A novel-1364A/C aquaporin 5 gene promoter polymorphism influences the responses to salt loading of the renin-angiotensin-aldosterone system and of blood pressure in young healthy men

Aquaporin-5 Dynamic Regulation

Aquaporin-5 (AQP5), belonging to the aquaporins (AQPs) family of transmembrane water channels, facilitates osmotically driven water flux across biological membranes and the movement of hydrogen peroxide and CO₂. Various mechanisms have been shown to dynamically regulate AQP5 expression, trafficking, and function. Besides fulfilling its primary water permeability function, AQP5 has been shown to regulate downstream effectors playing roles in various cellular processes. This review provides a comprehensive overview of the current knowledge of the upstream and downstream effectors of AQP5 to gain an in-depth understanding of the physiological and pathophysiological processes involving AQP5.

AQP5-1364A/C Polymorphism Affects AQP5 Promoter Methylation

The quantity of aquaporin 5 protein in neutrophil granulocytes is associated with human sepsis-survival. The C-allele of the aquaporin (AQP5)-1364A/C polymorphism was shown to be associated with decreased AQP5 expression, which was shown to be relevant in this context leading towards improved outcomes in sepsis. To date, the underlying mechanism of the C-allele—leading to lower AQP5 expression—has been unknown. Knowing the detailed mechanism depicts a crucial step with a target to further interventions. Genotype-dependent regulation of AQP5 expression might be mediated by the epigenetic mechanism of promoter methylation and treatment with epigenetic-drugs could maybe provide benefit. Hence, we tested the hypothesis that AQP5 promoter methylation differs between genotypes in specific types of immune cells.: AQP5 promoter methylation was quantified in cells of septic patients and controls by methylation-specific polymerase chain reaction and quantified by a standard curve. In cell-line models, AQP5 expression was analyzed after demethylation to determine the impact of promoter methylation on AQP5 expression. C-allele of AQP5-1364 A/C promoter polymorphism is associated with a five-fold increased promoter methylation in neutrophils (p = 0.0055) and a four-fold increase in monocytes (p = 0.0005) and lymphocytes (p = 0.0184) in septic patients and healthy controls as well. In addition, a decreased AQP5 promoter methylation was accompanied by an increased AQP5 expression in HL-60 (p = 0.0102) and REH cells (p = 0.0102). The C-allele which is associated with lower gene expression in sepsis is accompanied by a higher methylation level of the AQP5 promoter. Hence, AQP5 promoter methylation could depict a key mechanism in genotype-dependent expression.

Hypotheses about sub-optimal hydration in the weeks before coronavirus disease (COVID-19) as a risk factor for dying from COVID-19

To address urgent need for strategies to limit mortality from coronavirus disease 2019 (COVID-19), this review describes experimental, clinical and epidemiological evidence that suggests that chronic sub-optimal hydration in the weeks before infection might increase risk of COVID-19 mortality in multiple ways. Sub-optimal hydration is associated with key risk factors for COVID-19 mortality, including older age, male sex, race-ethnicity and chronic disease. Chronic hypertonicity, total body water deficit and/or hypovolemia cause multiple intracellular and/or physiologic adaptations that preferentially retain body water and favor positive total body water balance when challenged by infection. Via effects on serum/glucocorticoid-regulated kinase 1 (SGK1) signaling, aldosterone, tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), aquaporin 5 (AQP5) and/or Na⁺/K⁺-ATPase, chronic sub-optimal hydration in the weeks before exposure to COVID-19 may conceivably result in: greater abundance of angiotensin converting enzyme 2 (ACE2) receptors in the lung, which increases likelihood of COVID-19 infection, lung epithelial cells which are pre-set for exaggerated immune response, increased capacity for capillary leakage of fluid into the airway space, and/or reduced capacity for both passive and active transport of fluid out of the airways. The hypothesized hydration effects suggest hypotheses regarding strategies for COVID-19 risk reduction, such as public health recommendations to increase intake of drinking water, hydration screening alongside COVID-19 testing, and treatment tailored to the pre-infection hydration condition. Hydration may link risk factors and pathways in a unified mechanism for COVID-19 mortality. Attention to hydration holds potential to reduce COVID-19 mortality and disparities via at least 5 pathways simultaneously.

Major Adverse Kidney Events Are Associated with the Aquaporin 5 -1364A/C Promoter Polymorphism in Sepsis: A Prospective Validation Study

Since the functionally important AQP5 -1364A/C single nucleotide promoter polymorphism alters key mechanisms of inflammation and survival in sepsis, it may affect the risk of an acute kidney injury. Accordingly, we tested the hypothesis in septic patients that this AQP5 polymorphism is associated with major adverse kidney events and also validated its impact on 90-day survival. In this prospective observational monocentric genetic association study 282 septic patients were included and genotyped for the AQP5 –1364A/C polymorphism (rs3759129). The primary endpoint was the development of major adverse kidney events within 30 days. In AC/CC genotypes, major adverse kidney events were less frequent (41.7%) than in AA genotypes (74.3%; OR:0.34; 95%-CI: 0.18–0.62; p < 0.001). Ninety-day survival was also associated with the AQP5 polymorphism (p = 0.004), with 94/167 deaths (56.3%) in AA genotypes, but only 46/115 deaths (40.0%) in C-allele carriers. Multiple proportional hazard analysis revealed AC/CC genotypes to be at significantly lower risk for death within 90 days (HR: 0.60; 95%-CI: 0.42-0.86; p = 0.006). These findings confirm the important role of the AQP5 -1364A/C polymorphism as an independent prognostic factor in sepsis. Furthermore, we demonstrate a strong association between this AQP5 polymorphism and susceptibility for major adverse kidney events suggesting a promising characteristic in terms of precision medicine.

Aquaporin 5 -1364A/C Promoter Polymorphism Is Associated with Pulmonary Inflammation and Survival in Acute Respiratory Distress Syndrome

WHAT WE ALREADY KNOW ABOUT THIS TOPIC

Acute respiratory distress syndrome is defined according to clinical criteria, but lack of precise characterization may contribute to negative trials and impede personalized care. Polymorphisms of aquaporin-5, a key mediator of inflammation, may impact outcome.

WHAT THIS ARTICLE TELLS US THAT IS NEW

In acute respiratory distress syndrome attributable to bacterial pneumonia, the C-allele of the aquaporin-5 -1364A/C promoter polymorphism is associated with less pulmonary inflammation and greater survival. This may improve characterization of acute respiratory distress syndrome and ultimately facilitate individualized care.

BACKGROUND

The aquaporin-5 (AQP5) -1364A/C promoter single-nucleotide polymorphism is associated with an altered AQP5 expression and mortality in sepsis. Because AQP5 expression alters neutrophil cell migration, it could affect pulmonary inflammation and survival in bacterially evoked acute respiratory distress syndrome. Accordingly, the authors tested the hypotheses that the AC/CC genotype in patients with bacterially evoked pneumonia resulting in acute respiratory distress syndrome is associated with (1) attenuated pulmonary inflammation and (2) higher 30-day survival.

METHODS

In this prospective, observational study, bronchoalveolar lavage and blood sampling were performed within 24 h of intensive care unit admission. In 136 Caucasian patients with bacterially evoked acute respiratory distress syndrome, genotype of the AQP5 -1364A/C promoter polymorphism, bronchoalveolar lavage total protein, albumin, white cell concentrations, and lactate dehydrogenase activity were measured to evaluate the relationship between genotypes and survival.

RESULTS

AC/CC patients as well as survivors showed lower bronchoalveolar lavage protein (0.9 mg/ml vs. 2.3 mg/ml, P < 0.001 and 1.6 mg/ml vs. 2.6 mg/ml, P = 0.035), albumin (0.2 mg/ml vs. 0.6 mg/ml, P = 0.019 and 0.3 mg/ml vs. 0.6 mg/ml, P = 0.028), leukocytes (424 /ml vs. 1,430/ml; P = 0.016 and 768 /ml vs. 1,826/ml; P = 0.025), and lactate dehydrogenase activity (82 U/l vs. 232 U/l; P = 0.006 and 123 U/l vs. 303 U/l; P = 0.020). Thirty-day survival was associated with AQP5 -1364A/C genotypes (P = 0.005), with survival of 62% for AA genotypes (58 of 93) but 86% for C-allele carriers (37 of 43). Furthermore, multiple proportional hazard analysis revealed the AA genotype was at high risk for death within 30 days (hazard ratio, 3.53; 95% CI, 1.38 to 9.07; P = 0.009).

CONCLUSIONS

In acute respiratory distress syndrome attributable to bacterial pneumonia, the C-allele of the AQP5 -1364A/C promoter polymorphism is associated with an attenuated pulmonary inflammation and higher 30-day survival. Thus, the AQP5 genotype impacts on inflammation and prognosis in acute respiratory distress syndrome.

DNA methylation of a NF-κB binding site in the aquaporin 5 promoter impacts on mortality in sepsis

Altered aquaporin 5 (AQP5) expression in immune cells impacts on key mechanisms of inflammation and is associated with sepsis survival. Since epigenetic regulation via DNA methylation might contribute to a differential AQP5 expression in sepsis, we tested the hypotheses that DNA methylation of the AQP5 promotor (1) influences AQP5 expression, (2) is associated with the 30-day survival of septic patients, and (3) alters the nuclear transcription factor NF-κB binding. AQP5 mRNA expression was quantified by real-time PCR in whole blood samples of 135 septic patients. In silico computer analysis of the AQP5 promoter (nt-567 to nt-975) revealed seven putative inflammatory transcription factor binding sites and methylation of these sites was analyzed. Electrophoretic mobility shift assays were performed to assess the binding of nuclear NF-κB to the AQP5 promoter region nt-937. After adjustment for multiple testing, a greater methylation rate was found at cytosine site nt-937 in the AQP5 promoter linked to NF-κB binding in non-survivors compared to survivors (p = 0.002, p_adj = 0.014). This was associated with greater AQP5 mRNA expression in non-survivors (p = 0.037). Greater (≥16%) promoter methylation at nt-937 was also associated with an independently increased risk of death within 30 days (HR: 3.31; 95% CI: 1.54–6.23; p = 0.002). We detected a functionally important AQP5 promoter cytosine site (nt-937) linked to the binding of the inflammatorily acting nuclear transcription factor NF-κB, with increased methylation in sepsis non-survivors. Thus, nt-937 APQ5 promoter methylation, presumably related to NF-κB binding, is prognostically relevant in sepsis and demonstrates that epigenetic changes impact on sepsis outcome.

The Aquaporin 5 -1364A/C Promoter Polymorphism Is Associated With Cytomegalovirus Infection Risk in Kidney Transplant Recipients

Background: The aquaporin 5 (AQP5) −1364A/C promoter single nucleotide polymorphism affects key mechanisms of inflammation and immune cell migration. Thus, it could be involved in the pathogenesis of cytomegalovirus infection. Accordingly, we tested the hypothesis that the AQP5 promoter −1364A/C polymorphism is associated with the risk of cytomegalovirus infection in kidney transplantation recipients.

Methods: We included 259 adult patients who received a kidney transplant from 2007 and 2014 in this observational study. Patients were genotyped for the AQP5 promoter −1364A/C single nucleotide polymorphism and followed up for 12 months after transplantation. Kaplan–Meier plots and multivariable proportional hazard analyses were used to evaluate the relationship between genotypes and the incidence of cytomegalovirus infection.

Results: The incidences of cytomegalovirus infection within 12 months after kidney transplantation were 22.9% for the AA genotypes (43/188) and 42.3% for the AC/CC genotypes (30/71; p = 0.002). Furthermore, multivariable COX regression revealed the C-allele of the AQP5 −1364A/C polymorphism to be a strong and independent risk factor for cytomegalovirus infection. In this analysis, AC/CC subjects demonstrated a more than 2-fold increased risk for cytomegalovirus infection within the first year after kidney transplantation (hazard ratio: 2.28; 95% CI: 1.40–3.73; p = 0.001) compared to that in individuals with homozygous AA genotypes.

Conclusions: With respect to opportunistic cytomegalovirus infections (attributable to immunosuppression after kidney transplantation), the C-allele of the AQP5 −1364A/C promoter polymorphism is independently associated with an increased 12-months infection risk. These findings emphasize the importance of genetic variations as additional risk factors of cytomegalovirus infection after solid organ transplantations and might also facilitate the discovery of novel therapeutic targets.

Sodium sensitivity of blood pressure in Chinese populations

Hypertension is an enormous public-health challenge in the world due to its high prevalence and consequent increased cardiovascular disease morbidity and mortality. Observational epidemiologic studies and clinical trials have demonstrated a causal relationship between sodium intake and elevated blood pressure (BP). However, BP changes in response to sodium intervention vary among individuals-a trait called sodium sensitivity. This paper aims to review the recent advances in sodium-sensitivity research in Chinese and other populations. Older age, female gender, and black race are associated with high sodium sensitivity. Both genetic and environmental factors influence BP sodium sensitivity. Physical activity and dietary potassium intake are associated with reduced sodium sensitivity while obesity, metabolic syndrome, and elevated BP are associated with increased sodium sensitivity. Familial studies have documented a moderate heritability of sodium sensitivity. Candidate gene association studies, genome-wide association studies, whole-exome, and whole-genome sequencing studies have been conducted to elucidate the genomic mechanisms of sodium sensitivity. The Genetic Epidemiology Network of Salt Sensitivity (GenSalt) study, the largest family-based feeding study to date, was conducted among 1906 Han Chinese in rural northern China. This study showed that ~32.4% of Chinese adults were sodium sensitive. Additionally, several genetic variants were found to be associated with sodium sensitivity. Findings from the GenSalt Study and others indicate that sodium sensitivity is a reproducible trait and both lifestyle factors and genetic variants play a role in this complex trait. Discovering biomarkers and underlying mechanisms for sodium sensitivity will help to develop individualized intervention strategies for hypertension.

The aquaporin 5 -1364A/C promoter polymorphism impacts on resolution of acute kidney injury in pneumonia evoked ARDS

Background

Aquaporin 5 (AQP5) expression impacts on cellular water transport, renal function but also on key mechanisms of inflammation and immune cell migration that prevail in sepsis and ARDS. Thus, the functionally relevant AQP5 -1364A/C promoter single nucleotide polymorphism could impact on the development and resolution of acute kidney injury (AKI). Accordingly, we tested the hypothesis that the AQP5 promoter -1364A/C polymorphism is associated with AKI in patients suffering from pneumonia evoked ARDS.

Methods

This prospective study included 136 adult patients of Caucasian ethnicity with bacterially evoked pneumonia resulting in ARDS. Blood sampling was performed within 24 hours of ICU admission and patients were genotyped for the AQP5 promoter -1364A/C single nucleotide polymorphism. The development of an AKI and the cumulative net fluid balance was described over a 30-day observation period and compared between the AA and AC/CC genotypes, and between survivors and non-survivors.

Results

Incidence of an AKI upon admission did not differ in AA (58%) and AC/CC genotype carriers (60%; p = 0.791). However, on day 30, homozygous AA genotypes (57%) showed an increased prevalence of AKI compared to AC/CC genotypes (24%; p = 0.001). Furthermore, the AA genotype proved to be a strong, independent risk factor for predicting AKI persistence (odds-ratio: 3.35; 95%-CI: 1.2–9.0; p = 0.017). While a negative cumulative fluid balance was associated with increased survival (p = 0.001) the AQP5 promoter polymorphism had no impact on net fluid balance (p = 0.96).

Conclusions

In pneumonia evoked ARDS, the AA genotype of the AQP5 promoter polymorphism is associated with a decreased recovery rate from AKI and this is independent of fluid balance. Consequently, the role of AQP5 in influencing AKI likely rests in factors other than fluid balance.

Function of aquaporins in sepsis: a systematic review

BACKGROUND

Sepsis is a common cause of death in intensive care units worldwide. Due to the high complexity of this immunological syndrome development of novel therapeutic strategies is urgent. Promising drug targets or biomarkers may depict aquaporins (AQPs) as they regulate crucial key mechanisms of sepsis.

MAIN BODY

Here we report on base of the current literature that several AQPs are involved in different physiological processes of sepsis. In immune system mainly AQPs 3, 5 and 9 seem to be important, as they regulate the migration of different immune cells. Several studies showed that AQP3 is essential for T cell function and macrophage migration and that AQP5 and AQP9 regulate neutrophil cell migration and impact sepsis survival. Additionally, to the function in immune system AQPs 1 and 5 play a role in sepsis induced lung injury and their downregulation after inflammatory stimuli impair lung injury. By contrast, AQP4 expression is up-regulated during brain inflammation and aggravates brain edema in sepsis. In kidney AQP2 expression is downregulated during sepsis and can cause renal failure. Some studies also suggest a role of AQP1 in cardiac function.

CONCLUSION

In conclusion, AQPs are involved in many physiological dysfunctions in sepsis and their expressions are differently regulated. Additional research on the regulatory mechanisms of aquaporins may identify potential therapeutic targets.

Epigenome-wide association study reveals differential DNA methylation in individuals with a history of myocardial infarction

Cardiovascular diseases (CVDs) are the leading causes of death worldwide and represent a substantial economic burden on public health care systems. Epigenetic markers have potential as diagnostic markers before clinical symptoms have emerged, and as prognostic markers to inform the choice of clinical intervention. In this study, we performed an epigenome-wide association study (EWAS) for CVDs, to identify disease-specific alterations in DNA methylation. CpG methylation in blood samples from the northern Sweden population health study (NSPHS) (n = 729) was assayed on the Illumina Infinium HumanMethylation450 BeadChip. Individuals with a history of a CVD were identified in the cohort. It included individuals with hypertension (N = 147), myocardial infarction (MI) (N = 48), stroke (N = 27), thrombosis (N = 22) and cardiac arrhythmia (N = 5). Differential DNA methylation was observed at 211 CpG-sites in individuals with a history of MI (q <0.05). These sites represent 196 genes, of which 42 have been described in the scientific literature to be related to cardiac function, cardiovascular disease, cardiogenesis and recovery after ischemic injury. We have shown that individuals with a history of MI have a deviating pattern of DNA methylation at many genomic loci of which a large fraction has previously been linked to CVD. Our results highlight genes that might be important in the pathogenesis of MI or in recovery. In addition, the sites pointed out in this study can serve as candidates for further evaluation as potential biomarkers for MI.

AQP5-1364A/C polymorphism and the AQP5 expression influence sepsis survival and immune cell migration: a prospective laboratory and patient study

Background

The C-allele of the aquaporin (AQP5) -1364A/C polymorphism is associated with decreased AQP5 expression but increased 30-day survival in patients with severe sepsis. AQP5 expression might affect survival via an impact on cell migration. Consequently, we tested the hypothesis that (1) Aqp5 knockout (KO) compared to wild type (WT) mice show an increased survival following lipopolysaccharide (LPS) administration, and that (2) AQP5 expression and the AQP5 -1364A/C polymorphism alters immune cell migration.

Methods

We investigated Aqp5-KO and wild type mice after intraperitoneal injection of either E.coli lipopolysaccharide (LPS, serotype O127:B8, 20 mg/kg) or saline. Furthermore, neutrophils of volunteers with the AA-AQP5 or AC/CC-AQP5- genotype were incubated with 10⁻⁸ M Chemotactic peptide (fMLP) and their migration was assessed by a filter migration assay. Additionally, AQP5 expression after fMLP incubation was analyzed by RT-PCR and Western blot. Moreover, migration of AQP5 overexpressing Jurkat cells was studied after SDF-1α-stimulation. We used exact Wilcoxon–Mann–Whitney tests; exact Wilcoxon signed-rank tests and the Kaplan–Meier estimator for statistical analysis.

Results

Fifty-six percent of Aqp5-KO but only 22% of WT mice survived following LPS-injection. WT mice showed increased neutrophil migration into peritoneum and lung compared to Aqp5-KO mice. Target-oriented migration of neutrophils was seen after 0.5 h in AA-genotype cells but only after 1.5 h in AC/CC-genotype cells, with a threefold lower migrating cell count. AQP5 overexpressing Jurkat cells showed a 2.4 times stronger migration compared to native Jurkat cells.

Conclusion

The AQP5 genotype may influence survival following LPS by altering neutrophil cell migration.

Trial registration DRKS00010437. Retrospectively registered 26 April 2016

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1079-2) contains supplementary material, which is available to authorized users.

The Transcription Factor NMP4 Binds to the AQP5 Promoter and Is a Novel Transcriptional Regulator of the AQP5 Gene

Aquaporin 5 (AQP5) is a water channel that regulates water transport, cell migration, and proliferation. Therefore, knowledge of its genetic regulation could be relevant to study these mechanisms. The AQP5 promoter region containing the AQP5-1364 A/C single-nucleotide polymorphism (SNP) might be an important regulatory region because the SNP is associated with the etiopathology of several diseases. The aim of this study was to identify a transcription factor that binds to this AQP5 promoter region and to investigate its potential impact upon AQP5 expression. In silico analysis revealed nuclear matrix protein 4 (NMP4) as a putative candidate. Electrophoretic mobility shift assays showed specific binding of NMP4 to the AQP5 promoter region of nt -1370 to nt -1329. Overexpression of NMP4 increased AQP5 promoter activity of the analyzed promoter constructs from nt -469 to nt -1979. Furthermore, an additional NMP4 binding site at position nt -592/nt -602 of the AQP5 promoter was identified. NMP4 overexpression increased AQP5 mRNA expression by 2.5-fold in HEK293 cells. Summarizing, we identified NMP4 as a novel transcriptional regulator of AQP5 expression, which binds to two AQP5 promoter regions. Both regions appear to impact AQP5 expression significantly.

Aquaporin-5: from structure to function and dysfunction in cancer

Aquaporins, a highly conserved group of membrane proteins, are involved in the bidirectional transfer of water and small solutes across cell membranes taking part in many biological functions all over the human body. In view of the wide range of cancer malignancies in which aquaporin-5 (AQP5) has been detected, an increasing interest in its implication in carcinogenesis has emerged. Recent publications suggest that this isoform may enhance cancer cell proliferation, migration and survival in a variety of malignancies, with strong evidences pointing to AQP5 as a promising drug target and as a novel biomarker for cancer aggressiveness with high translational potential for therapeutics and diagnostics. This review addresses the structural and functional features of AQP5, detailing its tissue distribution and functions in human body, its expression pattern in a variety of tumors, and highlighting the underlying mechanisms involved in carcinogenesis. Finally, the actual progress of AQP5 research, implications in cancer biology and potential for cancer detection and prognosis are discussed.

Regulation of the perilymphatic-endolymphatic water shunt in the cochlea by membrane translocation of aquaporin-5

Volume homeostasis of the cochlear endolymph depends on radial and longitudinal endolymph movements (LEMs). LEMs measured in vivo have been exclusively recognized under physiologically challenging conditions, such as experimentally induced alterations of perilymph osmolarity or endolymph volume. The regulatory mechanisms that adjust LEMs to the physiological requirements of endolymph volume homeostasis remain unknown. Here, we describe the formation of an aquaporin (AQP)-based "water shunt" during the postnatal development of the mouse cochlea and its regulation by different triggers. The final complementary expression pattern of AQP5 (apical membrane) and AQP4 (basolateral membrane) in outer sulcus cells (OSCs) of the cochlear apex is acquired at the onset of hearing function (postnatal day (p)8-p12). In vitro, hyperosmolar perfusion of the perilymphatic fluid spaces or the administration of the muscarinic agonist pilocarpine in cochlear explants (p14) induced the translocation of AQP5 channel proteins into the apical membranes of OSCs. AQP5 membrane translocation was blocked by the muscarinic antagonist atropine. The muscarinic M3 acetylcholine (ACh) receptor (M3R) was identified in murine OSCs via mRNA expression, immunolabeling, and in vitro binding studies using an M3R-specific fluorescent ligand. Finally, the water shunt elements AQP4, AQP5, and M3R were also demonstrated in OSCs of the human cochlea. The regulation of the AQP4/AQP5 water shunt in OSCs of the cochlear apex provides a molecular basis for regulated endolymphatic volume homeostasis. Moreover, its dysregulation or disruption may have pathophysiologic implications for clinical conditions related to endolymphatic hydrops, such as Ménière's disease.

AQP1, AQP5, Bcl-2 and p16 in pharyngeal squamous cell carcinoma

Objective:

This study aimed to link expression patterns of AQP1, AQP5, Bcl-2 and p16 to clinicopathological characteristics of oro-hypopharyngeal squamous cell carcinomas.

Methods:

Immunohistochemical expression of AQP1, AQP5, Bcl-2 and p16 was investigated in 107 consecutive oro-hypopharyngeal squamous cell carcinoma cases. Molecular interrelationship and correlations with clinicopathological parameters and survival were computed.

Results:

AQP1 was expressed exclusively by a subgroup of basaloid-like squamous cell carcinomas. AQP5 was detected in 25.2 per cent of the samples, showing significant association with the absence of p16 and Bcl-2 (p = 0.018; p = 0.010). In multivariate analysis, overexpression of p16 was significantly correlated with favourable overall survival (p = 0.014).

Conclusion:

AQP5 defined a subset of patients with Bcl-2-negative and p16-negative tumours with a poor clinical outcome. AQP1 was found to be a marker of a subgroup of aggressive basaloid-like squamous cell carcinomas. These findings suggest that AQP1 and AQP5 are interesting candidates for further studies on risk group classification and personalised treatment of oro-hypopharyngeal squamous cell carcinomas.

Hydrocortisone fails to abolish NF-κB1 protein nuclear translocation in deletion allele carriers of the NFKB1 promoter polymorphism (-94ins/delATTG) and is associated with increased 30-day mortality in septic shock

Background

Previous investigations and meta-analyses on the effect of glucocorticoids on mortality in septic shock revealed mixed results. This heterogeneity might be evoked by genetic variations. Such candidate is a promoter polymorphism (-94ins/delATTG) of the gene encoding the ubiquitous transcription-factor nuclear-factor-κB (NF-κB) which binds to recognition elements in the promoter of several genes encoding for the innate immune-system. In turn, hydrocortisone inhibits NF-κB nuclear translocation and thus transcription of key immune-response regulators. Accordingly, we tested the hypotheses that hydrocortisone has a NFKB1 genotype dependent effect on 1) NF-κB1 nuclear translocation evoked by lipopolysaccharide (LPS) in monocytes in vitro, and 2) mortality in septic shock.

Methods

Monocytes of volunteers with the homozygous insertion (II; n = 5) or deletion (DD; n = 6) NFKB1 genotype were incubated with 10 µgml^-1 LPS ± hydrocortisone (10^-5M), and NF-κB1 nuclear translocation was assessed (immunofluorescence). Furthermore, we analyzed 30-day-mortality in 160 patients with septic shock stratified for both genotype and hydrocortisone therapy.

Results

Hydrocortisone inhibited LPS induced nuclear translocation of NF-κB1 in II (25%±11;p = 0.0001) but not in DD genotypes (51%±15;p = n.s.). Onehundredandfour of 160 patients with septic shock received hydrocortisone, at the discretion of the intensivist. NFKB1 deletion allele carriers (ID/DD) receiving hydrocortisone had a much greater 30-day-mortality (57.6%) than II genotypes (24.4%; HR:3.18, 95%-CI:1.61-6.28;p = 0.001). In contrast, 30-day mortality was 22.2% in ID/DD and 25.0% in II genotypes without hydrocortisone therapy. Results were similar when using propensity score matching to account for possible bias in the intensivists' decision to administer hydrocortisone.

Conclusion

Hydrocortisone fails to inhibit LPS induced nuclear NF-κB1 translocation in deletion allele carriers of the NFKB1 promoter polymorphism (-94ins/delATTG). In septic shock, hydrocortisone treatment is associated with markedly increased 30-day-mortality only in such carriers. Accordingly, previous heterogeneous results regarding the benefit of hydrocortisone in septic shock may be reconciled by genetic variation of the NFKB1 promoter polymorphism.

The expression and role of Aquaporin 5 in esophageal squamous cell carcinoma

BACKGROUND

Aquaporins (AQPs) are water channel proteins that facilitate transcellular water movements. Recent studies have shown that AQP5 is expressed in various cancers, and plays a role in tumor progression. However, its expression and role in esophageal squamous cell carcinoma (ESCC) have not been investigated. We examined the pathophysiologic role of AQP5 in cell proliferation and survival, and also investigated its expression and effects on the prognosis of ESCC patients.

METHODS

AQP5 expression in human ESCC cell lines was analyzed by Western blot testing. Knockdown experiments with AQP5 siRNA were conducted, and the effects on cell proliferation, cell cycle progression, and cell survival were analyzed. The cells' gene expression profiles were analyzed by microarray analysis. Immunohistochemistry of AQP5 for 68 primary tumor samples obtained from ESCC patients undergoing esophagectomy was performed.

RESULTS

AQP5 expression was high in TE2 and TE5 cells. In these cells, the knockdown of AQP5 using siRNA inhibited cell proliferation and G1-S phase progression, and induced apoptosis. The AQP5 siRNA transfected TE5 cells showed significant increase in p21 and decrease in CCND1 mRNA expression, respectively. The expression pattern of AQP5 and p21 protein was sharply contrasted, but AQP5 and CCND1 protein expression showed a similar pattern in ESCC tissue. These findings agree with the microarray results. Immunohistochemical staining of 68 ESCC patients showed the AQP5 expression is associated with tumor size, histological type, and tumor recurrence.

CONCLUSION

The AQP5 expression in ESCC cells may affect cell proliferation and survival, and impact on the prognosis of ESCC patients.

Water permeability of the mammalian cochlea: functional features of an aquaporin-facilitated water shunt at the perilymph-endolymph barrier

The cochlear duct epithelium (CDE) constitutes a tight barrier that effectively separates the inner ear fluids, endolymph and perilymph, thereby maintaining distinct ionic and osmotic gradients that are essential for auditory function. However, in vivo experiments have demonstrated that the CDE allows for rapid water exchange between fluid compartments. The molecular mechanism governing water permeation across the CDE remains elusive. We computationally determined the diffusional (PD) and osmotic (Pf) water permeability coefficients for the mammalian CDE based on in silico simulations of cochlear water dynamics integrating previously derived in vivo experimental data on fluid flow with expression sites of molecular water channels (aquaporins, AQPs). The PD of the entire CDE (PD = 8.18 × 10(-5) cm s(-1)) and its individual partitions including Reissner's membrane (PD = 12.06 × 10(-5) cm s(-1)) and the organ of Corti (PD = 10.2 × 10(-5) cm s(-1)) were similar to other epithelia with AQP-facilitated water permeation. The Pf of the CDE (Pf = 6.15 × 10(-4) cm s(-1)) was also in the range of other epithelia while an exceptionally high Pf was determined for an epithelial subdomain of outer sulcus cells in the cochlear apex co-expressing AQP4 and AQP5 (OSCs; Pf = 156.90 × 10(-3) cm s(-1)). The Pf/PD ratios of the CDE (Pf/PD = 7.52) and OSCs (Pf/PD = 242.02) indicate an aqueous pore-facilitated water exchange and reveal a high-transfer region or "water shunt" in the cochlear apex. This "water shunt" explains experimentally determined phenomena of endolymphatic longitudinal flow towards the cochlear apex. The water permeability coefficients of the CDE emphasise the physiological and pathophysiological relevance of water dynamics in the cochlea in particular for endolymphatic hydrops and Ménière's disease.

Expression of aquaporin 5 and the AQP5 polymorphism A(-1364)C in association with peritumoral brain edema in meningioma patients

Aquaporins (AQP) are a growing family of water-channel proteins, numbering 13 to date. Recent studies have reported AQP1 and AQP4 to be involved in the development and resorption of brain edemas of different origin. Other AQPs have also been detected in brain tissue, but their impact on brain edema remains to be shown. To evaluate a possible role of AQP5 in brain edema, we investigated the association of AQP5 expression and the functional AQP5 promoter polymorphism A(-1364)C with occurrence and intensity of peritumoral edema in meningioma patients. Peritumoral edema was classified in three degrees based on preoperative imaging in 89 meningioma patients treated at the University Hospital Essen between 2003 and 2006. AQP5 expression was assessed immunohistochemically in tumor tissue obtained during neurosurgical tumor resection. Genotypes of the A(-1364)C polymorphism were determined using the "slowdown" polymerase chain reaction. Higher levels of AQP5 expression were significantly correlated with the AQP5-1364 AA genotype (P = 0.02). AQP5 expression was positively correlated with edema (P = 0.04). AQP5 genotypes were not significantly associated with the occurrence, but with the intensity of peritumoral brain edema (P = 0.04). In our cohort, 40 % of patients with grade I, 66.7 % with grade II, and 76.5 % with grade III edema possessed at least one A allele. Development and intensity of peritumoral edema in meningiomas are associated with AQP5 expression. The intensity of edema correlates with the AQP5 A(-1364)C genotype. This suggests AQP5 as an interesting new candidate involved in peritumoral brain edema in meningioma patients.

Institutional Profile: Institute of Pharmacogenetics at the University Hospital Essen

Established in 2005, the Institute of Pharmacogenetics at the University Hospital Essen (Essen, Germany), headed by Winfried Siffert, is devoted to the discovery and validation of genetic variants that may impact upon drug responses especially in the field of cardiovascular disorders and cancer. Moreover, the institute provides pharmacogenetic testing for those drugs for which pharmacogenetic testing is recommended in order to prevent adverse drug reactions.

Genomic epidemiology of blood pressure salt sensitivity

High blood pressure (BP) is a complex trait determined by genetic and environmental factors, as well as their interactions. Over the past few decades, there has been substantial progress elucidating the genetic determinants underlying BP response to sodium intake, or BP salt sensitivity. Research of monogenic BP disorders has highlighted the importance of renal salt handling in BP regulation, implicating genes and biological pathways subsequently identified in candidate gene studies of salt sensitivity. Despite these advancements, certain candidate gene findings await replication evidence, and some biological pathways warrant further investigation. Furthermore, results from genome-wide association studies (GWASs) and sequencing work have yet to be reported. GWAS will be valuable for uncovering novel mechanisms underlying salt sensitivity, whereas future sequencing efforts promise the discovery of functional variants related to this complex trait. Delineating the genetic architecture of salt sensitivity will be critical to understanding how genes and dietary sodium interact to influence BP.

The -1364A/C Aquaporin 5 Gene Promoter Polymorphism Is Not Associated with Menière's Disease

Objective. Aquaporin 5 plays an important role in maintaining inner ear water and fluid homeostasis. Since the aquaporin (AQP) 5 promoter-1364A/C polymorphism is associated with altered AQP5 expression and this could impact upon key mechanisms of Menière's disease, we tested the hypothesis that genotypes of the AQP5 promoter-1364A/C polymorphism are associated with the incidences of Menière's disease (MD), familial Menière's disease (FMD), or endolymphatic hydrops (EH). Methods. With approval of the local ethics committee, DNA of 102 patients (39 with MD, 54 with FMD, and 9 with EH) and of 292-matched Caucasian controls was isolated from blood samples and genotyped for the AQP 5 promoter-1364A/C polymorphism. The χ²-test was applied to compare genotype distributions and allele frequencies between patients and controls. Results. Overall, genotype frequencies were not different between controls (AA 69%, AC 30%, CC 1%) and patients with MD AA: 65.7% (23 MD, 37 FMD, and 8 EH); AC: 23.5% (12 MD, 11 FMD, and 1 EH); CC: 3.9% (1 MD, 3 FMD, and 0 EH). However, subgroup analysis revealed the CC genotype to be more frequent in patients with FMD (5.9%) than in healthy controls (1%) (P = 0.042). Conclusions. Overall, genotypes of the -1364A/C AQP5 gene polymorphism are not associated with a significant increased risk for Menière's disease.

Gene-sodium interaction and blood pressure: findings from genomics research of blood pressure salt sensitivity

High blood pressure (BP) is a complex trait determined by both genetic and environmental factors, as well as the interactions between these factors. Over the past few decades, there has been substantial progress in elucidating the genetic determinants underlying the BP response to sodium intake, or BP salt sensitivity. Research of monogenic BP disorders has highlighted the importance of renal salt handling in BP regulation, implicating genes and biological pathways related to salt sensitivity. Candidate gene studies have contributed important information toward understanding the genomic mechanisms underlying the BP response to salt intake, identifying genes in the renin-angiotensin-aldosterone system, renal sodium channels/transporters, and the endothelial system related to this phenotype. Despite these advancements, genome-wide association studies are still needed to uncover novel mechanisms underlying salt sensitivity, while future sequencing efforts promise the discovery of functional variants related to this complex trait. Delineating the genetic architecture of salt sensitivity will be critical to understanding how genes and dietary sodium interact to influence BP.