Role of the Renal Lymphatic System in Heart Failure.

PURPOSE OF REVIEW: The lymphatic system plays a major but overlooked role in maintaining fluid homeostasis. Given the unique fluid homeostasis functions of the kidneys, dysregulation of the renal lymphatic system underlies the development of self-propagating congestive pathomechanisms. In this review, we outline the roles of the renal lymphatic system in heart failure (HF). RECENT FINDINGS: Studies have uncovered several pathomechanisms involving the renal lymphatic system in congestive states, such as impaired interstitial draining by the renal lymphatic system, impaired structure and valves of renal lymphatics, lymphatic-induced increase in renal reabsorption of water and sodium, and development of albuminuria with proteinuria-induced renal lymphangiogenesis. These self-propagating mechanisms result in "renal tamponade" with manifestations of cardiorenal syndrome and inappropriate renal response to diuretics. Dysregulation of the renal lymphatic system is integral to the development and progression of congestion in HF. Targeting renal lymphatics may provide a novel pathway to treat intractable congestion.

Renal pedicle lymphatic ligation for non-parasitic chyluria via retroperitoneal laparoscopic surgery: a single-center 12-year experience.

Background: Chyluria is a rare disease in which chylous is excreted in the urine. Currently, management of chyluria includes conservative treatments and surgical measures. This study aimed to report our experience in treating non-parasitic chyluria with retroperitoneal laparoscopic ligation of the renal lymphatic vessels. Methods: Data from 52 patients who underwent retroperitoneoscopic ligation of the renal lymphatic vessels for non-parasitic chyluria between December 2009 and May 2022 were reviewed. After general anesthesia, the patients were passively placed in the healthy lateral decubitus position and underwent three-port retroperitoneal laparoscopy. Detailed medical data, including demographic characteristics, intraoperative outcomes, postoperative data, and complications, were reviewed. Results: Fifty-two patients received surgery treatment at our institution. The mean disease course was 89.3 months. The mean age was 58.8 years, with females accounting for 57.7% (30/52); the majority of patients (33/52) had the laterality of chyluria on the left and 9 (17.3%) had a history of previous thoracic or abdominal surgery. Compared with the urine and blood data before the operation and on the first day after the operation, urinary protein, urinary tract infection, urinary red blood cells, hemoglobin, albumin, and serum total protein significantly improved 3 months after the operation. However, there were no significant differences in blood creatinine and blood urea nitrogen levels among the three groups. The mean surgery time was about 110.0 minutes, and the estimated total blood loss was 81.2 mL. The postoperative drainage volume was 229.9 mL. The average time to start a liquid diet and to be out of bed were 1.5 and 1.9 days, respectively. Transient postoperative gross hematuria occurred in eight patients, and complications occurred in five patients after surgery. The mean length of hospitalization was 6.6 days. The follow-up duration ranged from 3 to 152 months, and except for three patients who did not respond to treatment, the remaining patients had no recurrence and did not require reoperation. Conclusions: Our long-term follow-up results showed that renal pedicle lymphatic ligation via retroperitoneal laparoscopic surgery is an effective, safe, and reliable surgical option for patients with non-parasitic chyluria.

Mediators of Regional Kidney Perfusion during Surgical Pneumo-Peritoneum Creation and the Risk of Acute Kidney Injury-A Review of Basic Physiology.

Acute kidney injury (AKI), especially if recurring, represents a risk factor for future chronic kidney disease. In intensive care units, increased intra-abdominal pressure is well-recognized as a significant contributor to AKI. However, the importance of transiently increased intra-abdominal pressures procedures is less commonly appreciated during laparoscopic surgery, the use of which has rapidly increased over the last few decades. Unlike the well-known autoregulation of the renal cortical circulation, medulla perfusion is modulated via partially independent regulatory mechanisms and strongly impacted by changes in venous and lymphatic pressures. In our review paper, we will provide a comprehensive overview of this evolving topic, covering a broad range from basic pathophysiology up to and including current clinical relevance and examples. Key regulators of oxidative stress such as ischemia-reperfusion injury, the activation of inflammatory response and humoral changes interacting with procedural pneumo-peritoneum formation and AKI risk will be recounted. Moreover, we present an in-depth review of the interaction of pneumo-peritoneum formation with general anesthetic agents and animal models of congestive heart failure. A better understanding of the relationship between pneumo-peritoneum formation and renal perfusion will support basic and clinical research, leading to improved clinical care and collaboration among specialists.

Targeting tubulointerstitial remodeling in proteinuric nephropathy in rats.

Proteinuria is an important cause of tubulointerstitial damage. Anti-proteinuric interventions are not always successful, and residual proteinuria often leads to renal failure. This indicates the need for additional treatment modalities by targeting the harmful downstream consequences of proteinuria. We previously showed that proteinuria triggers renal lymphangiogenesis before the onset of interstitial inflammation and fibrosis. However, the interrelationship of these interstitial events in proteinuria is not yet clear. To this end, we specifically blocked lymphangiogenesis (anti-VEGFR3 antibody), monocyte/macrophage influx (clodronate liposomes) or lymphocyte and myofibroblast influx (S1P agonist FTY720) separately in a rat model to investigate the role and the possible interaction of each of these phenomena in tubulointerstitial remodeling in proteinuric nephropathy. Proteinuria was induced in 3-month old male Wistar rats by adriamycin injection. After 6 weeks, when proteinuria has developed, rats were treated for another 6 weeks by anti-VEGFR3 antibody, clodronate liposomes or FTY720 up to week 12. In proteinuric rats, lymphangiogenesis, influx of macrophages, T cells and myofibroblasts, and collagen III deposition and interstitial fibrosis significantly increased at week 12 vs week 6. Anti-VEGFR3 antibody prevented lymphangiogenesis in proteinuric rats, however, without significant effects on inflammatory and fibrotic markers or proteinuria. Clodronate liposomes inhibited macrophage influx and partly reduced myofibroblast expression; however, neither significantly prevented the development of lymphangiogenesis, nor fibrotic markers and proteinuria. FTY720 prevented myofibroblast accumulation, T-cell influx and interstitial fibrosis, and partially reduced macrophage number and proteinuria; however, it did not significantly influence lymphangiogenesis and collagen III deposition. This study showed that proteinuria-induced interstitial fibrosis cannot be halted by blocking lymphangiogenesis or the influx of macrophages. On the other hand, FTY720 treatment did prevent T-cell influx, myofibroblast accumulation and interstitial fibrosis, but not renal lymphangiogenesis and proteinuria. We conclude that tubulointerstitial fibrosis and inflammation are separate from lymphangiogenesis, at least under proteinuric conditions.

Modified technique of renal pedicle lymphatic disconnection for chyluria through the laparoscopic surgery.

Fifteen cases of chyluria were diagnosed by Sudan staining test and the sides of chylous reflux were determined by cystoscopy. All patients underwent the modified laparoscopic technique. The operations had been successfully without unexpected injury. The postoperative urine chyle tests were negative in all patients. Recurrence developed in 1 patient during the follow-up. The modified technique does not require complete disconnection of perirenal fat tissue and fasciectomy diminishing necessity of nephropexy and preventing renal torsion. It is a feasible and effective surgical procedure for chyluria with a short operation time, minimal invasion and few complications.