Stress (Amsterdam, Netherlands)
Raff, H;Glaeser, BL;Szabo, A;Olsen, CM;Everson, CA;
PMID: 36856367 | DOI: 10.1080/10253890.2023.2185864
Hypothalamic-pituitary-adrenal (HPA) axis dynamics are disrupted by opioids and may be involved in substance abuse; this persists during withdrawal and abstinence and is associated with co-morbid sleep disruption leading to vulnerability to relapse. We hypothesized that chronic sleep restriction (SR) alters the HPA axis diurnal rhythm and the sexually dimorphic response to acute stressor during opioid abstinence. We developed a rat model to evaluate the effect of persistent sleep loss during opioid abstinence on HPA axis dynamics in male and female rats. Plasma ACTH and corticosterone were measured diurnally and in response to acute restraint stress in rats Before (control) compared to During subsequent opioid abstinence without or with SR. Abstinence, regardless of sleep state, led to an increase in plasma ACTH and corticosterone in the morning in males. There was a tendency for higher PM plasma ACTH during abstinence in SR males (p = 0.076). ACTH and corticosterone responses to restraint were reduced in male SR rats whereas there was a failure to achieve the post-restraint nadir in female SR rats. There was no effect of the treatments or interventions on adrenal weight normalized to body weight. SR resulted in a dramatic increase in hypothalamic PVN AVP mRNA and plasma copeptin in male but not female rats. This corresponded to the attenuation of the HPA axis stress response in SR males during opioid abstinence. We have identified a potentially unique, sexually dimorphic role for magnocellular vasopressin in the control of the HPA axis during opioid abstinence and sleep restriction.
Dos Santos, WO;Wasinski, F;Tavares, MR;Campos, AMP;Elias, CF;List, EO;Kopchick, JJ;Szawka, RE;Donato, J;
PMID: 35803590 | DOI: 10.1210/endocr/bqac103
Growth hormone (GH) acts in several hypothalamic neuronal populations to modulate metabolism and the autoregulation of GH secretion via negative-feedback loops. However, few studies have investigated whether GH receptor (GHR) expression in specific neuronal populations is required for the homeostatic control of GH secretion and energy homeostasis. In the present study, we investigated the consequences of the specific GHR ablation in GABAergic (VGAT-expressing) or glutamatergic (VGLUT2-expressing) cells. GHR ablation in GABAergic neurons led to increased GH secretion, lean mass, and body growth in male and female mice. VGAT-specific GHR knockout (KO) male mice also showed increased serum insulin-like growth factor-1, hypothalamic Ghrh, and hepatic Igf1 messenger RNA levels. In contrast, normal GH secretion, but reduced lean body mass, was observed in mice carrying GHR ablation in glutamatergic neurons. GHR ablation in GABAergic cells increased weight loss and led to decreased blood glucose levels during food restriction, whereas VGLUT2-specific GHR KO mice showed blunted feeding response to 2-deoxy-D-glucose both in males and females, and increased relative food intake, oxygen consumption, and serum leptin levels in male mice. Of note, VGLUT2-cre female mice, independently of GHR ablation, exhibited a previously unreported phenotype of mild reduction in body weight without further metabolic alterations. The autoregulation of GH secretion via negative-feedback loops requires GHR expression in GABAergic cells. Furthermore, GHR ablation in GABAergic and glutamatergic neuronal populations leads to distinct metabolic alterations. These findings contribute to the understanding of the neuronal populations responsible for mediating the neuroendocrine and metabolic effects of GH.
Inflammatory bowel diseases
Etwebi, Z;Goldsmith, JR;Bou-Dargham, M;Tian, Y;Hood, R;Spitofsky, N;Li, M;Sun, H;Lou, Y;Liu, S;Lengner, C;Chen, YH;
PMID: 34894222 | DOI: 10.1093/ibd/izab306
Colorectal cancer (CRC) is the third leading cause of cancer in the United States, and inflammatory bowel disease patients have an increased risk of developing CRC due to chronic intestinal inflammation with it being the cause of death in 10% to 15% of inflammatory bowel disease patients. TIPE2 (TNF-alpha-induced protein 8-like 2) is a phospholipid transporter that is highly expressed in immune cells and is an important regulator of immune cell function.The azoxymethane/dextran sulfate sodium murine model of colitis-associated colon cancer (CAC) was employed in Tipe2 -/- and wild-type mice, along with colonoid studies, to determine the role of TIPE2 in CAC.Early on, loss of TIPE2 led to significantly less numbers of visible tumors, which was in line with its previously described role in myeloid-derived suppressor cells. However, as time went on, loss of TIPE2 promoted tumor progression, with larger tumors appearing in Tipe2 -/- mice. This was associated with increased interleukin-22/STAT3 phosphorylation signaling. Similar effects were also observed in primary colonoid cultures, together demonstrating that TIPE2 also directly regulated colonocytes in addition to immune cells.This work demonstrates that TIPE2 has dual effects in CAC. In the colonocytes, it works as a tumor suppressor. However, in the immune system, TIPE2 may promote tumorigenesis through suppressor cells or inhibit it through IL-22 secretion. Going forward, this work suggests that targeting TIPE2 for CRC therapy requires cell- and pathway-specific approaches and serves as a cautionary tale for immunotherapy approaches in general in terms of colon cancer, as intestinal inflammation can both promote and inhibit cancer.
LncRNA expression and SDHB mutations in pheochromocytomas and paragangliomas
Annals of diagnostic pathology
Li, H;Hardin, H;Zaeem, M;Huang, W;Hu, R;Lloyd, RV;
PMID: 34461576 | DOI: 10.1016/j.anndiagpath.2021.151801
Although pheochromocytomas and paragangliomas (PPGLs) are usual low-grade neoplasms, the metastatic forms of these lesions are associated with high morbidity and mortality. Recent studies have discovered multiple aberrantly expressed long non-coding RNAs (lncRNAs) in cancers that may have regulatory roles in tumor pathogenesis and metastasis; however, the roles of some lncRNAs in PPGLs are still unknown. The expression levels of lncRNAs including metastasis-associated lung adenocarcinoma transcript (MALAT1), prostate cancer antigen 3 (PCA3), and HOX transcript antisense intergenic RNA (HOTAIR) in PPGLs were analyzed by in situ hybridization, using two tissue microarrays (TMAs). The pheochromocytoma (PCC) TMA consisted of normal adrenal medulla (N = 25), non-metastatic PCCs (N = 76) and metastatic PCCs (N = 5) while the paraganglioma (PGL) TMA had 73 non-metastatic PGLs and 5 metastatic PGLs. Immunohistochemical staining was performed on all samples with an anti-SDHB antibody. The correlations between lncRNA expression, loss of SDHB expression and clinical characteristics including tumor progression and disease prognosis were investigated. The expression levels of MALAT1 and PCA3 were significantly elevated (2.5-3.9 folds) in both non-metastatic and metastatic PCCs compared to normal adrenal medulla, although there were no significant differences between the non-metastatic and metastatic neoplasms. In contrast to non-metastatic PGLs, metastatic PGLs had significantly upregulated expression of MALAT1, PCA3, and HOTAIR. SDHB loss was more frequently observed in PGLs (25 of 78), especially in metastatic PGLs (5 of 5), compared to PCCs (2 of 81) and in 0 of 5 metastatic PCCs. Patients with SDHB loss, in contrast to SDHB retained, were younger at diagnosis, had higher rates of tumor recurrence, metastatic disease, and mortality. In addition, PGLs with SDHB loss had significantly increased expression of PCA3 compared to tumors with intact SDHB expression. Our findings suggest that specific lncRNAs may be involved in the SDHx signaling pathways in the tumorigenesis and in the development of PPGL.
Comprehensive Search for Novel Circulating miRNAs and Axon Guidance Pathway Proteins Associated with Risk of End Stage Kidney Disease in Diabetes
Journal of the American Society of Nephrology : JASN
Satake, E;Saulnier, PJ;Kobayashi, H;Gupta, M;Looker, H;Wilson, J;Md Dom, Z;Ihara, K;O'Neil, K;Krolewski, B;Pipino, C;Pavkov, M;Nair, V;Bitzer, M;Niewczas, M;Kretzler, M;Mauer, M;Doria, A;Najafian, B;Kulkarni, R;Duffin, K;Pezzolesi, M;Kahn, CR;Nelson, R;Krolewski, A;
PMID: 34140396 | DOI: 10.1681/ASN.2021010105
Background Mechanisms underlying the progression of diabetic kidney disease to end-stage kidney disease (ESKD) are not fully understood. Methods We performed global micro-RNA (miRNA) analysis in plasma in two cohorts encompassing 375 individuals with type 1 and type 2 diabetes with late diabetic kidney disease and targeted proteomics analysis in plasma in four cohorts encompassing 746 individuals with late and early diabetic kidney disease. We examined structural lesions in kidney biopsies from the 105 individuals with early diabetic kidney disease. Human umbilical vein endothelial cells were used to assess the effects of miRNA mimics or inhibitors on regulation of candidate proteins. Results In the late diabetic kidney disease cohorts, we identified 17 circulating miRNAs represented by four exemplars (miR-1287-5p, miR-197-5p, miR-339-5p, miR-328-3p), which were strongly associated with 10-year risk of ESKD. These miRNAs targeted proteins in the axon guidance pathway. Circulating levels of six of these proteins-most notably EFNA4 and EPHA2-were strongly associated with 10-year risk of ESKD in all cohorts. Furthermore, circulating levels of these proteins correlated with severity of structural lesions in kidney biopsies. In contrast, expression levels of genes encoding these proteins had no apparent effects on the lesions. In in vitro experiments, mimics of miR-1287-5p and miR-197-5p and inhibitors of miR-339-5p and miR328-3p upregulated concentrations of EPHA2 in either cell lysate, supernatant, or both. Conclusions This study reveals novel mechanisms involved in progression to ESKD and points to the importance of systemic factors in the development of diabetic kidney disease. Some circulating miRNAs and axon guidance pathway proteins represent potential targets for new therapies to prevent and treat this condition.
HIV DNA reservoir and elevated PD-1 expression of CD4 T-cell subsets particularly persist in the terminal ileum of HIV-positive patients despite cART
Horn, C;Augustin, M;Ercanoglu, MS;Heger, E;Knops, E;Bondet, V;Duffy, D;Chon, SH;Nierhoff, D;Oette, M;Schäfer, H;Vivaldi, C;Held, K;Anderson, J;Geldmacher, C;Suárez, I;Rybniker, J;Klein, F;Fätkenheuer, G;Müller-Trutwin, M;Lehmann, C;
PMID: 33421299 | DOI: 10.1111/hiv.13031
Despite its importance as an HIV anatomic sanctuary, little is known about the characteristics of the HIV reservoir in the terminal ileum (TI). In blood, the immune checkpoint inhibitor programmed-death-1 (PD-1) has been linked to the HIV reservoir and T-cell immune dysfunction. We thus evaluated PD-1 expression and cell-associated HIV DNA in memory CD4 T-cell subsets from TI, peripheral blood (PB) and rectum (RE) of untreated and treated HIV-positive patients to identify associations between PD-1 and HIV reservoir in other sites. Using mononuclear cells from PB, TI and RE of untreated HIV-positive (N = 6), treated (n = 18) HIV-positive and uninfected individuals (n = 16), we identified and sorted distinct memory CD4 T-cell subsets by flow cytometry, quantified their cell-associated HIV DNA using quantitative PCR and assessed PD-1 expression levels using geometric mean fluorescence intensity. Combined HIV-1 RNA in situ hybridization and immunohistochemistry was performed on ileal biopsy sections. Combined antiretroviral therapy (cART)-treated patients with undetectable HIV RNA and significantly lower levels of HIV DNA in PB showed particularly high PD-1 expression in PB and TI, and high HIV DNA levels in TI, irrespective of clinical characteristics. By contrast, in treatment-naïve patients HIV DNA levels in memory CD4 T-cell subsets were high in PB and TI. Elevated PD-1 expression on memory CD4 T-cells in PB and TI despite treatment points to continuous immune dysfunction and underlines the importance of evaluating immunotherapy in reversing HIV latency and T-cell reconstitution. As HIV DNA particularly persists in TI despite cART, investigating samples from TI is crucial in understanding HIV immunopathogenesis.
Journal of immunology (Baltimore, Md. : 1950)
Chung, H;Komada, T;Lau, A;Chappellaz, M;Platnich, JM;de Koning, HD;Petri, B;Luque, Y;Walker, S;Benediktsson, H;Mesnard, L;Chun, J;Muruve, DA;
PMID: 34740957 | DOI: 10.4049/jimmunol.2100483
Absent in melanoma-2 (AIM2) is an inflammasome-forming innate immune sensor for dsDNA but also exhibits inflammasome-independent functions such as restricting cellular proliferation. AIM2 is expressed in the kidney, but its localization and function are not fully characterized. In normal human glomeruli, AIM2 localized to podocytes. In patients with glomerulonephritis, AIM2 expression increased in CD44+-activated parietal epithelial cells within glomerular crescents. To explore AIM2 effects in glomerular disease, studies in Aim2 -/- mice were performed. Aim2-/- glomeruli showed reduced expression of Wilm tumor gene-1 (WT1), WT1-driven podocyte genes, and increased proliferation in outgrowth assays. In a nephrotoxic serum (NTS)-induced glomerulonephritis model, Aim2-/- (B6) mice exhibited more severe glomerular crescent formation, tubular injury, inflammation, and proteinuria compared with wild-type controls. Inflammasome activation markers were absent in both Aim2 -/- and wild-type kidneys, despite an increased inflammatory transcriptomic signature in Aim2 -/- mice. Aim2 -/- mice also demonstrated dysregulated cellular proliferation and an increase in CD44+ parietal epithelial cells during glomerulonephritis. The augmented inflammation and epithelial cell proliferation in Aim2 -/- (B6) mice was not due to genetic background, as Aim2 -/- (B6.129) mice demonstrated a similar phenotype during NTS glomerulonephritis. The AIM2-like receptor (ALR) locus was necessary for the inflammatory glomerulonephritis phenotype observed in Aim2 -/- mice, as NTS-treated ALR -/- mice displayed equal levels of injury as wild-type controls. Podocyte outgrowth from ALR -/- glomeruli was still increased, however, confirming that the ALR locus is dispensable for AIM2 effects on epithelial cell proliferation. These results identify a noncanonical role for AIM2 in suppressing inflammation and epithelial cell proliferation during glomerulonephritis.
Pathological diagnosis of Coronavirus-related nephropathy: insight from postmortem studies
Critical reviews in clinical laboratory sciences
Sanguedolce, F;Zanelli, M;Froio, E;Bisagni, A;Zizzo, M;Ascani, S;Stallone, G;Netti, S;Ranieri, E;Falagario, U;Carrieri, G;Cormio, L;
PMID: 34236278 | DOI: 10.1080/10408363.2021.1944047
A novel coronavirus pneumonia first occurred in Wuhan, China in early December 2019; the causative agent was identified and named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the World Health Organization (WHO), and the resulting disease termed coronavirus disease 2019 (COVID-19), according to the WHO coronavirus disease situation reports. This condition has spread rapidly all over the world and caused more than 125 million cases globally, with more than 2 million related deaths. Two previous outbreaks due to zoonotic coronaviruses have occurred in the last 20 years, namely the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV), causing high morbidity and mortality in human populations upon crossing the species barriers. SARS-CoV-2, SARS-CoV, and MERS-CoV show several similarities in pathogenicity and clinical presentations, the latter ranging from asymptomatic infection to severe acute respiratory distress syndrome (ARDS) and multiorgan impairment. Acute kidney injury (AKI) has been commonly reported in patients with CoV infections; therefore, pathological analysis of renal parenchyma in these patients has been carried out in order to improve knowledge about underlying mechanisms. Viral infection has been demonstrated in the renal tubular epithelial cells by electron microscopy (EM), immunohistochemistry (IHC), and in situ hybridization (ISH), although with conflicting results. Light microscopy (LM) changes have been described in the renal parenchyma primarily in the form of acute renal tubular damage, possibly due to direct viral cytopathic effect and immune-mediated mechanisms such as cytokine storm syndrome. In this review, we describe and discuss the spectrum of histological, ultrastructural, and molecular findings in SARS-CoV, MERS-CoV, and SARS-CoV-2-related renal pathology obtained from postmortem studies, as well as intrinsic limitations and pitfalls of current diagnostic techniques.
Monocyte and macrophage derived myofibroblasts: Is it fate? A review of the current evidence
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society
Vierhout, M;Ayoub, A;Naiel, S;Yazdanshenas, P;Revill, SD;Reihani, A;Dvorkin-Gheva, A;Shi, W;Ask, K;
PMID: 34107123 | DOI: 10.1111/wrr.12946
Since the discovery of the myofibroblast over 50 years ago, much has been learned about its role in wound healing and fibrosis. Its origin, however, remains controversial, with a number of progenitor cells being proposed. Macrophage-myofibroblast transition (MMT) is a recent term coined in 2014 that describes the mechanism through which macrophages, derived from circulating monocytes originating in the bone marrow, transformed into myofibroblasts and contributed to kidney fibrosis. Over the past years, several studies have confirmed the existence of MMT in various systems, suggesting that MMT could potentially occur in all fibrotic conditions and constitute a reasonable therapeutic target to prevent progressive fibrotic disease. In this perspective, we examined recent evidence supporting the notion of MMT in both human disease and experimental models across organ systems. Mechanistic insight from these studies and information from in vitro studies is provided. The findings substantiating plausible MMT showcased the co-expression of macrophage and myofibroblast markers, including CD68 or F4/80 (macrophage) and α-SMA (myofibroblast), in fibroblast-like cells. Furthermore, fate-mapping experiments in murine models exhibiting myeloid-derived myofibroblasts in the tissue further provide direct evidence for MMT. Additionally, we provide some evidence from single cell RNA sequencing experiments confirmed by fluorescent in situ hybridisation studies, showing monocyte/macrophage and myofibroblast markers co-expressed in lung tissue from patients with fibrotic lung disease. In conclusion, MMT is likely a significant contributor to myofibroblast formation in wound healing and fibrotic disease across organ systems. Circulating precursors including monocytes and the molecular mechanisms governing MMT could constitute valid targets and provide insight for the development of novel antifibrotic therapies; however, further understanding of these processes is warranted.
Association of Matrix Metalloproteinase-2 mRNA Expression with Subtypes of Pediatric Cholesteatoma
BioMed research international
Kan, T;Ueda, H;Takahara, T;Tsuchiya, Y;Kishimoto, M;Uchida, Y;Ogawa, T;Ohashi, W;Tsuzuki, T;Fujimoto, Y;
PMID: 33778077 | DOI: 10.1155/2021/6644897
Cholesteatoma is a clinically heterogeneous disease, with some patients showing spontaneous regression, while others experiencing an aggressive, lethal disease. Cholesteatoma in children can be divided into two types: congenital and acquired. Identifying good prognostic markers is needed to help select patients who will require immediate surgical intervention. Matrix metalloproteinase-2 (MMP2) was previously reported to play an important role in cholesteatoma progression, by promoting bone destruction and keratinocyte infiltration. Herein, we analyzed MMP2 mRNA expression level in cholesteatoma using RNA-in situ hybridization in formalin-fixed, paraffin-embedded (FFPE) tissue samples. Sixty patients with cholesteatoma under 15 years old, who underwent their primary surgery at Aichi Medical University's Otolaryngology Department, were analyzed for MMP2 expression level, using RNA-in situ hybridization. There were no significant differences in MMP2 mRNA expression level between congenital cholesteatoma and acquired cholesteatomas. In congenital cholesteatoma, higher MMP2 signals were observed in the open type than in the closed type (p < 0.001). In acquired cholesteatoma, higher MMP2 signals were observed in the pars tensa than in the pars flaccida (p < 0.001). MMP2 mRNA expression level was almost exclusively found in the fibroblasts or in the inflammatory cells in the stroma, but not in the epithelium. Our study reveals that MMP2 mRNA expression level is strongly associated with the subtypes of cholesteatoma. The findings suggest that the level of expression of MMP2 mRNA may be related to the pathogenesis and aggressive features of cholesteatoma.
Journal of Cystic Fibrosis
Boas, S;Donaldson, S;McBennett, K;Liou, T;Howrylak, J;Johnson, L;Teneback, C;Dozor, A;Sawicki, G;Dumlao, J;Pan, A;Akella, L;Zhang, J;Carroll, S;Orford, K;Kuriakose, E;Mermis, J;
| DOI: 10.1016/S1569-1993(21)01953-6
Background: In CF, impaired nitric oxide (NO) production may contribute to impaired host antimicrobial defense, chronic airway infection, and compromised pulmonary function. L-arginine (Arg) is a required substrate of NO synthases for production of NO. Depletion of Arg by arginase, an abundant enzyme expressed and secreted into airways by neutrophils, contributes to NO deficiency. Clinical studies in CF patients have shown that administration of inhaled Arg improved fractional exhaled NO (FeNO) and trended toward improvement in FEV1. CB-280 is a potent, reversible, oral arginase inhibitor that generates sustained increases in systemic Arg. In preclinical studies in CF mouse models, CB-280 improved central airway resistance and decreased lung infection. We present the first 2 doseescalation cohorts of an ongoing phase 1b study of CB-280 versus placebo in adults with CF (NCT04279769; CX-280-202). Methods: Patients were randomized 3:1 to receive CB-280 or placebo orally over 14 days in 4 sequential dose-escalation cohorts (50, 100, 200, 400 mg twice a day; n = 8/cohort). Primary endpoint was safety and tolerability, as assessed by adverse events (AEs), laboratory changes, ECG, and spirometry. Results: Results are presented for 16 patients from the first 2 cohorts (n = 6 in 50-mg cohort, n = 6 in 100-mg cohort, n = 4 placebo). Median age was 31.5 and 69% were female. Median baseline ppFEV1 was 65%; 86% of patients were on elexacaftor/tezacaftor/ivacaftor at study entry. Treatmentemergent AEs occurred in 3 of 12 patients treated with CB-280 and 1 of 4 patients on placebo. Treatment-related AEs in CB-280-treated patients included Grade 1/2 dizziness and acne. No Grade 3 or greater events; doselimiting toxicities; serious AEs; or major adverse changes on lab assessments, ECG, or vital signs occurred in CB-280 patients. Spirometry showed no safety problems, and there was a positive trend in ppFEV1 with CB-280. CB-280 exhibited linear pharmacokinetics. Steady-state Ctrough at the 100-mg dose surpassed the IC90 for arginase inhibition in plasma, indicating continuous target coverage. Dose-related increases in plasma Arg were observed, with a mean 1.9-fold increase at the 100-mg dose. FeNO showed a slightly positive trend from baseline for patients on CB-280. Updated data will be presented. Conclusion: In conclusion, CB-280 was well tolerated in the initial dose cohorts of this study, with no CB-280 patients experiencing dose-limiting toxicities. CB-280 exhibited linear pharmacokinetics, achieving continuous target coverage in plasma at the 100-mg dose, and trended favorably in FEV1 and FeNO parameters.
Genetic Deletion of the Prostaglandin EP3 Receptor in the Kidney Tubule of Adult Mice Has No Impact on Kidney Water Handling
Esteva‐Font, C;Krogager, T;Hoorn, E;Fenton, R;
| DOI: 10.1096/fasebj.2021.35.S1.00332
Prostaglandin E2 (PGE2) is an important lipid mediator modulating various aspects of kidney function. PGE2 exerts its effects via four PGE2 receptors, EP1-EP4. The EP3 receptor is expressed in the thick ascending limb (TAL) and the collecting duct, where it is proposed to inhibit cAMP generation and NaCl and water reabsorption. However, EP3 is also expressed in endothelial cells of arteries and arterioles, which also play a role in kidney function. Therefore, to assess the tubular role of EP3 in adult mice we generated a mouse model based on the Pax8Cre system with doxycycline-dependent deletion of EP3 along the renal tubule and assessed their renal phenotype in respect to water handling. RNAscope confirmed that EP3 was highly expressed in cortical and medullary TAL and collecting ducts, but it was non-detected in proximal tubule and thin limbs. Two weeks after treatment with doxycycline, EP3 mRNA expression was reduced by >80% in whole kidney (RT-q-PCR) and non-detectable (RNAscope) in tubules of knockout mice compared to control mice. There were no compensatory changes in other EP receptors. Under basal conditions, there were no significant differences in food and water intake, bodyweight, urinary output or plasma and urine biochemistries in both male or female control and knockout mice. There were no differences between genotypes in their renal handling of water during an acute water load, or in their response to the vasopressin V2 receptor agonist dDAVP. Rats drinking 1% NaCl for several days in combination with an EP3 antagonist have increased urine output (Hao et al., 2016). However, relative to controls, we could not detect significant differences in urine volume or osmolality in tubular EP3 knockout mice during 1% NaCl intake. In conclusion, EP3 in the renal tubule is not important for renal water handling or compensatory mechanisms exist. This new model provides a novel tool for examination of the role of EP3 in other aspects of renal function or kidney disease independently of potential developmental abnormalities or systemic effects.