Role of Klotho, an antiaging protein, in pulmonary fibrosis

Serum klotho levels and mortality patterns in frail individuals: unraveling the u-shaped association

BACKGROUND

Frailty, a clinical syndrome intricately linked with the aging process, stands as a harbinger of numerous adverse outcomes, most notably mortality. This study aimed to elucidate the association between serum α-klotho concentration and mortality patterns, including all-cause and cause-specific mortality, in patients with frailty.

METHODS

The study employed Cox proportional hazard models, smoothed curve fitting, and supplementary analyses, encompassing threshold effect analysis, subgroup and sensitivity analyses, to explore the relationship between α-klotho levels and mortality, including all-cause, CVD, and cancer-related mortality.

RESULTS

Among the 2,608 frail individuals (mean age: 60.78 [SD 10.48] years; 59.89% female), the mortality stood at 25.35% during a median follow-up period of 6.95 years. Both unadjusted and adjusted models revealed a significant inverse association between higher serum α-klotho levels and the risk of all-cause and CVD-related mortality ([mean(95% CI) 0.68 (0.55, 0.83)] for all-cause mortality; [mean(95% CI) 0.48 (0.32, 0.74)] for CVD-related mortality, all P for trend < 0.001). Notably, log2-klotho displayed a U-shaped correlation with all-cause mortality and cancer mortality, characterized by thresholds of 9.48 and 9.55, respectively. The robustness of these findings was consistently supported by subgroup and sensitivity analyses.

CONCLUSION

This study unveils a U shaped association between serum α-klotho levels and both all-cause and cancer-related mortality among middle-aged and elderly individuals with frailty in the United States. The identified serum α-klotho thresholds, at 714.8 pg/ml for all-cause mortality and 750.6 pg/ml for cancer-related mortality, hold promise as potential targets for interventions aimed at mitigating the risks of premature death and cancer within this vulnerable population.

Inhibition of EZH2 mitigates peritoneal fibrosis and lipid precipitation in peritoneal mesothelial cells mediated by klotho

BACKGROUND

Peritoneal fibrosis caused by long-term peritoneal dialysis (PD) is the main reason why patients withdraw from PD treatment. Lipid accumulation in the peritoneum was shown to participate in fibrosis, and klotho is a molecule involved in lipid metabolism. GSK343 (enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) inhibitor) has been verified to inhibit epithelial mesenchymal transdifferentiation (EMT) and peritoneal fibrosis, but its related mechanism remains unclear. This study aimed to investigate whether lipid accumulation was involved in the effect of GSK343 and its related mechanism.

MATERIALS AND METHODS

First, the expression of EZH2, klotho and EMT indices in human peritoneal mesothelial cells (HMrSV5) incubated with high glucose (HG) levels was detected. After EZH2 was inhibited by GSK343, Western blot (WB), wound healing and Transwell assays were used to explore the effect of GSK343. EZH2 and klotho expression was also detected. Oil red O and Nile red staining and triglyceride (TG) detection kits were used to detect lipid accumulation. A rescue experiment with small interfering RNA specific for klotho (si-klotho) on the basis of GSK343 was also conducted to verify that GSK343 exerted its effect via klotho. In in vivo experiments, rats were administered GSK343, and the related index was assessed.

RESULTS

In our study, we revealed that the expression of EZH2 was significantly upregulated and klotho was significantly downregulated in HMrSV5 cells induced by high glucose. With the aid of GSK343, we found that lipid deposition caused by HG was significantly decreased. In addition, EMT and fibrosis were also significantly alleviated. Moreover, GSK343 could also restore the downregulation of klotho. To further verify whether klotho mediated the effect of EZH2, a rescue experiment with si-klotho was also conducted. The results showed that si-klotho could counteract the protective effect of GSK343 on high glucose-induced lipid accumulation and fibrosis. In vivo experiments also revealed that GSK343 could relieve peritoneal fibrosis, lipid deposition and EMT by mitigating EZH2 and restoring klotho expression.

CONCLUSIONS

Combining these findings, we found that EZH2 regulated lipid deposition, peritoneal fibrosis, and EMT mediated by klotho. To our knowledge, this is the first study to demonstrate the effect of the EZH2-klotho interaction on peritoneal fibrosis. Hence, EZH2 and klotho could act as potential targets for the treatment of peritoneal fibrosis.

Serum α-Klotho level, lung function, airflow obstruction and inflammatory markers in US adults

Background

α-Klotho is a pleiotropic protein that may have anti-oxidative and anti-inflammatory properties in the lung, but its role in airflow obstruction or lung function is largely unknown.

Methods

This was a cross-sectional study of 6046 adults aged 40-79 years in the US National Health and Nutrition Examination Survey (NHANES) 2007-2012. We used multivariable logistic or linear regression to examine the relation between serum α-Klotho level and airflow obstruction, defined as forced expiratory volume in 1 s (FEV1) <80% of predicted and FEV1/forced vital capacity (FVC) ratio <0.70; FEV1, FVC and FEV1/FVC as percentage of predicted; and inflammatory markers in blood (white blood cell count, eosinophils, neutrophils and C-reactive protein (CRP)).

Results

α-Klotho levels in the second to fourth quartiles (Q2-Q4) were associated with significantly decreased odds of airflow obstruction (adjusted OR for Q2-Q4 versus lowest quartile (Q1) 0.54 (95% CI 0.35-0.81)) in never-smokers and ex-smokers with <10 pack-years of smoking, but not in current smokers or ex-smokers with ≥10 pack-years of smoking. In all participants, each unit increment in log10-transformed α-Klotho level was significantly associated with 5.0% higher FEV1 % pred and 3.7% higher FVC % pred. Higher α-Klotho was also associated with lower eosinophils, neutrophils and CRP in participants both with and without airflow obstruction.

Conclusions

Higher serum α-Klotho is associated with lower inflammatory markers and higher lung function in adults with and without airflow obstruction, and with decreased odds of airflow obstruction in never-smokers and ex-smokers with <10 pack-years of smoking. Further studies are warranted to replicate our findings and evaluate underlying mechanisms.

High glucose dialysate-induced peritoneal fibrosis: Pathophysiology, underlying mechanisms and potential therapeutic strategies

Peritoneal dialysis is an efficient renal replacement therapy for patients with end-stage kidney disease. However, continuous exposure of the peritoneal membrane to dialysate frequently leads to peritoneal fibrosis, which alters the function of the peritoneal membrane and results in withdrawal from peritoneal dialysis in patients. Among others, high glucose dialysate is considered as a predisposing factor for peritoneal fibrosis in patients on peritoneal dialysis. Glucose-induced inflammation, metabolism disturbance, activation of the renin-angiotensin-aldosterone system, angiogenesis and noninflammation-induced reactive oxygen species are implicated in the pathogenesis of high glucose dialysate-induced peritoneal fibrosis. Specifically, high glucose causes chronic inflammation and recurrent peritonitis, which could cause migration and polarization of inflammatory cells, as well as release of cytokines and fibrosis. High glucose also interferes with lipid metabolism and glycolysis by activating the sterol-regulatory element-binding protein-2/cleavage-activating protein pathway and increasing hypoxia inducible factor-1α expression, leading to angiogenesis and peritoneal fibrosis. Activation of the renin-angiotensin-aldosterone system and Ras-mitogen activated protein kinase signaling pathway is another contributing factor in high glucose dialysate-induced fibrosis. Ultimately, activation of the transforming growth factor-β1/Smad pathway is involved in mesothelial-mesenchymal transition or epithelial-mesenchymal transition, which leads to the development of fibrosis. Although possible intervention strategies for peritoneal dialysate-induced fibrosis by targeting the transforming growth factor-β1/Smad pathway have occasionally been proposed, lack of laboratory evidence renders clinical decision-making difficult. We therefore aim to revisit the upstream pathways of transforming growth factor-beta1/Smad and propose potential therapeutic targets for high glucose-induced peritoneal fibrosis.

Physical Training Reduces Chronic Airway Inflammation and Mediators of Remodeling in Asthma

Several benefits of aerobic training for asthmatic patients have been demonstrated. However, its effects on systemic inflammation and on airway remodeling mediators and lung mechanics are unknown. This prospective study included 21 intermittent and mild asthma patients, and as primary outcomes, the evaluation of pro- and anti-inflammatory and pro- and antifibrotic mediators in exhaled breath condensate (EBC) and blood were performed, beyond the cell counting in blood and in induced sputum. Aerobic training was performed for 3 months, 3 times per week. Aerobic training increased the levels of anti-inflammatory cytokines and of antifibrotic mediators in the breath condensate: IL-1ra (p = 0.0488), IL-10 (p = 0.0048), relaxin-3 (p = 0.0019), and klotho (p < 0.0043), respectively. Similarly, in plasma, increased levels of IL-1ra (p = 0.0147), IL-10 (p < 0.0001), relaxin-3 (p = 0.004), and klotho (p = 0.0023) were found. On contrary, reduced levels of proinflammatory cytokines in the breath condensate, IL-1β (p = 0.0008), IL-4 (p = 0.0481), IL-5 (p < 0.0001), IL-6 (p = 0.0032), IL-13 (p = 0.0013), and TNF-α (p = 0.0001) and profibrotic markers VEGF (p = 0.0017) and TSLP (p = 0.0056) were found. Similarly, in plasma, aerobic training significantly reduced the levels of proinflammatory cytokines IL-1β (p = 0.0008), IL-4 (p = 0.0104), IL-5 (p = 0.0001), IL-6 (p = 0.006), IL-13 (p = 0.0341), and TNF-α (p = 0.0003) and of profibrotic markers VEGF (p = 0.0009) and TSLP (p < 0.0076). Fractional exhaled nitric oxide (FeNO) was reduced after the intervention (p = 0.0313). Regarding inflammatory cells in sputum, there was a reduction in total cells (p = 0.008), eosinophils (p = 0.009), and macrophages (p = 0.020), as well as of blood eosinophils (p = 0.0203) and lymphocytes (p = 0.0198). Aerobic training positively modulates chronic airway inflammation and remodeling mediators, beyond to improve systemic inflammation in intermittent and mild asthmatic patients.

Vitamin D Actions: The Lung Is a Major Target for Vitamin D, FGF23, and Klotho

Vitamin D is well known for its role as a calcium regulator and in maintenance of phosphate homeostasis in musculoskeletal health, and fibroblast growth factor 23 (FGF23) and its coreceptor α-klotho are known for their roles as regulators of serum phosphate levels. However, apart from these classical actions, recent data point out a relevant role of vitamin D and FGF23/klotho in lung health. The expression of the vitamin D receptor by different cell types in the lung and the fact that those cells respond to vitamin D or can locally produce vitamin D indicate that the lung represents a target for vitamin D actions. Similarly, the presence of the four FGF receptor isoforms in the lung and the ability of FGF23 to stimulate pulmonary cells support the concept that the lung is a target for FGF23 actions, whereas the contribution of klotho is still undetermined. This review will give an overview on how vitamin D or FGF23/klotho may act on the lung and interfere positively or negatively with lung health. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Klotho Alleviates Lung Injury Caused by Paraquat via Suppressing ROS/P38 MAPK-Regulated Inflammatory Responses and Apoptosis

Acute lung injury (ALI) induced by paraquat (PQ) progresses rapidly with high mortality; however, there is no effective treatment, and the specific mechanism is not well understood. The antiaging protein klotho (KL) has multiple functions and exerts significant influences on various pathophysiological processes. This work evaluated the impact of KL on PQ-induced ALI and investigated its underlying mechanisms. As for in vivo research, C57BL/6 mice were treated with PQ (30 mg/kg) intraperitoneal (IP) injection to create a toxicity model of ALI (PQ group). The mice were divided into control group, KL group, PQ group, and PQ+KL group. For in vitro experiment, A549 cells were incubated with or without KL and then treated in the presence or absence of PQ for 24 h. In vivo result indicated that KL reduced the mortality, reduced IL-1β and IL-6 in the bronchoalveolar lavage fluid (BALF), attenuated ALI, and decreased apoptosis in situ. In vitro result revealed that KL significantly improved cell viability, reduced the levels of IL-1β and IL-6 in culture supernatants, suppressed cell apoptosis, inhibited caspase-3 activation, and enhanced mitochondrial membrane potential (ΔΨm) after PQ treatment. Besides, KL effectively abated reactive oxygen species (ROS) production, improved GSH content, and lowered lipid peroxidation in PQ-exposed A549 cells. Further experiments indicated that phosphorylated JNK and P38 MAPK was increased after PQ treatment; however, KL pretreatment could significantly lower the phosphorylation of P38 MAPK. Suppression of P38 MAPK improved cell viability, alleviated inflammatory response, and reduced apoptosis-related signals; however, it had no obvious effect on the production of ROS. Treatment with N-acetylcysteine (NAC), a classic ROS scavenger, could suppress ROS production and P38 MAPK activation. These findings suggested that KL could alleviate PQ-caused ALI via inhibiting ROS/P38 MAPK signaling-regulated inflammatory responses and mitochondria-dependent apoptosis.

Alpha-Klotho, a critical protein for lung health, is not expressed in normal lung

Alpha-Klotho (αKlotho), produced by the kidney and selected organs, is essential for tissue maintenance and protection. Homozygous αKlotho-deficiency leads to premature multi-organ degeneration and death; heterozygous insufficiency leads to apoptosis, oxidative stress, and increased injury susceptibility. There is inconsistent data in the literature regarding whether αKlotho is produced locally in the lung or derived from circulation. We probed murine and human lung by immunohistochemistry (IHC) and immunoblot (IB) using two monoclonal (anti-αKlotho Kl1 and Kl2 domains) and three other common commercial antibodies. Monoclonal anti-Kl1 and anti-Kl2 yielded no labeling in lung on IHC or IB; specific labeling was observed in kidney (positive control) and also murine lungs following tracheal delivery of αKlotho cDNA, demonstrating specificity and ability to detect artificial pulmonary expression. Other commercial antibodies labeled numerous lung structures (IHC) and multiple bands (IB) incompatible with known αKlotho mobility; labeling was not abolished by blocking with purified αKlotho or using lungs from hypomorphic αKlotho-deficient mice, indicating nonspecificity. Results highlight the need for rigorous validation of reagents. The lung lacks native αKlotho expression and derives full-length αKlotho from circulation; findings could explain susceptibility to lung injury in extrapulmonary pathology associated with reduced circulating αKlotho levels, for example, renal failure. Conversely, αKlotho may be artificially expressed in the lung, suggesting therapeutic opportunities.

The axis of local cardiac endogenous Klotho-TGF-β1-Wnt signaling mediates cardiac fibrosis in human

BACKGROUND

Cardiovascular fibrosis is a major contributor to cardiovascular disease, the primary cause of death in patients with chronic kidney disease (CKD). We previously reported expression of endogenous Klotho in human arteries, and that CKD is a state of Klotho deficiency, resulting in vascular calcification, but myocardial expression of Klotho is poorly understood. This study aimed to further clarify endogenous Klotho's functional roles in cardiac fibrosis in patients with underlying CKD.

METHODS AND RESULTS

Human atrial appendage specimens were collected during cardiac surgery from individuals with or without CKD. Cardiac fibrosis was quantified using trichrome staining. For endogenous Klotho functional studies, primary human cardiomyocytes (HCMs) were treated with uremic serum from CKD patients or recombinant human TGF-β1. The effects of endogenous Klotho in HCMs were studied using Klotho-siRNA and Klotho-plasmid transfection. Both gene and protein expression of endogenous Klotho are found in human heart, but decreased Klotho expression is clearly associated with the degree of cardiac fibrosis in CKD patients. Moreover, we show that endogenous Klotho is expressed by HCMs and cardiac fibroblasts (HCFs) but that HCM expression is suppressed by uremic serum or TGF-β1. Klotho knockdown or overexpression aggravates or mitigates TGF-β1-induced fibrosis and canonical Wnt signaling in HCMs, respectively. Furthermore, co-culture of HCMs with HCFs increases TGF-β1-induced fibrogenic proteins in HCFs, but overexpression of endogenous Klotho in HCMs mitigates this effect, suggesting functional crosstalk between HCMs and HCFs.

CONCLUSIONS

Our data from analysis of human hearts as well as functional in vitro studies strongly suggests that the loss of cardiac endogenous Klotho in CKD patients, specifically in cardiomyocytes, facilitates intensified TGF-β1 signaling which enables more vigorous cardiac fibrosis through upregulated Wnt signaling. Upregulation of endogenous Klotho inhibits pathogenic Wnt/β-catenin signaling and may offer a novel strategy for prevention and treatment of cardiac fibrosis in CKD patients.

FGF23 Actions on Target Tissues-With and Without Klotho

Fibroblast growth factor (FGF) 23 is a phosphaturic hormone whose physiologic actions on target tissues are mediated by FGF receptors (FGFR) and klotho, which functions as a co-receptor that increases the binding affinity of FGF23 for FGFRs. By stimulating FGFR/klotho complexes in the kidney and parathyroid gland, FGF23 reduces renal phosphate uptake and secretion of parathyroid hormone, respectively, thereby acting as a key regulator of phosphate metabolism. Recently, it has been shown that FGF23 can also target cell types that lack klotho. This unconventional signaling event occurs in an FGFR-dependent manner, but involves other downstream signaling pathways than in "classic" klotho-expressing target organs. It appears that klotho-independent signaling mechanisms are only activated in the presence of high FGF23 concentrations and result in pathologic cellular changes. Therefore, it has been postulated that massive elevations in circulating levels of FGF23, as found in patients with chronic kidney disease, contribute to associated pathologies by targeting cells and tissues that lack klotho. This includes the induction of cardiac hypertrophy and fibrosis, the elevation of inflammatory cytokine expression in the liver, and the inhibition of neutrophil recruitment. Here, we describe the signaling and cellular events that are caused by FGF23 in tissues lacking klotho, and we discuss FGF23's potential role as a hormone with widespread pathologic actions. Since the soluble form of klotho can function as a circulating co-receptor for FGF23, we also discuss the potential inhibitory effects of soluble klotho on FGF23-mediated signaling which might-at least partially-underlie the pleiotropic tissue-protective functions of klotho.

Alpha-Klotho Enrichment in Induced Pluripotent Stem Cell Secretome Contributes to Antioxidative Protection in Acute Lung Injury

Induced pluripotent stem cells (iPSCs) have been reported to alleviate organ injury, although the mechanisms of action remain unclear and administration of intact cells faces many limitations. We hypothesized that cell-free conditioned media (CM) containing the secretome of iPSCs possess antioxidative constituents that can alleviate pulmonary oxidant stress damage. We derived iPSCs from human dermal fibroblasts and harvested the CM. Addition of iPSC CM to cultured human alveolar type-1 epithelial cells mitigated hyperoxia-induced depletion of endogenous total antioxidant capacity while tracheal instillation of iPSC CM into adult rat lungs enhanced hyperoxia-induced increase in TAC. In both the in vitro and in vivo models, iPSC CM ameliorated oxidative damage to DNA, lipid, and protein, and activated the nuclear factor (erythroid 2)-related factor 2 (Nrf2) network of endogenous antioxidant proteins. Compared with control fibroblast-conditioned or cell-free media, iPSC CM is highly enriched with αKlotho at a concentration up to more than 10-fold of that in normal serum. αKlotho is an essential antioxidative cell maintenance and protective factor and an activator of the Nrf2 network. Immunodepletion of αKlotho reduced iPSC CM-mediated cytoprotection by ∼50%. Thus, the abundant αKlotho content significantly contributes to iPSC-mediated antioxidation and cytoprotection. Results uncover a major mechanism of iPSC action, suggest a fundamental role of αKlotho in iPSC maintenance, and support the translational potential of airway delivery of cell-free iPSC secretome for protection against lung injury. The targeted cell-free secretome-based approach may also be applicable to the amelioration of injury in other organs. Stem Cells 2018;36:616-625.

Effects of Klotho on fibrosis and cancer: A renal focus on mechanisms and therapeutic strategies

Klotho is a membrane-bound protein predominantly expressed in the kidney, where it acts as a permissive co-receptor for Fibroblast Growth Factor 23. In its shed form, Klotho exerts anti-fibrotic effects in several tissues. Klotho-deficient mice spontaneously develop fibrosis and Klotho deficiency exacerbates the disease progression in fibrotic animal models. Furthermore, Klotho overexpression or supplementation protects against fibrosis in various models of renal and cardiac fibrotic disease. These effects are mediated at least partially by the direct inhibitory effects of soluble Klotho on TGFβ1 signaling, Wnt signaling, and FGF2 signaling. Soluble Klotho, as present in the circulation, appears to be the primary mediator of anti-fibrotic effects. Similarly, through inhibition of the TGFβ1, Wnt, FGF2, and IGF1 signaling pathways, Klotho also inhibits tumorigenesis. The Klotho promoter gene is generally hypermethylated in cancer, and overexpression or supplementation of Klotho has been found to inhibit tumor growth in various animal models. This review focuses on the protective effects of soluble Klotho in inhibiting renal fibrosis and fibrosis in distant organs secondary to renal Klotho deficiency. We also discuss the structure-function relationships of Klotho domains and biological effects in the context of potential targeted treatment strategies.

Measurement of Serum Klotho in Systemic Sclerosis

Background

The aim of our study was to evaluate the serum concentration of klotho in a cohort of systemic sclerosis (SSc) patients compared to that of healthy controls and to correlate its levels with the degree and the kind of organ involvement.

Methods

Blood samples obtained from both patients and controls were collected and analysed by an ELISA test for the determination of human soluble klotho. Scleroderma patients were evaluated for disease activity through clinical, laboratory, and instrumental assessment.

Results

Our cohort consisted of 81 SSc patients (74 females, mean age 63.9 ± 13.1 years) and 136 healthy controls (78 females, mean age 50.5 ± 10.7 years). When matched for age, serum klotho concentration significantly differed between controls and patients (p < 0.001). However, in SSc patients, we did not find any significant association between serum klotho and clinical, laboratory, and instrumental findings. Lower serum levels of klotho were detected in 4 patients who were anticitrullinated peptide antibody (ACPA) positive (p = 0.005).

Conclusions

Our data show a lower concentration of klotho in the serum of SSc patients compared to that of healthy controls, without any significant association with clinical manifestations and laboratory and instrumental findings. The association between serum klotho and ACPA positivity requires further investigation.

Tissue expression and source of circulating αKlotho

αKlotho (Klotho), a type I transmembrane protein and a coreceptor for Fibroblast Growth Factor-23, was initially thought to be expressed only in a limited number of tissues, most importantly the kidney, parathyroid gland and choroid plexus. Emerging data may suggest a more ubiquitous Klotho expression pattern which has prompted reevaluation of the restricted Klotho paradigm. Herein we systematically review the evidence for Klotho expression in various tissues and cell types in humans and other mammals, and discuss potential reasons behind existing conflicting data. Based on current literature and tissue expression atlases, we propose a classification of tissues into high, intermediate and low/absent Klotho expression. The functional relevance of Klotho in organs with low expression levels remain uncertain and there is currently limited data on a role for membrane-bound Klotho outside the kidney. Finally, we review the evidence for the tissue source of soluble Klotho, and conclude that the kidney is likely to be the principal source of circulating Klotho in physiology.

Synthetic Fluororutaecarpine Inhibits Inflammatory Stimuli and Activates Endothelial Transient Receptor Potential Vanilloid-Type 1

The natural product, rutaecarpine (RUT), is the main effective component of Evodia rutaecarpa which is a widely used traditional Chinese medicine. It has vasodilation, anticoagulation, and anti-inflammatory activities. However, further therapeutic applications are limited by its cytotoxicity. Thus, a derivative of RUT, 10-fluoro-2-methoxyrutaecarpine (F-RUT), was designed and synthesized that showed no cytotoxicity toward RAW264.7 macrophages at 20 μM. In an anti-inflammation experiment, it inhibited the production of nitric oxide (NO) and tumor necrosis factor (TNF)-α in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages; cyclooxygenase (COX)-2 and inducible NO synthase (iNOS) induced by LPS were also downregulated. After 24 h of treatment, F-RUT significantly inhibited cell migration and invasion of ovarian A2780 cells. Furthermore, F-RUT promoted expressions of transient receptor potential vanilloid type 1 (TRPV1) and endothelial (e)NOS in human aortic endothelial cells, and predominantly reduced the inflammation in ovalbumin/alum-challenged mice. These results suggest that the novel synthetic F-RUT exerts activities against inflammation and vasodilation, while displaying less toxicity than its lead compound.

Role of Klotho in migration and proliferation of human dermal microvascular endothelial cells

PURPOSE

To examine the possible role of Klotho (Kl) in human microvasculature.

METHODS

The expression level of Kl in primary human dermal microvascular endothelial cells (HDMECs) and primary human dermal fibroblasts (HFb) was detected by real-time polymerase chain reaction amplification (qRT-PCR), Western blot analyses and immunohistochemistry. Migration of HDMECs and HFb was examined in monolayer wound healing "scratch assay" and Transwell assay. Proliferation of these cells was examined using Cell Proliferation BrdU incorporation assay.

RESULTS

Our results have shown that downregulation of Kl abrogated HDMECs migration after 48h. On the other hand, migration of HFb significantly increased after blocking Kl. Lack of Kl decreased expression of genes involved in the activation of endothelial cells and enhanced expression of genes involved in extracellular matrix remodeling and organization of connective tissue.

CONCLUSIONS

This study for the first time provides the evidence that Kl is expressed in HDMECs and HFb. Additionally, we have demonstrated that Kl is implicated in the process of angiogenesis of human dermal microvasculature.

Premature aging in chronic kidney disease and chronic obstructive pulmonary disease: similarities and differences

PURPOSE OF REVIEW

There is increasing clinical and pathophysiological evidence that a premature aging process is involved in the pathogenesis of systemic complications of many chronic organ diseases, which result in analogous phenotypes, including premature vascular aging, osteoporosis and muscle wasting. Novel developments from research into the aging process will, therefore, have relevance for understanding complications of organ diseases, such as chronic kidney disease and chronic obstructive pulmonary disease. The aim of the present article is to combine recent literature on aging mechanisms with evidence on the pathogenesis of systemic complications of these two chronic debilitating disorders.

RECENT FINDINGS

Recently, nine hallmarks of aging have been identified. In this review, we argue that all of these hallmarks are relevant for the pathogenesis of premature aging processes in chronic obstructive pulmonary disease and chronic kidney disease. Additionally, organ-specific alterations in proaging mechanisms, which reveal differences in phenotype against a generic background of premature aging, will be addressed. However, within patient populations who share a common diagnosis, clusters of patients with different phenotypes may be identified, which may show overlap with patients with other chronic diseases.

SUMMARY

An increased understanding of the premature aging process as well as its systemic consequences may pave the way for 'precision' intervention as well as shared treatment opportunities between chronic debilitating diseases of various causes.

Cardio-Pulmonary-Renal Interactions: A Multidisciplinary Approach

Over the past decade, science has greatly advanced our understanding of interdependent feedback mechanisms involving the heart, lung, and kidney. Organ injury is the consequence of maladaptive neurohormonal activation, oxidative stress, abnormal immune cell signaling, and a host of other mechanisms that precipitate adverse functional and structural changes. The presentation of interorgan crosstalk may include an acute, chronic, or acute on chronic timeframe. We review the current, state-of-the-art understanding of cardio-pulmonary-renal interactions and their related pathophysiology, perpetuating nature, and cycles of increased susceptibility and reciprocal progression. To this end, we present a multidisciplinary approach to frame the diverse spectrum of published observations on the topic. Assessment of organ functional reserve and use of biomarkers are valuable clinical strategies to screen and detect disease, assist in diagnosis, assess prognosis, and predict recovery or progression to chronic disease.