Understanding the role of the cytoprotective transcription factor nuclear factor erythroid 2-related factor 2-lessons from evolution, the animal kingdom and rare progeroid syndromes

The Kidney-Immune-Brain Axis: The Role of Inflammation in the Pathogenesis and Treatment of Stroke in Chronic Kidney Disease

Cardiovascular diseases such as stroke are a major cause of morbidity and mortality for patients with chronic kidney disease (CKD). The underlying mechanisms connecting CKD and cardiovascular disease are yet to be fully elucidated, but inflammation is proposed to play an important role based on genetic association studies, studies of inflammatory biomarkers, and clinical trials of anti-inflammatory drug targets. There are multiple sources of both endogenous and exogenous inflammation in CKD, including increased production and decreased clearance of proinflammatory cytokines, oxidative stress, metabolic acidosis, chronic and recurrent infections, dialysis access, changes in adipose tissue metabolism, and disruptions in intestinal microbiota. This review focuses on the mechanisms of inflammation in CKD, dialysis and associated therapies, its proposed impact on stroke pathogenesis and prognosis, and the potential role of anti-inflammatory agents in the prevention and treatment of stroke in patients with CKD.

Harnessing Evolution and Biomimetics to Enhance Planetary Health: Kidney Insights

Planetary health encompasses the understanding that the long-term well-being of humanity is intrinsically linked to the health of global ecological systems. Unfortunately, current practices often overlook this principle, leading to a human-oriented (anthropocentric) worldview that has resulted in heightened greenhouse gas emissions, increased heat stress, lack of access to clean water, and pollution, threatening both the environment and health and survival of Homo sapiens and countless other species. One significant consequence of these environmental changes is the exacerbation of inflammatory and oxidative stressors, which not only contributes to common lifestyle diseases but also accelerates the aging process. We advocate for a shift away from our current anthropocentric frameworks to an approach that focuses on nature's solutions that developed from natural selection over the eons. This approach, which encompasses the field of biomimicry, may provide insights that can help protect against an inflammatory phenotype to mitigate physiological and cellular senescence and provide a buffer against environmental stressors. Gaining insights from how animals have developed ingenious approaches to combat adversity through the evolutionary process of natural selection not only provides solutions for climate change but also confronts the rising burden of lifestyle diseases that accumulate with age.

Lymphocytes and innate immune cells in acute kidney injury and repair

Acute kidney injury (AKI) is a common and serious disease entity that affects native kidneys and allografts but for which no specific treatments exist. Complex intrarenal inflammatory processes driven by lymphocytes and innate immune cells have key roles in the development and progression of AKI. Many studies have focused on prevention of early injury in AKI. However, most patients with AKI present after injury is already established. Increasing research is therefore focusing on mechanisms of renal repair following AKI and prevention of progression from AKI to chronic kidney disease. CD4+ and CD8+ T cells, B cells and neutrophils are probably involved in the development and progression of AKI, whereas regulatory T cells, double-negative T cells and type 2 innate lymphoid cells have protective roles. Several immune cells, such as macrophages and natural killer T cells, can have both deleterious and protective effects, depending on their subtype and/or the stage of AKI. The immune system not only participates in injury and repair processes during AKI but also has a role in mediating AKI-induced distant organ dysfunction. Targeted manipulation of immune cells is a promising therapeutic strategy to improve AKI outcomes.

Simultaneous induction of systemic hyperglycaemia and stress impairs brain redox homeostasis in the adult zebrafish

For diabetic patients it is crucial to constantly monitor blood glucose levels to mitigate complications due to hyperglycaemia, including neurological issues and cognitive impairments. This activity leads to psychological stress, called "diabetes distress," a problem for most patients living with diabetes. Diabetes distress can exacerbate the hyperglycaemia effects on brain and negatively impact the quality of life, but the underlying mechanisms remain poorly explored. We simulated diabetes distress in adult zebrafish by modelling hyperglycaemia, through exposure to dextrose solution, along with chronic unpredictable mild stress (CUMS), and evaluated brain redox homeostasis by assessing reactive oxygen species (ROS) content, the antioxidant system, and effects on mitochondrial biogenesis and fission/fusion processes. We also evaluated the total, cytosolic and nuclear content of nuclear factor erythroid 2-related factor 2 (NRF2), a critical regulator of redox balance, in the whole brain and total NRF2 in specific brain emotional areas. The combined CUMS + Dextrose challenge, but not the individual treatments, reduced total NRF2 levels in the entire brain, but strongly increased its levels in the nuclear fraction. Compensatory upregulation of antioxidant genes appeared inadequate to combat elevated levels of ROS, leading to lowering of the reduced glutathione content and total antioxidant capacity. CUMS + Dextrose treatment also upregulated transcription factors implicated in mitochondrial biogenesis and dynamics with a predominance of fission, which is consistent with increased oxidative stress. In conclusion, this study highlights the close interplay between hyperglycaemia and psychological distress causing overriding oxidative stress in the brain, rendering the organism vulnerable to the development of disease complications.

What Can the Gut Microbiota of Animals Teach Us about the Relationship between Nutrition and Burden of Lifestyle Diseases?

The gut microbiota performs several crucial roles in a holobiont with its host, including immune regulation, nutrient absorption, synthesis, and defense against external pathogens, significantly influencing host physiology. Disruption of the gut microbiota has been linked to various chronic conditions, including cardiovascular, kidney, liver, respiratory, and intestinal diseases. Studying how animals adapt their gut microbiota across their life course at different life stages and under the dynamics of extreme environmental conditions can provide valuable insights from the natural world into how the microbiota modulates host biology, with a view to translating these into treatments or preventative measures for human diseases. By modulating the gut microbiota, opportunities to address many complications associated with chronic diseases appear. Such a biomimetic approach holds promise for exploring new strategies in healthcare and disease management.

Food Polyphenols as Preventive Medicine

Reactive oxygen species (ROS) are the initiators in foods and in the stomach of oxidized dietary lipids, proteins, and lipid-oxidation end-products (ALEs), inducing in humans the development of several chronic diseases and cancer. Epidemiological, human clinical and animal studies supported the role of dietary polyphenols and derivatives in prevention of development of such chronic diseases. There is much evidence that polyphenols/derivatives at the right timing and concentration, which is critical, acts mostly in the aerobic stomach and generally in the gastrointestinal tract as reducing agents, scavengers of free radicals, trappers of reactive carbonyls, modulators of enzyme activity, generators of beneficial gut microbiota and effectors of cellular signaling. In the blood system, at low concentration, they act as generators of electrophiles and low concentration of H2O2, acting mostly as cellular signaling, activating the PI3K/Akt-mediated Nrf2/eNOS pathways and inhibiting the inflammatory transcription factor NF-κB, inducing the cells, organs and organism for eustress, adaptation and surviving.

Identification of Immune-Related Genes as Biomarkers for Uremia

Purpose

Uremia, which is characterized by immunodeficiency, is associated with the deterioration of kidney function. Immune-related genes (IRGs) are crucial for uremia progression.

Methods

The co-expression network was constructed to identify key modular genes associated with uremia. IRGs were intersected with differentially expressed genes (DEGs) between uremia and control groups and key modular genes to obtain differentially expressed IRGs (DEIRGs). DEIRGs were subjected to functional enrichment analysis. The protein-protein interaction (PPI) network was constructed. The candidate genes were identified using the cytoHubba tool. The biomarkers were identified using various machine learning algorithms. The diagnostic value of the biomarkers was evaluated using receiver operating characteristic (ROC) analysis. The immune infiltration analysis was implemented. The biological pathways of biomarkers were identified using gene set enrichment analysis and ingenuity pathway analysis. The mRNA expression of biomarkers was validated using blood samples of patients with uremia and healthy subjects with quantitative real-time polymerase chain reaction (qRT-PCR).

Results

In total, four biomarkers (PDCD1, NGF, PDGFRB, and ZAP70) were identified by machine learning methods. ROC analysis demonstrated that the area under the curve values of individual biomarkers were > 0.9, indicating good diagnostic power. The nomogram model of biomarkers exhibited good predictive power. The proportions of six immune cells significantly varied between the uremia and control groups. ZAP70 expression was positively correlated with the proportions of resting natural killer (NK) cells, naïve B cells, and regulatory T cells. Functional enrichment analysis revealed that the biomarkers were mainly associated with translational function and neuroactive ligand-receptor interaction. ZAP70 regulated NK cell signaling. The PDCD1 and NGF expression levels determined using qRT-PCR were consistent with those determined using bioinformatics analysis.

Conclusion

PDCD1, NGF, PDGFRB, and ZAP70 were identified as biomarkers for uremia, providing a theoretical foundation for uremia diagnosis.

Inflammation and gut dysbiosis as drivers of CKD-MBD

Two decades ago, Kidney Disease: Improving Global Outcomes coined the term chronic kidney disease-mineral and bone disorder (CKD-MBD) to describe the syndrome of biochemical, bone and extra-skeletal calcification abnormalities that occur in patients with CKD. CKD-MBD is a prevalent complication and contributes to the excessively high burden of fractures and cardiovascular disease, loss of quality of life and premature mortality in patients with CKD. Thus far, therapy has focused primarily on phosphate retention, abnormal vitamin D metabolism and parathyroid hormone disturbances, but these strategies have largely proved unsuccessful, thus calling for paradigm-shifting concepts and innovative therapeutic approaches. Interorgan crosstalk is increasingly acknowledged to have an important role in health and disease. Accordingly, mounting evidence suggests a role for both the immune system and the gut microbiome in bone and vascular biology. Gut dysbiosis, compromised gut epithelial barrier and immune cell dysfunction are prominent features of the uraemic milieu. These alterations might contribute to the inflammatory state observed in CKD and could have a central role in the pathogenesis of CKD-MBD. The emerging fields of osteoimmunology and osteomicrobiology add another level of complexity to the pathogenesis of CKD-MBD, but also create novel therapeutic opportunities.

The fructose survival hypothesis for obesity

The fructose survival hypothesis proposes that obesity and metabolic disorders may have developed from over-stimulation of an evolutionary-based biologic response (survival switch) that aims to protect animals in advance of crisis. The response is characterized by hunger, thirst, foraging, weight gain, fat accumulation, insulin resistance, systemic inflammation and increased blood pressure. The process is initiated by the ingestion of fructose or by stimulating endogenous fructose production via the polyol pathway. Unlike other nutrients, fructose reduces the active energy (adenosine triphosphate) in the cell, while blocking its regeneration from fat stores. This is mediated by intracellular uric acid, mitochondrial oxidative stress, the inhibition of AMP kinase and stimulation of vasopressin. Mitochondrial oxidative phosphorylation is suppressed, and glycolysis stimulated. While this response is aimed to be modest and short-lived, the response in humans is exaggerated due to gain of 'thrifty genes' coupled with a western diet rich in foods that contain or generate fructose. We propose excessive fructose metabolism not only explains obesity but the epidemics of diabetes, hypertension, non-alcoholic fatty liver disease, obesity-associated cancers, vascular and Alzheimer's dementia, and even ageing. Moreover, the hypothesis unites current hypotheses on obesity. Reducing activation and/or blocking this pathway and stimulating mitochondrial regeneration may benefit health-span. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

Medical Needs and Therapeutic Options for Melanoma Patients Resistant to Anti-PD-1-Directed Immune Checkpoint Inhibition

Available 4- and 5-year updates for progression-free and for overall survival demonstrate a lasting clinical benefit for melanoma patients receiving anti-PD-directed immune checkpoint inhibitor therapy. However, at least one-half of the patients either do not respond to therapy or relapse early or late following the initial response to therapy. Little is known about the reasons for primary and/or secondary resistance to immunotherapy and the patterns of relapse. This review, prepared by an interdisciplinary expert panel, describes the assessment of the response and classification of resistance to PD-1 therapy, briefly summarizes the potential mechanisms of resistance, and analyzes the medical needs of and therapeutic options for melanoma patients resistant to immune checkpoint inhibitors. We appraised clinical data from trials in the metastatic, adjuvant and neo-adjuvant settings to tabulate frequencies of resistance. For these three settings, the role of predictive biomarkers for resistance is critically discussed, as well as are multimodal therapeutic options or novel immunotherapeutic approaches which may help patients overcome resistance to immune checkpoint therapy. The lack of suitable biomarkers and the currently modest outcomes of novel therapeutic regimens for overcoming resistance, most of them with a PD-1 backbone, support our recommendation to include as many patients as possible in novel or ongoing clinical trials.

p53-Dependent Cytoprotective Mechanisms behind Resistance to Chemo-Radiotherapeutic Agents Used in Cancer Treatment

Resistance to chemoradiotherapy is the main cause of cancer treatment failure. Cancer cells, especially cancer stem cells, utilize innate cytoprotective mechanisms to protect themselves from the adverse effects of chemoradiotherapy. Here, we describe a few such mechanisms: DNA damage response (DDR), immediate early response gene 5 (IER5)/heat-shock factor 1 (HSF1) pathway, and p21/nuclear factor erythroid 2-related factor 2 (NRF2) pathway, which are regulated by the tumour suppressor p53. Upon DNA damage caused during chemoradiotherapy, p53 is recruited to the sites of DNA damage and activates various DNA repair enzymes including GADD45A, p53R2, DDB2 to repair damaged-DNA in cancer cells. In addition, the p53-IER5-HSF1 pathway protects cancer cells from proteomic stress and maintains cellular proteostasis. Further, the p53-p21-NRF2 pathway induces production of antioxidants and multidrug resistance-associated proteins to protect cancer cells from therapy-induced oxidative stress and to promote effusion of drugs from the cells. This review summarises possible roles of these p53-regulated cytoprotective mechanisms in the resistance to chemoradiotherapy.

Accelerated Vascular Aging in Chronic Kidney Disease: The Potential for Novel Therapies

The pathophysiology of vascular disease is linked to accelerated biological aging and a combination of genetic, lifestyle, biological, and environmental risk factors. Within the scenario of uncontrolled artery wall aging processes, CKD (chronic kidney disease) stands out as a valid model for detailed structural, functional, and molecular studies of this process. The cardiorenal syndrome relates to the detrimental bidirectional interplay between the kidney and the cardiovascular system. In addition to established risk factors, this group of patients is subjected to a plethora of other emerging vascular risk factors, such as inflammation, oxidative stress, mitochondrial dysfunction, vitamin K deficiency, cellular senescence, somatic mutations, epigenetic modifications, and increased apoptosis. A better understanding of the molecular mechanisms through which the uremic milieu triggers and maintains early vascular aging processes, has provided important new clues on inflammatory pathways and emerging risk factors alike, and to the altered behavior of cells in the arterial wall. Advances in the understanding of the biology of uremic early vascular aging opens avenues to novel pharmacological and nutritional therapeutic interventions. Such strategies hold promise to improve future prevention and treatment of early vascular aging not only in CKD but also in the elderly general population.

Lessons from evolution by natural selection: An unprecedented opportunity to use biomimetics to improve planetary health

Planetary health embraces the concept that long-term human welfare depends on the well-being of its ecological systems. Current practices, however, have often ignored this concept and have led to an anthropocentric world, with the consequence of increased greenhouse gas emissions, heat stress, lack of clean water and pollution, that are threatening the environment as well as the health and life of Homo sapiens and many other species. One consequence of environmental stressors has been the stimulation of inflammatory and oxidative stress that may not only promote common lifestyle diseases, but the ageing process. Despite the harshness of the current reality, treatment opportunities may exist 'in our backyard'. Biomimicry is an emerging field of research that explores how nature is structured and aims to mimic ingenious solutions that have evolved in nature for different applications that benefit human life. As nature always counteracts excesses from within, biodiversity could be a source of solutions that have evolved through the natural selection of animal species that have survived polluted, warm, and arid environments - i.e. the same presumptive changes that now threaten human health. One example from the emerging science suggests that animals use the cytoprotective Nrf2 antioxidant pathway to combat environmental stress and this may be a case example that we can apply to better human health. Learning from nature may provide opportunities for environmental management and solutions to the most challenging issue that face the future of the planet.

Beneficial effects of procyanidin B2 on adriamycin-induced nephrotic syndrome mice: the multi-action mechanism for ameliorating glomerular permselectivity injury

Despite considerable advances in prevention, diagnosis, and therapy, nephrotic syndrome (NS) remains a significant cause of high morbidity and mortality globally. As a result, there is an urgent need to identify novel effective preventative and therapeutic agents for NS. NS is implicated in glomerular permselectivity injury, which can be attributed to oxidative distress, inflammation, lipid nephrotoxicity, podocyte apoptosis, autophagy dysfunction, and slit diaphragm (SLD) dysfunction. In addition to its well-documented antioxidant potency, procyanidin B2 (PB2) may exhibit pleiotropic effects by targeting various canonical signaling events, such as NF-κB, PPARs, PI3K/Akt, mTOR, and the caspase family. As a result, PB2 may be a promising therapeutic target against NS. To test this hypothesis, we established an Adriamycin (ADR)-induced NS mouse model to evaluate the pleiotropic renoprotective effects of PB2 on NS. Here, we demonstrated that PB2 improves podocyte injury via inhibition of NOX4/ROS and Hsp90/NF-κB to exhibit antioxidant and anti-inflammatory potency, respectively. We also show that PB2 indirectly activates the PI3K/Akt axis by regulating SLD protein levels, resulting in normalized podocyte apoptosis and autophagy function. Further, loss of albumin (ALB) induces lipid nephrotoxicity, which we found to be alleviated by PB2 via activation of PPARα/β-mediated lipid homeostasis and the cholesterol efflux axis. Interestingly, our results also suggested that PB2 reduces electrolyte abnormalities and edema. In addition, PB2 may contribute protective effects against trace element dys-homeostasis, which, through alleviating serum ALB loss, leads to a protective effect on glomerular permselectivity injury. Taken together, our results reveal that the identified mechanisms of PB2 on NS are multifactorial and involve inhibition of oxidative distress and inflammatory responses, as well as improvements in podocyte apoptosis and autophagy dysfunction, amelioration of lipid nephrotoxicity, and modulation of electrolyte abnormalities and edema. Thus, we provide a theoretical basis for the clinical application of PB2 against NS.

Ageing - Oxidative stress, PTMs and disease

Post-translational modifications (PTMs) have been proposed as a link between the oxidative stress-inflammation-ageing trinity, thereby affecting several hallmarks of ageing. Phosphorylation, acetylation, and ubiquitination cover >90% of all the reported PTMs. Several of the main PTMs are involved in normal "healthy" ageing and in different age-related diseases, for instance neurodegenerative, metabolic, cardiovascular, and bone diseases, as well as cancer and chronic kidney disease. Ultimately, data from human rare progeroid syndromes, but also from long-living animal species, imply that PTMs are critical regulators of the ageing process. Mechanistically, PTMs target epigenetic and non-epigenetic pathways during ageing. In particular, epigenetic histone modification has critical implications for the ageing process and can modulate lifespan. Therefore, PTM-based therapeutics appear to be attractive pharmaceutical candidates to reduce the burden of ageing-related diseases. Several phosphorylation and acetylation inhibitors have already been FDA-approved for the treatment of other diseases and offer a unique potential to investigate both beneficial effects and possible side-effects. As an example, the most well-studied senolytic compounds dasatinib and quercetin, which have already been tested in Phase 1 pilot studies, also act as kinase inhibitors, targeting cellular senescence and increasing lifespan. Future studies need to carefully determine the best PTM-based candidates for the treatment of the "diseasome of ageing".

Fermented food: Should patients with cardiometabolic diseases go back to an early neolithic diet?

Fermentation has been used since the Early Neolithic period to preserve foods. It has inherent organoleptic and nutritive properties that bestow health benefits, including reducing inflammation and oxidative stress, supporting the growth of salutogenic microbiota, enhancing intestinal mucosal protection and promoting beneficial immunometabolic health effects. The fermentation of food with specific microbiota increases the production salutogenic bioactive compounds that can activate Nrf2 mediated cytoprotective responses and mitigate the effects of the 'diseasome of aging' and its associated inflammageing, which presents as a prominent feature of obesity, type-2 diabetes, cardiovascular and chronic kidney disease. This review discusses the importance of fermented food in improving health span, with special reference to cardiometabolic diseases.

Targeting NRF2 in Type 2 diabetes mellitus and depression: Efficacy of natural and synthetic compounds

Evidence supports a strong bidirectional association between depression and Type 2 diabetes mellitus (T2DM). The harmful impact of oxidative stress and chronic inflammation on the development of both disorders is widely accepted. Nuclear factor erythroid 2-related factor 2 (NRF2) is a pertinent target in disease management owing to its reputation as the master regulator of antioxidant responses. NRF2 influences the expression of various cytoprotective phase 2 antioxidant genes, which is hampered in both depression and T2DM. Through interaction and crosstalk with several signaling pathways, NRF2 endeavors to contain the widespread oxidative damage and persistent inflammation involved in the pathophysiology of depression and T2DM. NRF2 promotes the neuroprotective and insulin-sensitizing properties of its upstream and downstream targets, thereby interrupting and preventing disease advancement. Standard antidepressant and antidiabetic drugs may be powerful against these disorders, but unfortunately, they come bearing distressing side effects. Therefore, exploiting the therapeutic potential of NRF2 activators presents an exciting opportunity to manage such bidirectional and comorbid conditions.

Oxidative Stress and Cellular Senescence Are Involved in the Aging Kidney

Chronic kidney disease (CKD) can be considered as a clinical model for premature aging. However, non-invasive biomarkers to detect early kidney damage and the onset of a senescent phenotype are lacking. Most of the preclinical senescence studies in aging have been done in very old mice. Furthermore, the precise characterization and over-time development of age-related senescence in the kidney remain unclear. To address these limitations, the age-related activation of cellular senescence-associated mechanisms and their correlation with early structural changes in the kidney were investigated in 3- to 18-month-old C57BL6 mice. Inflammatory cell infiltration was observed by 12 months, whereas tubular damage and collagen accumulation occurred later. Early activation of cellular-senescence-associated mechanisms was found in 12-month-old mice, characterized by activation of the DNA-damage-response (DDR), mainly in tubular cells; activation of the antioxidant NRF2 pathway; and klotho downregulation. However, induction of tubular-cell-cycle-arrest (CCA) and overexpression of renal senescent-associated secretory phenotype (SASP) components was only found in 18-month-old mice. In aging mice, both inflammation and oxidative stress (marked by elevated lipid peroxidation and NRF2 inactivation) remained increased. These findings support the hypothesis that prolonged DDR and CCA, loss of nephroprotective factors (klotho), and dysfunctional redox regulatory mechanisms (NRF2/antioxidant defense) can be early drivers of age-related kidney-damage progression.

Inflammation and Oxidative Stress in Chronic Kidney Disease and Dialysis Patients

Significance: Chronic kidney disease (CKD) can be regarded as a burden of lifestyle disease that shares common underpinning features and risk factors with the aging process; it is a complex constituted by several adverse components, including chronic inflammation, oxidative stress, early vascular aging, and cellular senescence. Recent Advances: A systemic approach to tackle CKD, based on mitigating the associated inflammatory, cell stress, and damage processes, has the potential to attenuate the effects of CKD, but it also preempts the development and progression of associated morbidities. In effect, this will enhance health span and compress the period of morbidity. Pharmacological, nutritional, and potentially lifestyle-based interventions are promising therapeutic avenues to achieve such a goal. Critical Issues: In the present review, currents concepts of inflammation and oxidative damage as key patho-mechanisms in CKD are addressed. In particular, potential beneficial but also adverse effects of different systemic interventions in patients with CKD are discussed. Future Directions: Senotherapeutics, the nuclear factor erythroid 2-related factor 2-kelch-like ECH-associated protein 1 (NRF2-KEAP1) signaling pathway, the endocrine klotho axis, inhibitors of the sodium-glucose cotransporter 2 (SGLT2), and live bio-therapeutics have the potential to reduce the burden of CKD and improve quality of life, as well as morbidity and mortality, in this fragile high-risk patient group. Antioxid. Redox Signal. 35, 1426-1448.

Lactobacillus plantarum probiotic induces Nrf2-mediated antioxidant signaling and eNOS expression resulting in improvement of myocardial diastolic function

Yorkshire swine were fed standard diet (n = 7) or standard diet containing applesauce rich in caffeic acid with Lactobacillus plantarum (n = 7) for 3 wk. An ameroid constrictor was next placed around the left coronary circumflex artery, and the dietary regimens were continued. At 14 wk, cardiac function, myocardial perfusion, vascular density, and molecular signaling in ischemic myocardium were evaluated. The L. plantarum-applesauce augmented NF-E2-related factor 2 (Nrf2) in the ischemic myocardium and induced Nrf2-regulated antioxidant enzymes heme oxygenase-1 (HO-1), NADPH dehydrogenase quinone 1 (NQO-1), and thioredoxin reductase (TRXR-1). Improved left ventricular diastolic function and decreased myocardial collagen expression were seen in animals receiving the L. plantarum-applesauce supplements. The expression of endothelial nitric oxide synthase (eNOS) was increased in ischemic myocardial tissue of the treatment group, whereas levels of asymmetric dimethyl arginine (ADMA), hypoxia inducible factor 1α (HIF-1α), and phosphorylated MAPK (pMAPK) were decreased. Collateral-dependent myocardial perfusion was unaffected, whereas arteriolar and capillary densities were reduced as determined by α-smooth muscle cell actin and CD31 immunofluorescence in ischemic myocardial tissue. Dietary supplementation with L. plantarum-applesauce is a safe and effective method of enhancing Nrf2-mediated antioxidant signaling cascade in ischemic myocardium. Although this experimental diet was associated with a reduction in hypoxic stimuli, decreased vascular density, and without any change in collateral-dependent perfusion, the net effect of an increase in antioxidant activity and eNOS expression resulted in improvement in diastolic function.NEW & NOTEWORTHY Colonization of the gut microbiome with certain strains of L. Plantarum has been shown to convert caffeic acid readily available in applesauce to 4-vinyl-catechol, a potent activator of the Nrf2 antioxidant defense pathway. In this exciting study, we show that simple dietary supplementation with L. Plantarum-applesauce-mediated Nrf2 activation supports vascular function, ameliorates myocardial ischemic diastolic dysfunction, and upregulates expression of eNOS.

Should we care about the ocular surface in the anophthalmic patient?

PURPOSE

To assess clinical and biomolecular changes of the conjunctival epithelium in anophthalmic patients wearing an ocular prosthesis.

METHODS

Thirty-five unilateral anophthalmic patients were enrolled. Patients with blepharitis, lid abnormalities, and topical/systemic medication affecting the ocular surface were excluded. Symptom Assessment in Dry Eye (SANDE) questionnaire and tear function test (Schirmer Test Type I) were recorded. Conjunctival inflammation and meibomian gland dysfunction (MGD) were graded in the anophthalmic side and fellow eye. Impression cytology sampling of the upper, lower tarsal, and posterior/bulbar conjunctiva from the anophthalmic socket were collected and compared to healthy controls.

RESULTS

Patients had significantly higher SANDE (p < 0.001), Schirmer I test (p = 0.004), conjunctival inflammation (p < 0.001), and MGD scores (p < 0.001) on the anophthalmic side compared to the fellow eye. Mucin 5AC, inflammatory markers (MMP-9, ICAM-1) expression (p < 0.001), and response to oxidative stress (NRF2-KEAP1 signaling pathway) (p < 0.05) were significantly upregulated in the posterior conjunctival surface in the anophthalmic socket.

CONCLUSIONS

Anophthalmic patients complained of more pronounced dry eye symptoms and presented more significant signs of inflammation and MGD on the anophthalmic side. The bulbar conjunctiva, behind the prosthesis, showed more significant hyperexpression of mucins, markers of inflammation, and increased response to oxidative stress compared to the tarsal conjunctiva. Patients wearing ocular prosthesis had signs of inflammation resembling dry eye disease.

Panax Ginseng C.A.Mey. as Medicine: The Potential Use of Panax Ginseng C.A.Mey. as a Remedy for Kidney Protection from a Pharmacological Perspective

Panax ginseng C.A.Mey. has been widely consumed as food/diet supplements from natural sources, and its therapeutic properties have also aroused widespread concern. Therapeutic properties of Panax ginseng C.A.Mey. such as anti-inflammatory, ameliorating chronic inflammation, enhancing the immunity, resisting the oxidation again, and regulating the glucose and lipid metabolism have been widely reported. Recent years, lots of interesting studies have reported the potential use of Panax ginseng C.A.Mey. in the management of DKD. DKD has become the leading cause of end-stage renal disease worldwide, which increases the risk of premature death and poses a serious financial burden. Although DKD is somehow controllable with different drugs such as Angiotensin-Converting Enzyme Inhibitors (ACEI), Angiotensin Receptor Blockers (ARB) and lowering-glucose agents, modern dietary changes associated with DKD have facilitated research to assess the preventive and therapeutic merits of diet supplements from natural sources as medicine including Panax ginseng C.A.Mey. Findings from many scientific evidences have suggested that Panax ginseng C.A.Mey. can relieve the pathological status in cellular and animal models of DKD. Moreover, a few studies showed that alleviation of clinical phenotype such as reducing albuminuria, serum creatinine and renal anemia in DKD patients after application or consumption of Panax ginseng C.A.Mey.. Therefore, this review aims to discuss the effectiveness of Panax ginseng C.A.Mey. as medicine for targeting pathological phenotypes in DKD from a pharmacological perspective. This review will provide new insights into the potential understanding use of Panax ginseng C.A.Mey. in the management of DKD in clinical settings.

The Idiosyncratic Physiological Traits of the Naked Mole-Rat; a Resilient Animal Model of Aging, Longevity, and Healthspan

The subterranean-dwelling naked mole-rat (Heterocephalus glaber) is an extremophilic rodent, able to thrive in the harsh underground conditions of sub-Saharan Northeast Africa. This pelage-free mammal exhibits numerous unusual ecophysiological features including pronounced tolerance of thermolability, hypoxia, hypercapnia and noxious substances. As a mammal, the naked mole-rat provides a proof-of-concept that age-related changes in physiology are avoidable. At ages far beyond their expected lifespans given both their body size and/or the timing of early developmental milestones, naked mole-rats fail to exhibit meaningful changes in physiological health or demographic mortality. Lack of physiological deterioration with age is also evident in lean and fat mass, bone quality, and reproductive capacity. Rather, regardless of age, under basal conditions naked mole-rats appear to "idle on low" with their "shields up" as is manifested by low body temperature, metabolic rate, cardiac output and kidney concentrating ability, enabling better protection of organs and cellular function. When needed, they can nevertheless ramp up these functions, increasing cardiac output and metabolism 2-5 fold. Here we review many unusual aspects of their physiology and examine how these attributes facilitate both tolerance of the diverse suite of hostile conditions encountered in their natural milieu as well as contribute to their extraordinary longevity and resistance to common, age-related chronic diseases.

Manipulating the exposome to enable better ageing

The sum total of life course exposures creates an exposome that has a significant impact on age-related health. Understanding the interplay between exposome factors and the (epi) genome, offers pertinent insights into the ageing process and its relationship with the accumulation of allostatic load. We propose to exploit this to develop a biomimetic approach that will provide insight into how evolution through natural selection in other species has solved many age related human health issues. In particular, we will emphasise the need to reconnect a more mechanistic approach to medical science with a broader natural sciences approach, using biomimetics to mitigate the global burden of age related ill health. In particular, we will discuss how such an approach indicates leverage of the activities of the Nrf 2 gene to enhance health span via reintroduction of the classical 'Food as Medicine' concept, including modulation of the microbiome and the creation of more salutogenic and biophilic environments. Additionally, we will discuss how this approach integrates with novel and developing senotherapies.

Chronic Inflammation in Chronic Kidney Disease Progression: Role of Nrf2

Despite recent advances in the management of chronic kidney disease (CKD), morbidity and mortality rates in these patients remain high. Although pressure-mediated injury is a well-recognized mechanism of disease progression in CKD, emerging data indicate that an intermediate phenotype involving chronic inflammation, oxidative stress, hypoxia, senescence, and mitochondrial dysfunction plays a key role in the etiology, progression, and pathophysiology of CKD. A variety of factors promote chronic inflammation in CKD, including oxidative stress and the adoption of a proinflammatory phenotype by resident kidney cells. Regulation of proinflammatory and anti-inflammatory factors through NF-κB- and nuclear factor, erythroid 2 like 2 (Nrf2)-mediated gene transcription, respectively, plays a critical role in the glomerular and tubular cell response to kidney injury. Chronic inflammation contributes to the decline in glomerular filtration rate (GFR) in CKD. Whereas the role of chronic inflammation in diabetic kidney disease (DKD) has been well-elucidated, there is now substantial evidence indicating unresolved inflammatory processes lead to fibrosis and eventual end-stage kidney disease (ESKD) in several other diseases, such as Alport syndrome, autosomal-dominant polycystic kidney disease (ADPKD), IgA nephropathy (IgAN), and focal segmental glomerulosclerosis (FSGS). In this review, we aim to clarify the mechanisms of chronic inflammation in the pathophysiology and disease progression across the spectrum of kidney diseases, with a focus on Nrf2.

A biomimetic natural sciences approach to understanding the mechanisms of ageing in burden of lifestyle diseases

The worldwide landscape of an ageing population and age-related disease brings with it huge socio-economic and public healthcare concerns across nations. Correspondingly, monumental human and financial resources have been invested in biomedical research, with a mission to decode the mechanisms of ageing and how these contribute to age-related disease. Multiple hallmarks of ageing have been identified that are common across taxa, highlighting their fundamental importance. These include dysregulated mitochondrial metabolism and telomeres biology, epigenetic modifications, cell-matrix interactions, proteostasis, dysregulated nutrient sensing, stem cell exhaustion, inflammageing and immuno-senescence. While our understanding of the molecular basis of ageing is improving, it remains a complex and multifactorial process that remains to be fully understood. A key aspect of the shortfall in our understanding of the ageing process lies in translating data from standard animal models to humans. Consequently, we suggest that a 'biomimetic' and comparative approach, integrating knowledge from species in the wild, as opposed to inbred genetically homogenous laboratory animals, can provide powerful insights into human ageing processes. Here we discuss some particularities and comparative patterns among several species from the animal kingdom, endowed with longevity or short lifespans and unique metabolic profiles that could be potentially exploited to the understanding of ageing and age-related diseases. Based upon lessons from nature, we also highlight several avenues for renewed focus in the pathophysiology of ageing and age-related disease (i.e. diet-microbiome-health axis, oxidative protein damage, adaptive homoeostasis and planetary health). We propose that a biomimetic alliance with collaborative research from different disciplines can improve our understanding of ageing and age-related diseases with long-term sustainable utility.

Biomimetics provides lessons from nature for contemporary ways to improve human health

Homo sapiens is currently living in serious disharmony with the rest of the natural world. For our species to survive, and for our well-being, we must gather knowledge from multiple perspectives and actively engage in studies of planetary health. The enormous diversity of species, one of the most striking aspects of life on our planet, provides a source of solutions that have been developed through evolution by natural selection by animals living in extreme environments. The food system is central to finding solutions; our current global eating patterns have a negative impact on human health, driven climate change and loss of biodiversity. We propose that the use of solutions derived from nature, an approach termed biomimetics, could mitigate the effects of a changing climate on planetary health as well as human health. For example, activation of the transcription factor Nrf2 may play a role in protecting animals living in extreme environments, or animals exposed to heat stress, pollution and pesticides. In order to meet these challenges, we call for the creation of novel interdisciplinary planetary health research teams.

Inflammation, Oxidative Stress, and Bone in Chronic Kidney Disease in the Osteoimmunology Era

Bone is not only a mineralized and apparently non-vital structure that provides support for locomotion and protection to inner organs. An increasing number of studies are unveiling new biologic functions and connections to other systems, giving the rise to new fields of research, such as osteoimmunology. The bone marrow niche, a new entity in bone physiology, seems to represent the site where a complex crosstalk between bone and immune/inflammatory responses takes place. An impressive interplay with the immune system is realized in bone marrow, with reciprocal influences between bone cells and haematopoietic cells. In this way, systemic chronic inflammatory diseases realize a crosstalk with bone, resulting in bone disease. Thus, pathogenetic links between chronic kidney disease-mineral bone disorders and osteoporosis, cardiovascular disease, and ageing are common. The aim of this narrative review is to provide a general view of the progresses in the field of bone research and their potential clinical implications, with emphasis on the links with inflammation and the connections to osteoimmunology and chemokines.

Systematic review of the nuclear factor erythroid 2-related factor 2 (NRF2) system in human chronic kidney disease: alterations, interventions, and relation to morbidity

BACKGROUND

NRF2 and its effectors NAD(P)H:quinoneoxidoreductase 1 (NQO1) and heme oxygenase 1 (HO-1) are of interest in kidney disease. We therefore reviewed studies about their status in patients with chronic kidney disease (CKD).

METHODS

We undertook systematic searches of PubMed and EMBASE databases. Alterations of NRF2, NQO1 and HO-1 in CKD, their responses to interventions and their relation to clinically relevant parameters were reported.

RESULTS

We identified 1373 articles, of which 32 studies met the inclusion criteria. NRF2 levels were decreased in the majority of analyses of CKD patients. Half of the analyses showed a similar or increased NQO1 level vs. control, whereas NQO1 was decreased in half of the analyses. Most of the studies reported either an increased or similar HO-1 level in CKD patients compared to controls. For patients with CKD stages 1-4, studies reported positive correlations to markers of kidney disease severity. Also, positive associations of NQO1/HO-1 levels to inflammation and comorbidities were reported. One third of the studies showed discordant changes between gene expression and protein level of NRF2 system components. Two thirds of intervention studies (50% dietary, such as using resistant starch) reported an increase of NRF2, NQO1, or HO-1.

CONCLUSIONS

In patients with CKD, NRF2 expression was downregulated, while NQO1 and HO-1 showed varying alterations related to inflammation, comorbidities, and severity of kidney damage. Interventions that increased NRF2 system components were described, but their effectiveness and clinical relevance require further clinical studies of high quality. Research on gene expression together with protein analyses is indispensable to understand NRF2 system alterations in CKD.

Nutrition-Based Management of Inflammaging in CKD and Renal Replacement Therapies

Access to renal transplantation guarantees a substantial improvement in the clinical condition and quality of life (QoL) for end-stage renal disease (ESRD) patients. In recent years, a greater number of older patients starting renal replacement therapies (RRT) have shown the long-term impact of conservative therapies for advanced CKD and the consequences of the uremic milieu, with a frail clinical condition that impacts not only their survival but also limits their access to transplantation. This process, referred to as “inflammaging,” might be reversible with a tailored approach, such as RRT accompanied by specific nutritional support. In this review, we summarize the evidence demonstrating the presence of several proinflammatory substances in the Western diet (WD) and the positive effect of unprocessed food consumption and increased fruit and vegetable intake, suggesting a new approach to reduce inflammaging with the improvement of ESRD clinical status. We conclude that the Mediterranean diet (MD), because of its modulative effects on microbiota and its anti-inflammaging properties, may be a cornerstone in a more precise nutritional support for patients on the waiting list for kidney transplantation.

Role of Uremic Toxins in Early Vascular Ageing and Calcification

In patients with advanced chronic kidney disease (CKD), the accumulation of uremic toxins, caused by a combination of decreased excretion secondary to reduced kidney function and increased generation secondary to aberrant expression of metabolite genes, interferes with different biological functions of cells and organs, contributing to a state of chronic inflammation and other adverse biologic effects that may cause tissue damage. Several uremic toxins have been implicated in severe vascular smooth muscle cells (VSMCs) changes and other alterations leading to vascular calcification (VC) and early vascular ageing (EVA). The above mentioned are predominant clinical features of patients with CKD, contributing to their exceptionally high cardiovascular mortality. Herein, we present an update on pathophysiological processes and mediators underlying VC and EVA induced by uremic toxins. Moreover, we discuss their clinical impact, and possible therapeutic targets aiming at preventing or ameliorating the harmful effects of uremic toxins on the vasculature.

Food as medicine: targeting the uraemic phenotype in chronic kidney disease

The observation that unhealthy diets (those that are low in whole grains, fruits and vegetables, and high in sugar, salt, saturated fat and ultra-processed foods) are a major risk factor for poor health outcomes has boosted interest in the concept of 'food as medicine'. This concept is especially relevant to metabolic diseases, such as chronic kidney disease (CKD), in which dietary approaches are already used to ameliorate metabolic and nutritional complications. Increased awareness that toxic uraemic metabolites originate not only from intermediary metabolism but also from gut microbial metabolism, which is directly influenced by diet, has fuelled interest in the potential of 'food as medicine' approaches in CKD beyond the current strategies of protein, sodium and phosphate restriction. Bioactive nutrients can alter the composition and metabolism of the microbiota, act as modulators of transcription factors involved in inflammation and oxidative stress, mitigate mitochondrial dysfunction, act as senolytics and impact the epigenome by altering one-carbon metabolism. As gut dysbiosis, inflammation, oxidative stress, mitochondrial dysfunction, premature ageing and epigenetic changes are common features of CKD, these findings suggest that tailored, healthy diets that include bioactive nutrients as part of the foodome could potentially be used to prevent and treat CKD and its complications.

Klotho, Aging, and the Failing Kidney

Klotho has been recognized as a gene involved in the aging process in mammals for over 30 years, where it regulates phosphate homeostasis and the activity of members of the fibroblast growth factor (FGF) family. The α-Klotho protein is the receptor for Fibroblast Growth Factor-23 (FGF23), regulating phosphate homeostasis and vitamin D metabolism. Phosphate toxicity is a hallmark of mammalian aging and correlates with diminution of Klotho levels with increasing age. As such, modulation of Klotho activity is an attractive target for therapeutic intervention in the diseasome of aging; in particular for chronic kidney disease (CKD), where Klotho has been implicated directly in the pathophysiology. A range of senotherapeutic strategies have been developed to directly or indirectly influence Klotho expression, with varying degrees of success. These include administration of exogenous Klotho, synthetic and natural Klotho agonists and indirect approaches, via modulation of the foodome and the gut microbiota. All these approaches have significant potential to mitigate loss of physiological function and resilience accompanying old age and to improve outcomes within the diseasome of aging.

Alport Syndrome Classification and Management

Alport syndrome affects up to 60,000 people in the United States. The proposed reclassification of thin basement membrane nephropathy and some cases of focal segmental glomerulosclerosis as Alport syndrome could substantially increase the affected population. The reclassification scheme categorizes Alport syndrome as 3 distinct diseases of type IV collagen α3/4/5 based on a genetic evaluation: X-linked, autosomal, and digenic. This approach has the advantage of identifying patients at risk for progressive loss of kidney function. Furthermore, the shared molecular cause of Alport syndrome and thin basement membrane nephropathy arises from mutations in the COL4A3, COL4A4, and COL4A5 genes, which contribute to downstream pathophysiologic consequences, including chronic kidney inflammation. Recent evidence indicates that chronic inflammation and its regulation through anti-inflammatory nuclear factor erythroid 2-related factor 2 (Nrf2) and proinflammatory nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) transcription factors plays a central role in renal tubular and glomerular cell responses to injury. Crosstalk between the Nrf2 and NF-κB pathways is important in the regulation of inflammation in patients with chronic kidney disease; moreover, there is evidence that an insufficient Nrf2 response to inflammation contributes to disease progression. Given the association between type IV collagen abnormalities and chronic inflammation, there is renewed interest in targeted anti-inflammatory therapies in Alport syndrome and other forms of progressive chronic kidney disease.

Association between Nrf2 and CDKN2A expression in patients with end-stage renal disease: a pilot study

Patients with end-stage renal disease (ESRD) display phenotypic features of premature biological aging, characterized by disproportionately high morbidity and mortality at a younger age. Nuclear factor erythroid 2-related factor 2 (Nrf2) activity, a master regulator of antioxidative responses, declines with age and is implicated in the pathogenesis of age-related disorders; however, little is known about the association between Nrf2 and premature biological aging in ESRD patients. In a cross-sectional pilot cohort of 34 ESRD patients receiving maintenance hemodialysis, we measured the expression of Nrf2 and cyclin-dependent kinase inhibitor 2A (CDKN2A, or p16^INK4a, a biomarker of biological aging) genes in whole blood and examined the association of Nrf2 with CDKN2A expression, using Spearman's rank correlation and multivariable linear regression models with adjustment for potential confounders. There was a significant negative correlation between Nrf2 and CDKN2A expression (rho=-0.51, P=0.002); while no significant correlation was found between Nrf2 expression and chronological age (rho=-0.02, P=0.91). After multivariable adjustment, Nrf2 expression remained significantly and negatively associated with CDKN2A expression (β coefficient=-1.51, P=0.01), independent of chronological age, gender, race, and diabetes status. These findings suggest a potential contribution of Nrf2 dysfunction to the development of premature biological aging and its related morbidities in ESRD patients.

AKI: an increasingly recognized risk factor for CKD development and progression

Acute kidney injury (AKI) is an increasing health burden with high morbidity and mortality rates worldwide. AKI is a risk factor for chronic kidney disease (CKD) development and progression to end stage renal disease (ESRD). Rapid action is required to find treatment options for AKI, plus to anticipate the development of CKD and other complications. Therefore, it is essential to understand the pathophysiology of AKI to CKD transition. Over the last several years, research has revealed maladaptive repair to be an interplay of cell death, endothelial dysfunction, tubular epithelial cell senescence, inflammatory processes and more-terminating in fibrosis. Various pathological mechanisms have been discovered and reveal targets for potential interventions. Furthermore, there have been clinical efforts measures for AKI prevention and progression including the development of novel biomarkers and prediction models. In this review, we provide an overview of pathophysiological mechanisms involved in kidney fibrosis. Furthermore, we discuss research gaps and promising therapeutic approaches for AKI to CKD progression.

Inflammation and Premature Ageing in Chronic Kidney Disease

Persistent low-grade inflammation and premature ageing are hallmarks of the uremic phenotype and contribute to impaired health status, reduced quality of life, and premature mortality in chronic kidney disease (CKD). Because there is a huge global burden of disease due to CKD, treatment strategies targeting inflammation and premature ageing in CKD are of particular interest. Several distinct features of the uremic phenotype may represent potential treatment options to attenuate the risk of progression and poor outcome in CKD. The nuclear factor erythroid 2-related factor 2 (NRF2)-kelch-like erythroid cell-derived protein with CNC homology [ECH]-associated protein 1 (KEAP1) signaling pathway, the endocrine phosphate-fibroblast growth factor-23-klotho axis, increased cellular senescence, and impaired mitochondrial biogenesis are currently the most promising candidates, and different pharmaceutical compounds are already under evaluation. If studies in humans show beneficial effects, carefully phenotyped patients with CKD can benefit from them.

Fructose metabolism as a common evolutionary pathway of survival associated with climate change, food shortage and droughts

Mass extinctions occur frequently in natural history. While studies of animals that became extinct can be informative, it is the survivors that provide clues for mechanisms of adaptation when conditions are adverse. Here, we describe a survival pathway used by many species as a means for providing adequate fuel and water, while also providing protection from a decrease in oxygen availability. Fructose, whether supplied in the diet (primarily fruits and honey), or endogenously (via activation of the polyol pathway), preferentially shifts the organism towards the storing of fuel (fat, glycogen) that can be used to provide energy and water at a later date. Fructose causes sodium retention and raises blood pressure and likely helped survival in the setting of dehydration or salt deprivation. By shifting energy production from the mitochondria to glycolysis, fructose reduced oxygen demands to aid survival in situations where oxygen availability is low. The actions of fructose are driven in part by vasopressin and the generation of uric acid. Twice in history, mutations occurred during periods of mass extinction that enhanced the activity of fructose to generate fat, with the first being a mutation in vitamin C metabolism during the Cretaceous-Paleogene extinction (65 million years ago) and the second being a mutation in uricase that occurred during the Middle Miocene disruption (12-14 million years ago). Today, the excessive intake of fructose due to the availability of refined sugar and high-fructose corn syrup is driving 'burden of life style' diseases, including obesity, diabetes and high blood pressure.

Biomimetics - Nature's roadmap to insights and solutions for burden of lifestyle diseases

There are over 8 million species in this world that live in widely varying environments, from hot thermal fissures to cold arctic settings. These species have evolved over millions of years and vary markedly in how they have adapted to their environments. In the last decades, studies of how species have succeeded in surviving in different environments and with different resources have been recognized to provide not only insights into disease but also novel means for developing treatments. Here, we provide an overview of two related and overlapping approaches (biomimetics and zoobiquity), which are turning to the natural world for insights to better understand, treat and prevent human 'burden of lifestyle' pathologies from heart disease and cancer to degeneration and premature ageing. We suggest that expanding biomedical investigation beyond its decades old conventional practices to new approaches based on a broad awareness of the diversity of animal life and comparative physiology can accelerate innovations in health care under the motto 'Nature knows best'.

The role of the microbiota in sedentary lifestyle disorders and ageing: lessons from the animal kingdom

A paradox of so-called developed countries is that, as the major historical causes of human mortality are eliminated or mitigated by medical progress, lifestyle-related diseases have become major killers. Furthermore, as lifespan is extended by the combined effects of modern medicine, health span is struggling to keep apace because of the burden of noncommunicable diseases linked to diet and sedentary lifestyle. The gut microbiome is now recognized as a plastic environmental risk factor for many of these diseases, the microbiome being defined as the complex community of co-evolved commensal microbes that breaks down components of a complex diet, modulates innate immunity, and produces signalling molecules and metabolites that can impact on diverse regulatory systems in mammals. Aspects of the so-called 'Western' lifestyle linked to disease risk such as energy dense diet and antibiotic treatment are known to affect the composition and function of the microbiome. Here, we review the detailed mechanisms whereby the gut microbiome may modulate risk of diseases linked to sedentary lifestyle and ageing-related health loss. We focus on the comparative value of natural animal models such as hibernation for studying metabolic regulation and the challenge of extrapolating from animal models to processes that occur in human ageing.

Early vascular ageing in chronic kidney disease: impact of inflammation, vitamin K, senescence and genomic damage

Chronic kidney disease (CKD) is a clinical model of premature ageing characterized by cardiovascular disease, persistent uraemic inflammation, osteoporosis muscle wasting and frailty. The accelerated early vascular ageing (EVA) process mediated by medial vascular calcification (VC) is a hallmark of senescence as well as a strong predictor of cardiovascular morbidity and mortality in the CKD population. Current clinical therapeutic strategies and novel treatments for VC have not yet been proven to prevent or reverse VC progression in patients with CKD. Knowledge of the fundamental mechanism underlying EVA is urgently needed to identify and develop novel and efficient therapeutic targets for VC and EVA. An accumulating body of evidence indicates that deoxyribonucleic acid (DNA) damage-induced cellular senescence and 'inflammaging' may largely contribute to such pathological conditions characterized by accelerated EVA. Growing evidence shows that nuclear factor erythroid 2-related factor 2 (NRF2) signalling and vitamin K play a crucial role in counteracting oxidative stress, DNA damage, senescence and inflammaging, whereby NRF2 activation and vitamin K supplementation may provide a novel treatment target for EVA. In this review we discuss the link between senescence and EVA in the context of CKD, with a focus on the role of NRF2 and vitamin K in DNA damage signalling, senescence and inflammaging.

Nrf2 in early vascular ageing: Calcification, senescence and therapy

Under normal physiological conditions, free radical generation and antioxidant defences are balanced, and reactive oxygen species (ROS) usually act as secondary messengers in a plethora of biological processes. However, when this balance is impaired, oxidative stress develops due to imbalanced redox homeostasis resulting in cellular damage. Oxidative stress is now recognized as a trigger of cellular senescence, which is associated with multiple chronic 'burden of lifestyle' diseases, including atherosclerosis, type-2 diabetes, chronic kidney disease and vascular calcification; all of which possess signs of early vascular ageing. Nuclear factor erythroid 2-related factor 2 (Nrf2), termed the master regulator of antioxidant responses, is a transcription factor found to be frequently dysregulated in conditions characterized by oxidative stress and inflammation. Recent evidence suggests that activation of Nrf2 may be beneficial in protecting against vascular senescence and calcification. Both natural and synthetic Nrf2 agonists have been introduced as promising drug classes in different phases of clinical trials. However, overexpression of the Nrf2 pathway has also been linked to tumorigenesis, which highlights the requirement for further understanding of pathways involving Nrf2 activity, especially in the context of cellular senescence and vascular calcification. Therefore, comprehensive translational pre-clinical and clinical studies addressing the targeting capabilities of Nrf2 agonists are urgently required. The present review discusses the impact of Nrf2 in senescence and calcification in early vascular ageing, with focus on the potential clinical implications of Nrf2 agonists and non-pharmacological Nrf2 therapeutics.

Allostatic load and ageing: linking the microbiome and nutrition with age-related health

Ageing is a process of decline in physiological function and capability over time. It is an anticipated major burden on societal health-care costs due to an increasingly aged global population. Accelerated biological ageing is a feature of age-related morbidities, which also appear to share common underpinning features, including low-grade persistent inflammation, phosphate toxicity, diminished Nrf2 activity, a depleted metabolic capability, depressed mitochondrial biogenesis and a low diversity gut microbiome.Social, psychological, lifestyle and nutritional risk factors can all influence the trajectory of age-related health, as part of an individual's exposome, which reflects the interplay between the genome and the environment. This is manifest as allostatic (over)load reflecting the burden of lifestyle/disease at both a physiological and molecular level. In particular, age-related genomic methylation levels and inflammatory status reflect exposome differences. These features may be mediated by changes in microbial diversity. This can drive the generation of pro-inflammatory factors, such as TMAO, implicated in the 'diseasome' of ageing. Additionally, it can be influenced by the 'foodome', via nutritional differences affecting the availability of methyl donors required for maintenance of the epigenome and by the provision of nutritionally derived Nrf2 agonists. Both these factors influence age-related physiological resilience and health. This offers novel insights into possible interventions to improve health span, including a rage of emerging senotherapies and simple modifications of the nutritional and environmental exposome. In essence, the emerging strategy is to treat ageing processes common to the diseasome of ageing itself and thus preempt the development or progression of a range of age-related morbidities.

Long-lived animals with negligible senescence: clues for ageing research

Among several theories to explain the complicated process of human ageing, the mitochondrial oxidative stress hypothesis has received recent attention. Considering that lifespan and ageing rates vary considerably across taxa, a better understanding of factors that lead to negligible or extremely rapid senescence in mammals may generate novel approaches to target human ageing. Several species, such as naked mole rats, ocean quahog, rockfish and Greenland shark, have been identified that exhibit negligible senescence and superior resistance to age-related diseases. Considering that the available literature suggests that their outstanding stress resistance is linked to maintenance of protein homeostasis and robust mitochondrial functions, treatments that target protein modification and upregulation of matrix antioxidants may have implications for extending human health span.

Early Vascular Ageing and Cellular Senescence in Chronic Kidney Disease

Chronic kidney disease (CKD) is a clinical model of premature ageing characterized by progressive vascular disease, systemic inflammation, muscle wasting and frailty. The predominant early vascular ageing (EVA) process mediated by medial vascular calcification (VC) results in a marked discrepancy between chronological and biological vascular age in CKD. Though the exact underlying mechanisms of VC and EVA are not fully elucidated, accumulating evidence indicates that cellular senescence - and subsequent chronic inflammation through the senescence-associated secretary phenotype (SASP) - plays a fundamental role in its initiation and progression. In this review, we discuss the pathophysiological links between senescence and the EVA process in CKD, with focus on cellular senescence and media VC, and potential anti-ageing therapeutic strategies of senolytic drugs targeting cellular senescence and EVA in CKD.