Impact of acute kidney injury on major adverse cardiovascular events in intensive care survivors

Background

Acute kidney injury commonly occurs in patients admitted to ICU. After acute kidney injury, kidney function may not completely recover leading to increased risk of future cardiovascular events. We sought to ascertain the rates of cardiovascular events in ICU survivors and if these rates were affected by the presence of acute kidney injury whilst in ICU.

Methods

This retrospective observational cohort study utilised routinely collected data to identify patients who had survived an admission to one of two ICUs between July 2015 and June 2018. Baseline serum creatinine and subsequent values were used to identify acute kidney injury. Major adverse cardiovascular events described were myocardial injury, coronary artery intervention, or radiological evidence of stroke.

Results

Of the 3994 ICU survivors, major adverse cardiovascular events were identified in 385 patients (9.6%; 95% confidence interval [CI] 8.8-10.6%). Presence of acute kidney injury whilst in ICU was significantly associated with future major adverse cardiovascular events (hazard ratio=1.38; 95% CI 1.12-1.70; P-value=0.003) and future biochemical myocardial injury (hazard ratio=1.48; 95% CI 1.16-1.89; P-value=0.001). Acute kidney injury did not have a statistically significant association with future coronary artery interventions or future cerebrovascular events.

Conclusions

One in 10 ICU survivors experiences a major adverse cardiovascular event after discharge. Acute kidney injury whilst in ICU was associated with an increased risk of major adverse cardiovascular events and specifically myocardial injury. Further research is warranted on whether ICU survivors with acute kidney injury merit enhanced strategies for cardiovascular protection.

SIRT2: tumour suppressor or tumour promoter in operable breast cancer?

PURPOSE

Sirtuins comprise a family of genes involved in cellular stress, survival and damage responses. They have been implicated in a range of diseases including cancer, with most information pertaining to their function in tumourigenesis being derived from in vitro studies, or model organisms. Their putative roles as tumour suppressors or tumour promoters remain to be validated in vivo. Little is known about their role in breast tumourigenesis. We sought to evaluate the seven sirtuin family members (SIRT1-7) in a human breast cancer cohort, in relation to clinico-pathological features and outcome of the disease.

MATERIALS AND METHODS

Immunohistochemical analysis of SIRT1-7 protein levels was undertaken in 392 oestrogen receptor (ER+ve) and 153 ER-ve breast tumour samples. SIRT1-7 transcriptional levels were assessed in normal (n=25), non-malignant (n=73) and malignant (n=70) breast tissue using Relative Quantitative Real Time PCR. Statistical analyses determined if SIRT1-7 transcription or protein expression was associated with clinical parameters or outcome.

RESULTS

In ER-ve tumours, high protein levels of nuclear SIRT2 were associated with reduced time to recurrence and disease-specific death. This association was only observed in Grade 3 tumours. In the ER+ve cohort, high SIRT2 nuclear levels were associated with shorter disease-free survival and time to recurrence whilst on Tamoxifen, in patients with Grade 3 tumours. Conversely, in Grade 2 tumours, high SIRT2 levels were associated with increased time to recurrence.

CONCLUSIONS

Our data suggest that SIRT2 is the sirtuin predominantly involved in breast tumourigenesis and prognosis. It indicates that SIRT2 acts as a tumour suppressor or tumour promoter dependent upon breast tumour grade.

Evaluating the Role of Sirtuins 5, 6 & 7 in Breast Cancer

As cancer is a disease of ageing, genes involved in biological ageing may be informative in investigating the mechanisms of cancer pathogenesis. One such group of genes are the Sirtuins (SIRT1-7), orthologues of the yeast SIR2 gene, which are involved in cell processes including DNA repair, cell-cycle regulation and ageing. A definitive SIRT5 function is as yet unconfirmed, SIRT6 plays a role in DNA repair and suppression of genomic instability, whilst SIRT7 promotes ribosome biogenesis. Recently, altered sirtuin gene expression has been linked with a variety of cancers including breast. This study aimed to explore the role of SIRT5, 6 and 7 protein expression as predictive/prognostic markers in breast cancer patients.392 oestrogen receptor positive breast tumours were analysed for SIRT 5, 6 & 7 protein expression using an immunohistochemical approach. Prospective follow-up data was available for these patients; all patients received tamoxifen for a median of 5 years. Two observers independently scored the staining using a weighted histoscore method. Statistical analysis was carried out using the SPSS statistical program. For survival analysis, patients were split into two groups those that expressed high levels of the protein and those that expressed low levels. High levels were defined as IHC scores equal to or greater than the median value, whilst low levels were defined as scores less than the median value.Analysis of SIRT5 and SIRT7 expression yielded no significant associations with any clinical parameter investigated. SIRT6 protein expression did not affect overall survival for the 392 patients. However, it was observed that the mean time to relapse which occurred 5 years post diagnosis was significantly shorter in those patients with low SIRT6 expression compared to those with high SIRT6 expression (13.41yrs vs 15.84yrs p=0.032). Patients with low SIRT6 had a 2.26 times greater risk of relapse after 5 years than those with high SIRT6 expression (p=0.038). Furthermore when analysis of recurrence, which occurred 5 years post diagnosis, was stratified by progesterone receptor (PR) status, it was observed that SIRT6 failed to influence time to relapse in patients who were PR negative. However PR positive patients with low nuclear SIRT6 expression experienced a shorter mean time to recurrence compared to those with higher nuclear SIRT6 expression (13.88yrs vs 16.90yrs, p=0.045). PR positive patients with low SIRT6 expression had a similar mean time to recurrence, as those who were PR negative and had low SIRT6 expression.Current 5 year survival rates for breast cancer are approximately 80% however, it is well established that risk of recurrence persists after 5 years, these results indicate that low SIRT6 protein levels are associated with decreased time to relapse 5 years post diagnosis. This may be due to the fact that these patients are unable to maintain genomic integrity due to the role SIRT6 plays in BER. Furthermore low SIRT6 expression overrides the beneficial effects of PR positivity suggesting maintenance of genomic stability is more important than PR status in terms of recurrence. This study suggests that SIRT6 possibly represents a novel prognostic marker; furthermore it may identify patients who require additional therapies following tamoxifen treatment.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3034.