Urinary extracellular vesicles: A position paper by the Urine Task Force of the International Society for Extracellular Vesicles.

Urine is commonly used for clinical diagnosis and biomedical research. The discovery of extracellular vesicles (EV) in urine opened a new fast-growing scientific field. In the last decade urinary extracellular vesicles (uEVs) were shown to mirror molecular processes as well as physiological and pathological conditions in kidney, urothelial and prostate tissue. Therefore, several methods to isolate and characterize uEVs have been developed. However, methodological aspects of EV separation and analysis, including normalization of results, need further optimization and standardization to foster scientific advances in uEV research and a subsequent successful translation into clinical practice. This position paper is written by the Urine Task Force of the Rigor and Standardization Subcommittee of ISEV consisting of nephrologists, urologists, cardiologists and biologists with active experience in uEV research. Our aim is to present the state of the art and identify challenges and gaps in current uEV-based analyses for clinical applications. Finally, recommendations for improved rigor, reproducibility and interoperability in uEV research are provided in order to facilitate advances in the field.

Circadian variation in the release of small extracellular vesicles can be normalized by vesicle number or TSG101.

Numerous candidate biomarkers in urine extracellular vesicles (EVs) have been described for kidney diseases, but none are yet in clinical use, possibly due to a lack of proper normalization. Proper normalization corrects for normal biological variation in urine flow rate or concentration, which can vary by over one order of magnitude. Here, we observed inter- and intra-animal variation in urine excretion rates of small EVs (<200 nm in diameter) in healthy rats as a series of six 4-h fractions. To visualize intra-animal variation, we normalized a small EV excretion rate to a peak excretion rate, revealing a circadian pattern for each rat. This circadian pattern was distinct from urine volume, urine albumin, urine creatinine, and urine albumin-to-creatinine ratio. Furthermore, urine small EV excretion was not significantly altered by sex, food/water deprivation, or ischemic acute kidney injury. Urine excretion of the exosomal/small EV marker protein tumor susceptibility gene 101 (TSG101) displayed a similar circadian pattern to urine small EV excretion; both measurements were highly correlated (R2 = 0.85), with an average stoichiometry of 10.0 molecules of TSG101/vesicle in healthy rats. The observed stoichiometry of TSG101/vesicle in rat urine translated to human spot urine samples (10.2 molecules/vesicle) and cultured kidney-derived cell lines (human embryonic kidney-293 and normal rat kidney 52E cells). Small EV number and its surrogate, TSG101 protein, can normalize for circadian variation when testing candidate biomarkers in small EVs. Just as creatinine has emerged as the customary normalization factor for liquid-phase urine biomarkers, vesicle number and its surrogate, molecules of exosome/small EV-associated TSG101, should be considered as viable, normalizing factors for small EV biomarkers.

The role of adenosine 1a receptor signaling on GFR early after the induction of sepsis.

Sepsis and acute kidney injury (AKI) synergistically increase morbidity and mortality in the ICU. How sepsis reduces glomerular filtration rate (GFR) and causes AKI is poorly understood; one proposed mechanism includes tubuloglomerular feedback (TGF). When sodium reabsorption by the proximal tubules is reduced in normal animals, the macula densa senses increased luminal sodium chloride, and then adenosine-1a receptor (A1aR) signaling triggers tubuloglomerular feedback, reducing GFR through afferent arteriole vasoconstriction. We measured GFR and systemic hemodynamics early during cecal ligation and puncture-induced sepsis in wild-type and A1aR-knockout mice. A miniaturized fluorometer was attached to the back of each mouse and recorded the clearance of FITC-sinistrin via transcutaneous fluorescence to monitor GFR. Clinical organ injury markers and cytokines were measured and hemodynamics monitored using implantable transducer telemetry devices. In wild-type mice, GFR was stable within 1 h after surgery, declined by 43% in the next hour, and then fell to less than 10% of baseline after 2 h and 45 min. In contrast, in A1aR-knockout mice GFR was 37% below baseline immediately after surgery and then gradually declined over 4 h. A1aR-knockout mice had similar organ injury and inflammatory responses, albeit with lower heart rate. We conclude that transcutaneous fluorescence can accurately monitor GFR and detect changes rapidly during sepsis. Tubuloglomerular feedback plays a complex role in sepsis; initially, TGF helps maintain GFR in the 1st hour, and over the subsequent 3 h, TGF causes GFR to plummet. By 18 h, TGF has no cumulative effect on renal or extrarenal organ damage.

Prevalence of HIV Infection among U.S. Hodgkin lymphoma cases.

BACKGROUND: Hodgkin lymphoma is uncommon in the U.S. general population; however, Hodgkin lymphoma risk is elevated in people with human immunodeficiency virus (HIV) infection. Thus, despite the low HIV prevalence in the United States, the HIV epidemic may have contributed substantially to the general population burden of Hodgkin lymphoma. METHODS: We used data from 14 U.S. cancer registries in the Surveillance, Epidemiology, and End Results Program that recorded HIV status of Hodgkin lymphoma cases at diagnosis during 2000 to 2010. We computed the HIV prevalence in Hodgkin lymphoma cases by demographic and tumor characteristics, the proportion of deaths among Hodgkin lymphoma cases because of HIV, and 5-year mortality by HIV status. RESULTS: Of 22,355 Hodgkin lymphoma cases, 848 (3.79%) were HIV infected at diagnosis. HIV prevalence in Hodgkin lymphoma cases was greater among males than females (6.0% vs. 1.2%). Among males, HIV prevalence was greatest among 40- to 59-year-olds (14.2%), non-Hispanic blacks (16.9%), Hispanics (9.9%), and among cases of lymphocyte-depleted (15.1%), and mixed cellularity Hodgkin lymphoma (10.5%). Eight percent of male and 1.5% of female Hodgkin lymphoma cases died from HIV. Five-year mortality was two-fold higher in HIV-infected Hodgkin lymphoma cases (36.9% vs. 17.5%). CONCLUSION: In the United States, a substantial proportion of lymphocyte-depleted and mixed cellularity Hodgkin lymphoma cases and Hodgkin lymphoma cases among non-Hispanic black, Hispanic, and middle-aged men are HIV infected. In addition, HIV is an important cause of death among Hodgkin lymphoma cases. IMPACT: Clinicians should be aware of the high prevalence of HIV in certain subgroups of patients with Hodgkin lymphoma and routine HIV testing should be recommended for all patients presenting with Hodgkin lymphoma.