Kidney Aging: From Phenotype to Genetics

The Consequences of Aging On the Response to Injury and Critical Illness

Changing demographic trends have led to an increase in the overall geriatric trauma patient volume. Furthermore, the intersection of aging and injury can be problematic because geriatric patients have multiple comorbidities, geriatric-specific syndromes, and reduced physiological reserve. Despite mounting evidence that frail geriatric patients have inferior outcomes following trauma, very few studies have examined the effect of aging on the biological response to injury. In the present article, we review the current literature and explore the pathophysiological rationale underlying observed data, available evidence, and future directions on this topic.

Methionine restriction delays senescence and suppresses the senescence-associated secretory phenotype in the kidney through endogenous hydrogen sulfide

Aging is a risk factor for various acute and chronic kidney injuries. Kidney aging is accompanied by the secretion of growth factors, proteases, and inflammatory cytokines, known as the senescence-associated secretory phenotype (SASP). These factors accelerate the aging process and senescence-associated changes. Delaying kidney senescence may prevent acute and chronic kidney injury. Methionine restriction (MR) was found to be an effective intervention for delaying senescence. However, the mechanism of MR remains unclear. In this study, we investigated the effect of MR on the survival rate and renal aging of C57BL/6 mice and examined the relevant mechanisms. MR increased the survival rate and decreased the levels of senescence markers in the aging kidney. Both in vivo and in vitro, MR upregulated the transsulfuration pathway to increase H₂S production, downregulated senescence markers and the SASP, and activated AMPK. The ability of MR to delay aging was reduced when AMPK was inhibited. These results suggest that MR may slow animal aging and kidney senescence through H₂S production and AMPK pathway activation. Abbreviations: DR: diet restriction; MR: methionine restriction; SASP: senescence-associated secretory phenotype; AL: ad libitum; CKD, chronic kidney disease; AKI: acute kidney disease; TSP: transsulfuration pathway; CGL: cystathionine g-lyase; H₂S: hydrogen sulfide; AMPK: AMP-activated protein kinase; mTOR: mammalian target of rapamycin; IS: indoxyl sulfate; CC: compound C.

Aging Kidney and Aging-Related Disease

With the development of society and improvement of health care, the life span is much longer than before, which brings serious aging problems. Among all the aging problems, renal aging grows to be nonnegligible issue. The aging process of kidney is always accompanied with structural and functional changes. Molecular changes, including Klotho and Sirtuins, are the basic causes of phenotypical changes. Cell senescence and cell autophagy play fundamental roles in the process of renal aging. To effectively intervene in the process of renal aging, different methods have been tried separately, which could produce different effects. Effective intervention of renal aging could be meaningful for healthy state of the whole body.

End-Stage Organ Failure: Will Regenerative Medicine Keep its Promise?

End-stage organ failure is a major cause of death worldwide that can occur in patients of all ages and transplantation is the current standard of care for chronic end-stage disease of many organs. Despite the success of organ transplantation, it is becoming clear that there will never be enough organs made available through donation to meet the increasing demand. The past decade's rapid advancement in stem cell biology and tissue engineering generated an explosive outburst of reports that gave rise to regenerative medicine, a new field that promises to “fix” damaged organs through regeneration provided by transplanted cells, stimulation of endogenous repair mechanisms, or implantation of bioengineered tissue. Whether, and if so when, regenerative medicine will keep its promise is uncertain. As we continue to strive to find new effective solutions, alternative approaches based on the development of targeted, preventive interventions aimed at maintaining normal organ function, instead of repairing organ damage, should also be pursued.

The Expression Changes of Inflammasomes in the Aging Rat Kidneys

The mechanisms of kidney aging are not yet clear. Studies have shown that immunological inflammation is related to kidney aging. Inflammasomes are important components of innate immune system in the body. However, the function of inflammasomes and their underlying mechanisms in renal aging remain unclear. In this study, for the first time, we systematically investigated the role of the inflammasomes and the inflammatory responses activated by inflammasomes during kidney aging. We found that during kidney aging, the expression levels of the molecules associated with the activation of inflammasomes, including toll-like receptor-4 and interleukin-1 receptor (IL-1R), were significantly increased; their downstream signaling pathway molecule interleukin-1 receptor-associated kinase-4 (IRAK4) was markedly activated (Phospho-IRAK4 was obviously increased); the nuclear factor-κB (NF-κB) signaling pathway was activated (the activated NF-κB pathway molecules Phospho-IKKβ, Phospho-IκBα, and Phospho-NF-κBp65 were significantly elevated); the levels of the inflammasome components NOD-like receptor P3 (NLRP3), NLRC4, and pro-caspase-1 were prominently upregulated; and the proinflammatory cytokines IL-1β and IL-18 were notably increased in the kidneys of 24-month-old (elderly group) rats. These results showed that inflammasomes are markedly activated during the renal aging process and might induce inflamm-aging by promoting the maturation and secretion of the proinflammatory cytokines IL-1β and IL-18.

Hepatoprotective Effects of Swimming Exercise against D-Galactose-Induced Senescence Rat Model

This study investigates whether a 12-week swimming exercise training can prevent liver damage or senescence associated biomarkers in an experimental aging model in rats. Twenty-three male Sprague-Dawley rats were divided into four groups: vehicle treatment with sedentary control (C, n = 6), aging induction with sedentary (A, n = 6), vehicle treatment with swimming exercise (SW, n = 5), and aging induction with swimming exercise (A + SW, n = 6). Rats in groups A and AS received intraperitoneal d-galactose injections (150 mg/kg/day) for 12 weeks to induce aging. Rats in groups SW and A + SW were subjected to swimming exercise training for 12 weeks. Body weight, liver weight, epididymal fat mass, blood biochemistry, and liver pathology were performed at the end of the experiment. Hepatic senescence protein markers such as β-galactosidase, p53, and p21, as well as the inflammatory mediator, IL-6, were examined. The d-galactose-treated rats exhibited increases in AST and γ-GT plasma levels and β-galactosidase protein expression compared to the control group. Swimming exercise significantly reduced BW, epididymal fat mass, γ-GT activity, and p53, p21, and IL-6 protein levels compared to the aging group. These results suggest that a 12-week swimming exercise program suppresses senescence markers and downregulates inflammatory mediator in the liver tissues of d-galactose-induced aging rats.

Unique Aspects of the Elderly Surgical Population: An Anesthesiologist's Perspective

Increasing life expectancies paired with age-related comorbidities have resulted in the continued growth of the elderly surgical population. In this group, age-associated changes and decreased physiological reserve impede the body's ability to maintain homeostasis during times of physiological stress, with a subsequent decrease in physiological reserve. This can lead to age-related physiological and cognitive dysfunction resulting in perioperative complications. Changes in the cardiovascular, pulmonary, nervous, hepatorenal, endocrine, skin, and soft tissue systems are discussed as they are connected to the perioperative experience. Alterations affect both the pharmacodynamics and pharmacokinetics of administered drugs. Elderly patients with coexisting diseases are at a greater risk for polypharmacy that can further complicate anesthetic management. Consequently, the importance of conducting a focused preoperative evaluation and identifying potential risk factors is strongly emphasized. Efforts to maintain intraoperative normothermia have been shown to be of great importance. Procedures to maintain stable body temperature throughout the perioperative period are presented. The choice of anesthetic technique, in regard to a regional versus general anesthetic approach, is debated widely in the literature. The type of anesthesia to be administered should be assessed on a case-by-case basis, with special consideration given to the health status of the patient, the type of operation being conducted, and the expertise of the anesthesiologist. Specifically addressed in this article are age-related cognitive issues such as postoperative cognitive dysfunction and postoperative delirium. Strategies are suggested for avoiding these pitfalls.

Trauma in the elderly: considerations for anesthetic management

The volume of geriatric trauma patients is expected to increase significantly in coming years. Recognition of severe injuries may be delayed because they are less likely to mount classic symptoms of hemodynamic instability. Head injuries of any severity may place geriatric patients at increased risk of mortality, but there are currently no geriatric-specific treatment recommendations that differ from usual adult guidelines. Our understanding of best practices in geriatric trauma and anesthesia care continues to expand, as it does in all other areas of medicine.

Renal senescence in 2008: progress and challenges

Kidneys are significantly affected by profound anatomic and functional changes with senescence. These changes lead to decline in glomerular filtration rate, decreased urinary concentrating and diluting ability, diminished urinary acidification, and impaired potassium clearance, to list a few. Such changes make the elderly prone to drug toxicity and serious fluid and electrolyte imbalance. While the entire mystery of aging is far from being clear, the role of oxidative stress, telomere length, Klotho gene expression, and the renin angiotensin system seem to be the key mechanisms involved in aging. Aging, being a complex process, involves an array of intertwined molecular pathways. Simultaneous study of multiple molecular pathways in parallel could provide invaluable information in understanding the clinical course of kidney aging and elucidating mechanisms that play key roles in the aging process. A better understanding of these mechanisms may help to preserve renal function, improve morbidity and mortality, and hopefully reduce healthcare costs for the aging population.

Telomere dysfunction in hypertension

Aging is a major risk factor for hypertension and associated cardiovascular disease. In most proliferative tissues, aging is characterized by shortening of the DNA component of telomeres, the specialized genetic segments that cap the end of eukaryotic chromosomes and protect them from end-to-end fusions. By inducing genomic instability, replicative senescence and apoptosis, telomere shortening is thought to contribute to organismal aging and to the development of age-related diseases. Here, we review animal and human studies that have investigated the possible links between telomere ablation and the pathogenesis of hypertension and related target organ damage. Although evidence is mounting that alterations in telomerase activity and telomere shortening may play a role in the pathogenesis of hypertension, additional studies are required to understand the molecular mechanisms by which telomere dysfunction and hypertension are functionally connected. As our knowledge on this emerging field grows, the challenge will be to ascertain whether all this information might translate into clinical applications.

Chronic kidney disease after myeloablative allogeneic hematopoietic stem cell transplantation

Because survival of recipients of allogeneic hematopoietic stem cell transplantation (HSCT) has improved, long-term complications become more important. We studied the incidence and risk factors of chronic kidney disease in these patients and evaluated associated posttransplant complications and mortality. We performed a retrospective cohort study of 266 adults who received myeloablative allogeneic HSCT and who survived for >6 months in an 11-year period at a Dutch university medical center. Primary outcome was the incidence of chronic kidney disease defined as a glomerular filtration rate (GFR) of <60 mL/min/1.73 m(2). Chronic kidney disease developed in 61 (23%) of 266 patients, with a cumulative incidence rate of 27% at 10 years. Severe kidney disease (GFR of <30 mL/min/1.73 m(2)) developed in 3% of patients. Only 6 patients developed the thrombotic microangiopathic syndrome SCT nephropathy, and 2 of them needed dialysis. Pretransplant risk factors for chronic kidney disease were lower GFR at day 0 (P < .0001, odds ratio [OR] 0.95 95% confidence interval [CI] 0.93-0.97), female gender, and higher age (P = .001 and P < .0001, respectively). The occurrence of hypertension after transplantation was associated with chronic kidney disease (P < .0001, OR 0.34 95% CI 0.18-0.62). Mortality was 39% after a mean follow-up of 5.1 years. There was no significant difference in survival between patients with and without chronic kidney disease. Chronic kidney disease is a common late complication of myeloablative allogeneic HSCT. Because of the natural decline in renal function with time there is a risk of developing end-stage renal disease in the future. SCT nephropathy seems to be a specific cause of chronic kidney disease that is typically associated with severe kidney disease.

Geriatric trauma: special considerations in the anesthetic management of the injured elderly patient

Modern society is characterized as having an ever enlarging population of older adults. There are more elderly patients, and the average age of this group is increasing. The anesthetic management of surgery for the elderly trauma victim is more complicated than in younger adults. Evaluation of the physiologic status of the geriatric patient should take into account the variability of the changes associated with advancing age. Care of the injured elderly patient requires thorough preoperative assessment and planning and the involvement of a multidisciplinary clinical team knowledgeable about and interested in the management of the elderly surgical patient.

Transplantation and regeneration in the heart of the Mediterranean

The second half of the 20th century witnessed the birth of organ transplantation, and failing organs can now be replaced with healthy ones procured from living or cadaveric donors, allowing their recipient to start, or return to, an active life. Major milestones in the field were set in the eighties and nineties at the University of Pittsburgh Medical Center (UPMC), an institution that made it a mission to spread its expertise internationally. A successful partnership between UPMC and the Region of Sicily gave rise to the Mediterranean Institute for Transplantation and Highly Specialized Therapies (ISMETT), the only Italian facility entirely dedicated to transplantation of all solid organs and therapies for the treatment of end-stage organ failure. In its first seven years of activity, ISMETT has become a major referral center for patients from the entire Mediterranean Basin and the Middle East. Despite the fact that organ transplantation is the current gold standard for end-stage organ failure, the field is facing a worldwide emergency represented by the chronic shortage of organ donors. Research aimed at understanding the molecular networks involved in organ-specific ageing and their relationship with maintenance networks and organ failure should be actively encouraged and supported as it could ultimately allow to control organ performance and lifespan, increasing the number of organs available for transplant.