Tacrolimus Modulates TGF-β Signaling to Induce Epithelial-Mesenchymal Transition in Human Renal Proximal Tubule Epithelial Cells

Enhanced eNOS/nitric oxide production by nebivolol interferes with TGF-β1/Smad3 signaling and collagen I deposition in the kidney after prolonged tacrolimus administration

AIMS

Tacrolimus is an effective immunosuppressant commonly used post-transplantation and in certain autoimmune diseases. However, its long-term administration is associated with renal fibrosis through transforming growth factor-beta/suppressor of mother against decapentaplegic (TGF-β/Smad) signaling that could be partly attributed to endothelial dysfunction alongside decreased nitric oxide (NO) release. Our study aimed to investigate the prospective renal anti-fibrotic effect of enhanced NO production by nebivolol against tacrolimus-stimulated TGF-β1/Smad3 signaling.

MATERIALS AND METHODS

To illustrate the proposed mechanism of nebivolol, Nω-nitro-L-arginine methyl ester (L-NAME); nitric oxide synthase inhibitor; was co-administered with nebivolol. Rats were treated for 30 days as control, tacrolimus, tacrolimus/nebivolol, tacrolimus/L-NAME, and tacrolimus/nebivolol/L-NAME groups.

KEY FINDINGS

Our results revealed that renal NO content was reduced in tacrolimus-treated rats, while treatment with tacrolimus/nebivolol enhanced NO content via up-regulated endothelial nitric oxide synthase (eNOS), but down-regulated inducible nitric oxide synthase (iNOS) expression. That participated in the inhibition of TGF-β1/Smad3 signaling induced by tacrolimus, where the addition of L-NAME abolished the defensive effects of nebivolol. Subsequently, the deposition of collagen I and alpha-smooth muscle actin (α-SMA) was retarded by nebivolol, emphasized by reduced Masson's trichrome staining. In accordance, there was a strong negative correlation between eNOS and both TGF-β1 and collagen I protein expression. The protective effects of nebivolol were further confirmed by the improvement in kidney function biomarkers and histological features.

SIGNIFICANCE

It can be suggested that treatment with nebivolol along with tacrolimus could effectively suppress renal TGF-β1/Smad3 fibrotic signaling via the enhancement of endothelial NO production, thus curbing renal fibrosis development.

Targeting CXCR2 ameliorated tacrolimus-induced nephrotoxicity by alleviating overactivation of PI3K/AKT/mTOR pathway and calcium overload

OBJECTIVES

The purposes of this study were to (i) verify the role of CXCR2 in tacrolimus-induced nephrotoxicity, (ii) explore the specific mechanism of CXCR2-mediated tacrolimus nephrotoxicity, and (iii) target the antagonism of CXCR2 and provide a potential target for the treatment of tacrolimus-induced nephrotoxicity in children.

METHODS

CXCR2 knockout (CXCR2-KO) mice were used to evaluate the role of CXCR2 in tacrolimus-induced nephrotoxicity. Wistar rats were used to explore the underlying mechanism.

RESULTS

In the knockout mice, compared with N-WT group, the renal function index was deteriorative (P < 0.01), the degree of renal fibrosis was aggravated (P < 0.01), the pathological expression of E-cadherin (P < 0.01) and α-SMA (P < 0.01) were occurred in T-WT group. Inversely, compared with T-WT group, the above indicators were improved in T-KO group (P < 0.01). In wistar rats, compared with N group, the renal function index was deteriorative (P < 0.05 or P < 0.01), fibrosis and calcium overload occurred (P < 0.01), CXCL2-CXCR2 was activated (P < 0.05), and meanwhile PI3K/AKT/mTOR pathway was activated (P < 0.05 or P < 0.01) in T group. Inversely, compared with T group, the above indicators were reversed in C group (P < 0.05 or P < 0.01).

CONCLUSION

The present study was firstly to report that CXCL2-CXCR2 activated PI3K/AKT/mTOR pathway and calcium overload in tacrolimus-induced nephrotoxicity, and targeting CXCR2 could inhibit the progression of tacrolimus-induced nephrotoxicity.

The protective effect of 1400W against ischaemia and reperfusion injury is countered by transient medullary kidney endothelial dysregulation

Renal ischaemia and reperfusion (I/R) is caused by a sudden temporary impairment of the blood flow. I/R is a prevalent cause of acute kidney injury. As nitric oxide generated by inducible nitric oxide synthase (iNOS) has detrimental effects during I/R, the pharmacological blockade of iNOS has been proposed as a potential strategy to prevent I/R injury. The aim of this study was to improve the understanding of 1400W (an iNOS inhibitor) on renal I/R as a pharmacological strategy against kidney disease. BALB/c mice received 30 min of bilateral ischaemia, followed by 48 h or 28 days of reperfusion. Vehicle or 1400W (10 mg/kg) was administered 30 min before inducing ischaemia. We found that after 48 h of reperfusion 1400W decreased the serum creatinine, blood urea nitrogen, neutrophil gelatinase-associated lipocalin and proliferating cell nuclear antigen 3 in the I/R animals. Unexpectedly, we observed mRNA upregulation of genes involved in kidney injury, cell-cycle arrest, inflammation, mesenchymal transition and endothelial activation in the renal medulla of sham animals treated with 1400W. We also explored if 1400W promoted chronic kidney dysfunction 28 days after I/R and did not find significant alterations in renal function, fibrosis, blood pressure or mortality. The results provide evidence that 1400W may have adverse effects in the renal medulla. Importantly, our data point to 1400W-induced endothelial dysfunction, establishing therapeutic limitations for its use. KEY POINTS: Acute kidney injury is a global health problem associated with high morbidity and mortality. The pharmacological blockade of inducible nitric oxide synthase (iNOS) has been proposed as a potential strategy to prevent AKI induced by ischaemia and reperfusion (I/R). Our main finding is that 1400W, a selective and irreversible iNOS inhibitor with low toxicity that is proposed as a therapeutic strategy to prevent kidney I/R injury, produces aberrant gene expression in the medulla associated to tissue injury, cell cycle arrest, inflammation, mesenchymal transition and endothelial activation. The negative effect of 1400W observed in the renal medulla at 48 h from drug administration, is transient as it did not translate into a chronic kidney disease condition.

Exploration of the mechanism of NORAD activation of TGF-β1/Smad3 through miR-136-5p and promotion of tacrolimus-induced renal fibrosis

BACKGROUND

Tacrolimus is a potent immunosuppressant, but has various side effects, with nephrotoxicity being the most common. Renal fibrosis is an important process of tacrolimus nephrotoxicity. Therefore, it is important to identify the factors that contribute to renal fibrosis after tacrolimus nephrotoxicity, and control its development.

METHODS

The present study aims to determine whether tacrolimus may speed up the course of renal fibrosis by upregulating noncoding RNA activated by DNA damage (NORAD) to compete with miR-136-5p, and activating the TGF-β1/Smad3 pathway. Furthermore, in vivo rat models and in vitro cell models were established. Then, the expression levels of NORAD and miR-136-5p were determined by RT-qPCR, while the expression of the TGF-β1/Smad3 pathway was determined by western blot and RT-qPCR. In order to investigate the interaction between NORAD and miR-136-5p, as well as miR-136-5p and SYK, two luciferase reporters were employed. The renal fibrosis of mice was observed using Masson and PAS staining. The expression of inflammatory factors IL-1, IL-6, MCP-1 and TNF-α was detected by ELISA.

RESULTS

In the in vitro experiments, NORAD was upregulated, while miR-136-5p was downregulated after tacrolimus induction. The expression of the TGF-β1/Smad3 pathway correspondingly changed after the induction by tacrolimus. In the in vivo experiments, the expression of NORAD and miR-136-5p, and the trend for renal fibrosis were consistent with the results in the in vitro experiments. Furthermore, the inflammatory factors correspondingly changed with the severity of renal fibrosis. Moreover, the expression trend of the TGF-β1/Smad3 pathway in tacrolimus-induced rats was consistent with that in the in vitro experiments.

CONCLUSION

Through in vitro and in vivo experiments, the present study was able to successfully prove that tacrolimus upregulates NORAD to compete with miR-136-5p, resulting in a decrease in miR-136-5p expression, which in turn activates the TGF-β1/smad3 pathway, and finally induces the aggravation of renal fibrosis.

A multi-omics investigation of tacrolimus off-target effects on a proximal tubule cell-line

INTRODUCTION

Tacrolimus, an immunosuppressive drug prescribed to a majority of organ transplant recipients is nephrotoxic, through still unclear mechanisms. This study on a lineage of proximal tubular cells using a multi-omics approach aims to detect off-target pathways modulated by tacrolimus that can explain its nephrotoxicity.

METHODS

LLC-PK1 cells were exposed to 5µM of tacrolimus for 24h in order to saturate its therapeutic target FKBP12 and other high-affine FKBPs and favour its binding to less affine targets. Intracellular proteins and metabolites, and extracellular metabolites were extracted and analysed by LC-MS/MS. The transcriptional expression of the dysregulated proteins PCK-1, as well as of the other gluconeogenesis-limiting enzymes FBP1 and FBP2, was measured using RT-qPCR. Cell viability with this concentration of tacrolimus was further checked until 72h.

RESULTS

In our cell model of acute exposure to a high concentration of tacrolimus, different metabolic pathways were impacted including those of arginine (e.g., citrulline, ornithine) (p<0.0001), amino acids (e.g., valine, isoleucine, aspartic acid) (p<0.0001) and pyrimidine (p<0.01). In addition, it induced oxidative stress (p<0.01) as shown by a decrease in total cell glutathione quantity. It impacted cell energy through an increase in Krebs cycle intermediates (e.g., citrate, aconitate, fumarate) (p<0.01) and down-regulation of PCK-1 (p<0.05) and FPB1 (p<0.01), which are key enzymes in gluconeogenesis and acid-base balance control.

DISCUSSION

The variations found using a multi-omics pharmacological approach clearly point towards a dysregulation of energy production and decreased gluconeogenesis, a hallmark of chronic kidney disease which may also be an important toxicity pathways of tacrolimus.

Tacrolimus induces fibroblast-to-myofibroblast transition via a TGF-β-dependent mechanism to contribute to renal fibrosis

Use of immunosuppressant calcineurin inhibitors (CNIs) is limited by irreversible kidney damage, hallmarked by renal fibrosis. CNIs directly damage many renal cell types. Given the diverse renal cell populations, additional targeted cell types and signaling mechanisms warrant further investigation. We hypothesized that fibroblasts contribute to CNI-induced renal fibrosis and propagate profibrotic effects via the transforming growth factor-β (TGF-β)/Smad signaling axis. To test this, kidney damage-resistant mice (C57BL/6) received tacrolimus (10 mg/kg) or vehicle for 21 days. Renal damage markers and signaling mediators were assessed. To investigate their role in renal damage, mouse renal fibroblasts were exposed to tacrolimus (1 nM) or vehicle for 24 h. Morphological and functional changes in addition to downstream signaling events were assessed. Tacrolimus-treated kidneys displayed evidence of renal fibrosis. Moreover, α-smooth muscle actin expression was significantly increased, suggesting the presence of fibroblast activation. TGF-β receptor activation and downstream Smad2/3 signaling were also upregulated. Consistent with in vivo findings, tacrolimus-treated renal fibroblasts displayed a phenotypic switch known as fibroblast-to-myofibroblast transition (FMT), as α-smooth muscle actin, actin stress fibers, cell motility, and collagen type IV expression were significantly increased. These findings were accompanied by concomitant induction of TGF-β signaling. Pharmacological inhibition of the downstream TGF-β effector Smad3 attenuated tacrolimus-induced phenotypic changes. Collectively, these findings suggest that 1) tacrolimus inhibits the calcineurin/nuclear factor of activated T cells axis while inducing TGF-β1 ligand secretion and receptor activation in renal fibroblasts; 2) aberrant TGF-β receptor activation stimulates Smad-mediated production of myofibroblast markers, notable features of FMT; and 3) FMT contributes to extracellular matrix expansion in tacrolimus-induced renal fibrosis. These results incorporate renal fibroblasts into the growing list of CNI-targeted cell types and identify renal FMT as a process mediated via a TGF-β-dependent mechanism.NEW & NOTEWORTHY Renal fibrosis, a detrimental feature of irreversible kidney damage, remains a sinister consequence of long-term calcineurin inhibitor (CNI) immunosuppressive therapy. Our study not only incorporates renal fibroblasts into the growing list of cell types negatively impacted by CNIs but also identifies renal fibroblast-to-myofibroblast transition as a process mediated via a TGF-β-dependent mechanism. This insight will direct future studies investigating the feasibility of inhibiting TGF-β signaling to maintain CNI-mediated immunosuppression while ultimately preserving kidney health.

Tacrolimus induces a pro-fibrotic response in donor-derived human proximal tubule cells dependent on common variants of the CYP3A5 and ABCB1 genes

BACKGROUND

Common genetic variants of the enzymes and efflux pump involved in tacrolimus disposition have been associated with calcineurin inhibitor nephrotoxicity, but their importance is unclear because of the multifactorial background of renal fibrosis. This study explores the pro-fibrotic response of tacrolimus exposure in relation to the differential capacity for tacrolimus metabolism in proximal tubule cells (PTCs) with a variable (pharmaco)genetic background.

METHODS

PTCs were obtained from protocol allograft biopsies with different combinations of CYP3A5 and ABCB1 variants and were incubated with tacrolimus within the concentration range found in vivo. Gene and protein expression, CYP3A5 and P-glycoprotein function, and tacrolimus metabolites were measured in PTC. Connective tissue growth factor (CTGF) expression was assessed in protocol biopsies of kidney allograft recipients.

RESULTS

PTCs produce CTGF in response to escalating tacrolimus exposure, which is approximately 2-fold higher in cells with the CYP3A5*1 and ABCB1 TT combination in vitro. Increasing tacrolimus exposure results in relative higher generation of the main tacrolimus metabolite {13-O-desmethyl tacrolimus [M1]} in cells with this same genetic background. Protocol biopsies show a larger increase in in vivo CTGF tissue expression over time in TT vs. CC/CT but was not affected by the CYP3A5 genotype.

CONCLUSIONS

Tacrolimus exposure induces a pro-fibrotic response in a PTC model in function of the donor pharmacogenetic background associated with tacrolimus metabolism. This finding provides a mechanistic insight into the nephrotoxicity associated with tacrolimus treatment and offers opportunities for a tailored immunosuppressive treatment.

Boosting the anti-inflammatory effect of self-assembled hybrid lecithin-chitosan nanoparticles via hybridization with gold nanoparticles for the treatment of psoriasis: elemental mapping and in vivo modeling

Gold nanoparticles are a promising drug delivery system for treatment of inflammatory skin conditions, including psoriasis, due to their small size and anti-inflammatory properties. The aim of this study was to conjugate gold nanoparticles with anti-psoriatic formulations that previously showed successful results in the treatment of psoriasis (tacrolimus-loaded chitosan nanoparticles and lecithin-chitosan nanoparticles) by virtue of their surface charges, then examine whether the hybridization with gold nanoparticles would enhance the anti-psoriatic efficacy in vivo. Successful formation of gold nanoparticles was examined by elemental mapping and selected area electron diffraction (SAED). Hybrid conjugates were examined in terms of particle size and zeta potential by dynamic light scattering (DLS). Morphological features were captured by transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis was conducted, as well. All characterization was conducted for the conjugated nanoparticles and compared with their bare counterparts. The in vivo results on imiquimod (IMQ)-induced mouse model showed promising anti-psoriatic effects upon application of gold conjugated tacrolimus-loaded lecithin-chitosan hybrid nanoparticles with a significant difference from the bare hybrid nanoparticles in some of the inflammatory markers. The anti-inflammatory effect of the gold conjugate was also evident by a lower spleen to body weight ratio and a better histopathological skin condition compared to other tested formulations.

The mTOR inhibitor everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats

AIMS

Tacrolimus-a widely used immunosuppressant to prevent allograft rejection after organ transplantation-is nephrotoxic, increasing the risk of kidney injury accompanied by kidney fibrosis. The mammalian target of rapamycin (mTOR) inhibitor, everolimus, is an immunosuppressant used together with tacrolimus. Although mTOR signaling inhibition has been demonstrated to exhibit antifibrotic effects, the efficacy of everolimus against tacrolimus-induced kidney fibrosis has not been explored. Therefore, we evaluated the protective effects of everolimus against tacrolimus-induced kidney fibrosis.

MAIN METHODS

To assess antifibrotic effect of everolimus against tacrolimus-induced kidney fibrosis, male Wistar rats were subcutaneously administered vehicle or tacrolimus (5 mg/kg per day) and/or everolimus (0.2 mg/kg per day) for 2 weeks after bilateral renal ischemia for 45 min. The antifibrotic effect of everolimus was also assessed using rat kidney fibroblast cell line (NRK-49F).

KEY FINDINGS

Tacrolimus administration increased predominant profibrotic cytokine transforming growth factor-β (TGF-β) and fibroblast activation marker α-smooth muscle actin (α-SMA) expression and promoted the infiltration of macrophages in the kidney cortex, resulting in renal interstitial fibrosis in rats. Tacrolimus increased serum creatinine, blood urea nitrogen, kidney injury molecule-1 (KIM-1), and kidney injuries, such as tubular dilation, vacuolization, and glomerular atrophy. Everolimus administration attenuated tacrolimus-induced kidney fibrosis and the associated abnormalities. Everolimus strongly suppressed TGF-β-induced kidney fibroblast activation and extracellular matrix protein expression by the mTOR signaling inhibition.

SIGNIFICANCE

We demonstrated that everolimus attenuates tacrolimus-induced renal interstitial fibrosis in rats. Owing to its protective effect against tacrolimus-induced kidney fibrosis, everolimus may be useful when used concomitantly with tacrolimus.

Self-assembled tacrolimus-loaded lecithin-chitosan hybrid nanoparticles for in vivo management of psoriasis

Lecithin-chitosan hybrid nanoparticles are emerging as a promising nanocarrier for topical drug delivery. They could achieve a maximized encapsulation of hydrophobic drugs due to the lipophilic nature of lecithin that comprises the core while enhancing retention in the upper skin layers using the positively charged polymeric coat of chitosan. The aim of this study is to incorporate tacrolimus; a hydrophobic anti-proliferative agent into lecithin chitosan hybrid nanoparticles by ethanolic injection technique using a suitable co-solvent to enhance encapsulation of the drug and allow a satisfactory release profile in the upper skin layers. Tacrolimus was successfully incorporated into the synthesized particles using olive oil and Tween 80 as co-solvents, with particle size (160.9 nm ± 15.9 and 118.7 nm ± 13.3, respectively) and EE (88.27% ± 4.3 and 66.72% ± 1.8, respectively). The in vitro drug release profile showed a faster release pattern for the Tween 80-containing particles over a 48-hour period (79.98% vs. 35.57%), hence, were selected for further investigation. The hybrid nanoparticles achieved significantly higher skin deposition than the marketed product (63.51% vs. 34.07%) through a 24-hour time interval, particularly, to the stratum corneum and epidermis skin layers. The in vivo results on IMQ-mouse models revealed superior anti-psoriatic efficacy of the synthesized nanoparticles in comparison to the marketed product in terms of visual observation of the skin condition, PASI score and histopathological examination of autopsy skin samples. Additionally, the in vivo drug deposition showed superior skin deposition of the nanoparticles compared to the marketed product (74.9% vs. 13.4%).

Tacrolimus-loaded chitosan nanoparticles for enhanced skin deposition and management of plaque psoriasis

Tacrolimus is a natural macrolide that exhibits an anti-proliferative action by T-lymphocytic cells inhibition. Hence, it was tested as a potential topical treatment to improve and control psoriatic plaques. In this study, for the first time the lipophilic tacrolimus in chitosan nanoparticles was used to achieve the desired response and dermal retention of the drug using a modified ionic gelation technique. The hydrophobic drug, tacrolimus, was successfully encapsulated into the synthesized positively-charged particles (140.8 nm ± 50.0) and EE of (65.5% ± 1.3). Local skin deposition of the drug was significantly enhanced with 82.0% ± 0.6 of the drug retained in the skin compared to 34.0% ± 0.9 from tarolimus® ointment. An outstanding response to the prepared formula was the enhanced hair growth rate in the treated animals, which can be considered an excellent sign of the skin recovery from the induced psoriatic plaques after only three days of treatment.

Foremost Concepts in Mechanisms of De Novo Post-Liver Transplantation Malignancy

In liver transplant patients, solid tumors and post-transplant lymphoproliferative disorders (PTLD) have emerged as significant long-term mortality causes. Additionally, it is assumed that de novo malignancy (DNM) after liver transplantation (LT) is the second-leading cause of death after cardiovascular complications. Well-established risk factors for PTLD and solid tumors are calcineurin inhibitors (CNIs), tacrolimus (TAC), and cyclosporine, the cornerstones of all immunosuppressive (IS) therapies used after LT. The loss of immunocompetence facilitated by the host immune system due to prolonged IS therapy leads to cancer development, including in LT patients. Hindering DNA repair mechanisms, promoting tumor cell invasiveness, and hampering apoptosis are critical events in tumorigenesis and tumor growth in LT patients resulting from IS administration. This paper aims to overview the refined mechanisms of IS-induced tumorigenesis after LT and the loss of immunocompetence facilitated by the host immune system due to prolonged IS therapy. In addition, we also discuss in detail the mechanisms of action in different types of IS regimen used after LT, and their putative effect on DNM.

Vernal keratoconjunctivitis: An update

Vernal keratoconjunctivitis (VKC) and atopic keratoconjunctivitis (AKC) are potentially severe and complex disease in its management among the various allergic eye diseases. In this regard, studies clarified the etiopathogenetic mechanisms. The workup should be multidisciplinary. The treatment includes topical and systemic medications with anti-inflammatory and immunosuppressant activity. However, a definition of nationally- and internationally-shared diagnostic protocols would also be needed and validated access to therapeutic options of proven safety and efficacy to avoid the use of galenic preparations, up to now still essential in the management of moderate-severe VKC. Finally, recognizing VKC and AKC, among rare diseases, at a national and international level would be an essential step to allow the management of VKC with adequate timings and settings within the National Health System.

Calcineurin inhibitors: a double-edged sword

Recently, research has directed its interests into identifying molecular pathways implicated in calcineurin inhibitor (CNI)-induced renal fibrosis. An emerging body of studies investigating calcineurin (CnA) activity has identified distinct actions of two main ubiquitously expressed isoforms: CnAα and CnAβ. CNIs have the capacity to inhibit both of these CnA isoforms. In the kidney, CnAα is required for development, whereas CnAβ predominantly modulates the immune response and glomerular hypertrophic signaling powered by activation of the transcription factor, nuclear factor of activated T lymphocytes (NFAT). Interestingly, data have shown that loss of CnAα activity contributes to the expression of profibrotic proteins in the kidney. Although this finding is of great significance, follow-up studies are needed to identify how loss of the CnAα isoform causes progressive renal damage. In addition, it is also necessary to identify downstream mediators of CnAα signaling that assist in upregulation of these profibrotic proteins. The goal of this review is to provide insight into strides taken to close the gap in elucidating CnA isoform-specific mechanisms of CNI-induced renal fibrosis. It is with hope that these contributions will lead to the development of newer generation CNIs that effectively blunt the immune response while circumventing extensive renal damage noted with long-term CNI use.

Sirolimus Prolongs Survival after Living Donor Liver Transplantation for Hepatocellular Carcinoma Beyond Milan Criteria: A Prospective, Randomised, Open-Label, Multicentre Phase 2 Trial

Sirolimus (SRL) has been reported to benefit patients undergoing liver transplantation (LT) for hepatocellular carcinoma (HCC). This study aimed to compare SRL with tacrolimus (TAC) in living-donor LT (LDLT) recipients beyond the Milan criteria. This study was initially designed to enrol 45 recipients who underwent LDLT for HCC beyond the Milan criteria. At 1 month after LT, the patients were randomly assigned to either SRL or TAC-based treatment, with both groups receiving mycophenolate mofetil. The primary outcome was three-year recurrence-free survival (RFS) and the secondary outcome was overall survival (OS). A total of 42 patients completed the study. HCC recurrence occurred in 8 of 22 (36.4%) patients in the SRL group and in 5 of 22 (25%) patients in the TAC group. No differences in RFS and OS were found between the two groups in simple comparison. The type of immunosuppressant remained a nonsignificant factor for recurrence in multivariate analysis; however, SRL significantly prolonged OS (TAC hazard ratio: 15 [1.3–172.85], p = 0.03) after adjusting for alpha-fetoprotein and positron emission tomography standardised uptake value ratio (tumour/background liver). In conclusion, SRL does not decrease HCC recurrence but prolongs OS after LDLT for HCC beyond the Milan criteria.

Destruction of the stem cell Niche, Pathogenesis and Promising Treatment Targets for Primary Scarring Alopecias

The Primary Scarring Alopecias are characterised by the irreversible destruction and fibrosis of hair follicles, leading to permanent and often disfiguring loss of hair. The pathophysiology of these diseases is not well understood. However, follicular-fibrosis and loss of the stem-cell niche appears to be a common theme. This review explores the pathogenesis of primary scarring alopecias, asking what happens to the stem cells of the hair follicle and how they may contribute to the progression of these diseases. Bulge-resident cells are lost (leading to loss of capacity for hair growth) from the follicle either by inflammatory-mediate apoptosis or through epigenetic reprogramming to assume a mesenchymal-like identity. What proportion of bulge cells is lost to which process is unknown and probably differs depending on the individual PCA and its specific inflammatory cell infiltrate. The formation of fibroblast-like cells from follicular stem cells may also mean that the cells of the bulge have a direct role in the pathogenesis. The identification of specific cells involved in the pathogenesis of these diseases could provide unique diagnostic and therapeutic opportunities to prevent disease progression by preventing EMT and specific pro-fibrotic signals.

Tacrolimus ameliorates tubulointerstitial inflammation in diabetic nephropathy via inhibiting the NFATc1/TRPC6 pathway

Tubulointerstitial inflammation is crucial for the progression of diabetic nephropathy (DN), and tubular cells act as a driving force in the inflammatory cascade. Emerging data suggested that tacrolimus (TAC) ameliorates podocyte injury and macrophage infiltration in streptozotocin (STZ) mice. However, the effect of TAC on tubulointerstitial inflammation remains unknown. We found that albuminuria and tubulointerstitial damage improved in db/db mice treated with TAC. Macrophage infiltration and expression of IL‐6, TNF‐α, fibronectin, collagen 1 and cleaved caspase 3 were inhibited as well. In addition, the expression of nuclear factor of activated T cell 1 (NFATc1) and transient receptor potential channel 6 (TRPC6) was up‐regulated in the kidneys of DN patients and correlated with tubular injury and inflammation. The expression of NFATc1 and TRPC6 also increased in the kidneys of db/db mice and HK‐2 cells with high glucose (HG), while TAC inhibited these effects. HG‐induced inflammatory markers and apoptosis were reversed by TAC and NFATc1 siRNA in HK‐2 cells, which was abolished by TRPC6 plasmid. Furthermore, HG‐induced TRPC6 expression was inhibited by NFATc1 siRNA, while NFATc1 nuclear translocation was inhibited by TAC, but was restored by TRPC6 plasmid in HK‐2 cells under HG conditions. These findings suggest that TAC ameliorates tubulointerstitial inflammation in DN through NFATc1/TRPC6 feedback loop.

Development and Evaluation of a Prototype Scratch Apparatus for Wound Assays Adjustable to Different Forces and Substrates

Scratch assays enable the study of the migration process of an injured adherent cell layer in vitro. An apparatus for the reproducible performance of scratch assays and cell harvesting has been developed that meets the requirements for reproducibility in tests as well as easy handling. The entirely autoclavable setup is divided into a sample translation and a scratching system. The translational system is compatible with standard culture dishes and can be modified to adapt to different cell culture systems, while the scratching system can be adjusted according to angle, normal force, shape, and material to adapt to specific questions and demanding substrates. As a result, a fully functional prototype can be presented. This system enables the creation of reproducible and clear scratch edges with a low scratch border roughness within a monolayer of cells. Moreover, the apparatus allows the collection of the migrated cells after scratching for further molecular biological investigations without the need for a second processing step. For comparison, the mechanical properties of manually performed scratch assays are evaluated.

Tacrolimus increases the expression level of the chemokine receptor CXCR2 to promote renal fibrosis progression

Tacrolimus is one of the most used and effective immunosuppressive agents currently available in the clinic; however, its use is limited by nephrotoxicity, which is the main secondary effect of this drug. The mechanisms underlying tacrolimus-induced nephrotoxicity remain unknown. The present study aimed to investigate the mechanism underlying tacrolimus-induced nephrotoxicity and to identify novel potential targets. Masson staining, Sirius red staining and periodic acid-silver methenamine staining were used to observe kidney pathological changes. Immunohistochemical and immunofluorescent analyses were performed to examine the expression levels of vimentin, E-cadherin and α-smooth muscle actin (α-SMA). Transcriptomics and bioinformatics analyses were performed to investigate the nephrotoxicity mechanism induced by tacrolimus using RNA-sequencing, differentially expressed genes identification and annotation, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The present results demonstrated that compared with the normal control group, the tacrolimus nephrotoxicity group exhibited severe renal fibrosis (P<0.05), upregulated vimentin (P<0.01), downregulated E-cadherin (P<0.05) and upregulated α-SMA (P<0.01). Transcriptomics and bioinformatics analyses identified the pathway 'cytokine-cytokine receptor interaction' as the most significantly enriched (P<0.05). Moreover, KEGG pathway enrichment analysis identified that tacrolimus increased the expression levels of chemokine (C-X-C) motif ligand (CXCL)1, CXCL2 and CXCL3 and the chemokine receptor C-X-C chemokine receptor type 2 (CXCR2). Collectively, the present study suggested that tacrolimus increases the level of chemokine receptor CXCR2 to promote renal fibrosis progression, which is one of the potential mechanisms underlying tacrolimus-induced nephrotoxicity.

Clinical prospects of biomarkers for the early detection and/or prediction of organ injury associated with pharmacotherapy

Several biomarkers are used to monitor organ damage caused by drug toxicity. Traditional markers of kidney function, such as serum creatinine and blood urea nitrogen are commonly used to estimate glomerular filtration rate. However, these markers have several limitations including poor specificity and sensitivity. A number of serum and urine biomarkers have recently been described to detect kidney damage caused by drugs such as cisplatin, gentamicin, vancomycin, and tacrolimus. Neutrophil gelatinase-associated lipocalin (NGAL), liver-type fatty acid-binding protein (L-FABP), kidney injury molecule-1 (KIM-1), monocyte chemotactic protein-1 (MCP-1), and cystatin C have been identified as biomarkers for early kidney damage. Hy's Law is widely used as to predict a high risk of severe drug-induced liver injury caused by drugs such as acetaminophen. Recent reports have indicated that glutamate dehydrogenase (GLDH), high-mobility group box 1 (HMGB-1), Keratin-18 (k18), MicroRNA-122 and ornithine carbamoyltransferase (OCT) are more sensitive markers of hepatotoxicity compared to the traditional markers including the blood levels of amiotransferases and total bilirubin. Additionally, the rapid development of proteomic technologies in biofluids and tissue provides a new multi-marker panel, leading to the discovery of more sensitive biomarkers. In this review, an update topics of biomarkers for the detection of kidney or liver injury associated with pharmacotherapy.

Shen-Kang protects against tacrolimus-induced renal injury

BACKGROUND/AIMS

Evidence suggests that Shen-Kang (SK), a traditional Chinese herbal medicine, protects against various types of renal injury. In this study, we evaluated whether SK treatment confers renoprotection in a rat model of chronic tacrolimus (TAC) nephropathy.

METHODS

Rats were treated daily with TAC (1.5mg/kg, subcutaneously) and SK (450 mg/kg, intravenously) for 4 weeks. The effects of SK on TAC-induced renal injury were assessed by measuring renal function, urine albumin excretion, histopathology, inflammatory cell infiltration, expression of profibrotic (transforming growth factor β1 [TGF-β1] and TGF-β inducible gene-h3 [βig-h3]) and proinflammatory cytokines, oxidative stress, and apoptotic cell death.

RESULTS

Administration of SK preserved glomerular integrity (fractional mesangial area and Wilms tumor 1-positive glomeruli), attenuated tubulointerstitial fibrosis, and reduced the number of ectodermal dysplasia 1-positive cells, and this was paralleled by improved urine albumin excretion and renal dysfunction. At the molecular level, SK treatment suppressed expression of TGF-β1/Smad2/3, βig-h3, and proinflammatory cytokines. Oxidative stress and apoptotic cell death were significantly decreased with SK treatment, and apoptosis-related genes were regulated toward cell survival (active caspase-3 and the B-cell lymphoma-2/Bcl2-associated X [Bcl-2/Bax] ratio).

CONCLUSION

SK protects against TAC-induced renal injury.

Activation of BMP Signaling by FKBP12 Ligands Synergizes with Inhibition of CXCR4 to Accelerate Wound Healing

The combination of AMD3100 and low-dose FK506 has been shown to accelerate wound healing in vivo. Although AMD3100 is known to work by releasing hematopoietic stem cells into circulation, the mechanism of FK506 in this setting has remained unknown. In this study, we investigated the activities of FK506 in human cells and a diabetic-rat wound model using a non-immunosuppressive FK506 analog named FKVP. While FKVP was incapable of inhibiting calcineurin, wound-healing enhancement with AMD3100 was unaffected. Further study showed that both FK506 and FKVP activate BMP signaling in multiple cell types through FKBP12 antagonism. Furthermore, selective inhibition of BMP signaling abolished stem cell recruitment and wound-healing enhancement by combination treatment. These results shed new light on the mechanism of action of FK506 in acceleration of wound healing, and raise the possibility that less toxic FKBP ligands such as FKVP can replace FK506 for the treatment of chronic wounds.

The long-term effect of tacrolimus on alkali burn-induced corneal neovascularization and inflammation surpasses that of anti-vascular endothelial growth factor

Purpose

To investigate the effect of tacrolimus in alkali burn-induced corneal neovascularization (NV) and inflammation and to compare with anti-vascular endothelial growth factor (anti-VEGF).

Methods

After corneal alkali-burn, 84 Wistar rats were randomly divided into three groups and received either saline solution or 0.05% tacrolimus (0.5 mg/mL) four times daily, or subconjunctival anti-VEGF injection (0.5 mg/0.05 mL). Corneal NV, opacity and epithelial defects, the status of inflammation, and the levels of proinflammatory and angiogenic cytokines were assessed on Days 3, 7, 14 and 28 post-injury.

Results

Compared with the control, tacrolimus significantly reduced corneal NV on Days 7, 14 and 28 post-injury, and anti-VEGF significantly reduced corneal NV at each assessment. Nevertheless, the tacrolimus group had significantly less corneal NV than the anti-VEGF group on Days 14 and 28. Furthermore, both tacrolimus and anti-VEGF significantly decreased the VEGF-A expression on Days 7 and 14, with no significant difference between the two groups. Moreover, corneal inflammatory response was alleviated, and corneal opacity and epithelial defects were significantly reduced by tacrolimus. Additionally, the expression of IL-1β, IL-6, monocyte chemotactic protein-1, macrophage inflammatory protein-1α and TGF-β were significantly decreased by tacrolimus.

Conclusion

Our findings suggested that 0.05% tacrolimus suspension eye drops effectively reduced alkali burn-induced corneal NV and inflammation, with a better effect than subconjunctival anti-VEGF injections on Days 14 and 28.

Ginsenoside Rg1 Attenuates Cigarette Smoke-Induced Pulmonary Epithelial-Mesenchymal Transition via Inhibition of the TGF-β1/Smad Pathway

Epithelial-mesenchymal transition (EMT) is a process associated with airway remodeling in chronic obstructive pulmonary disease (COPD), which leads to progressive pulmonary destruction. Panax ginseng is a traditional herbal medicine that has been shown to improve pulmonary function and exercise capacity in patients with COPD. Ginsenoside Rg1 is one of the main active components and was shown to inhibit oxidative stress and inflammation. The present study investigated the hypothesis that ginsenoside Rg1 attenuates EMT in COPD rats induced by cigarette smoke (CS) and human bronchial epithelial (HBE) cells exposed to cigarette smoke extract (CSE). Our data showed that CS or CSE exposure increased expression of the mesenchymal marker α-smooth muscle actin (α-SMA) and decreased expression of the epithelial marker epithelial cadherin (E-cad) in both lung tissues and HBE cells, which was markedly suppressed by ginsenoside Rg1. Importantly, CS-induced upregulation of TGF-β1/Smad pathway components, including TGF-β1, TGF-βR1, phospho-Smad2, and phospho-Smad3, was also inhibited by ginsenoside Rg1. Additionally, ginsenoside Rg1 mimicked the effect of SB525334, a TGF-βR1-Smad2/3 inhibitor, on suppression of EMT in CSE-induced HBE cells. Collectively, we concluded that ginsenoside Rg1 alleviates CS-induced pulmonary EMT, in both COPD rats and HBE cells, via inhibition of the TGF-β1/Smad pathway.

Influence of tacrolimus metabolism rate on renal function after solid organ transplantation

The calcineurin inhibitor (CNI) tacrolimus (TAC) is an integral part of the immunosuppressive regimen after solid organ transplantation. Although TAC is very effective in prevention of acute rejection episodes, its highly variable pharmacokinetic and narrow therapeutic window require frequent monitoring of drug levels and dose adjustments. TAC can cause CNI nephrotoxicity even at low blood trough levels (4-6 ng/mL). Thus, other factors besides the TAC trough level might contribute to CNI-related kidney injury. Unfortunately, TAC pharmacokinetic is determined by a whole bunch of parameters. However, for daily clinical routine a simple application strategy is needed. To address this problem, we and others have evaluated a simple calculation method in which the TAC blood trough concentration (C) is divided by the daily dose (D). Fast TAC metabolism (C/D ratio < 1.05) was identified as a potential risk factor for an inferior kidney function after transplantation. In this regard, we recently showed a strong association between fast TAC metabolism and CNI nephrotoxicity as well as BKV infection. Therefore, the TAC C/D ratio may assist transplant clinicians in a simple way to individualize the immunosuppressive regimen.

Hypertension in the Pediatric Kidney Transplant Recipient

Hypertension after kidney transplant is a frequent occurrence in pediatric patients. It is a risk factor for graft loss and contributes to the significant burden of cardiovascular disease (CVD) in this population. The etiology of posttransplant hypertension is multifactorial including donor factors, recipient factors, medications, and lifestyle factors similar to those prevalent in the general population. Ambulatory blood pressure monitoring has emerged as the most reliable method for measuring hypertension in pediatric transplant recipients, and many consider it to be essential in the care of these patients. Recent technological advances including measurement of carotid intima-media thickness, pulse wave velocity, and myocardial strain using specked echocardiography and cardiac magnetic resonance imaging have improved our ability to assess CVD burden. Since hypertension remains underrecognized and inadequately treated, an early diagnosis and an appropriate control should be the focus of therapy to help improve patient and graft survival.