Targeting the TLK1/NEK1 DDR axis with Thioridazine suppresses outgrowth of androgen independent prostate tumors.

Standard therapy for advanced Prostate Cancer (PCa) consists of antiandrogens, which provide respite from disease progression, but ultimately fail resulting in the incurable phase of the disease: mCRPC. Targeting PCa cells before their progression to mCRPC would greatly improve the outcome. Combination therapy targeting the DNA Damage Response (DDR) has been limited by general toxicity, and a goal of clinical trials is how to target the DDR more specifically. We now show that androgen deprivation therapy (ADT) of LNCaP cells results in increased expression of TLK1B, a key kinase upstream of NEK1 and ATR and mediating the DDR that typically results in a temporary cell cycle arrest of androgen responsive PCa cells. Following DNA damage, addition of the TLK specific inhibitor, thioridazine (THD), impairs ATR and Chk1 activation, establishing the existence of a ADT > TLK1 > NEK1 > ATR > Chk1, DDR pathway, while its abrogation leads to apoptosis. Treatment with THD suppressed the outgrowth of androgen-independent (AI) colonies of LNCaP and TRAMP-C2 cells cultured with bicalutamide. Moreover, THD significantly inhibited the growth of several PCa cells in vitro (including AI lines). Administration of THD or bicalutamide was not effective at inhibiting long-term tumor growth of LNCaP xenografts. In contrast, combination therapy remarkably inhibited tumor growth via bypass of the DDR. Moreover, xenografts of LNCaP cells overexpressing a NEK1-T141A mutant were durably suppressed with bicalutamide. Collectively, these results suggest that targeting the TLK1/NEK1 axis might be a novel therapy for PCa in combination with standard of care (ADT).

Protocadherin 7 is overexpressed in castration resistant prostate cancer and promotes aberrant MEK and AKT signaling.

BACKGROUND: Castrate resistant prostate cancer (CRPC) accounts for almost all prostate cancer (PCa) deaths. Aberrant activation of ERK/MEK and PI3K/AKT signaling pathways plays an important role in subsets of patients with CRPC. The role of protocadherin 7 (PCDH7) in modulating these signaling pathways is investigated for the first time in PCa in the present investigation. METHODS: PCDH7 expression was analyzed in CRPC/neuroendocrine prostate cancer (NEPC) dataset. Protein expression was assessed by Western blotting and immunohistochemistry, and messenger RNA (mRNA) by quantitative real-time polymerase chain reaction. Small hairpin ribonucleic acid was used to knockdown PCDH7. Colony formation, cell migration, and invasion studies were done using standard protocols. RESULTS: PCDH7 amplification/mRNA upregulation was observed in 41% of patients in CRPC/NEPC dataset. PCDH7 was also overexpressed in CRPC cells. Increased PCDH protein expression was observed during tumor progression in PCa tissues and in TRAMP mice. Epidermal growth factor treatment resulted in aberrant activation of ERK/AKT. Knockdown of PCDH7 decreased ERK, AKT, and RB phosphorylation and reduced colony formation, decreased cell invasion, and cell migration. CONCLUSIONS: These data show for the first time that PCDH7 is overexpressed in a large number of patients with CRPC and suggest that PCDH7 may be an attractive target in subsets of patients with CRPC for whom there is no cure to-date.

Eukaryotic Translation Initiation Factor 4 Gamma 1 (EIF4G1): a target for cancer therapeutic intervention?

BACKGROUND: Cap-dependent mRNA translation is essential for the translation of key oncogenic proteins at optimal levels and is highly regulated by the rate limiting, initiation step in protein synthesis. Eukaryotic Translation Initiation Factor 4 Gamma 1 (EIF4G1) serves as a scaffold for assembly of cap-dependent translation components in EIF4F complex formation. In the current study, we analyzed the role and expression of EIF4G1 in Pan human cancer panels through various approaches. METHODS: Immunohistochemistry analysis of EIF4G1 protein was done on high-density multi-organ Human Cancer tissue microarray (TMA) derived from the patient samples from different cancers. We used multiple clinical cohorts to analyze the EIF4G1 mRNA expression across human cancers. TCGA data analysis of EIF4G1 was done through Ualcan and c-bioportal web servers. Western blots for EIF4G1 protein was done for different cell lines in representing the multiple cancer types. Dependency score was calculated through Cancer Dependency Map. Clonogenic, tumorosphere assay and cell invasion assay were done with EIF4G complex inhibitor. Association of EIF4G1 mRNA and Kaplan-Meier survival analysis was done on available TCGA datasets. RESULTS: We observed an increase in EIF4G1 protein levels in tissue sections from different cancers as compared to their respective normal tissue. Our analysis of the TCGA data revealed that EIF4G1 mRNA expression is significantly increased in tumor tissues compared to respective control tissues across human cancers and variable expression was observed among different datasets. We discovered that alteration frequency in EIF4G1 is prevalent in human cancers e.g. prostate cancer (~ 25%), ovarian cancer (~ 15%), Head and Neck cancer (~ 13%) and cervical cancer (~ 12.5%). EIF4G1 mRNA and protein levels were high across cancer cell lines from multiple organs. Our analysis of DepMap datasets utilizing depletion assays revealed that EIF4G1 is critical for cancer cell survival. Treatment with EIF4G complex inhibitor impaired clonogenic, tumorosphere formation potential and inhibited cell invasion. Moreover, higher EIF4G1 mRNA level was associated with a lower median survival of patients in multiple tumor types. CONCLUSIONS: These studies show that EIF4G1 is amplified/over-expressed in multiple cancers and plays an essential role in cancer cell survival, as such EIF4G1 could serve as a novel potential target for therapeutic intervention across many cancers.

The transcription factor sterile alpha motif (SAM) pointed domain-containing ETS transcription factor (SPDEF) is required for E-cadherin expression in prostate cancer cells.

Loss of E-cadherin is one of the key steps in tumor progression. Our previous studies demonstrate that SAM pointed domain-containing ETS transcription factor (SPDEF) inhibited prostate cancer metastasis in vitro and in vivo. In the present study, we evaluated the relationship between SPDEF and E-cadherin expression in an effort to better understand the mechanism of action of SPDEF in prostate tumor cell invasion and metastasis. The results presented here demonstrate a direct correlation between expression of E-cadherin and SPDEF in prostate cancer cells. Additional data demonstrate that modulation of E-cadherin and SPDEF had similar effects on cell migration/invasion. In addition, siRNA-mediated knockdown of E-cadherin was sufficient to block the effects of SPDEF on cell migration and invasion. We also show that stable forced expression of SPDEF results in increased expression of E-cadherin, whereas down-regulation of SPDEF decreased E-cadherin expression. In addition, we demonstrate that SPDEF expression is not regulated by E-cadherin. Moreover, our chromatin immunoprecipitation and luciferase reporter assay revealed that SPDEF occupies E-cadherin promoter site and acts as a direct transcriptional inducer of E-cadherin in prostate cancer cells. Taken together, to the best of our knowledge, these studies are the first demonstrating requirement of SPDEF for expression of E-cadherin, an essential epithelial cell junction protein. Given that loss of E-cadherin is a central tenant in tumor metastasis, the results of our studies, by providing a new mechanism for regulation of E-cadherin expression, could have far reaching impact.

Oxalate upregulates expression of IL-2Rß and activates IL-2R signaling in HK-2 cells, a line of human renal epithelial cells.

The role of inflammation in oxalate-induced nephrolithiasis is debated. Our gene expression study indicated an increase in interleukin-2 receptor ß (IL-2Rß) mRNA in response to oxalate (Koul S, Khandrika L, Meacham RB, Koul HK. PLoS ONE 7: e43886, 2012). Herein, we evaluated IL-2Rß expression and its downstream signaling pathway in HK-2 cells in an effort to understand the mechanisms of oxalate nephrotoxicity. HK-2 cells were exposed to oxalate for various time points in the presence or absence of SB203580, a specific p38 MAPK inhibitor. Gene expression data were analyzed by Ingenuity Pathway Analysis software. mRNA expression was quantitated via real-time PCR, and changes in protein expression/kinase activation were analyzed by Western blotting. Exposure of HK-2 cells to oxalate resulted in increased transcription of IL-2Rß mRNA and increased protein levels. Oxalate treatment also activated the IL-2Rß signaling pathway (JAK1/STAT5 phosphorylation). Moreover, the increase in IL-2Rß protein was dependent upon p38 MAPK activity. These results suggest that oxalate-induced activation of the IL-2Rß pathway may lead to a plethora of cellular changes, the most common of which is the induction of inflammation. These results suggest a central role for the p38 MAPK pathway in mediating the effects of oxalate in renal cells, and additional studies may provide the key to unlocking novel biochemical targets in stone disease.

Partial bladder outlet obstruction in mice may cause E-cadherin repression through hypoxia induced pathway.

PURPOSE: Posterior urethral valves are the most common cause of partial bladder outlet obstruction in the pediatric population. Posterior urethral valves is a devastating clinical problem that ultimately results in urinary incontinence, neurogenic bladder and renal impairment. Despite improvements in medical and surgical management at least a third of patients with this condition progress to end stage renal disease and half will have problems with urinary incontinence. To achieve better understanding of the mechanism associated with clinical events we generated partial bladder outlet obstruction in male mice. In this model we investigated pathological consequences and underlying molecular mechanisms secondary to partial bladder outlet obstruction. MATERIALS AND METHODS: Five to 8-week-old male C57BL/6 mice were divided into a surgical obstruction group and a sham operated group that served as controls. Bladders and kidneys were harvested from each group 1, 2, 3, 5 and 7 days postoperatively, respectively. We examined histological and biochemical alterations, and further investigated our hypothesis that partial bladder outlet obstruction induces hypoxia activated profibrotic signaling and changes in gene expression in the bladder. RESULTS: Mice with partial bladder outlet obstruction demonstrated significant increases in bladder mass and urinary retention compared to sham operated mice. Obstruction caused fibrosis in the bladder and induced up-regulation of profibrotic genes, hypoxia-inducible factors and epithelial-mesenchymal transition-inducing transcription factors, resulting in E-cadherin down-regulation. CONCLUSIONS: Obstruction induced significant histological and molecular alterations, including activation of the hypoxia-inducible factors pathway in the mouse bladder. Activation of epithelial-mesenchymal transition-inducing transcription factors by hypoxia-inducible factors might have an important role in the pathogenesis of partial bladder outlet obstruction.

Tetrandrine for Targeting Therapy Resistance in Cancer.

During the last five decades, there has been tremendous development in our understanding of cancer biology and the development of new and novel therapeutics to target cancer. However, despite these advances, cancer remains the second leading cause of death across the globe. Most cancer deaths are attributed to the development of resistance to current therapies. There is an urgent and unmet need to address cancer therapy resistance. Tetrandrine, a bis-benzyl iso-quinoline, has shown a promising role as an anti-cancer agent. Recent work from our laboratory and others suggests that tetrandrine and its derivatives could be an excellent adjuvant to the current arsenal of anti-cancer drugs. Herein, we provide an overview of resistance mechanisms to current therapeutics and review the existing literature on the anti-cancer effects of tetrandrine and its potential use for overcoming therapy resistance in cancer.

The transcription factor SPDEF suppresses prostate tumor metastasis.

Emerging evidence suggests that the SAM pointed domain containing ETS transcription factor (SPDEF) plays a significant role in tumorigenesis in prostate, breast, colon, and ovarian cancer. However, there are no in vivo studies with respect to the role of SPDEF in tumor metastasis. The present study examined the effects of SPDEF on tumor cell metastasis using prostate tumor cells as a model. Utilizing two experimental metastasis models, we demonstrate that SPDEF inhibits cell migration and invasion in vitro and acts a tumor metastasis suppressor in vivo. Using stable expression of SPDEF in PC3-Luc cells and shRNA-mediated knockdown of SPDEF in LNCaP-Luc cells, we demonstrate for the first time that SPDEF diminished the ability of disseminated tumors cells to survive at secondary sites and establish micrometastases. These effects on tumor metastasis were not a result of the effect of SPDEF on cell growth as SPDEF expression had no effect on cell growth in vitro or subcutaneous tumor xenograft-growth in vivo. Transcriptional analysis of several genes associated with tumor metastasis, invasion, and the epithelial-mesenchymal transition demonstrated that SPDEF expression selectively down-regulated MMP9 and MMP13 in prostate cancer cells. Further analysis indicated that forced MMP9 or MMP13 expression rescued the invasive phenotype in SPDEF expressing PC3 cells in vitro, suggesting that the effects of SPDEF on tumor invasion are mediated, in part, through the suppression of MMP9 and MMP13 expression. These results demonstrate for the first time, in any system, that SPDEF functions as a tumor metastasis suppressor in vivo.

Clinical-pathologic correlation between transperineal mapping biopsies of the prostate and three-dimensional reconstruction of prostatectomy specimens.

BACKGROUND: Extended transrectal ultrasound guided biopsies (TRUSB) of the prostate may not accurately convey true morphometric information and Gleason score (GS) of prostate cancer (PCa) and the clinical use of template-guided (5-mm grid) transperineal mapping biopsies (TPMBs) remains controversial. METHODS: We correlated the clinical-pathologic results of 1,403 TPMB cores obtained from 25 men diagnosed with PCa with 64 cancer lesions found in their corresponding radical prostatectomy (RP) specimens. Special computer models of three-dimensional, whole-mounted radical prostatectomy (3D-WMRP) specimens were generated and used as gold standard to determine tumor morphometric data. Between-sample rates of upgrade and downgrade (highest GS and a novel cumulative GS) and upstage and downstage (laterality) were determined. Lesions ≥ 0.5 cm(3) or GS ≥ 7 were considered clinically significant. RESULTS: From 64 separate 3D-WMRP lesions, 25 had significant volume (mean 1.13 cm(3)) and 39 were insignificant (mean 0.09 cm(3)) (P < 0.0001); 18/64 lesions were missed by TPMB, but only one was clinically significant with GS-8 (0.02 cm(3)). When comparing the cumulative GS of TPMB versus RP, 72% (n = 18) had identical scores, 12% (n = 3) were upgraded, and only 16% (n = 4) were downgraded. Laterality of TPMB and RP was strongly correlated, 80% same laterality, 4% were up-staged, and 16% down-staged. CONCLUSIONS: Our clinical-pathology correlation showed very high accuracy of TPMB with a 5-mm grid template to detect clinically significant PCa lesions as compared with 3D-WMRP, providing physicians and patients with a reliable assessment of grade and stage of disease and the opportunity to choose the most appropriate therapeutic options.

Regulation of SPDEF expression by DNA methylation in advanced prostate cancer.

Introduction: Prostate cancer (PCa) presents a significant health challenge in men, with a substantial number of deaths attributed to metastatic castration resistant PCa (mCRPC). Moreover, African American men experience disproportionately high mortality rates due to PCa. This study delves into the pivotal role of SPDEF, a prostate specific Ets transcription factor, and its regulation by DNA methylation in the context of PCa progression. Methods: We performed Epigenetic reprogramming using daily treatment with non-toxic dose of 5Aza-2-deoxycytidine (5Aza-dC) for two weeks to assess its impact on PDEF expression in prostate cancer cells. Next, we conducted functional studies on reprogrammed cells, including cell migration (wound-healing assay), invasion (Boyden-Chamber test), and proliferation (MTT assay) to comprehensively evaluate the consequences of altered PDEF expression. We used bisulfite sequencing (BSP) to examine DNA methylation at SPDEF promoter. Simultaneously, we utilized siRNA-mediated targeting of key DNMTs (DNMT1, DNMT3A, and DNMT3B) to elucidate their specific role in regulating PDEF. We measured mRNA and protein expressions using qRT-PCR and immune-blotting techniques, respectively. Results: In this report, we observed that: a) there is a gradual decrease in SPDEF expression with a concomitant increase in methylated CpG sites within the SPDEF gene during prostate cancer progression from lower to higher Gleason grade; b) Expression of DNMT's (DNMT1, 3a and 3b) is increased during prostate cancer progression, and there is an inverse correlation between SPDEF and DNMT expression; c) SPDEF levels are decreased in RC77/T, a line of PCa cells from African American origin similar to PC3 and DU145 cells (CRPC cells), as compared to LNCaP cells , a line of androgen dependent cells,; d) the 5' CpG island of SPDEF gene are hypermethylated in SPDEF-negative CRPC ( PC3, DU145 and RC77/T) cell lines but the same regions are hypomethylated in SPDEF-positive castrate sensitive (LNCaP) cell line ; (e) expression of SPDEF in PCa cells lacking SPDEF decreases cell migration and invasion, but has no significant effect on cell proliferation, and; (f) treatment with the demethylating agent, 5-aza-2'-deoxycytidine, or silencing of the DNMT's by siRNA, partially restores SPDEF expression in SPDEF-negative PCa cell lines, and decreases cell migration and invasion. Discussion: These results indicate hypermethylation is a prevalent mechanism for decreasing SPDEF expression during prostate cancer progression. The data demonstrate that loss of SPDEF expression in prostate cancer cells, a critical step in cellular plasticity, results from a potentially reversible process of aberrant DNA methylation. These studies suggest DMNT activity as a potential therapeutic vulnerability that can be exploited for limiting cellular plasticity, tumor progression, and therapy resistance in prostate cancer.

ISGylation is increased in the peripheral blood mononuclear cells derived from symptomatic COVID-19 patients.

Cytokine-driven hyper inflammation has been identified as a critical factor behind poor outcomes in patients severely infected with SARS-CoV-2 virus. Notably, protein ISGylation, a protein conjugated form of Type 1 IFN-inducible ubiquitin-like protein ISG15 (Interferon-Stimulated Gene 15), induces cytokine storm (CS) and augments colonic inflammation in colitis-associated colon cancers in mouse models. However, whether ISGylation is increased and causally responsible for CS and hyper inflammation in symptomatic COVID-19 patients is unknown. Here, we measured ISGylation levels in peripheral blood mononuclear cells (PBMCs) from 10 symptomatic (SARS-CoV-2-positive with symptoms) and asymptomatic (SARS-CoV-2-positive with no symptoms) COVID-19 patients, and 4 uninfected individuals (SARS-CoV-2-negative), using WesTm assay. Strikingly, we note significant increases in protein ISGylation and MX-1 (myxovirus-resistance protein-1) protein levels, both induced by type-I IFN, in symptomatic but not in asymptomatic patients and uninfected individuals. Knowing that ISGylation augments CS and intestinal inflammation in colon cancers, we propose that increased ISGylation may be an underlying cause of CS and inflammation in symptomatic patients.

The role of 3-dimensional mapping biopsy in decision making for treatment of apparent early stage prostate cancer.

PURPOSE: We determined the impact of a grid based, transperineal 3-dimensional mapping biopsy on decision making for primary management of early stage prostate cancer. MATERIALS AND METHODS: We prospectively performed 3-dimensional mapping biopsy on 180 consecutive men who presented to our clinic between 2006 and 2009 with early stage, organ confined prostate cancer based on transrectal ultrasound guided 10 to 12-core biopsy, and on 35 with prior negative transrectal ultrasound biopsies. RESULTS: At presentation median patient age was 60.5 years (range 43 to 77), median prostate specific antigen was 4.8 ng/ml (range 0.5 to 72.4) and median prostate volume was 35 cc (range 9 to 95). The median number of cores acquired by transrectal ultrasound and 3-dimensional mapping biopsy was 12 and 56, and the median number of positive cores was 1 and 2, respectively. We documented Gleason score upgrade in 49 of 180 cases (27.2%) and up-stage in 82 (45.6%). The incidence of urinary retention catheter requirement of greater than 48 hours was 3.2% and the incidence of transient orthostatic hypotension was 5%. No urinary tract infections were documented. A total of 38 men received radical extirpative therapy, 11 radiation and 45 cryotherapy while 60 enrolled in a targeted focal therapy study, 44 entered active surveillance and 5 underwent other focal investigational treatments. Post-mapping data on 12 men were not available for analysis. CONCLUSIONS: Three-dimensional mapping biopsy revealed that a significant portion of men initially diagnosed with apparently low risk disease harbored clinically significant cancers requiring more aggressive therapy. The technique also enabled a number of men with low risk disease to elect surveillance or another less morbid option.

Potentiation of mitomycin C tumoricidal activity for transitional cell carcinoma by histone deacetylase inhibitors in vitro.

PURPOSE: Histone deacetylase inhibitors represent promising cancer treatments since they offer improved access to target DNA/protein complexes by cytotoxic agents. We hypothesized that histone deacetylase inhibitors would be most effective when combined with DNA damaging agents such as mitomycin C. Valproic acid is a safe, affordable histone deacetylase inhibitor. We examined the effect of the combination of valproic acid and mitomycin C on human bladder cancer cells in vitro and compared this to the effect of valproic acid or mitomycin C alone on the cells. MATERIALS AND METHODS: We used HTB5 and HTB9 cells derived from low and high grade bladder tumors, respectively. HTB5 and HTB9 cells were grown in modified Eagle's and RPMI medium, respectively. Cell growth and proliferation were measured by standard methods. Apoptosis was evaluated microscopically after dual staining of cells with annexin V-fluorescein isothiocyanate/propidium iodide. The change in protein expression was analyzed by Western blot. RESULTS: Treatment of HTB5 and HTB9 bladder cancer cells for 24 to 72 hours with valproic acid and mitomycin C resulted in concentration and time dependent decreases in viability and proliferation. HTB9 cells showed marked sensitivity to mitomycin C with a 48-hour 50% median inhibitory concentration of 1 µg. Cells were less sensitive to valproic acid alone with a 48-hour 50% median inhibitory concentration of 2.5 mM. The chromatin structure relaxation induced by valproic acid pretreatment sensitized the bladder cancer cell lines, augmenting the cytotoxic action of mitomycin C. Valproic acid potentiated the induction of cell death by mitomycin C in each cell line in synergistic fashion. The effect of combining the 2 drugs was greater than the sum effect of each drug alone. CONCLUSIONS: Results indicate that the valproic acid and mitomycin C combination is effective, likely due to synergistic mechanisms. Animal model validation is needed but early results suggest promising intravesical treatments for superficial bladder cancer.

Pancreatic cancer: genetics, disease progression, therapeutic resistance and treatment strategies.

Pancreatic cancer is a deadly disease and the third-highest cause of cancer-related deaths in the United States. It has a very low five-year survival rate (< 5%) in the United States as well as in the world (about 9%). The current gemcitabine-based therapy soon becomes ineffective because treatment resistance and surgical resection also provides only selective benefit. Signature mutations in pancreatic cancer confer chemoresistance by deregulating the cell cycle and promoting anti-apoptotic mechanisms. The stroma-rich tumor microenvironment impairs drug delivery and promotes tumor-specific immune escape. All these factors render the current treatment incompetent and prompt an urgent need for new, improved therapy. In this review, we have discussed the genetics of pancreatic cancer and its role in tumor evolution and treatment resistance. We have also evaluated new treatment strategies for pancreatic cancer, like targeted therapy and immunotherapy.

Retraction notice to "Differential effects of valproic acid on growth, proliferation and metastasis in HTB-5 and HTB-9 bladder cancer cell lines" [Canc. Lett. 281/2 (2009) 196-202].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article is being retracted following correspondence from an Investigation Committee at the University of Colorado Denver. An internal investigation into this manuscript by the University of Colorado Denver, found evidence that there was image manipulation and that these actions warrant retraction to correct the scientific record. Bands on blot obscured or removed, apparent when the images are enhanced (Fig 4A p21 band "C" at 24hr, Fig 4B p21 band "C" at 24hr, and Fig 4B Cyclin A band "10" at 48 hr).

Hippo pathway: Regulation, deregulation and potential therapeutic targets in cancer.

Hippo pathway is a master regulator of development, cell proliferation, stem cell function, tissue regeneration, homeostasis, and organ size control. Hippo pathway relays signals from different extracellular and intracellular events to regulate cell behavior and functions. Hippo pathway is conserved from Protista to eukaryotes. Deregulation of the Hippo pathway is associated with numerous cancers. Alteration of the Hippo pathway results in cell invasion, migration, disease progression, and therapy resistance in cancers. However, the function of the various components of the mammalian Hippo pathway is yet to be elucidated in detail especially concerning tumor biology. In the present review, we focused on the Hippo pathway in different model organisms, its regulation and deregulation, and possible therapeutic targets for cancer treatment.

Transcriptome and Functions of Granulocytic Myeloid-Derived Suppressor Cells Determine their Association with Disease Severity of COVID-19.

COVID-19 ranges from asymptomatic in 35% of cases to severe in 20% of patients. Differences in the type and degree of inflammation appear to determine the severity of the disease. Recent reports show an increase in circulating monocytic-myeloid-derived suppressor cells (M-MDSC) in severe COVID 19, that deplete arginine but are not associated with respiratory complications. Our data shows that differences in the type, function and transcriptome of Granulocytic-MDSC (G-MDSC) may in part explain the severity COVID-19, in particular the association with pulmonary complications. Large infiltrates by Arginase 1 + G-MDSC (Arg + G-MDSC), expressing NOX-1 and NOX-2 (important for production of reactive oxygen species) were found in the lungs of patients who died from COVID-19 complications. Increased circulating Arg + G-MDSC depleted arginine, which impaired T cell receptor and endothelial cell function. Transcriptomic signatures of G-MDSC from patients with different stages of COVID-19, revealed that asymptomatic patients had increased expression of pathways and genes associated with type I interferon (IFN), while patients with severe COVID-19 had increased expression of genes associated with arginase production, and granulocyte degranulation and function. These results suggest that asymptomatic patients develop a protective type I IFN response, while patients with severe COVID-19 have an increased inflammatory response that depletes arginine, impairs T cell and endothelial cell function, and causes extensive pulmonary damage. Therefore, inhibition of arginase-1 and/or replenishment of arginine may be important in preventing/treating severe COVID-19.

Severe COVID-19 Is Characterized by an Impaired Type I Interferon Response and Elevated Levels of Arginase Producing Granulocytic Myeloid Derived Suppressor Cells.

COVID-19 ranges from asymptomatic in 35% of cases to severe in 20% of patients. Differences in the type and degree of inflammation appear to determine the severity of the disease. Recent reports show an increase in circulating monocytic-myeloid-derived suppressor cells (M-MDSC) in severe COVID 19 that deplete arginine but are not associated with respiratory complications. Our data shows that differences in the type, function and transcriptome of granulocytic-MDSC (G-MDSC) may in part explain the severity COVID-19, in particular the association with pulmonary complications. Large infiltrates by Arginase 1+ G-MDSC (Arg+G-MDSC), expressing NOX-1 and NOX-2 (important for production of reactive oxygen species) were found in the lungs of patients who died from COVID-19 complications. Increased circulating Arg+G-MDSC depleted arginine, which impaired T cell receptor and endothelial cell function. Transcriptomic signatures of G-MDSC from patients with different stages of COVID-19, revealed that asymptomatic patients had increased expression of pathways and genes associated with type I interferon (IFN), while patients with severe COVID-19 had increased expression of genes associated with arginase production, and granulocyte degranulation and function. These results suggest that asymptomatic patients develop a protective type I IFN response, while patients with severe COVID-19 have an increased inflammatory response that depletes arginine, impairs T cell and endothelial cell function, and causes extensive pulmonary damage. Therefore, inhibition of arginase-1 and/or replenishment of arginine may be important in preventing/treating severe COVID-19.