Paricalcitol reduces peritoneal fibrosis in mice through the activation of regulatory T cells and reduction in IL-17 production

Melatonin inhibits the formation of chemically induced experimental encapsulating peritoneal sclerosis through modulation of T cell differentiation by suppressing of NF-κB activation in dendritic cells

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). Surgery is a therapeutic strategy for the treatment of complete intestinal obstruction. However, complete intestinal obstruction in long-term PD results in high mortality and morbidity rates after surgery. Immunopathogenesis participates in EPS formation: CD8, Th1, and Th17 cell numbers increased during the formation of EPS. The anti-inflammatory and immunomodulatory effects of melatonin may have beneficial effects on this EPS. In the present study, we determined that melatonin treatment significantly decreases the Th1 and Th17 cell populations in mice with EPS, decreases the production of IL-1β, TNF-α, IL-6, and IFN-γ, and increases the production of IL-10. The suppression of Th1 and Th17 cell differentiation by melatonin occurs through the inhibition of dendritic cell (DC) activation by affecting the initiation of the NF-κB signaling pathway in DCs. Our study suggests that melatonin has preventive potential against the formation of EPS in patients with PD.

Novel Aspects of the Immune Response Involved in the Peritoneal Damage in Chronic Kidney Disease Patients under Dialysis

Chronic kidney disease (CKD) incidence is growing worldwide, with a significant percentage of CKD patients reaching end-stage renal disease (ESRD) and requiring kidney replacement therapies (KRT). Peritoneal dialysis (PD) is a convenient KRT presenting benefices as home therapy. In PD patients, the peritoneum is chronically exposed to PD fluids containing supraphysiologic concentrations of glucose or other osmotic agents, leading to the activation of cellular and molecular processes of damage, including inflammation and fibrosis. Importantly, peritonitis episodes enhance peritoneum inflammation status and accelerate peritoneal injury. Here, we review the role of immune cells in the damage of the peritoneal membrane (PM) by repeated exposure to PD fluids during KRT as well as by bacterial or viral infections. We also discuss the anti-inflammatory properties of current clinical treatments of CKD patients in KRT and their potential effect on preserving PM integrity. Finally, given the current importance of coronavirus disease 2019 (COVID-19) disease, we also analyze here the implications of this disease in CKD and KRT.

Steviol glycosides as an alternative osmotic agent for peritoneal dialysis fluid

Background: Peritoneal dialysis (PD) is a renal replacement technique that requires repeated exposure of the peritoneum to hyperosmolar PD fluids (PDFs). Unfortunately, it promotes alterations of the peritoneal membrane (PM) that affects its functionality, including mesothelial-mesenchymal transition (MMT) of mesothelial cells (MCs), inflammation, angiogenesis, and fibrosis. Glucose is the most used osmotic agent, but it is known to be at least partially responsible, together with its degradation products (GDP), for those changes. Therefore, there is a need for more biocompatible osmotic agents to better maintain the PM. Herein we evaluated the biocompatibility of Steviol glycosides (SG)-based fluids.

Methods: The ultrafiltration and transport capacities of SG-containing and glucose-based fluids were analyzed using artificial membranes and an in vivo mouse model, respectively. To investigate the biocompatibility of the fluids, Met-5A and human omental peritoneal MCs (HOMCs) were exposed in vitro to different types of glucose-based PDFs (conventional 4.25% glucose solution with high-GDP level and biocompatible 2.3% glucose solution with low-GDP level), SG-based fluids or treated with TGF-β1. Mice submitted to surgery of intraperitoneal catheter insertion were treated for 40 days with SG- or glucose-based fluids. Peritoneal tissues were collected to determine thickness, MMT, angiogenesis, as well as peritoneal washings to analyze inflammation.

Results: Dialysis membrane experiments demonstrated that SG-based fluids at 1.5%, 1%, and 0.75% had a similar trend in weight gain, based on curve slope, as glucose-based fluids. Analyzing transport capacity in vivo, 1% and 0.75% SG-based fluid-exposed nephrectomized mice extracted a similar amount of urea as the glucose 2.3% group. In vitro, PDF with high-glucose (4.25%) and high-GDP content induced mesenchymal markers and angiogenic factors (Snail1, Fibronectin, VEGF-A, FGF-2) and downregulates the epithelial marker E-Cadherin. In contrast, exposition to low-glucose-based fluids with low-GDP content or SG-based fluids showed higher viability and had less MMT. In vivo, SG-based fluids preserved MC monolayer, induced less PM thickness, angiogenesis, leukocyte infiltration, inflammatory cytokines release, and MMT compared with glucose-based fluids.

Conclusion: SG showed better biocompatibility as an osmotic agent than glucose in vitro and in vivo, therefore, it could alternatively substitute glucose in PDF.

Effects of Hypocalcemic Vitamin D Analogs in the Expression of DNA Damage Induced in Minilungs from hESCs: Implications for Lung Fibrosis

In our previous work, we evaluated the therapeutic effects of 1α,25-Dihydroxyvitamin D₃, the biologically active form of vitamin D, in the context of bleomycin-induced lung fibrosis. Contrary to the expected, vitamin D supplementation increased the DNA damage expression and cellular senescence in alveolar epithelial type II cells and aggravated the overall lung pathology induced in mice by bleomycin. These effects were probably due to an alteration in the cellular DNA double-strand breaks’ repair capability. In the present work, we have evaluated the effects of two hypocalcemic vitamin D analogs (calcipotriol and paricalcitol) in the expression of DNA damage in the context of minilungs derived from human embryonic stem cells and in the cell line A549.

17,20S(OH)2pD Can Prevent the Development of Skin Fibrosis in the Bleomycin-Induced Scleroderma Mouse Model

Systemic sclerosis (SSc; scleroderma) is a chronic fibrotic disease involving TGF-β1. Low serum vitamin D (vit D) correlates with the degree of fibrosis and expression of TGF-β1. This study was designed to determine whether the noncalcemic vit D analog, 17,20S(OH)₂pD, suppresses fibrosis and mediators of the TGF-β1 pathway in the bleomycin (BLM) model of fibrosis. Fibrosis was induced into the skin of female C57BL/6 mice by repeated injections of BLM (50 μg/100 μL) subcutaneously. Mice received daily oral gavage with either vehicle (propylene glycol) or 17,20S(OH)₂pD using 5, 15, or 30 μg/kg for 21 days. The injected skin was biopsied; analyzed histologically; examined for total collagen by Sircol; and examined for mRNA expression of MMP-13, BMP-7, MCP-1, Gli1, and Gli2 by TR-PCR. Spleen was analyzed for lymphocytes using flow cytometry. Serum was analyzed for cytokines using a multiplexed ELISA. Results showed that all three doses of 17,20S(OH)₂pD suppressed net total collagen production, dermal thickness, and total collagen content in the BLM fibrosis model. 17,20S(OH)₂pD also increased MMP-13 expression, decreased MCP-1 and Gli-2 expression in vivo, and suppressed serum levels of IL-13, TNF-α, IL-6, IL-10, IL-17, and IL-12p70. In summary, 17,20S(OH)₂pD modulates the mediators of fibrosis in vivo and suppresses total collagen production and dermal thickness. This antifibrotic property of 17,20S(OH)₂pD offers new therapeutic approaches for fibrotic disorders.

Mitochondrial Dysfunction Plays a Relevant Role in Pathophysiology of Peritoneal Membrane Damage Induced by Peritoneal Dialysis

Preservation of the peritoneal membrane is an essential determinant of the long-term outcome of peritoneal dialysis (PD). Epithelial-to-mesenchymal transition (EMT) plays a central role in the pathogenesis of PD-related peritoneal membrane injury. We hypothesized that mitochondria may be implicated in the mechanisms that initiate and sustain peritoneal membrane damage in this setting. Hence, we carried out ex vivo studies of effluent-derived human mesothelial cells, which disclosed a significant increase in mitochondrial reactive oxygen species (mtROS) production and a loss of mitochondrial membrane potential in mesothelial cells with a fibroblast phenotype, compared to those preserving an epithelial morphology. In addition, in vitro studies of omentum-derived mesothelial cells identified mtROS as mediators of the EMT process as mitoTEMPO, a selective mtROS scavenger, reduced fibronectin protein expression induced by TGF-ß1. Moreover, we quantified mitochondrial DNA (mtDNA) levels in the supernatant of effluent PD solutions, disclosing a direct correlation with small solute transport characteristics (as estimated from the ratio dialysate/plasma of creatinine at 240 min), and an inverse correlation with peritoneal ultrafiltration. These results suggest that mitochondria are involved in the EMT that human peritoneal mesothelial cells suffer in the course of PD therapy. The level of mtDNA in the effluent dialysate of PD patients could perform as a biomarker of PD-induced damage to the peritoneal membrane.

The Effect of Vitamin D Deficiency on Overgrowth of Uterine Fibroids: A Blinded Randomized Clinical Trial

Background

To evaluate the effects of vitamin D (vitD) supplement on uterine fibroid growth.

Materials and Methods

A randomized blinded clinical trial was conducted at a tertiary university-based hospital from August 2017 to September 2018. Totally, 204 women were enrolled into the study. They had at least one uterine fibroid >10 mm on transvaginal ultrasound and their vitD level was insufficient (i.e. 20-30 ng/ml). The intervention group was treated with vitD 50000 U supplements for two months. After 2 months, ultrasound screening and vitD level measurement was done in both groups.

Results

At first, the mean serum vitD levels in intervention and control group were 23.62 and 23.20 ng/ml, respec- tively. After 8 weeks, the mean serum vitD levels in the control and intervention group were 22.72 and 28.56 ng/ml respectively (P<0.05). Also, mean fibroma diameter in the intervention group before and after 8 weeks of vitD supple- mentation was 43 ± 4.68 and 42.6 ± 1.31 mm, respectively. Mean uterine fibroid diameter in the control group which did not receive vitD supplements, before and after 8 weeks was 41.98 ± 5.25 and 47.81 ± 3.42 mm, respectively. The variation in the mean size of the uterine fibroid between the control and intervention group which was respectively about 5.83 mm increase and 0.48 mm decrease, was significant (P<0.001).

Conclusion

Our results showed that vitD supplementation prevents fibroid growth. It seems that vitD supple- ment is a simple, safe and inexpensive modality for leiomyoma growth prevention (Registration number: IRCT201703122576N15).

Experimental models in peritoneal dialysis (Review)

Peritoneal dialysis (PD) is one of the most commonly used dialysis methods and plays an important role in maintaining the quality of life of patients with end-stage renal disease. However, long-term PD treatment is associated with adverse effects on the structure and function of peritoneal tissue, which may lead to peritoneal ultrafiltration failure, resulting in dialysis failure and eventually PD withdrawal. In order to prevent the occurrence of these effects, the important issues that need to be tackled are improvement of ultrafiltration, protection of peritoneal function and extension of dialysis time. In basic PD research, a reasonable experimental model is key to the smooth progress of experiments. A good PD model should not only simulate the process of human PD as accurately as possible, but also help researchers to understand the evolution process and pathogenesis of various complications related to PD treatment. To better promote the clinical application of PD technology, the present review will summarize and evaluate the in vivo PD experimental models available, thus providing a reference for relevant PD research.

IL-17A as a Potential Therapeutic Target for Patients on Peritoneal Dialysis

Chronic kidney disease (CKD) is a health problem reaching epidemic proportions. There is no cure for CKD, and patients may progress to end-stage renal disease (ESRD). Peritoneal dialysis (PD) is a current replacement therapy option for ESRD patients until renal transplantation can be achieved. One important problem in long-term PD patients is peritoneal membrane failure. The mechanisms involved in peritoneal damage include activation of the inflammatory and immune responses, associated with submesothelial immune infiltrates, angiogenesis, loss of the mesothelial layer due to cell death and mesothelial to mesenchymal transition, and collagen accumulation in the submesothelial compact zone. These processes lead to fibrosis and loss of peritoneal membrane function. Peritoneal inflammation and membrane failure are strongly associated with additional problems in PD patients, mainly with a very high risk of cardiovascular disease. Among the inflammatory mediators involved in peritoneal damage, cytokine IL-17A has recently been proposed as a potential therapeutic target for chronic inflammatory diseases, including CKD. Although IL-17A is the hallmark cytokine of Th17 immune cells, many other cells can also produce or secrete IL-17A. In the peritoneum of PD patients, IL-17A-secreting cells comprise Th17 cells, γδ T cells, mast cells, and neutrophils. Experimental studies demonstrated that IL-17A blockade ameliorated peritoneal damage caused by exposure to PD fluids. This article provides a comprehensive review of recent advances on the role of IL-17A in peritoneal membrane injury during PD and other PD-associated complications.

Vitamin D Attenuates Loss of Endothelial Biomarker Expression in Cardio-Endothelial Cells

Vitamin D is associated with cardiovascular health through activating the vitamin D receptor that targets genes related to cardiovascular disease (CVD). The human cardiac microvascular endothelial cells (HCMECs) were used to develop mechanically and TGF-β1-induced fibrosis models, and the rat was used as the isoproterenol (ISO)-induced fibrosis model. The rats were injected with ISO for the first five days, followed by vitamin D injection for the consecutive three weeks before being sacrificed on the fourth week. Results showed that mechanical stretching reduced endothelial cell marker CD31 and VE-cadherin protein expressions, as well as increased α-smooth muscle actin (α-SMA) and fibronectin (FN). The transforming growth factor-β1 (TGF-β1) reduced CD31, and increased α-SMA and FN protein expression levels. Vitamin D presence led to higher protein expression of CD31, and lower protein expressions of α-SMA and FN compared to the control in the TGF-β1-induced fibrosis model. Additionally, protein expression of VE-cadherin was increased and fibroblast-specific protein-1 (FSP1) was decreased after vitamin D treatment in the ISO-induced fibrosis rat. In conclusion, vitamin D slightly inhibited fibrosis development in cell and animal models. Based on this study, the beneficial effect of vitamin D may be insignificant; however, further investigation of vitamin D’s effect in the long-term is required in the future.

Paricalcitol regulatory effect on inflammatory, fibrotic and anticalcificating parameters in renal patiente. Far beyond mineral bone disease regulation

BACKWARD

Cardiovascular events are the major cause of morbidity and mortality in patients with chronic kidney disease (CKD). Inflammation and mineral-bone disorder are pathological conditions that have been associated with an increased cardiovascular risk.

OBJECTIVE

Show paricalcitol regulation overinflammatory, fibrotic and mineral disorder parameters in CKD.

MATERIAL AND METHODS

Prospective Study in 46 CKD stages III-V patients without dialysis patients whith elevated parathormone in which we introduced paricalcitol. We evaluated classic and newest mineral and bone metabolism serum parameters (calcium, phosphorus, parathormone, fibroblast growth factor-23 [FGF-23], Klotho, calcidiol), inflammatory-fibrosis and anticalcifying parameters (interleukin-6 and 10, tumor necrosis factor-a [TNF- α], transforming growth factor-b [TGF-β],bone morphogenic protein-7 [BMP-7] and fetuin-A) for four months.

RESULTS

At the end of study soluble Klotho increased (p=.001), FGF-23 remained stable, calcium and phosphorus levels were not increased, calcidiol increased (p=.010) and PTH decreased (p=.002). Inflammation-fibrosis and calcification parameters showed positive regulation after paricalcitol treatment: interleukin-6 decreased significantly (p=.001) and also TNF-α did (p=.005), on the contrary, interleukin-10 and fetuin-A increased (p=.001 for both). Anti-fibrosis marker BMP-7 increased (p=.001) and TGF-b decreased (p=.001). We did not find significant changes in renal function.

CONCLUSIONS

Paricalcitol treatment might be profitable in regulating inflammatory and anticalcificant parameters, unmodified calcium or phosphorus seric levels and preserving kidney function in renal patients with no dialysis. Our selected parameters could indicate paricalcitol effects in mineral and endothelial disorder related to renal disease.

Paricalcitol improves experimental autoimmune encephalomyelitis (EAE) by suppressing inflammation via NF-κB signaling

Multiple sclerosis (MS) is known as an autoimmune disease in the central nervous system (CNS) characterized by motor deficits, pain, fatigue, cognitive impairment, and sensory and visual dysfunction. MS is considered to be resulted from significant inflammatory response. Paricalcitol (Pari) is a vitamin D2 analogue, which has been indicated to show anti-inflammatory activities in kidney and heart diseases. In the present study, if Pari could ameliorate the experimental autoimmune encephalomyelitis (EAE) was investigated. Here, the C57BL/6 mice were immunized using myelin oligodendrocyte glycoprotein 35-55 (MOG_35-55). Subsequently, Pari was intraperitoneally injected into the mice. As for in vitro analysis, RAW264.7 and Jurkat cells were incubated with Pari together with corresponding stimulus. The results indicated that Pari administration reduced the paralytic severity, neuropathology and apoptosis in MOG-treated mice compared to the MOG single group. Pari also exhibited a significantly inhibitory effect on immune cell infiltration, glial cell activation, expression of pro-inflammatory factors and the activation of nuclear factor κB (NF-κB). The expression of pro-inflammatory regulators and the translocation of NF-κB from cytoplasm into nuclear in RAW264.7 and Jurkat cells under specific stimulation was clearly down-regulated by Pari incubation. Furthermore, we found that suppressing NF-κB with its inhibitor combined with Pari could further reduce the expression of pro-inflammatory factors and associated proteins. These data illustrated that Pari could diminish MOG-triggered EAE, as well as macrophages and T cells activation through blocking NF-κB activation. Collectively, Pari might have therapeutic effects in mouse models with MS.

The Clinical Implication of Vitamin D Nanomedicine for Peritoneal Dialysis-Related Peritoneal Damage

PURPOSE

Vitamin D is a novel potential therapeutic agent for peritoneal dialysis (PD)-related peritoneal fibrosis, but it can induce hypercalcemia and vascular calcification, which limits its applicability. In this study, we create nanotechnology-based drug delivery systems to investigate its therapeutics and side effects.

MATERIALS AND METHODS

1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N- [amino-(polyethylene glycol)2000] (DSPE-PEG) and L-α-phosphatidylcholine (PC), which packages with 1α,25(OH)2D3, were used to construct vitamin D nanoliposomes. To confirm the function and safety of vitamin D nanoliposomes, peritoneal mesothelial cells were treated with TGF-β1 and the reverse was attempted using vitamin D nanoliposomes. Antibodies (Ab) against the peritoneum-glycoprotein M6A (GPM6A) Ab were conjugated with vitamin D nanoliposomes. These particles were implanted into mice by intraperitoneal injection and the animals were monitored for the distribution and side effects induced by vitamin D.

RESULTS

Vitamin D nanoliposomes were taken up by the mesothelial cells over time without cell toxicity and it also provided the same therapeutic effect in vitro. In vivo study, fluorescent imaging showed vitamin D nanoliposomes allow specific peritoneum target effect and also ameliorate vitamin D side effect.

CONCLUSION

Nanoliposomes vitamin D delivery systems for the prevention of PD-related peritoneal damage may be a potential clinical strategy in the future.

Genetic or pharmacologic blockade of enhancer of zeste homolog 2 inhibits the progression of peritoneal fibrosis

Dysregulation of histone methyltransferase enhancer of zeste homolog 2 (EZH2) has been implicated in the pathogenesis of many cancers. However, the role of EZH2 in peritoneal fibrosis remains unknown. We investigated EZH2 expression in peritoneal dialysis (PD) patients and assessed its role in peritoneal fibrosis in cultured human peritoneal mesothelial cells (HPMCs) and murine models of peritoneal fibrosis induced by chlorhexidine gluconate (CG) or high glucose peritoneal dialysis fluid (PDF) by using 3-deazaneplanocin A (3-DZNeP), and EZH2 conditional knockout mice. An abundance of EZH2 was detected in the peritoneum of patients with PD associated peritonitis and the dialysis effluent of long-term PD patients, which was positively correlated with expression of TGF-β1, vascular endothelial growth factor, and IL-6. EZH2 was found highly expressed in the peritoneum of mice following injury by CG or PDF. In both mouse models, treatment with 3-DZNeP attenuated peritoneal fibrosis and inhibited activation of several profibrotic signaling pathways, including TGF-β1/Smad3, Notch1, epidermal growth factor receptor and Src. EZH2 inhibition also inhibited STAT3 and nuclear factor-κB phosphorylation, and reduced lymphocyte and macrophage infiltration and angiogenesis in the injured peritoneum. 3-DZNeP effectively improved high glucose PDF-associated peritoneal dysfunction by decreasing the dialysate-to-plasma ratio of blood urea nitrogen and increasing the ratio of dialysate glucose at 2 h after PDF injection to initial dialysate glucose. Moreover, delayed administration of 3-DZNeP inhibited peritoneal fibrosis progression, reversed established peritoneal fibrosis and reduced expression of tissue inhibitor of metalloproteinase 2, and matrix metalloproteinase-2 and -9. Finally, EZH2-KO mice exhibited less peritoneal fibrosis than EZH2-WT mice. In HPMCs, treatment with EZH2 siRNA or 3-DZNeP suppressed TGF-β1-induced upregulation of α-SMA and Collagen I and preserved E-cadherin. These results indicate that EZH2 is a key epigenetic regulator that promotes peritoneal fibrosis. Targeting EZH2 may have the potential to prevent and treat peritoneal fibrosis. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

MiR-125a-5p Regulates Vitamin D Receptor Expression in a Mouse Model of Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) is a chronic and incurable autoimmune neurodegenerative disease of the central nervous system. Although the symptoms of MS can be managed by vitamin D3 treatment alone, this condition cannot be completely eradicated. Thus, there might be unknown factors capable of regulating the vitamin D receptor (VDR). Genome-wide analysis showed that miRNAs were associated with VDRs. We sought to determine the role and mechanism of action of miRNA-125a-5p and VDRs in a model of MS, mice with experimental autoimmune encephalomyelitis (EAE), which was induced by myelin oligodendrocyte glycoprotein 35-55 peptides. EAE mice showed decreased mean body weight but increased mean clinical scores compared with vehicle or control mice. And inflammatory infiltration was found in the lumbosacral spinal cord of EAE mice. In addition, VDR expression was significantly lower while the expression of miR-125a-5p was markedly higher in the spinal ventral horn of EAE mice than in vehicle or control mice. Importantly, activation of VDRs by paricalcitol or inhibition of miR-125a-5p by its antagomir markedly decreased the mean clinical scores in EAE mice. Interestingly, VDR and miR-125a-5p were co-localized in the same neurons of the ventral horn. More importantly, inhibition of miR-125a-5p remarkably blocked the decrease of VDRs in EAE mice. These results support a critical role for miR-125a-5p in modulating VDR activity in EAE and suggest potential novel therapeutic interventions.

Adoptive transfer of DMSO-induced regulatory T cells exhibits a similar preventive effect compared to an in vivo DMSO treatment for chemical-induced experimental encapsulating peritoneal sclerosis in mice

Encapsulating peritoneal sclerosis (EPS) is a severe complication of peritoneal dialysis (PD). This disease leads to intestinal obstruction with or without peritonitis. The imbalance between the populations of Th17 and regulatory T (Treg) cells (higher Th17 cells and lower Treg cells) is part of the pathogenesis of EPS formation. We demonstrated that dimethyl sulfoxide (DMSO) effectively inhibited autoimmune diabetes recurrence in the islet transplantation of NOD mice via the induction of the differentiation of Treg cells. In this study, we investigated the therapeutic potential of DMSO in the inhibition of EPS formation by a mouse model. Under DMSO treatment, the thickening of the parietal and visceral peritoneum was significantly reduced. The populations of CD4, CD8, and IFN-γ-producing CD4 and CD8 T cells were decreased. The populations of IL-4-producing CD4 T lymphocytes, IL-10-producing CD4 T lymphocytes, CD4 CD69 T lymphocytes and Treg lymphocytes were increased. The expression levels of the cytokines IFN-γ, IL-17a, TNF-α and IL-23, in ascites, were significantly decreased following the DMSO treatment. Furthermore, the differentiation of Treg cells was induced by DMSO from naïve CD4 T cells in vitro, and these cells were adoptively transferred into the EPS mice and significantly prevented EPS formation, exhibiting a comparable effect to the in vivo DMSO treatment. We also demonstrated that the differentiation of Treg cells by DMSO occurred via the activation of STAT5 by its epigenetic effect, without altering the PI3K-AKT-mTOR or Raf-ERK pathways. Our results demonstrated, for the first time, that in vivo DMSO treatment suppresses EPS formation in a mouse model. Furthermore, the adoptive transfer of Treg cells that were differentiated from naïve CD4 T cells by an in vitro DMSO treatment exhibited a similar effect to the in vivo DMSO treatment for the prevention of EPS formation.

Interleukin-17 pathways in systemic sclerosis-associated fibrosis

Fibrosis is unregulated tissue repair that may cause impairment of organ function, especially in end-organ damage. Systemic sclerosis (SSc) is the prototype systemic fibrosing disorder. Classical targets for fibrosis in SSc like transforming growth factor Beta (TGF-β), Interleukin-6 (IL-6), and multiple tyrosine kinases, have not yielded therapeutic benefit. There is multitude of evidence from across different tissues like the heart, lung, skin, liver, colon, and, to some extent, the kidney, that interleukin-17 (IL-17) and its downstream pathways are strongly associated with the initiation and propagation of fibrosis. Data from scleroderma patients, as well as from animal models of SSc, mirror these findings. Interestingly, hitherto unknown to be related to IL-17, newer molecules like Programmed Death-protein1 (PD-1), the phosphatase SHP2, along with known signal transducers like signal transducer and activator of transcription (STAT3), have been recently shown to be involved in the pathogenesis of fibrosis. Related molecules include the intracellular signalling molecules Ras/Erk, mammalian target organ of rapamycin (mTOR), and complement components. The biology of these pathways has not yet been fully elucidated to predict regulatory mechanisms, redundancies, and potential off-target effects. All these need to be better understood in the context of each other, in an effort to arrive at the optimal target to modulate fibrosis.

IL-17 in Peritoneal Dialysis-Associated Inflammation and Angiogenesis: Conclusions and Perspectives

Long-term peritoneal dialysis (PD) is associated with peritoneal membrane remodeling. This includes changes in peritoneal vasculature, which may ultimately lead to inadequate solute and water removal and treatment failure. The potential cause of such alterations is chronic inflammation induced by repeated episodes of infectious peritonitis and/or exposure to bioincompatible PD fluids. While these factors may jeopardize the peritoneal membrane integrity, it is not clear why adverse peritoneal remodeling develops only in some PD patients. Increasing evidence points to the differences that occur between patients in response to the same invading microorganism and/or the differences in the course of inflammatory reaction triggered by different species. Such differences may be related to the involvement of different inflammatory mediators. Here, we discuss the potential role of IL-17 in these processes with emphasis on its impact on peritoneal mesothelial cells and peritoneal vascularity.

Surgical Techniques for Catheter Placement and 5/6 Nephrectomy in Murine Models of Peritoneal Dialysis

Peritoneal dialysis (PD) is a renal replacement therapy consistent on the administration and posterior recovery of a hyperosmotic fluid in the peritoneal cavity to drain water and toxic metabolites that functionally-insufficient kidneys are not able to eliminate. Unfortunately, this procedure deteriorates the peritoneum. Tissue damage triggers the onset of inflammation to heal the injury. If the injury persists and inflammation becomes chronic, it may lead to fibrosis, which is a common occurrence in many diseases. In PD, chronic inflammation and fibrosis, along with other specific processes related to these ones, lead to ultrafiltration capacity deterioration, which means the failure and subsequent cessation of the technique. Working with human samples provides information about this deterioration but presents technical and ethical limitations to obtain biopsies. Animal models are essential to study this deterioration since they overcome these shortcomings. A chronic mouse infusion model was developed in 2008, which benefits from the wide range of genetically modified mice, opening up the possibility of studying the mechanisms involved. This model employs a customized device designed for mice, consisting of a catheter attached to an access port that is placed subcutaneously at the back of the animal. This procedure avoids continuous puncture of the peritoneum during long-term experiments, reducing infections and inflammation due to injections. Thanks to this model, peritoneal damage induced by chronic PD fluid exposure has been characterized and modulated. This technique allows the infusion of large volumes of fluids and could be used for the study of other diseases in which inoculation of drugs or other substances over extended periods of time is necessary. This article shows the method for the surgical placement of the catheter in mice. Moreover, it explains the procedure for a 5/6 nephrectomy to mimic the state of renal insufficiency present in PD patients.

Replenishing Regulatory T Cells to Halt Depigmentation in Vitiligo

Vitiligo is a cutaneous autoimmune disease, especially devastating to patients with darker skin tones because of the contrast between unaffected and lesional skin. We studied immune cells infiltrating vitiligo skin and found very few regulatory T cells (Tregs). Vitiligo was not associated with a reduced frequency or function of circulating Tregs. To manipulate Treg function, we used mouse models expressing melanocyte-reactive TCRs, following changes in pelage color. We also isolated splenocytes to measure Treg function and evaluated cutaneous Treg abundance. Even small numbers of Tregs transferred into depigmenting mice could effectively interfere with depigmentation. The same holds true for treatment with rapamycin, readily translatable for use in human patients; such treatment may be well tolerated. Because vitiligo skin is relatively devoid of cells that produce the chemokine CCL22, whereas circulating Tregs express normal levels of its receptor CCR4, we overexpressed Ccl22 in the skin of vitiligo-prone mice to assess the resulting levels of depigmentation. Markedly reduced depigmentation was accompanied by Treg infiltration to the skin. With several options available to support a healthy balance between Tregs and effector T cells, the next challenge will be to render such treatment antigen specific and avoid general immunosuppression.

Differences in peritoneal response after exposure to low-GDP bicarbonate/lactate-buffered dialysis solution compared to conventional dialysis solution in a uremic mouse model

Background

Long-term exposure of conventional peritoneal dialysis (PD) fluid is associated with structural membrane alterations and technique failure. Previously, it has been shown that infiltrating IL-17-secreting CD4+T cells and pro-fibrotic M2 macrophages play a critical role in the PD-induced pathogenesis. Although more biocompatible PD solutions are recognized to better preserve the peritoneal membrane integrity, the impact of these fluids on the composition of the peritoneal cell infiltrate is unknown.

Materials and methods

In a uremic PD mouse model, we compared the effects of daily instillation of standard lactate (LS) or bicarbonate/lactate-buffered solutions (BLS) and respective controls on peritoneal fibrosis, vascularisation, and inflammation.

Results

Daily exposure of LS fluid during a period of 8 weeks resulted in a peritoneal increase of αSMA and collagen accompanied with new vessel formation compared to the BLS group. Effluent from LS-treated mouse showed a higher percentage of CD4⁺ IL-17⁺ cell population while BLS exposure resulted in an increased macrophage population. Significantly enhanced inflammatory cytokines such as TGFβ1, TNFα, INFγ, and MIP-1β were detected in the effluent of BLS-exposed mice when compared to other groups. Further, immunohistochemistry of macrophage subset infiltrates in the BLS group confirmed a higher ratio of pro-inflammatory M1 macrophages over the pro-fibrotic M2 subset compared to LS.

Conclusion

Development of the peritoneal fibrosis and angiogenesis was prevented in the BLS-exposed mice, which may underlie its improved biocompatibility. Peritoneal recruitment of M1 macrophages and lower number of CD4⁺ IL-17⁺ cells might explain the peritoneal integrity preservation observed in BLS-exposed mouse.

Paricalcitol and Peritoneal Protein Loss in Peritoneal Dialysis: A Double-Center Study

BACKGROUND/AIMS

Peritoneal protein loss (PPL) is associated with cardiovascular disease and mortality in peritoneal dialysis (PD). Controversial results have been published about the effect of paricalcitol in PPL among PD patients. This study intends to analyze the relationship between paricalcitol and PPL in PD.

METHODS

In a retrospective study, prevalent PD patients were divided into 2 groups: "with paricalcitol" and "without paricalcitol". X2-test, Student's t test, Pearson correlation coefficient and Logistic Regression analysis were applied.

RESULTS

Eighty-two patients were included. PPL was lower among patients medicated with paricalcitol (5.17 ± 1.71 vs. 6.79 ± 2.10 g/24 h, p = 0.0001). In multivariate analysis, paricalcitol and dialysate/plasma ratio of creatinine (D/P creatinine) were independently related to PPL (OR 4.270 [1.437-12.684], p = 0.009 and OR 0.205 [0.064-0.659], p = 0.008, respectively), adjusted for diabetes.

CONCLUSION

Paricalcitol and D/P creatinine were independently related to PPL. Paricalcitol may have an effect on PPL in PD patients.

Prominent Levels of the Profibrotic Chemokine CCL18 during Peritonitis: In Vitro Downregulation by Vitamin D Receptor Agonists

Peritoneal dialysis (PD) is used as a renal replacement therapy, which can be limited by peritoneal membrane ultrafiltration failure (UFF) secondary to fibrotic processes. Peritonitis, a frequent complication of PD, is a major risk factor for peritoneal membrane fibrosis and UFF. Low peritoneal levels of the chemokine CCL18 are associated with preservation of peritoneal membrane function in PD. Given that CCL18 is involved in fibrotic processes and recurrent peritonitis, it is a risk factor for peritoneal membrane failure; thus, we evaluated CCL18 concentrations in peritoneal effluents from patients undergoing peritonitis episodes. Pharmacological interventions aimed at diminishing the production of CCL18 were also explored. Fivefold higher CCL18 peritoneal concentrations were found during acute bacterial peritonitis, in parallel with the increased infiltration of macrophages. Unexpectedly, CCL18 was also highly (50-fold) increased during sterile eosinophilic peritonitis, and peritoneal eosinophils were found to express CCL18. In vitro treatment of peritoneal macrophages with the vitamin D receptor agonist paricalcitol was able to reduce the secretion and the expression of CCL18 in isolated peritoneal macrophages. In conclusion, our study suggests that the chemokine CCL18 can be a mediator of peritoneal membrane failure associated with peritonitis episodes as well as providing a new potential therapeutic target.

Effects of Oral Paricalcitol and Calcitriol Treatment on Peritoneal Membrane Characteristics of Peritoneal Dialysis Patients - A Pilot Study

BACKGROUND

Long-term peritoneal dialysis (PD) is frequently complicated by technique failure preceded by peritoneal remodeling. Vitamin D has potent immunomodulatory characteristics: anti-inflammatory, anti-angiogenic, anti-fibrotic properties, and influences on the macrophage phenotype. Little is known about the relation between pleiotropic effects attributed to vitamin D₃ and the peritoneal membrane and what is the most appropriate vitamin D sterol in prevention of peritoneal remodeling in PD patients. Animal studies have suggested that paricalcitol has advantageous effects: decrease in plasma markers of inflammation, less peritoneal fibrosis, less pronounced PD-induced omental angiogenesis, and prevention of loss of ultrafiltration. We investigated whether paricalcitol is advantageous over calcitriol in PD patients.

METHOD

A multicenter open-label 1:1 randomized non-blinded clinical pilot study enrolled prevalent continous ambulatory PD (CAPD) patients for a period of 6 months comparing paricalcitol with calcitriol. All patients were treated with biocompatible PD fluids. The primary endpoint was peritoneal transport parameters, exploratory endpoints were biomarkers of peritoneal damage and cell analysis (including M1/M2 macrophages), and safety endpoints were metabolic parameters.

RESULTS

Twenty-seven patients were included. Fourteen were randomized to treatment with paricalcitol. There was no difference in peritoneal transport parameters between the groups. We found similar Kt/V, D/P creatinine, D/D0 glucose, ultrafiltration, residual renal function and 24-h urine volume during the study. There was no difference in biomarker concentrations in peritoneal effluents, and no difference in leucocyte differentiation or mesothelial cells between the groups at any time point. Parathyroid hormone (PTH) levels decreased after administration of calcitriol after 12 and 24 weeks compared with baseline (p = 0.001; p = 0.025). Parathyroid hormone levels in the paricalcitol group did not change significantly.

CONCLUSION

In this pilot study we investigated the effect of active vitamin D in PD patients. We found no specific benefit of active vitamin D₃ in vitamin D₃-sufficient PD patients. Additional studies in preferably incident patients, with an adequate PTH suppression in the intervention groups and during a longer period, are required to test the beneficial effects of active vitamin D₃ over no treatment and to investigate whether in 25(OH)D₃-deficient PD patients the type of active vitamin D₃ matters.

Peritoneal Membrane Preservation

Peritoneal dialysis (PD) is a successfully used method for renal replacement therapy. However, long-term PD may be associated with peritoneal fibrosis and ultrafiltration failure. The key factors linked to their appearance are repeated episodes of inflammation associated with peritonitis and long-term exposure to bioincompatible PD fluids. Different strategies have been proposed to preserve the peritoneal membrane. This article reviews the functional and structural alterations related to PD and strategies whereby we may prevent them to preserve the peritoneal membrane. The use of new, more biocompatible, PD solutions is promising, although further morphologic studies in patients using these solutions are needed. Blockade of the renin-angiotensin-aldosterone system appears to be efficacious and strongly should be considered. Other agents have been proven in experimental studies, but most of them have not yet been tested appropriately in human beings.

Vitamin D Enhances Alveolar Development in Antenatal Lipopolysaccharide-Treated Rats through the Suppression of Interferon-γ Production

Bronchopulmonary dysplasia (BPD) is characterized by the premature arrest of alveolar development. Antenatal exposure to inflammation inhibits lung morphogenesis, thereby increasing the risk for the development of BPD. Here, we investigated whether vitamin D (VitD) enhances alveolar development in antenatal lipopolysaccharide (LPS)-treated rats, which is a model for BPD. We used an established animal model of BPD, and random assignment to the control group, LPS group, or LPS with VitD group. Levels of interferon (IFN)-γ and interleukin-4 were detected by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay. IFN-γ producing CD8+ T cells were assessed by flow cytometry, and the methylation status of the VitD-response element (VDRE) was analyzed by bisulfite sequencing PCR. 25-hydroxyvitamin D levels were measured by liquid chromatography tandem mass spectrometry in maternal serum samples collected from 86 pregnant women in a prospective birth cohort enrolled from 2012 to 2013. Our results showed that VitD effectively alleviated the simplification of the lung alveolar structure in BPD rats and suppressed LPS-induced IFN-γ expression in the lung and spleen tissues. Further investigation revealed that VitD suppressed IFN-γ production in CD8+ T cells. Specifically, VitD increased the methylation percentage of the VDRE in the IFN-γ-promoter region and suppressed LPS-induced expression of IFN-γ. Additionally, we observed an association between maternal VitD exposure during pregnancy and neonatal IFN-γ levels in a prospective birth cohort, with a trend similar to that observed in the animal model. Our data suggested that supplementation of VitD could suppress IFN-γ production, resulting in improved alveolar development in an LPS-induced BPD rat model.

Vitamin D Receptor: A Novel Therapeutic Target for Kidney Diseases

BACKGROUND

Kidney disease is a serious problem that adversely affects human health, but critical knowledge is lacking on how to effectively treat established chronic kidney disease. Mounting evidence from animal and clinical studies has suggested that Vitamin D Receptor (VDR) activation has beneficial effects on various renal diseases.

METHODS

A structured search of published research literature regarding VDR structure and function, VDR in various renal diseases (e.g., IgA nephropathy, idiopathic nephrotic syndrome, renal cell carcinoma, diabetic nephropathy, lupus nephritis) and therapies targeting VDR was performed for several databases.

RESULT

Included in this study are the results from 177 published research articles. Evidence from these papers indicates that VDR activation is involved in the protection against renal injury in kidney diseases by a variety of mechanisms, including suppression of RAS activation, anti-inflammation, inhibiting renal fibrogenesis, restoring mitochondrial function, suppression of autoimmunity and renal cell apoptosis.

CONCLUSION

VDR offers an attractive druggable target for renal diseases. Increasing our understanding of VDR in the kidney is a fertile area of research and may provide effective weapons in the fight against kidney diseases.

Alternative Oral Agents in Prophylaxis and Therapy of Uterine Fibroids-An Up-to-Date Review

Uterine fibroids (UFs) are the most common tumors of the female genital tract. The effect of UFs on the quality of life and the overall cost of treatment are significant issues worldwide. Tumor size and location are the two specific factors which influence the occurrence of symptoms, the need for, and method of, treatment (some tumors require surgery while some can be treated with selected drugs). Primary prevention and treatment of early UF disease are worthy goals that might have a great impact on health care systems. Several treatments and prophylactic methods can be used in this endeavor. This publication presents current data about lesser-known substances which may have a beneficial effect on the treatment or prophylaxis of UFs and can be administered orally, serving as an alternative to (or complement of) surgery or selective progesterone receptor modulators (SPRMs). Early prevention and treatment of UFs in women from high-risk groups should be our priority. Innovative forms of UF management are under intensive investigation and may be promising options in the near future. Many of them evaluated vitamin D, paricalcitol, epigallocatechin gallate (EGCG), elagolix, aromatase inhibitors (AIs), and cabergoline and deemed them to be safe and effective. The next step in such projects should be properly constructed randomized control trials (RCTs), carried out by successive phases.

Experimental Autoimmune Encephalomyelitis Is Successfully Controlled by Epicutaneous Administration of MOG Plus Vitamin D Analog

Multiple sclerosis (MS) is an inflammatory and demyelinating disorder of the central nervous system (CNS). Experimental autoimmune encephalomyelitis (EAE) has been widely employed to evaluate new strategies to control MS, including procedures to induce immunological tolerance. Considering that skin exposure to protein antigens can induce tolerance and that vitamin D analogs conserve immunomodulatory potential and are less toxic, we investigated the efficacy of epicutaneous application of a myelin oligodendrocyte glycoprotein peptide (MOG_35–55) associated with paricalcitol (PARI) on EAE development. Three and 11 days after EAE induction, C57BL/6 mice were treated with an occlusive patch containing MOG plus PARI. Clinical parameters were daily assessed, whereas immunological and histological evaluations were performed during the acute EAE phase. MOG and MOG + PARI significantly controlled disease development reducing weight loss and clinical score. Moreover, MOG and MOG + PARI reduced the inflammatory process and preserved the myelin sheath in the CNS. High percentages of Foxp3⁺ regulatory T cells (Tregs) and lower MHCII fluorescence intensity in dendritic cells in draining lymph nodes were concomitantly observed. MOG + PARI association was, however, more efficient being able to reduce disease incidence and clinical scores more significantly than MOG or PARI alone. This experimental group also displayed a higher ratio between mRNA expression for Foxp3 and RORc and a higher percentage of Foxp3⁺ cells in the CNS. Modulation of activation markers observed in microglial cells eluted from EAE treated mice were confirmed by in vitro studies with the BV-2 microglial cell line. The results show that MOG + PARI association applied by an epicutaneous route controlled EAE development. Protective involved mechanisms include mainly a higher proportion of Tregs and also a direct immunomodulatory effect of PARI on microglial cells.

Immunity and Fibrogenesis: The Role of Th17/IL-17 Axis in HBV and HCV-induced Chronic Hepatitis and Progression to Cirrhosis

Cirrhosis is a common final pathway for most chronic liver diseases; representing an increasing burden worldwide and is associated with increased morbidity and mortality. Current evidence has shown that, after an initial injury, the immune response has a significant participation in the ongoing damage, and progression from chronic viral hepatitis (CVH) to cirrhosis, driving the activation and maintenance of main fibrogenic pathways. Among immune deregulations, those related to the subtype 17 of T helper lymphocytes (Th17)/interleukin-17 (IL-17) axis have been recognized as key immunopathological and prognostic elements in patients with CVH. The Th17/IL-17 axis has been found involved in several points of fibrogenesis chain from the activation of stellate cells, increased expression of profibrotic factors as TGF-β, promotion of the myofibroblastic or epithelial–mesenchymal transition, stimulation of the synthesis of collagen, and induction of imbalance between matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). It also promotes the recruitment of inflammatory cells and increases the expression of proinflammatory cytokines such as IL-6 and IL-23. So, the Th17/IL-17 axis is simultaneously the fuel and the flame of a sustained proinflammatory and profibrotic environment. This work aims to present the immunopathologic and prognostic role of the Th17/IL-17 axis and related pathways in fibrogenesis and progression to cirrhosis in patients with liver disease due to hepatitis B virus (HBV) and hepatitis C virus (HCV).

Sensitive and non-invasive method for the in vivo analysis of membrane permeability in small animals

Tissue membranes are boundaries that isolate organs or cavities in the body. These semi-permeable membranes are responsible for passive protection that acts through the regulation of nutrient absorption, secretion and filtration of small molecules. These functions could be altered as a consequence of inflammation or trauma, which in turn could lead to changes in permeability, allowing the entrance of toxins, antigens, proteins or facilitating the spread of tumors. Membrane permeability therefore plays an important role in numerous diseases. However, current experimental techniques that are available to quantify membrane permeability in small animals have limited precision and temporal specificity. Improvements in such measurements would lead to a deeper understanding of disease pathogenesis and this may accelerate the development of specific therapies. The study reported here concerns the efficacy of a novel, non-invasive imaging analysis-based measurement method that significantly improves the quantification of tissue membrane permeability in small animals, while at the same time mitigating the adverse effects experienced by the animals under study.

Biomarker research to improve clinical outcomes of peritoneal dialysis: consensus of the European Training and Research in Peritoneal Dialysis (EuTRiPD) network

Peritoneal dialysis (PD) therapy substantially requires biomarkers as tools to identify patients who are at the highest risk for PD-related complications and to guide personalized interventions that may improve clinical outcome in the individual patient. In this consensus article, members of the European Training and Research in Peritoneal Dialysis Network (EuTRiPD) review the current status of biomarker research in PD and suggest a selection of biomarkers that can be relevant to the care of PD patients and that are directly accessible in PD effluents. Currently used biomarkers such as interleukin-6, interleukin-8, ex vivo-stimulated interleukin-6 release, cancer antigen-125, and advanced oxidation protein products that were collected through a Delphi procedure were first triaged for inclusion as surrogate endpoints in a clinical trial. Next, novel biomarkers were selected as promising candidates for proof-of-concept studies and were differentiated into inflammation signatures (including interleukin-17, M₁/M₂ macrophages, and regulatory T cell/T helper 17), mesothelial-to-mesenchymal transition signatures (including microRNA-21 and microRNA-31), and signatures for senescence and inadequate cellular stress responses. Finally, the need for defining pathogen-specific immune fingerprints and phenotype-associated molecular signatures utilizing effluents from the clinical cohorts of PD patients and "omics" technologies and bioinformatics-biostatistics in future joint-research efforts was expressed. Biomarker research in PD offers the potential to develop valuable tools for improving patient management. However, for all biomarkers discussed in this consensus article, the association of biological rationales with relevant clinical outcomes remains to be rigorously validated in adequately powered, prospective, independent clinical studies.

1,25(OH)2D3 treatment attenuates high glucose‑induced peritoneal epithelial to mesenchymal transition in mice

It has been previously demonstrated that 1,25(OH)2D3 prevents the progression of epithelial to mesenchymal transition (EMT). However, it remains unclear whether 1,25(OH)2D3 has a role in peritoneal EMT stimulated by high glucose (HG) peritoneal dialysis fluid (PDF). The present study was performed to investigate the role of 1,25(OH)2D3 in the progression of EMT in the peritoneal mesothelium. A total of 35 male Kunming mice were randomly assigned into seven groups. In the control group, no diasylate or saline was infused. In the saline group, the mice were intraperitoneally injected with saline every day for 4 weeks. In the vitamin D group, the mice were subjected to intraperitoneal injections of 1 or 5 µg/kg of 1,25(OH)2D3 once weekly (every Monday) for 4 weeks. The peritoneal dialysis (PD) group were intraperitoneally injected with a conventional 4.25% PDF daily for 4 weeks. The vitamin D+PD group were intraperitoneally injected with 4.25% PDF daily and co‑treated with 1 µg/kg or 5 µg/kg 1,25(OH)2D3 once weekly, for 4 weeks. The peritoneal morphology and thickness were assessed by hematoxylin and eosin and Masson's trichrome staining. The peritoneal protein level of EMT markers (α‑smooth muscle actin, fibronectin and E‑cadherin), vitamin D receptor (VDR), B cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X protein, transforming growth factor (TGF)‑β and Smad3 were evaluated by western blot analysis or immunohistochemical staining. Furthermore, apoptosis was assessed using a Caspase‑3 activity assay. The results demonstrated that after 4 weeks of intraperitoneal injections in mice, HG‑PDF decreased the expression of VDR, promoted EMT and apoptosis, and increased the thickness of the peritoneal membrane. However, 1,25(OH)2D3 treatment attenuated HG‑induced EMT and apoptosis, and decreased peritoneal thickness, which may partially occur through inhibition of transforming growth factor TGF‑β/Smad pathways via 1,25(OH)2D3 binding to VDR. The present study demonstrated that 1,25(OH)2D3 attenuated HG‑induced EMT and apoptosis in the peritoneal mesothelium through TGF‑β/Smad pathways. 1,25(OH)2D3 treatment in conjunction with HG dialysate may provide an improved solution to the peritoneal injury in the process of PD.

In situ targeting of dendritic cells sets tolerogenic environment and ameliorates CD4+ T-cell response in the postischemic liver

CD4⁺ T cells recruited to the liver play a key role in the pathogenesis of ischemia/reperfusion (I/R) injury. The mechanism of their activation during alloantigen-independent I/R is not completely understood. We hypothesized that liver-resident dendritic cells (DCs) interact with CD4⁺ T cells in the postischemic liver and that modulation of DCs or T-cell-DC interactions attenuates liver inflammation. In mice, warm hepatic I/R (90/120-240 min) was induced. Tolerogenic DCs were generated in situ by pretreatment of animals with the vitamin D analog paricalcitol. A mAb-CD44 was used for blockade of CD4⁺ T-cell-DC interactions. As shown by 2-photon in vivo microscopy as well as confocal microscopy, CD4⁺ T cells were closely colocalized with DCs in the postischemic liver. Pretreatment with paricalcitol attenuated I/R-induced maturation of DCs (flow cytometry), CD4⁺ T-cell recruitment into the liver (intravital microscopy), and hepatocellular/microvascular damage (intravital microscopy, alanine aminotransferase/aspartate aminotransferase, histology). However, interruption of T-cell-DC interaction increased proinflammatory DC maturation and even enhanced tissue damage. Simultaneous treatment with an anti-CD44mAb completely abolished the beneficial effect of paricalcitol on T-cell migration and tissue injury. Our study demonstrates for the first time that hepatic DCs interact with CD4⁺ T cells in the postischemic liver in vivo; modulation of DCs and/or generation of tolerogenic DCs attenuates intrahepatic CD4⁺ T-cell recruitment and reduces I/R injury; and interruption of CD44-dependent CD4⁺ T-cell-DC interactions enhances tissue injury by preventing the modulatory effect of hepatic DCs on T cells, especially type 1 T helper effector cells. Thus, hepatic DCs are strongly involved in the promotion of CD4⁺ T-cell-dependent postischemic liver inflammation.-Funken, D., Ishikawa-Ankerhold, H., Uhl, B., Lerchenberger, M., Rentsch, M., Mayr, D., Massberg, S., Werner, J., Khandoga, A. In situ targeting of dendritic cells sets tolerogenic environment and ameliorates CD4⁺ T-cell response in the postischemic liver.

Mesothelial-to-mesenchymal transition as a possible therapeutic target in peritoneal metastasis of ovarian cancer

Peritoneal dissemination is the primary metastatic route of ovarian cancer (OvCa), and is often accompanied by the accumulation of ascitic fluid. The peritoneal cavity is lined by mesothelial cells (MCs), which can be converted into carcinoma‐associated fibroblasts (CAFs) through mesothelial‐to‐mesenchymal transition (MMT). Here, we demonstrate that MCs isolated from ascitic fluid (AFMCs) of OvCa patients with peritoneal implants also undergo MMT and promote subcutaneous tumour growth in mice. RNA sequencing of AFMCs revealed that MMT‐related pathways – including transforming growth factor (TGF)‐β signalling – are differentially regulated, and a gene signature was verified in peritoneal implants from OvCa patients. In a mouse model, pre‐induction of MMT resulted in increased peritoneal tumour growth, whereas interfering with the TGF‐β receptor reduced metastasis. MC‐derived CAFs showed activation of Smad‐dependent TGF‐β signalling, which was disrupted in OvCa cells, despite their elevated TGF‐β production. Accordingly, targeting Smad‐dependent signalling in the peritoneal pre‐metastatic niche in mice reduced tumour colonization, suggesting that Smad‐dependent MMT could be crucial in peritoneal carcinomatosis. Together, these results indicate that bidirectional communication between OvCa cells and MC‐derived CAFs, via TGF‐β‐mediated MMT, seems to be crucial to form a suitable metastatic niche. We suggest MMT as a possible target for therapeutic intervention and a potential source of biomarkers for improving OvCa diagnosis and/or prognosis. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Is there such a thing as biocompatible peritoneal dialysis fluid?

Introduction of the so-called biocompatible peritoneal dialysis (PD) fluids was based on a large body of experimental evidence and various clinical trials suggesting important clinical benefits. Of these, until now, only preservation of residual renal function-likely due to lower glucose degradation product load and, in case of icodextrin, improved fluid and blood pressure control-have consistently been proven, whereas the impact on important clinical endpoints such as infectious complications, preservation of PD membrane transport function, and patient outcome, are still debated. In view of the high morbidity and mortality rates of PD patients, novel approaches are warranted and comprise the search for alternative osmotic agents and enrichment of PD fluids with specific pharmacologic agents, such as alanyl-glutamine, potentially counteracting local but also systemic sequelae of uremia and PD.

Novel CD8+ T-Cell Subsets Demonstrating Plasticity in Patients with Inflammatory Bowel Disease

BACKGROUND

Distinct CD8+ T-cell subsets such as interleukin-17-expressing Tc17 and Foxp3-expressing Tcreg are functionally similar to CD4+ T cells. Though CD4+ T cells are dysregulated in patients with inflammatory bowel disease (IBD), CD8+ T cells are not well investigated. Vitamin D is an environmental factor which influences T-cell subsets. We assessed the prevalence of CD8+ T-cell subsets among peripheral blood mononuclear cells (PBMC) and lamina propria mononuclear cells (LPMC) of patients with Crohn's disease, patients with ulcerative colitis, and healthy controls. We then tested the effect of 1α,25-dihydroxyvitamin D3 on CD8+ T-cell subsets.

METHODS

A total of 73 patients with Crohn's disease, 49 patients with ulcerative colitis, and 47 healthy controls were studied. LPMC or PBMC were isolated and flow cytometry was performed. CD3+ T cells, isolated from PBMC, were cultured with or without 1α,25-dihydroxyvitamin D3, before flow cytometry.

RESULTS

In LPMC, the prevalence of Tcreg was higher in patients with IBD (P < 0.05), whereas Tc17 were higher in patients with ulcerative colitis compared with patients with Crohn's disease and healthy controls (P < 0.05). In PBMC, both Tcreg and Tc17 were higher in patients with IBD (P < 0.01). Double-expressing interferon-γ+ interleukin-17+ and Foxp3+ interleukin-17+ CD8+ T cells were also identified indicating possible CD8+ plasticity. 1α,25-dihydroxyvitamin D3 decreased interferon-γ-expressing Tc1 (P < 0.05), but had no effect on Tc17 or Tcreg.

CONCLUSIONS

The prevalence of novel CD8+ T-cell subsets is altered in patients with IBD. Double-expressing cells indicate plasticity and were identified in patients with IBD. Vitamin D may have a limited effect on CD8+ T cells by decreasing interferon-γ expression.

Immune-Regulatory Molecule CD69 Controls Peritoneal Fibrosis

Patients with ESRD undergoing peritoneal dialysis develop progressive peritoneal fibrosis, which may lead to technique failure. Recent data point to Th17-mediated inflammation as a key contributor in peritoneal damage. The leukocyte antigen CD69 modulates the setting and progression of autoimmune and inflammatory diseases by controlling the balance between Th17 and regulatory T cells (Tregs). However, the relevance of CD69 in tissue fibrosis remains largely unknown. Thus, we explored the role of CD69 in fibroproliferative responses using a mouse model of peritoneal fibrosis induced by dialysis fluid exposure under either normal or uremic status. We found that cd69^-/- mice compared with wild-type (WT) mice showed enhanced fibrosis, mesothelial to mesenchymal transition, IL-17 production, and Th17 cell infiltration in response to dialysis fluid treatment. Uremia contributed partially to peritoneal inflammatory and fibrotic responses. Additionally, antibody-mediated CD69 blockade in WT mice mimicked the fibrotic response of cd69^-/- mice. Finally, IL-17 blockade in cd69^-/- mice decreased peritoneal fibrosis to the WT levels, and mixed bone marrow from cd69^-/- and Rag2^-/-_γc^-/- mice transplanted into WT mice reproduced the severity of the response to dialysis fluid observed in cd69^-/- mice, showing that CD69 exerts its regulatory function within the lymphocyte compartment. Overall, our results indicate that CD69 controls tissue fibrosis by regulating Th17-mediated inflammation.

Protective Effects of Paricalcitol on Peritoneal Remodeling during Peritoneal Dialysis

Peritoneal dialysis (PD) is associated with structural and functional alterations of the peritoneal membrane, consisting of fibrosis, angiogenesis, and loss of ultrafiltration capacity. Vitamin D receptor activation (VDRA) plays an important role in mineral metabolism and inflammation, but also antiangiogenic and antifibrotic properties have been reported. Therefore, the effects of active vitamin D treatment on peritoneal function and remodeling were investigated. Rats were either kept naïve to PDF exposure or daily exposed to 10 mL PDF and were treated for five or seven weeks with oral paricalcitol or vehicle control. Non-PDF-exposed rats showed no peritoneal changes upon paricalcitol treatment. Paricalcitol reduced endogenous calcitriol but did not affect mineral homeostasis. However, upon PDF exposure, loss of ultrafiltration capacity ensued which was fully rescued by paricalcitol treatment. Furthermore, PD-induced ECM thickening was significantly reduced and omental PD-induced angiogenesis was less pronounced upon paricalcitol treatment. No effect of paricalcitol treatment on total amount of peritoneal cells, peritoneal leukocyte composition, and epithelial to mesenchymal transition (EMT) was observed. Our data indicates that oral VDRA reduces tissue remodeling during chronic experimental PD and prevents loss of ultrafiltration capacity. Therefore, VDRA is potentially relevant in the prevention of treatment technique failure in PD patients.

A Novel Mouse Model of Peritoneal Dialysis: Combination of Uraemia and Long-Term Exposure to PD Fluid

Different animal models for peritoneal dialysis (PD) have been used in the past decades to develop PD fluids compatible with patient life and to identify markers of peritoneal fibrosis and inflammation. Only few of those studies have taken into account the importance of uraemia-induced alterations at both systemic and peritoneal levels. Moreover, some animal studies which have reported about PD in a uremic setting did not always entirely succeed in terms of uraemia establishment and animal survival. In the present study we induced uraemia in the recently established mouse PD exposure model in order to obtain a more clinically relevant mouse model for kidney patients. This new designed model reflected both the slight thickening of peritoneal membrane induced by uraemia and the significant extracellular matrix deposition due to daily PD fluid instillation. In addition the model offers the opportunity to perform long-term exposure to PD fluids, as it is observed in the clinical setting, and gives the advantage to knock out candidate markers for driving peritoneal inflammatory mechanisms.

Vitamin D can ameliorate chlorhexidine gluconate-induced peritoneal fibrosis and functional deterioration through the inhibition of epithelial-to-mesenchymal transition of mesothelial cells

BACKGROUND

Peritoneal dialysis (PD) can induce fibrosis and functional alterations in PD patients' peritoneal membranes, due to long-term unphysiological dialysate exposure, partially occurring via triggering of epithelial-to-mesenchymal transition (EMT) in peritoneal mesothelial cells (MCs). Vitamin D can ameliorate these negative effects; however, the mechanism remains unexplored. Therefore, we investigated its possible links to MCs EMT inhibition.

METHODS

Peritoneal fibrosis was established in Sprague-Dawley rats by chlorhexidine gluconate (CG) intraperitoneal injection for 21 days, with and without 1α,25(OH)2D3 treatment. Morphological and functional evaluation and western blot analysis of EMT marker were performed upon peritoneum tissue. In vitro study was also performed in a primary human peritoneal MC culture system; MCs were incubated with transforming growth factor-β1 (TGF-β1) in the absence or presence of 1α,25(OH)2D3. EMT marker expression, migration activities, and cytoskeleton redistribution of MCs were determined.

RESULTS

1α,25(OH)2D3 ameliorated CG-induced morphological and functional deterioration in animal model, along with CG-induced upregulation of α-SMA and downregulation of E-cadherin expression. Meanwhile, 1α,25(OH)2D3 also ameliorated TGF-β1-induced decrease in E-cadherin expression, increase in Snai1 and α-SMA expression, intracellular F-actin redistribution, and migration activity in vitro.

CONCLUSION

1α,25(OH)2D3 can ameliorate CG-induced peritoneal fibrosis and attenuate functional deterioration through inhibiting MC EMT.

Paricalcitol Inhibits Aldosterone-Induced Proinflammatory Factors by Modulating Epidermal Growth Factor Receptor Pathway in Cultured Tubular Epithelial Cells

Chronic kidney disease is characterized by Vitamin D deficiency and activation of the renin-angiotensin-aldosterone system. Increasing data show that vitamin D receptor agonists (VDRAs) exert beneficial effects in renal disease and possess anti-inflammatory properties, but the underlying mechanism remains unknown. Emerging evidence suggests that "a disintegrin and metalloproteinase" (ADAM)/epidermal growth factor receptor (EGFR) signalling axis contributes to renal damage. Aldosterone induces EGFR transactivation regulating several processes including cell proliferation and fibrosis. However, data on tubular epithelial cells is scarce. We have found that, in cultured tubular epithelial cells, aldosterone induced EGFR transactivation via TGF-α/ADAM17. Blockade of the TGF-α/ADAM17/EGFR pathway inhibited aldosterone-induced proinflammatory gene upregulation. Moreover, among the potential downstream mechanisms, we found that TGF-α/ADAM17/EGFR inhibition blocked ERK and STAT-1 activation in response to aldosterone. Next, we investigated the involvement of TGF-α/ADAM17/EGFR axis in VDRA anti-inflammatory effects. Preincubation with the VDRA paricalcitol inhibited aldosterone-induced EGFR transactivation, TGF-α/ADAM-17 gene upregulation, and downstream mechanisms, including proinflammatory factors overexpression. In conclusion, our data suggest that the anti-inflammatory actions of paricalcitol in tubular cells could depend on the inhibition of TGF-α/ADAM17/EGFR pathway in response to aldosterone, showing an important mechanism of VDRAs action.

T Helper 17/Regulatory T Cell Balance and Experimental Models of Peritoneal Dialysis-Induced Damage

Fibrosis is a general complication in many diseases. It is the main complication during peritoneal dialysis (PD) treatment, a therapy for renal failure disease. Local inflammation and mesothelial to mesenchymal transition (MMT) are well known key phenomena in peritoneal damage during PD. New data suggest that, in the peritoneal cavity, inflammatory changes may be regulated at least in part by a delicate balance between T helper 17 and regulatory T cells. This paper briefly reviews the implication of the Th17/Treg-axis in fibrotic diseases. Moreover, it compares current evidences described in PD animal experimental models, indicating a loss of Th17/Treg balance (Th17 predominance) leading to peritoneal damage during PD. In addition, considering the new clinical and animal experimental data, new therapeutic strategies to reduce the Th17 response and increase the regulatory T response are proposed. Thus, future goals should be to develop new clinical biomarkers to reverse this immune misbalance and reduce peritoneal fibrosis in PD.