carcinoma

Mounting evidence indicates that immune status plays a crucial role in tumor progress and metastasis, while there are no effective and easily assayed biomarkers to reflect it in uterine corpus endometrial carcinoma (UCEC) patients. Here, we attempted to identify the potential biomarkers that were differentially expressed between normal and tumor tissues and involved in prognosis and immune microenvironment of UCEC patients. RNA-seq data with relevant clinical information were obtained from The Cancer Genome Atlas (TCGA). ssGSEA algorithm was applied to calculate the enrichment scores of every tumor infiltration lymphocyte (TIL) set in each sample, and patients were then divided into three clusters using multiple R packages. Cox analysis, ESTIMATE, and CIBERSORT were utilized to determine the differentially expressed immune-related genes (DEIGs) with overall survival, and to explore their roles in prognosis, immune microenvironment, and immunotherapeutic response. The TIMER and TISIDB databases were utilized to predict the effectiveness of immunotherapy in UCEC patients. LTA was finally identified to be significantly upregulated in tumor tissues and closely associated with prognosis and immunological status, which was then verified in GSE17025. In multivariate analysis, the hazard ratio of LTA was 0.42 with 95% CI (0.22–0.80) (p = 0.008). Patients with high LTA expression had better survival and apparently immune-activated phenotypes, such as more tumor mutation burden (TMB), stronger immune cell infiltrations, higher expression of immunosuppressive points, and higher immunophenoscore, meaning they had an immunotherapeutic advantage over those with low LTA expression. TIMER and TISIDB indicated that LTA was highly expressed in UCEC, and its expression was negatively correlated with stages and positively related to prognosis. Additionally, we found that LTA ectopic expression weakened the proliferation ability of RL95-2 cells. All these findings indicated that LTA could act as a novel and easily assayed biomarker to predict immunological status and clinical outcomes and even as an antioncogene to explore UCEC in depth.

Multi-omics analysis of an immune-based prognostic predictor in non-small cell lung cancer

BACKGROUND

Inhibitors targeting immune checkpoints, such as PD-1/PD-L1 and CTLA-4, have prolonged survival in small groups of non-small cell lung cancer (NSCLC) patients, but biomarkers predictive of the response to the immune checkpoint inhibitors (ICIs) remain rare.

METHODS

The nonnegative matrix factorization (NMF) was performed for TCGA-NSCLC tumor samples based on the LM22 immune signature to construct subgroups. Characterization of NMF subgroups involved the single sample gene set variation analysis (ssGSVA), and mutation/copy number alteration and methylation analyses. Construction of RNA interaction network was based on the identification of differentially expressed RNAs (DERs). The prognostic predictor was constructed by a LASSO-Cox regression model. Four GEO datasets were used for the validation analysis.

RESULTS

Four immune based NMF subgroups among NSCLC patients were identified. Genetic and epigenetic analyses between subgroups revealed an important role of somatic copy number alterations in determining the immune checkpoint expression on specific immune cells. Seven hub genes were recognized in the regulatory network closely related to the immune phenotype, and a three-gene prognosis predictor was constructed.

CONCLUSIONS

Our study established an immune-based prognosis predictor, which might have the potential to select subgroups benefiting from the ICI treatment, for NSCLC patients using publicly available databases.

Biological relevance of Granzymes A and K during E. coli sepsis

Aims: Recent in vitro findings suggest that the serine protease Granzyme K (GzmK) may act as a proinflammatory mediator. However, its role in sepsis is unknown. Here we aim to understand the role of GzmK in a mouse model of bacterial sepsis and compare it to the biological relevance of Granzyme A (GzmA).

Methods: Sepsis was induced in WT, GzmA^-/- and GzmK^-/- mice by an intraperitoneal injection of 2x10⁸ CFU from E. coli. Mouse survival was monitored during 5 days. Levels of IL-1α, IL-1β, TNFα and IL-6 in plasma were measured and bacterial load in blood, liver and spleen was analyzed. Finally, profile of cellular expression of GzmA and GzmK was analyzed by FACS.

Results: GzmA and GzmK are not involved in the control of bacterial infection. However, GzmA and GzmK deficient mice showed a lower sepsis score in comparison with WT mice, although only GzmA deficient mice exhibited increased survival. GzmA deficient mice also showed reduced expression of some proinflammatory cytokines like IL1-α, IL-β and IL-6. A similar result was found when extracellular GzmA was therapeutically inhibited in WT mice using serpinb6b, which improved survival and reduced IL-6 expression. Mechanistically, active extracellular GzmA induces the production of IL-6 in macrophages by a mechanism dependent on TLR4 and MyD88.

Conclusions: These results suggest that although both proteases contribute to the clinical signs of E. coli-induced sepsis, inhibition of GzmA is sufficient to reduce inflammation and improve survival irrespectively of the presence of other inflammatory granzymes, like GzmK.

Inflammatory cell death induced by cytotoxic lymphocytes: a dangerous but necessary liaison

Cytotoxic lymphocytes (CLs), and more specifically Tc and NK cells, are the main executors of cell death in the immune system, playing a key role during both immunosurveillance and immunotherapy. These cells induce regulated cell death (RCD) by different mechanisms, being granular exocytosis and expression of death ligands the most prominent and best characterized ones. Apoptosis, a traditionally considered low-inflammatory type of cell death, has been accepted for years as the paradigm of RCD induced by CLs. However, several recent studies have demonstrated that NK cells and Tc cells can also induce more inflammatory forms of cell death, namely, necroptosis, pyroptosis, and ferroptosis. Activation of these highly inflammatory types of cell death appears to critically contribute to the activation of a successful antitumour immune response. Additionally, the role of specific cell death pathways in immunogenic cell death is still under intense debate, especially considering the interconnections with other inflammatory forms of cell death. These evidences, together with the advent of new cancer immunotherapies, highlight the necessity to deepen our understanding of the link between the cell death triggered by CLs and inflammation. This knowledge will be instrumental to maximize the antitumour potential of immunotherapies, minimizing deleterious effects associated with these treatments. In this review, we will briefly summarize the main features of apoptosis, necroptosis, pyroptosis and ferroptosis, to subsequently discuss the most recent evidences about the role of these RCD pathways during the elimination of cancer cells mediated by CLs and its modulation to increase the efficacy of cancer immunotherapy.

Granzyme K - A novel marker to identify the presence and rupture of abdominal aortic aneurysm

BACKGROUND

Immune inflammatory dysfunction is a hallmark of abdominal aortic aneurysm (AAA). Granzyme K (GZMK) is involved in the regulation of inflammation. However, the correlation between GZMK expression and AAA risk remains unknown.

METHODS

This case-control study included 112 AAA patients and 112 controls. Serum GZMK levels were determined by enzyme-linked immunosorbent assay and immunohistochemistry was utilized to determine GZMK expression in aortic tissues.

RESULTS

Compared with controls, AAA patients had higher levels of serum GZMK, and GZMK expression in AAA tissues was increased and positively associated with its serum levels (r = 0.688, P = 0.019). A positive association of serum GZMK levels with CRP or AAA diameter was confirmed, while there was a relationship between tissue GZMK expression and AAA diameter. The AUC of serum GZMK for AAA diagnosis was 0.78 with the sensitivity and specificity of 62.5% and 81.2%, whereas AUC for rupture detection was 0.76 with a sensitivity of 90.0% and specificity of 51.3%. A combination of clinically used inflammatory parameters with serum GZMK could enhance the accuracy of WBC or CRP alone in detecting AAA or rupture type. Multiple logistic analyses revealed an association of per unit increase of serum GZMK with AAA presence (OR = 1.046, P < 0.001) and its rupture risk (OR = 1.015, P = 0.048) after adjusting for confounding factors.

CONCLUSIONS

Our study provides proof that elevated GZMK expression both in serum and tissues is correlated with the presence of AAA, and serum GZMK may be a useful non-invasive marker that helps to identify AAA and its rupture risk in clinical practice.

Lung metastases share common immune features regardless of primary tumor origin

Background

Only certain disseminated cells are able to grow in secondary organs to create a metastatic tumor. Under the hypothesis that the immune microenvironment of the host tissue may play an important role in this process, we have categorized metastatic samples based on their immune features.

Methods

Gene expression data of metastatic samples (n=374) from four secondary sites (brain, bone, liver and lung) were used to characterize samples based on their immune and stromal infiltration using gene signatures and cell quantification tools. A clustering analysis was done that separated metastatic samples into three different immune categories: high, medium and low.

Results

Significant differences were found between the immune profiles of samples metastasizing in distinct organs. Metastases in lung showed a higher immunogenic score than metastases in brain, liver or bone, regardless of their primary site of origin. Also, they preferentially clustered in the high immune group. Samples in this cluster exhibited a clear inflammatory phenotype, higher levels of immune infiltrate, overexpression of programmed death-ligand 1 (PD-L1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA4) pathways and upregulation of genes predicting clinical response to programmed cell death protein 1 (PD-1) blockade (T-cell inflammatory signature). A decision tree algorithm was used to select CD74 as a biomarker that identify samples belonging to this high-immune subtype of metastases, having specificity of 0.96 and sensitivity of 1.

Conclusions

We have found a group of lung-enriched metastases showing an inflammatory phenotype susceptible to be treated with immunotherapy.

The impact of aging on innate and adaptive immunity in the human female genital tract

Mucosal tissues in the human female reproductive tract (FRT) are primary sites for both gynecological cancers and infections by a spectrum of sexually transmitted pathogens, including human immunodeficiency virus (HIV), that compromise women's health. While the regulation of innate and adaptive immune protection in the FRT by hormonal cyclic changes across the menstrual cycle and pregnancy are being intensely studied, little to nothing is known about the alterations in mucosal immune protection that occur throughout the FRT as women age following menopause. The immune system in the FRT has two key functions: defense against pathogens and reproduction. After menopause, natural reproductive function ends, and therefore, two overlapping processes contribute to alterations in immune protection in aging women: menopause and immunosenescence. The goal of this review is to summarize the multiple immune changes that occur in the FRT with aging, including the impact on the function of epithelial cells, immune cells, and stromal fibroblasts. These studies indicate that major aspects of innate and adaptive immunity in the FRT are compromised in a site‐specific manner in the FRT as women age. Further, at some FRT sites, immunological compensation occurs. Overall, alterations in mucosal immune protection contribute to the increased risk of sexually transmitted infections (STI), urogenital infections, and gynecological cancers. Further studies are essential to provide a foundation for the development of novel therapeutic interventions to restore immune protection and reverse conditions that threaten women's lives as they age.

Extracellular Granzyme A Promotes Colorectal Cancer Development by Enhancing Gut Inflammation

If not properly regulated, the inflammatory immune response can promote carcinogenesis, as evident in colorectal cancer (CRC). Aiming to gain mechanistic insight into the link between inflammation and CRC, we perform transcriptomics analysis of human CRC, identifying a strong correlation between expression of the serine protease granzyme A (GzmA) and inflammation. In a dextran sodium sulfate and azoxymethane (DSS/AOM) mouse model, deficiency and pharmacological inhibition of extracellular GzmA both attenuate gut inflammation and prevent CRC development, including the initial steps of cell transformation and epithelial-to-mesenchymal transition. Mechanistically, extracellular GzmA induces NF-κB-dependent IL-6 production in macrophages, which in turn promotes STAT3 activation in cultured CRC cells. Accordingly, colon tissues from DSS/AOM-treated, GzmA-deficient animals present reduced levels of pSTAT3. By identifying GzmA as a proinflammatory protease that promotes CRC development, these findings provide information on mechanisms that link immune cell infiltration to cancer progression and present GzmA as a therapeutic target for CRC.

Long Non-coding RNA LINC02474 Affects Metastasis and Apoptosis of Colorectal Cancer by Inhibiting the Expression of GZMB

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed malignancies. Metastasis is the main event that impedes the therapeutic effect on CRC, and its underlying mechanisms remain largely unclear. LINC02474 is a novel long noncoding RNA (lncRNA) associated with metastasis of CRC, while little is known about how LINC02474 regulates these malignant characteristics.

Methods

Expressions of LINC02474 and granzyme B (GZMB) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) or Western blotting analysis. Cell metastasis was detected by transwell assay and metastatic nude mouse model, and apoptosis was determined by Western blotting analysis and flow cytometry. Besides, the interaction between LINC02474 and GZMB was detected by dual-luciferase reporter assays.

Results

The expression of LINC02474 was significantly up-regulated in CRC tissues. Moreover, depletion of LINC02474 damaged the metastatic abilities of CRC cells in vivo and in vitro while boosting apoptosis. Besides, up-regulation of LINC02474 could promote migration and invasion, while apoptosis was inhibited in CRC cells. Besides, down-regulation of LINC02474 promoted the expression of GZMB, and interference of GZMB could increase the metastatic abilities of CRC cells while reducing apoptosis. Furthermore, LINC02474 was related to the transcriptional repression of GZMB in CRC cells determined by the dual-luciferase reporter assay.

Conclusions

The findings revealed that a novel lncRNA, LINC02474, as an oncogene, could promote metastasis, but limit apoptosis partly by impeding GZMB expression in CRC. Besides, LINC02474 had the potential to be used as a biomarker in the prognosis of CRC.

Interaction Networks Converging on Immunosuppressive Roles of Granzyme B: Special Niches Within the Tumor Microenvironment

Granzyme B is a renowned effector molecule primarily utilized by CTLs and NK cells against ill-defined and/or transformed cells during immunosurveillance. The overall expression of granzyme B within tumor microenvironment has been well-established as a prognostic marker indicative of priming immunity for a long time. Until recent years, increasing immunosuppressive effects of granzyme B are unveiled in the setting of different immunological context. The accumulative evidence confounded the roles of granzyme B in immune responses, thereby arousing great interests in characterizing detailed feature of granzyme B-positive niche. In this paper, the granzyme B-related regulatory effects of major suppressor cells as well as the tumor microenvironment that defines such functionalities were longitudinally summarized and discussed. Multiplex networks were built upon the interactions among different transcriptional factors, cytokines, and chemokines that regarded to the initiation and regulation of granzyme B-mediated immunosuppression. The conclusions and prospect may facilitate better interpretations of the clinical significance of granzyme B, guiding the rational development of therapeutic regimen and diagnostic probes for anti-tumor purposes.

Multiplexed Single-Cell Leukocyte Enzymatic Secretion Profiling from Whole Blood Reveals Patient-Specific Immune Signature

Enzymatic secretion of immune cells (leukocytes) plays a dominant role in host immune responses to a myriad of biological triggers, including infections, cancers, and cardiovascular diseases. Current tools to probe these leukocytes inadequately profile these vital biomarkers; the need for sample preprocessing steps of cell lysis, labeling, washing, and pipetting inevitably triggers the cells, changes its basal state, and dilutes the individual cell secretion in bulk assays. Using a fully integrated system for multiplexed profiling of native immune single-cell enzyme secretion from 50 μL of undiluted blood, we eliminate sample handling. With a total analysis time of 60 min, the integrated platform performs six tasks of leukocyte extraction, cell washing, fluorescent enzyme substrate mixing, single-cell droplet making, droplet incubation, and real-time readout for leukocyte secretion profiling of neutrophil elastase, granzyme B, and metalloproteinase. We calibrated the device, optimized the protocols, and tested the leukocyte secretion of acute heart failure (AHF) patients at admission and predischarge. This paper highlights the presence of single-cell enzymatic immune phenotypes independent of CD marker labeling, which could potentially elucidate the innate immune response states. We found that patients recovering from AHF showed a corresponding reduction in immune-cell enzymatic secretion levels and donor-specific enzymatic signatures were observed, which suggests patient-to-patient heterogeneous immune response. This platform presents opportunities to elucidate the complexities of the immune response from a single drop of blood and bridge the current technological, biological, and medical gap in understanding immune response and biological triggers.

Requirement of DNMT1 to orchestrate epigenomic reprogramming for NPM-ALK-driven lymphomagenesis

Malignant transformation depends on genetic and epigenetic events that result in a burst of deregulated gene expression and chromatin changes. To dissect the sequence of events in this process, we used a T-cell-specific lymphoma model based on the human oncogenic nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) translocation. We find that transformation of T cells shifts thymic cell populations to an undifferentiated immunophenotype, which occurs only after a period of latency, accompanied by induction of the MYC-NOTCH1 axis and deregulation of key epigenetic enzymes. We discover aberrant DNA methylation patterns, overlapping with regulatory regions, plus a high degree of epigenetic heterogeneity between individual tumors. In addition, ALK-positive tumors show a loss of associated methylation patterns of neighboring CpG sites. Notably, deletion of the maintenance DNA methyltransferase DNMT1 completely abrogates lymphomagenesis in this model, despite oncogenic signaling through NPM-ALK, suggesting that faithful maintenance of tumor-specific methylation through DNMT1 is essential for sustained proliferation and tumorigenesis.

Granzyme A inhibition reduces inflammation and increases survival during abdominal sepsis

Aims: Peritonitis is one of the most common causes of sepsis, a serious syndrome characterized by a dysregulated systemic inflammatory response. Recent evidence suggests that Granzyme A (GzmA), a serine protease mainly expressed by NK and T cells, could act as a proinflammatory mediator and could play an important role in the pathogenesis of sepsis. This work aims to analyze the role and the therapeutic potential of GzmA in the pathogenesis of peritoneal sepsis. Methods: The level of extracellular GzmA as well as GzmA activity were analyzed in serum from healthy volunteers and patients with confirmed peritonitis and were correlated with the Sequential Organ Failure Assessment (SOFA) score. Peritonitis was induced in C57Bl/6 (WT) and GzmA-/- mice by cecal ligation and puncture (CLP). Mice were treated intraperitoneally with antibiotics alone or in combination serpinb6b, a specific GzmA inhibitor, for 5 days. Mouse survival was monitored during 14 days, levels of some proinflammatory cytokines were measured in serum and bacterial load and diversity was analyzed in blood and spleen at different times. Results: Clinically, elevated GzmA was observed in serum from patients with abdominal sepsis suggesting that GzmA plays an important role in this pathology. In the CLP model GzmA deficient mice, or WT mice treated with an extracellular GzmA inhibitor, showed increased survival, which correlated with a reduction in proinflammatory markers in both serum and peritoneal lavage fluid. GzmA deficiency did not influence bacterial load in blood and spleen and GzmA did not affect bacterial replication in macrophages in vitro, indicating that GzmA has no role in bacterial control. Analysis of GzmA in lymphoid cells following CLP showed that it was mainly expressed by NK cells. Mechanistically, we found that extracellular active GzmA acts as a proinflammatory mediator in macrophages by inducing the TLR4-dependent expression of IL-6 and TNFα. Conclusions: Our findings implicate GzmA as a key regulator of the inflammatory response during abdominal sepsis and provide solid evidences about its therapeutic potential for the treatment of this severe pathology.

Immune-related lncRNAs as predictors of survival in breast cancer: a prognostic signature

Background

Breast cancer is a highly heterogeneous disease, this poses challenges for classification and management. Long non-coding RNAs play acrucial role in the breast cancersdevelopment and progression, especially in tumor-related immune processes which have become the most rapidly investigated area. Therefore, we aimed at developing an immune-related lncRNA signature to improve the prognosis prediction of breast cancer.

Methods

We obtained breast cancer patient samples and corresponding clinical data from The Cancer Genome Atlas (TCGA) database. Immune-related lncRNAs were screened by co-expression analysis of immune-related genes which were downloaded from the Immunology Database and Analysis Portal (ImmPort). Clinical patient samples were randomly separated into training and testing sets. In the training set, univariate Cox regression analysis and LASSO regression were utilized to build a prognostic immune-related lncRNA signature. The signature was validated in the training set, testing set, and whole cohorts by the Kaplan–Meier log-rank test, time-dependent ROC curve analysis, principal component analysis, univariate andmultivariate Cox regression analyses.

Results

A total of 937 immune- related lncRNAs were identified, 15 candidate immune-related lncRNAs were significantly associated with overall survival (OS). Eight of these lncRNAs (OTUD6B-AS1, AL122010.1, AC136475.2, AL161646.1, AC245297.3, LINC00578, LINC01871, AP000442.2) were selected for establishment of the risk prediction model. The OS of patients in the low-risk group was higher than that of patients in the high-risk group (p = 1.215e − 06 in the training set; p = 0.0069 in the validation set; p = 1.233e − 07 in whole cohort). The time-dependent ROC curve analysis revealed that the AUCs for OS in the first, eighth, and tenth year were 0.812, 0.81, and 0.857, respectively, in the training set, 0.615, 0.68, 0.655 in the validation set, and 0.725, 0.742, 0.741 in the total cohort. Multivariate Cox regression analysis indicated the model was a reliable and independent indicator for the prognosis of breast cancer in the training set (HR = 1.432; 95% CI 1.204–1.702, p < 0.001), validation set (HR = 1.162; 95% CI 1.004–1.345, p = 0.044), and whole set (HR = 1.240; 95% CI 1.128–1.362, p < 0.001). GSEA analysis revealed a strong connection between the signature and immune-related biological processes and pathways.

Conclusions

We constructed and verified a robust signature of 8 immune-related lncRNAs for the prediction of breast cancer patient survival.

Granzyme B in Inflammatory Diseases: Apoptosis, Inflammation, Extracellular Matrix Remodeling, Epithelial-to-Mesenchymal Transition and Fibrosis

Inflammation is strictly interconnected to anti-inflammatory mechanisms to maintain tissue homeostasis. The disruption of immune homeostasis can lead to acute and chronic inflammatory diseases, as cardiovascular, pulmonary, metabolic diseases and cancer. The knowledge of the mechanisms involved in the development and progression of these pathological conditions is important to find effective therapies. Granzyme B (GrB) is a serine protease produced by a variety of immune, non-immune and tumor cells. Apoptotic intracellular and multiple extracellular functions of GrB have been recently identified. Its capability of cleaving extracellular matrix (ECM) components, cytokines, cell receptors and clotting proteins, revealed GrB as a potential multifunctional pro-inflammatory molecule with the capability of contributing to the pathogenesis of different inflammatory conditions, including inflammaging, acute and chronic inflammatory diseases and cancer. Here we give an overview of recent data concerning GrB activity on multiple targets, potentially allowing this enzyme to regulate a wide range of crucial biological processes that play a role in the development, progression and/or severity of inflammatory diseases. We focus our attention on the promotion by GrB of perforin-dependent and perforin-independent (anoikis) apoptosis, inflammation derived by the activation of some cytokines belonging to the IL-1 cytokine family, ECM remodeling, epithelial-to-mesenchymal transition (EMT) and fibrosis. A greater comprehension of the pathophysiological consequences of GrB-mediated multiple activities may favor the design of new therapies aim to inhibit different inflammatory pathological conditions such as inflammaging and age-related diseases, EMT and organ fibrosis.

The Role of Granzyme B Containing Cells in the Progression of Chronic Obstructive Pulmonary Disease

Background

Lung inflammation plays a vital role in the pathogenesis of chronic obstructive pulmonary disease (COPD), but the characteristics of the inflammatory process remain unclear. There is growing interest in the role of granzyme B (GzmB) because CD8⁺ T cells can induce apoptosis of target cells by releasing GzmB, which in turn may cause tissue injury and remodeling. However, GzmB is also expressed by regulatory cells, which are able to suppress CD8⁺ T cell. The role of GzmB⁺ cells needs to be defined in COPD.

Methods

GzmB⁺ and CD8⁺ cells on alveolar wall of surgically resected lungs of microscopically classified 12 nonsmoking control, 12 panlobular emphysema (PLE) and 30 centrilobular emphysema (CLE) subjects were localized by immunohistochemical method. Positively stained cells on alveolar wall were counted and length of corresponding alveolar wall was measured. The results were expressed as mean number of positively stained cells per mm of alveolar wall in each subject.

Results

The number of GzmB⁺ and CD8⁺ cells on alveolar wall of CLE was greater than that of control or PLE subjects (p<0.05 and p<0.001, respectively). There was a positive relationship between the number of alveolar GzmB⁺ cells and forced expiratory volume in 1 second (FEV₁) (r=0.610, p=0.003) in CLE subjects. The number of alveolar GzmB⁺ cells progressively decreased with decline of FEV₁.

Conclusion

Our finding that number of alveolar GzmB⁺ cells was associated with FEV₁ suggests that GzmB⁺ cells might have protective role in the progression of lung destruction and airflow limitation in CLE, which is the predominant emphysema subtype of COPD.

Manganese is critical for antitumor immune responses via cGAS-STING and improves the efficacy of clinical immunotherapy

CD8⁺ T cell-mediated cancer clearance is often suppressed by the interaction between inhibitory molecules like PD-1 and PD-L1, an interaction acts like brakes to prevent T cell overreaction under normal conditions but is exploited by tumor cells to escape the immune surveillance. Immune checkpoint inhibitors have revolutionized cancer therapeutics by removing such brakes. Unfortunately, only a minority of cancer patients respond to immunotherapies presumably due to inadequate immunity. Antitumor immunity depends on the activation of the cGAS-STING pathway, as STING-deficient mice fail to stimulate tumor-infiltrating dendritic cells (DCs) to activate CD8⁺ T cells. STING agonists also enhance natural killer (NK) cells to mediate the clearance of CD8⁺ T cell-resistant tumors. Therefore STING agonists have been intensively sought after. We previously discovered that manganese (Mn) is indispensable for the host defense against cytosolic dsDNA by activating cGAS-STING. Here we report that Mn is also essential in innate immune sensing of tumors and enhances adaptive immune responses against tumors. Mn-insufficient mice had significantly enhanced tumor growth and metastasis, with greatly reduced tumor-infiltrating CD8⁺ T cells. Mechanically, Mn²⁺ promoted DC and macrophage maturation and tumor-specific antigen presentation, augmented CD8⁺ T cell differentiation, activation and NK cell activation, and increased memory CD8⁺ T cells. Combining Mn²⁺ with immune checkpoint inhibition synergistically boosted antitumor efficacies and reduced the anti-PD-1 antibody dosage required in mice. Importantly, a completed phase 1 clinical trial with the combined regimen of Mn²⁺ and anti-PD-1 antibody showed promising efficacy, exhibiting type I IFN induction, manageable safety and revived responses to immunotherapy in most patients with advanced metastatic solid tumors. We propose that this combination strategy warrants further clinical translation.

Loss of BAP1 expression is associated with an immunosuppressive microenvironment in uveal melanoma, with implications for immunotherapy development

Immunotherapy using immune checkpoint inhibitors (ICIs) induces durable responses in many metastatic cancers. Metastatic uveal melanoma (mUM), typically occurring in the liver, is one of the most refractory tumours to ICIs and has dismal outcomes. Monosomy 3 (M3), polysomy 8q, and BAP1 loss in primary uveal melanoma (pUM) are associated with poor prognoses. The presence of tumour‐infiltrating lymphocytes (TILs) within pUM and surrounding mUM – and some evidence of clinical responses to adoptive TIL transfer – strongly suggests that UMs are indeed immunogenic despite their low mutational burden. The mechanisms that suppress TILs in pUM and mUM are unknown. We show that BAP1 loss is correlated with upregulation of several genes associated with suppressive immune responses, some of which build an immune suppressive axis, including HLA‐DR, CD38, and CD74. Further, single‐cell analysis of pUM by mass cytometry confirmed the expression of these and other markers revealing important functions of infiltrating immune cells in UM, most being regulatory CD8⁺ T lymphocytes and tumour‐associated macrophages (TAMs). Transcriptomic analysis of hepatic mUM revealed similar immune profiles to pUM with BAP1 loss, including the expression of IDO1. At the protein level, we observed TAMs and TILs entrapped within peritumoural fibrotic areas surrounding mUM, with increased expression of IDO1, PD‐L1, and β‐catenin (CTNNB1), suggesting tumour‐driven immune exclusion and hence the immunotherapy resistance. These findings aid the understanding of how the immune response is organised in BAP1⁻ mUM, which will further enable functional validation of detected biomarkers and the development of focused immunotherapeutic approaches. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

The Multifaceted Function of Granzymes in Sepsis: Some Facts and a Lot to Discover

Sepsis is a serious global health problem. In addition to a high incidence, this syndrome has a high mortality and is responsible for huge health expenditure. The pathophysiology of sepsis is very complex and it is not well-understood yet. However, it is widely accepted that the initial phase of sepsis is characterized by a hyperinflammatory response while the late phase is characterized by immunosuppression and immune anergy, increasing the risk of secondary infections. Granzymes (Gzms) are a family of serine proteases classified according to their cleavage specificity. Traditionally, it was assumed that all Gzms acted as cytotoxic proteases. However, recent evidence suggests that GzmB is the one with the greatest cytotoxic capacity, while the cytotoxicity of others such as GzmA and GzmK is not clear. Recent studies have found that GzmA, GzmB, GzmK, and GzmM act as pro-inflammatory mediators. Specially, solid evidences show that GzmA and GzmK function as extracellular proteases that regulate the inflammatory response irrespectively of its ability to induce cell death. Indeed, studies in animal models indicate that GzmA is involved in the cytokine release syndrome characteristic of sepsis. Moreover, the GZM family also could regulate other biological processes involved in sepsis pathophysiology like the coagulation cascade, platelet function, endothelial barrier permeability, and, in addition, could be involved in the immunosuppressive stage of sepsis. In this review, we provide a comprehensive overview on the contribution of these novel functions of Gzms to sepsis and the new therapeutic opportunities emerging from targeting these proteases for the treatment of this serious health problem.

Differential Cytotoxic Function of Resident and Non-resident CD8+ T Cells in the Human Female Reproductive Tract Before and After Menopause

The functional characterization and regulation of tissue resident and non-resident CD8+ T cells in the human female reproductive tract (FRT) as women age remains a gap in our knowledge. Here we characterized the cytotoxic activity and granular contents of CD8+ T cells from the FRT in pre- and postmenopausal women. We found that under steady-state conditions, CD8+ T cells from endometrium (EM), endocervix and ectocervix displayed direct cytotoxic activity, and that cytotoxicity increased in the EM after menopause. Cytotoxic activity was sensitive to suppression by TGFβ exclusively in the EM, and sensitivity to TGFβ was reduced after menopause. Under steady-state conditions, cytotoxic activity (measured as direct killing activity), cytotoxic potential (measured as content of cytotoxic molecules) and proliferation are enhanced in non-resident CD8+ (CD103−) T cells compared to tissue resident (CD103+) T cells. Upon activation, CD103+ T cells displayed greater degranulation compared to CD103− T cells, however the granular content of perforin, granzyme A (GZA) or granzyme B (GZB) was significantly lower. After menopause, degranulation significantly increased, and granular release switched from predominantly GZB in premenopausal to GZA in postmenopausal women. Postmenopausal changes affected both CD103+ and CD103− subpopulations. Finally, CD103+ T cells displayed reduced proliferation compared to CD103− T cells, but after proliferation, cytotoxic molecules were similar in each population. Our results highlight the complexity of regulation of cytotoxic function in the FRT before and after menopause, and are relevant to the development of protective strategies against genital infections and gynecological cancers as women age.

Modulation of Inflammation by Extracellular Granzyme A

Granzyme A (GrA) has long been recognized as one of the key players in the induction of cell death of neoplastic, foreign or infected cells after granule delivery by cytotoxic cells. While the cytotoxic potential of GrA is controversial in current literature, accumulating evidence now indicates roles for extracellular GrA in modulating inflammation and inflammatory diseases. This paper aims to explore the literature presenting current knowledge on GrA as an extracellular modulator of inflammation by summarizing (i) the presence and role of extracellular GrA in several inflammatory diseases, and (ii) the potential molecular mechanisms of extracellular GrA in augmenting inflammation.

Pembrolizumab for management of patients with NSCLC and brain metastases: long-term results and biomarker analysis from a non-randomised, open-label, phase 2 trial

BACKGROUND

We did a phase 2 trial of pembrolizumab in patients with non-small-cell lung cancer (NSCLC) or melanoma with untreated brain metastases to determine the activity of PD-1 blockade in the CNS. Interim results were previously published, and we now report an updated analysis of the full NSCLC cohort.

METHODS

This was an open-label, phase 2 study of patients from the Yale Cancer Center (CT, USA). Eligible patients were at least 18 years of age with stage IV NSCLC with at least one brain metastasis 5-20 mm in size, not previously treated or progressing after previous radiotherapy, no neurological symptoms or corticosteroid requirement, and Eastern Cooperative Oncology Group performance status less than two. Modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria was used to evaluate CNS disease; systemic disease was not required for participation. Patients were treated with pembrolizumab 10 mg/kg intravenously every 2 weeks. Patients were in two cohorts: cohort 1 was for those with PD-L1 expression of at least 1% and cohort 2 was patients with PD-L1 less than 1% or unevaluable. The primary endpoint was the proportion of patients achieving a brain metastasis response (partial response or complete response, according to mRECIST). All treated patients were analysed for response and safety endpoints. This study is closed to accrual and is registered with ClinicalTrials.gov, NCT02085070.

FINDINGS

Between March 31, 2014, and May 21, 2018, 42 patients were treated. Median follow-up was 8·3 months (IQR 4·5-26·2). 11 (29·7% [95% CI 15·9-47·0]) of 37 patients in cohort 1 had a brain metastasis response. There were no responses in cohort 2. Grade 3-4 adverse events related to treatment included two patients with pneumonitis, and one each with constitutional symptoms, colitis, adrenal insufficiency, hyperglycaemia, and hypokalaemia. Treatment-related serious adverse events occurred in six (14%) of 42 patients and were pneumonitis (n=2), acute kidney injury, colitis, hypokalaemia, and adrenal insufficiency (n=1 each). There were no treatment-related deaths.

INTERPRETATION

Pembrolizumab has activity in brain metastases from NSCLC with PD-L1 expression at least 1% and is safe in selected patients with untreated brain metastases. Further investigation of immunotherapy in patients with CNS disease from NSCLC is warranted.

FUNDING

Merck and the Yale Cancer Center.

Retinal Distribution and Extracellular Activity of Granzyme B: A Serine Protease That Degrades Retinal Pigment Epithelial Tight Junctions and Extracellular Matrix Proteins

Granzymes are a family of serine proteases first shown to be intracellular initiators of immune-mediated cell death in target pathogenic cells. In addition to its intracellular role, Granzyme B (GzmB) has important extracellular functions in immune regulation and extracellular matrix (ECM) degradation. Verified substrates of extracellular GzmB activity include tight junctional and ECM proteins. Interestingly, little is known about the activity of GzmB in the outer human retina, a tissue in which the degradation of the tight junctional contacts of retinal pigment epithelial (RPE) cells and within the external limiting membrane, as well as remodeling of the ECM in Bruch's membrane, cause the breakdown of the blood-retinal barrier and slowing of metabolite transport between neuroretina and choroidal blood supply. Such pathological changes in outer retina signal early events in the development of age-related macular degeneration (AMD), a multifactorial, chronic inflammatory eye disease. This study is the first to focus on the distribution of GzmB in the outer retina of the healthy and diseased post-mortem human eye. Our results revealed that GzmB is present in RPE and choroidal mast cells. More immunoreactive cells are present in older (>65 years) compared to younger (<55 years) donor eyes, and choroidal immunoreactive cells are more numerous in eyes with choroidal neovascularization (CNV), while RPE immunoreactive cells are more numerous in eyes with soft drusen, an early AMD event. In vitro studies demonstrated that RPE-derived tight junctional and ECM proteins are cleaved by exogenous GzmB stimulation. These results suggest that the increased presence of GzmB immunoreactive cells in outer retina of older (healthy) eyes as well as in diseased eyes with CNV (from AMD) and eyes with soft drusen exacerbate ECM remodeling in the Bruch's membrane and degradation of the blood-retinal barrier. Currently there are no treatments that prevent remodeling of the Bruch's membrane and/or the loss of function of the outer blood-retinal barrier, known to promote early AMD changes, such as drusen deposition, RPE dysfunction and pro-inflammation. Specific inhibitors of GzmB, already in preclinical studies for non-ocular diseases, may provide new strategies to stop these early events associated with the development of AMD.

The Coming Decade of Cell Death Research: Five Riddles

Active cell death, in its many forms, is a fundamental biological process. Studies over the past several decades have explored the functions and consequences of cellular demise and elucidated several of the key cell death pathways. Here, I pose five questions, or riddles, that might provide a guide to the next decade of cell death research. Focusing mainly on four types of active cell death (apoptosis, necroptosis, pyroptosis, and ferroptosis) mainly in mammals, this Perspective explores the possible research directions that might answer these riddles, or at least prompt new ones.

Extracellular matrix, regional heterogeneity of the aorta, and aortic aneurysm

Aortic aneurysm is an asymptomatic disease with dire outcomes if undiagnosed. Aortic aneurysm rupture is a significant cause of death worldwide. To date, surgical repair or endovascular repair (EVAR) is the only effective treatment for aortic aneurysm, as no pharmacological treatment has been found effective. Aortic aneurysm, a focal dilation of the aorta, can be formed in the thoracic (TAA) or the abdominal (AAA) region; however, our understanding as to what determines the site of aneurysm formation remains quite limited. The extracellular matrix (ECM) is the noncellular component of the aortic wall, that in addition to providing structural support, regulates bioavailability of an array of growth factors and cytokines, thereby influencing cell function and behavior that ultimately determine physiological or pathological remodeling of the aortic wall. Here, we provide an overview of the ECM proteins that have been reported to be involved in aortic aneurysm formation in humans or animal models, and the experimental models for TAA and AAA and the link to ECM manipulations. We also provide a comparative analysis, where data available, between TAA and AAA, and how aberrant ECM proteolysis versus disrupted synthesis may determine the site of aneurysm formation.

A review of aneurysm formation, swelling in blood vessel, in the aorta, examines distinctions between two forms of the condition and the role of proteins in the extracellular matrix which surrounds cells of the arterial wall. Rupture of aneurysms in the aorta, the body’s main artery, is a major cause of death. Researchers led by Zamaneh Kassiri at the University of Alberta, Edmonton, Canada, emphasize that aneurysms in the thoracic and abdominal regions of the aorta are distinct conditions with crucial differences in their causes. Disrupted production and assembly of the extracellular matrix and its proteins may underlie thoracic aneurysm formation. Factors triggering the degradation of extracellular matrix proteins may be more significant in abdominal aneurysms. Understanding the differing molecular mechanisms involved could help address the current lack of effective drug treatments for these dangerous conditions.

Extracellular NK histones promote immune cell anti-tumor activity by inducing cell clusters through binding to CD138 receptor

Background

Natural killer (NK) cells are important anti-tumor cells of our innate immune system. Their anti-cancer activity is mediated through interaction of a wide array of activating and inhibitory receptors with their ligands on tumor cells. After activation, NK cells also secrete a variety of pro-inflammatory molecules that contribute to the final immune response by modulating other innate and adaptive immune cells. In this regard, external proteins from NK cell secretome and the mechanisms by which they mediate these responses are poorly defined.

Methods

TRANS-stable-isotope labeling of amino acids in cell culture (TRANS-SILAC) combined with proteomic was undertaken to identify early materials transferred between cord blood-derived NK cells (CB-NK) and multiple myeloma (MM) cells. Further in vitro and in vivo studies with knock-down of histones and CD138, overexpression of histones and addition of exogenous histones were undertaken to confirm TRANS-SILAC results and to determine functional roles of this material transferred.

Results

We describe a novel mechanism by which histones are actively released by NK cells early after contact with MM cells. We show that extracellular histones bind to the heparan sulfate proteoglycan CD138 on the surface of MM cells to promote the creation of immune-tumor cell clusters bringing immune and MM cells into close proximity, and thus facilitating not only NK but also T lymphocyte anti-MM activity.

Conclusion

This study demonstrates a novel immunoregulatory role of NK cells against MM cells mediated by histones, and an additional role of NK cells modulating T lymphocytes activity that will open up new avenues to design future immunotherapy clinical strategies.

s-SHIP Promoter Expression Identifies Mouse Mammary Cancer Stem Cells

During normal mammary gland development, s-SHIP promoter expression marks a distinct type of mammary stem cells, at two different stages, puberty and early mid-pregnancy. To determine whether s-SHIP is a marker of mammary cancer stem cells (CSCs), we generated bitransgenic mice by crossing the C3(1)-SV40 T-antigen transgenic mouse model of breast cancer, and a transgenic mouse (11.5kb-GFP) expressing green fluorescent protein from the s-SHIP promoter. Here we show that in mammary tumors originating in these bitransgenic mice, s-SHIP promoter expression enriches a rare cell population with CSC activity as demonstrated by sphere-forming assays in vitro and limiting dilution transplantation in vivo. These s-SHIP-positive CSCs are characterized by lower expression of Delta-like non-canonical Notch ligand 1 (DLK1), a negative regulator of the Notch pathway. Inactivation of Dlk1 in s-SHIP-negative tumor cells increases their tumorigenic potential, suggesting a role for DLK1 in mammary cancer stemness.

Perforin and Granzyme B Expressed by Murine Myeloid-Derived Suppressor Cells: A Study on Their Role in Outgrowth of Cancer Cells

A wide-range of myeloid-derived suppressor cell (MDSC)-mediated immune suppressive functions has previously been described. Nevertheless, potential novel mechanisms by which MDSCs aid tumor progression are, in all likelihood, still unrecognized. Next to its well-known expression in natural killer cells and cytotoxic T lymphocytes (CTLs), granzyme B (GzmB) expression has been found in different cell types. In an MDSC culture model, we demonstrated perforin and GzmB expression. Furthermore, similar observations were made in MDSCs isolated from tumor-bearing mice. Even in MDSCs from humans, GzmB expression was demonstrated. Of note, B16F10 melanoma cells co-cultured with perforin/GzmB knock out mice (KO) MDSCs displayed a remarkable decrease in invasive potential. B16F10 melanoma cells co-injected with KO MDSCs, displayed a significant slower growth curve compared to tumor cells co-injected with wild type (WT) MDSCs. In vivo absence of perforin/GzmB in MDSCs resulted in a higher number of CD8⁺ T-cells. Despite this change in favor of CD8⁺ T-cell infiltration, we observed low interferon-γ (IFN-γ) and high programmed death-ligand 1 (PD-L1) expression, suggesting that other immunosuppressive mechanisms render these CD8⁺ T-cells dysfunctional. Taken together, our results suggest that GzmB expression in MDSCs is another means to promote tumor growth and warrants further investigation to unravel the exact underlying mechanism.

Increased circulating granzyme B in type 2 diabetes patients with low-grade systemic inflammation

In metabolic diseases, like type 2 diabetes (T2D), adipose tissue (AT) is infiltrated by macrophages and other leukocytes - which secrete many bioactive peptides leading to local and systemic low-grade chronic inflammation - and undergoes remodeling and aberrant fibrosis. Granzyme B (GrB) is a serine protease produced by some leukocytes, including cytotoxic lymphocytes and macrophages. It exerts both intracellular apoptotic function and extracellular functions, leading to tissue injury, inflammation and repair. Elevated circulating GrB levels have been found in aging- and inflammation-associated diseases and a role for GrB in the pathogenesis of several chronic inflammatory diseases has been reported. Aims of this study were to investigate circulating GrB levels in T2D patients in relation to their systemic inflammatory profile and to unravel its correlates. For this cross-sectional study, we recruited 51 consecutive T2D patients referring to our diabetes outpatient clinics (Sapienza University, Rome, Italy) for metabolic evaluations, and 29 sex, age and body mass index comparable non-diabetic subjects as control group. Study participants underwent clinical work-up; fasting blood sampling was performed for routine biochemistry and for inflammatory profile (CRP, IL-2, IL-4, IL-6, IL-8, IL-10, TNF-α, IFN-γ, GM-CSF, adiponectin, WISP1); serum GrB was measured by Human Granzyme-B Platinum Elisa kit (Affymetrix EBIO). We found that T2D patients had serum levels of GrB significantly higher than the control group (10.17 ± 12.6 vs 7.2 ± 14.1 pg/ml, p = 0.03). Moreover, in T2D patients increased GrB correlated with unfavorable inflammatory profile, as described by elevated levels of validated adipokines such as IL-6 (p = 0.04), TNF-α (p = 0.019) and WISP1 (p = 0.005). Furthermore, multivariate linear regression analysis showed that increased GrB was associated with T2D diagnosis independently from possible confounders. In conclusion, our results show that increased levels of circulating GrB are associated with T2D diagnosis and correlates with markers of AT-linked systemic inflammation, suggesting a potential role for GrB in the inflammatory and reactive processes occurring in metabolic diseases.