Septic acute kidney injury and gut microbiome: Should we change our approach?

Incidence of acute kidney injury (AKI) remained relatively stable over the last decade and the adjusted risks for it and mortality are similar across different continents and regions. Also, the mortality of septic-AKI can reach 70% in critically-ill patients. These sole facts can give rise to a question: is there something we do not understand yet? Currently, there are no specific therapies for septic AKI and the treatment aims only to maintain the mean arterial pressure over 65mmHg by ensuring a good fluid resuscitation and by using vasopressors, along with antibiotics. On the other hand, there is an increased concern about the different hemodynamic changes in septic AKI versus other forms and the link between the gut microbiome and the severity of septic AKI. Fortunately, progress has been made in the form of administration of pre- and probiotics, short chain fatty acids (SCFA), especially acetate, and also broad-spectrum antibiotics or selective decontaminants of the digestive tract in a successful attempt to modulate the microbial flora and to decrease both the severity of AKI and mortality. In conclusion, septic-AKI is a severe form of kidney injury, with particular hemodynamic changes and with a strong link between the kidney and the gut microbiome. By modulating the immune response we could not only treat but also prevent severe forms. The most difficult part is to categorize patients and to better understand the key mechanisms of inflammation and cellular adaptation to the injury, as these mechanisms can serve in the future as target therapies.

Septic acute kidney injury and gut microbiome: Should we change our approach? / Lesión renal aguda secundaria a sepsis y microbioma intestinal: ¿debemos modificar nuestro enfoque?

Incidence of acute kidney injury (AKI) remained relatively stable over the last decade and the adjusted risks for it and mortality are similar across different continents and regions. Also, the mortality of septic-AKI can reach 70% in critically-ill patients. These sole facts can give rise to a question: is there something we do not understand yet? Currently, there are no specific therapies for septic AKI and the treatment aims only to maintain the mean arterial pressure over 65mmHg by ensuring a good fluid resuscitation and by using vasopressors, along with antibiotics. On the other hand, there is an increased concern about the different hemodynamic changes in septic AKI versus other forms and the link between the gut microbiome and the severity of septic AKI. Fortunately, progress has been made in the form of administration of pre- and probiotics, short chain fatty acids (SCFA), especially acetate, and also broad-spectrum antibiotics or selective decontaminants of the digestive tract in a successful attempt to modulate the microbial flora and to decrease both the severity of AKI and mortality. In conclusion, septic-AKI is a severe form of kidney injury, with particular hemodynamic changes and with a strong link between the kidney and the gut microbiome. By modulating the immune response we could not only treat but also prevent severe forms. The most difficult part is to categorize patients and to better understand the key mechanisms of inflammation and cellular adaptation to the injury, as these mechanisms can serve in the future as target therapies.(AU)

La incidencia de la lesión renal aguda (LRA) se ha mantenido relativamente estable a lo largo de la última década, con unos riesgos ajustados de padecer y morir a consecuencia de esta enfermedad similares en los distintos continentes y regiones. La mortalidad asociada a la LRA secundaria a sepsis puede llegar a 70% en los pacientes que se encuentran en estado crítico. Estos hechos, por sí mismos, deben llevarnos a plantearnos la siguiente pregunta: ¿se nos escapa algo que aún no comprendemos? Actualmente no se dispone de terapias específicas para la LRA secundaria a sepsis y el tratamiento se centra únicamente en mantener la presión arterial media por encima de los 65mmHg mediante una rehidratación adecuada, vasopresores y antibióticos. Asimismo, cada vez existe mayor interés por las diferentes alteraciones hemodinámicas que se producen en comparación con otras formas de la enfermedad, así como por la relación existente entre el microbioma intestinal y la gravedad. Afortunadamente, se ha avanzado notablemente en la forma en la que se administran los prebióticos y los probióticos, los ácidos grasos de cadena corta (AGCC), especialmente el acetato, los antibióticos de amplio espectro o los detoxificantes selectivos del tracto digestivo, en un intento exitoso de modular la flora microbiana y disminuir tanto la gravedad de la LRA como su mortalidad. En conclusión, la LRA secundaria a sepsis es una forma grave de lesión renal que provoca unos cambios hemodinámicos específicos y en la que se observa una estrecha relación entre la función renal y el microbioma intestinal. La modulación de la respuesta inmunitaria no solo permitiría tratar esta enfermedad, sino también prevenir las formas graves de la misma. La parte más difícil de este enfoque radica en clasificar correctamente a los pacientes y comprender mejor los mecanismos clave de la inflamación y la adaptación celular a la lesión, ya que estos pueden convertirse en futuras dianas terapéuticas.(AU)

Chronic Kidney Disease, Urinary Tract Infections and Antibiotic Nephrotoxicity: Are There Any Relationships?

Chronic kidney disease (CKD) has been a constant burden worldwide, with a prevalence of more than 10% of the population and with mortality reaching 1.2 million deaths and 35.8 million disability-adjusted life years (DALYs) in 2017, as it is claimed by the Global Burden of Diseases. Moreover, an increase in its prevalence is expected in the next years due to a rise in the number of people suffering from obesity, diabetes mellitus and hypertension. On the other hand, with cardiovascular morbidity and mortality showing a downward trend, maybe it is time to focus on CKD, to minimize the preventable risk factors involved in its progression toward end-stage kidney disease (ESKD) and to offer a better quality of life. Another major health burden is represented by infectious diseases, particularly urinary tract infections (UTIs), as it is considered that approximately 40-50% of women and 5% of men will have at least one episode during their lifetime. Additionally, CKD consists of a constellation of immunological and metabolical disturbances that lead to a greater risk of UTIs: increased apoptosis of lymphocytes, elevated levels of tumor necrosis factor α and interleukin 6, which lower the function of neutrophils and increased levels of uremic toxins like p-cresyl sulfate and indoxyl sulfate, which alter the adherence and migration of leukocytes to the sites of injury. Moreover, UTIs can lead to a more rapid decline of kidney function, especially in stages G3-G5 of CKD, with all the complications involved. Last, but not least, antibiotherapy is often complicated in this category of patients, as antibiotics can also negatively affect the kidneys. This review will try to focus on the particularities of the urinary microbiome, asymptomatic bacteriuria and UTIs and the subtle balance between the risks of them and the risks of antibiotherapy in the evolution of CKD.

Clinical and pathological considerations on renal diseases in patients with chronic viral hepatitis.

Chronic viral hepatitis B and C may associate different extrahepatic manifestations and renal disease is the most frequent. Kidney damage is represented in most cases by glomerulopathies, which include membranous nephropathy, membranoproliferative glomerulonephritis (MPGN), IgA nephropathy, focal and segmental glomerulosclerosis and diabetic nephropathy. We conducted a retrospective study on 639 patients diagnosed with chronic viral hepatitis B and C and different renal diseases. Complete evaluation of liver and renal status was performed and, in selected cases, renal biopsy. The evaluation of our cases allowed us to uncover that 82 (12.8%) patients presented a renal disease that could be linked to the viral infection. In order to identify the histopathological type of the renal lesions, kidney biopsy was performed in 39 of our patients. In hepatitis B virus (HBV) infection, the most frequent glomerulopathy was represented by membranous nephropathy, while in chronic hepatitis C infection, MPGN was responsible for the majority of glomerulonephritis. Most patients with MPGN and hepatitis C virus (HCV) also presented mixed cryoglobulinemia. Immunoglobulin A (IgA) nephropathy was present in both liver diseases while diabetic nephropathy was only found in HCV infection, in the context in which chronic hepatitis C is a risk factor for the development of type II diabetes mellitus.