Indicators of acute and persistent renal damage in adult thrombotic microangiopathy

Underlying Mechanisms and Treatment of Hypertension in Glomerular Diseases

PURPOSE OF REVIEW

This review aims to explore the underlying mechanisms that lead to hypertension in glomerular diseases and the advancements in treatment strategies and to provide clinicians with valuable insights into the pathophysiological mechanisms and evidence-based therapeutic approaches for managing hypertension in patients with glomerular diseases.

RECENT FINDINGS

In recent years, there have been remarkable advancements in our understanding of the immune and non-immune mechanisms that are involved in the pathogenesis of hypertension in glomerular diseases. Furthermore, this review will encompass the latest data on management strategies, including RAAS inhibition, endothelin receptor blockers, SGLT2 inhibitors, and immune-based therapies. Hypertension (HTN) and cardiovascular diseases are leading causes of mortality in glomerular diseases. The latter are intricately related with hypertension and share common pathophysiological mechanisms. Hypertension in glomerular disease represents a complex and multifaceted interplay between kidney dysfunction, immune-mediated, and non-immune-mediated pathology. Understanding the complex mechanisms involved in this relationship has evolved significantly over the years, shedding light on the pathophysiological processes underlying the development and progression of glomerular disease-associated HTN, and is crucial for developing effective therapeutic strategies and improving patients' outcomes.

Thrombocytopenia Secondary to COVID-19: Outcomes Analysis in Terms of Thrombotic Microangiopathy, Acute Kidney Injury, and Mortality

Background: COVID-19 usually complicates respiratory failure; microvascular, macrovascular, and renal complications are common. Both micro and macrovascular complications are associated with multi-organ dysfunction and in-hospital mortality. Thrombotic microangiopathy (TMA) causes microvascular thromboses associated with organ failure, including acute kidney injury (AKI). Materials and Methods: This Retrospective Cohort study included 100 COVID-19 patients with thrombocytopenia, followed up in a university hospital's intensive care unit (ICU). The primary endpoints were in-hospital mortality or discharge from the hospital and assessing the occurrence of TMA and AKI during the hospitalization. The effect of thrombotic microangiopathy and acute kidney injury on mortality was investigated using logistic regression models in Stata software version 12.1. Results: The TMA and AKI were associated with in-hospital mortality in COVID-19 patients presenting with thrombocytopenia in multivariate regression analysis, adjusted for other variables. The effect of AKI on mortality was obtained (adjusted OR 4.09, 95% CI: 1.33-12.53, p = 0.01). Moreover, the odds of mortality due to TMA were ten-fold higher in the patients who had TMA than those who did not (adjusted OR 10.26, 95% CI: 1.26-83.76, p = 0.03). Conclusion: We outlined TMA in COVID-19 patients, which could be responsible for kidney injury and mortality in critically COVID-19 patients.

What is the impact of blood pressure on neurological symptoms and the risk of ESKD in primary and secondary thrombotic microangiopathies based on clinical presentation: a retrospective study

Background

The impact of blood pressure on neurological symptoms and risk of end-stage kidney disease (ESKD) is unknown in primary and secondary thrombotic microangiopathies (TMAs).

Methods

We measured baseline systolic (SBP) and diastolic (DBP) BP in consecutive 563 patients with adjudicated primary and secondary TMAs, and assessed its association with the risk of ESKD.

Results

Normal BP, grade 1, 2 and 3 hypertension were present in 243 (43.1%), 132 (23.4%), 101 (17.9%) and 88 (15.6%), respectively.

Significant BP differences were noted in relation to the cause of TMA: highest BP values were found in patients with atypical hemolytic-uremic syndrome (aHUS), pregnancy, transplantation and auto-immune-related TMAs. Normal BP or grade 1 hypertension was found in 17/18 (94.4%) patients with thrombotic thrombocytopenic patients (only 1/18 (5.6%) had a SBP value>150 mmHg). In contrast, BP values could not differentiate isolated “essential” malignant hypertension (MH) from MH associated with aHUS (isolated MH (n=15): BP (median (IQR)): 220 (182-249)/132 (101-150) mmHg; MH with aHUS (n=5): BP: 223 (196-245)/131 (111-144) mmHg).

The risk of vigilance disturbances (6.9%, 15.0%, 25.0%, respectively), epileptic seizures (1.5%, 4.0%, 12.5%, respectively) and posterior reversible encephalopathy syndrome (0.76%, 2.97%, 6.82%, respectively) increased with increasing baseline BP values from grade 1 to grade 3 hypertension.

ESKD occurred in 35/563 (6.2%) patients (1.23%, 2.27%, 11.9% and 19.3% of patients with normal BP, grade 1, 2 and 3 hypertension, respectively). As compared to patients with normal BP (<120/139 mmHg), grade 1, grade 2 and grade 3 hypertension were associated with a greater risk of ESKD in univariate (OR: 1.91 [0.83-4.40], 13.2 [3.56-48.9] and 34.8 [9.31-130], respectively) and multivariate (OR: 0.89 [0.30-2.69], 7.00 [1.57-31.3] and 19.7 [4.53-85.2], respectively) analyses. The association between BP and the risk of ESRD was unchanged after adjustment on eculizumab use (OR: 3.46 [1.41-8.49], 17.7 [4.44-70.0] and 70.6 [8.61-579], respectively). Patients with MH, regardless of its cause, had a greater risk of ESKD (OR: 26.4 [10.0-69.8] vs other patients).

Conclusions

Baseline BP differs in primary and secondary TMAs. High BP reduces the neurological tolerance of TMAs and is a powerful independent risk factor of ESKD, even after adjustment on TMA’s cause.

Infection-related hospitalization and risk of end-stage renal disease in patients with systemic lupus erythematosus: a nationwide population-based study

Background

Infections are a major cause of morbidity in patients with systemic lupus erythematosus (SLE), and may lead to death. No nationally representative study of patients with SLE has examined the rates of infection-related hospitalization and the risk of end-stage renal disease (ESRD).

Methods

We conducted a nationwide cohort study of 7326 patients with newly diagnosed SLE and no history of ESRD. All data were from Taiwan's National Health Insurance claims database for the period 2000-11.

Results

Among all SLE patients, 316 (4.3%) developed ESRD (mean follow-up time: 8.1 years). Multivariate Cox regression analysis indicated that the risk of ESRD increased with the number of infection-related hospitalizations. For patients with three or more infection-related admissions, the hazard ratio (HR) for ESRD was 5.08 [95% confidence interval (CI): 3.74-6.90] relative to those with no infection-related admission. Analysis by type of infection indicated that bacteremia patients had the greatest risk for ESRD (HR: 4.82; 95% CI: 3.40-6.85). Analysis of age of SLE onset indicated that patients with juvenile-onset (<18 years) and three or more infection-related hospitalizations had a greatly increased risk for ESRD (HR: 14.49; 95% CI: 5.34-39.33).

Conclusions

Infection-related hospitalizations are associated with a significantly increased risk of ESRD in patients with SLE, especially those with juvenile-onset SLE. Among patients with different types of infectious diseases, those with bacteremia were more likely to develop ESRD.

Comparison of clinical and immunological findings in gnotobiotic piglets infected with Escherichia coli O104:H4 outbreak strain and EHEC O157:H7

Background

Shiga toxin (Stx) producing Escherichia coli (E. coli) (STEC) is the most frequent cause of diarrhoea-positive haemolytic uraemic syndrome (D + HUS) in humans. In 2011, a huge outbreak with an STEC O104:H4 strain in Germany highlighted the limited possibilities for causative treatment of this syndrome. The responsible STEC strain was found to combine Stx production with adherence mechanisms normally found in enteroaggregative E. coli (EAEC). Pathotypes of E. coli evolve and can exhibit different adhesion mechanisms. It has been shown previously that neonatal gnotobiotic piglets are susceptible for infection with STEC, such as STEC O157:H7 as well as for EAEC, which are considered to be the phylogenetic origin of E. coli O104:H4. This study was designed to characterise the host response to infection with the STEC O104:H4 outbreak strain in comparison to an STEC O157:H7 isolate by evaluating clinical parameters (scoring) and markers of organ dysfunction (biochemistry), as well as immunological (flow cytometry, assessment of cytokines/chemokines and acute phase proteins) and histological alterations (light- and electron microscopy) in a gnotobiotic piglet model of haemolytic uraemic syndrome.

Results

We observed severe clinical symptoms, such as diarrhoea, dehydration and neurological disorders as well as attaching-and-effacing lesions (A/E) in the colon in STEC O157:H7 infected piglets. In contrast, STEC O104:H4 challenged animals exhibited only mild clinical symptoms including diarrhoea and dehydration and HUS-specific/severe histopathological, haematological and biochemical alterations were only inconsistently presented by individual piglets. A specific adherence phenotype of STEC O104:H4 could not be observed. Flow cytometric analyses of lymphocytes derived from infected animals revealed an increase of natural killer cells (NK cells) during the course of infection revealing a potential role of this subset in the anti-bacterial activity in STEC disease.

Conclusions

Unexpectedly, E. coli O104:H4 infection caused only mild symptoms and minor changes in histology and blood parameters in piglets. Outcome of the infection trial does not reflect E. coli O104:H4 associated human disease as observed during the outbreak in 2011. The potential role of cells of the innate immune system for STEC related disease pathogenesis should be further elucidated.

Predictive features of chronic kidney disease in atypical haemolytic uremic syndrome

Chronic kidney disease (CKD) is a frequent and serious complication of atypical haemolytic uremic syndrome (aHUS). We aimed to develop a simple accurate model to predict the risk of renal dysfunction in aHUS based on clinical and biological features available at hospital admission. Renal function at 1-year follow-up, based on an estimated glomerular filtration rate < 60mL/min/1.73m2 as assessed by the Modification of Diet in Renal Disease equation, was used as an indicator of significant CKD. Prospectively collected data from a cohort of 156 aHUS patients who did not receive eculizumab were used to identify predictors of CKD. Covariates associated with renal impairment were identified by multivariate analysis. The model performance was assessed and a scoring system for clinical practice was constructed from the regression coefficient. Multivariate analyses identified three predictors of CKD: a high serum creatinine level, a high mean arterial pressure and a mildly decreased platelet count. The prognostic model had a good discriminative ability (area under the curve = .84). The scoring system ranged from 0 to 5, with corresponding risks of CKD ranging from 18% to 100%. This model accurately predicts development of 1-year CKD in patients with aHUS using clinical and biological features available on admission. After further validation, this model may assist in clinical decision making.

Long-term outcomes of thrombotic microangiopathy treated with plasma exchange: A systematic review

With the adoption of plasma exchange as standard treatment for thrombotic microangiopathy (TMA), more patients are surviving and long-term outcomes have greater relevance. We conducted a systematic review to synthesize and evaluate the quality of evidence on long-term outcomes of TMA among adults treated with plasma exchange and to identify factors that may be associated with a worse long-term prognosis. We searched databases from 1980 to 2013 for eligible articles published in any language. We included studies that reported outcomes in at least ten adults with a history of TMA treated with plasma exchange and at least 6 months of follow-up. We abstracted data in duplicate and assessed the methodological quality of each study using an assessment tool developed based on recommended validity criteria. We screened 6672 articles, reviewed 213, and included 34 studies totaling 1182 patients (study median [range], 24 [10-118]). The mean (or median) follow-up ranged from 6 months to 13 years. The cumulative incidence of relapse and mortality was highly variable and ranged from 3 to 84 and 0 to 61%, respectively. The incidence of other outcomes across 10 studies also varied (outcomes included hypertension, kidney disease, preeclampsia, stroke, seizure, severe cognitive impairment, and depression); in three other studies, long-term neurocognitive function and health-related quality of life were significantly lower than in the general population. Patients who survive an episode of TMA may be susceptible to long-term vascular complications, but the magnitude of this risk and how to mitigate it remains unclear. Am. J. Hematol. 91:623-630, 2016. © 2016 Wiley Periodicals, Inc.

Use of belatacept as alternative immunosuppression in three renal transplant patients with de novo drug-induced thrombotic microangiopathy

Thrombotic microangiopathy (TMA), a severe complication of renal transplantation, is a pathological process involving microvascular occlusion, thrombocytopenia, and microangiopathic hemolytic anemia. It generally appears within the first weeks after transplantation, when immunosuppressive drugs are used at high doses. De novo TMA may also be drug-induced when calcineurin inhibitors or proliferation signal inhibitors are used. We report three cases of de novo drug-induced TMA in renal transplant patients who were managed by replacing calcineurin inhibitors or proliferation signal inhibitors with belatacept, a primary maintenance immunosuppressive drug, which blocks the CD28 costimulation pathway, preventing the activation of T lymphocytes. To identify the cause of TMA, we ruled out HUS, hepatitis C serology, HIV serology, parvovirus B19, cytomegalovirus, anti-HLA antibodies, and prolonged activated partial thromboplastin time. We suspect that the TMA was caused by the calcineurin inhibitors or proliferation signal inhibitors. Belatacept treatment was initiated at a dose of 10 mg/kg on days 1, 5, 14, 28, 60, and 90; maintenance treatment was 5 mg/kg once a month for 1 year. Belatacept, in combination with other agents, prevented graft rejection in three patients.

Management and outcomes for patients with TTP: analysis of 100 cases at a single institution

The advent of plasma exchange has led to a dramatic improvement in the survival of patients with thrombotic thrombocytopenic purpura (TTP), though approximately 10% of patients still die and a third suffer relapses. Clinical features that identify poor risk patients have not been clearly identified. We reviewed 100 patients who were treated for a first episode of TTP at the Cleveland Clinic between 2000 and 2012 to identify factors predictive of poor outcomes. On multivariate analysis, increasing age, especially age > 60 (RR: 7.08, 95% CI: 2.15-23.39, P = 0.002), severe neurological symptoms at presentation (RR: 18.37, 95% CI: I4.19-80.13, P < 0.001) and a persistently elevated LDH level after two plasma exchanges were predictive of mortality. Patients with ADAMTS13 activity above or below 5% did not differ in terms of clinical presentation or mortality and relapse rates, although ADAMTS13 activity > 5% was an independent predictor of adverse renal outcomes (need for dialysis and progression to chronic kidney disease). These variables may be useful for risk stratification and identification of patients who could potentially benefit from early institution of adjunctive therapy.