The inflammation-lipocalin 2 axis may contribute to the development of chronic kidney disease

The bidirectional association between diabetes and periodontitis, from basic to clinical

The prevalence and severity of periodontitis are increased and advanced in diabetes. Severe periodontitis elicits adverse effects on diabetes by impairing insulin actions due to systemic microinflammation. Recent studies unveil the emerging findings and molecular basis of the bidirectional relationship between periodontitis and diabetes. In addition to conventional mechanisms such as hyperglycemia, hyperlipidemia, and chronic inflammation, deficient insulin action may play a pathogenic role in the progression of periodontitis under diabetes. Epidemiologically, from the viewpoint of the adverse effect of periodontitis on diabetes, recent studies have suggested that Asians including Japanese and Asian Americans with diabetes and mild obesity (BMI <25 kg/m2) should pay more attention to their increased risk for cardiovascular diseases. In this review, we summarize recent findings on the effect of diabetes on periodontitis from the viewpoint of abnormalities in metabolism and insulin resistance with novel mechanisms, and the influence of periodontitis on diabetes mainly focused on micro-inflammation related to mature adipose tissue and discuss future perspectives about novel approaches to interrupt the adverse interrelationship.

Mechanisms of Rostellularia procumbens (L.) Nees on treating chronic glomerulonephritis explored by network pharmacology, RNA-seq, and in vitro experiments

BACKGROUND

The purpose of this study was to demonstrate the in vitro anti-nephritis activity of Rostellularia procumbens (L.) Nees (R. procumbens) extract and to make a preliminary investigation of its anti-nephritis mechanism.

METHODS

A prediction network was built that describes the relationship between R. procumbens and CGN. Then, the potential targets for R. procumbens against CGN were imported into the DAVID database for Gene Ontology (GO) biological annotation analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. A lipopolysaccharide (LPS)-stimulated rat mesangial cell HBZY-1 model in vitro was used to examine the anti-inflammatory activity of R. procumbens extract. RNA-seq was utilized to investigate differentially expressed genes (DEGs) and enriched signaling pathways between groups. Finally, qPCR was used for the validation analysis of the experimental results.

RESULTS

The results of network pharmacology showed that R. procumbens exerts its therapeutic effect on CGN through the AGE-RAGE signaling pathway in diabetic complications, PI3K-Akt, IL-17 signaling pathway, and so on. R. procumbens n-butanol extract (J-NE) can effectively relieve inflammation in HBZY-1. The results of KEGG pathway enrichment suggest that J-NE attenuated CGN was associated with the IL-17 signaling pathway, and the results of RNA-seq were consistent with network pharmacology. Targets enriched in the IL-17 signaling pathway, including Chemokine (C-C motif) ligand 7 (CCL7), Lipocalin 2 (LCN2), Chemokine (C-C motif) ligand 2 (CCL2), and Chemokine (C-X-C motif) ligand 1 (CXCL1), have been identified as crucial targets attenuating CGN by J-NE.

CONCLUSION

R. procumbens is a promising pharmacological candidate for the treatment of CGN in the present era.

The Association between Influenza Vaccine and Risk of Chronic Kidney Disease/Dialysis in Patients with Hypertension

BACKGROUNDS

Influenza vaccination could decrease the risk of major cardiac events in patients with hypertension. However, the vaccine's effects on decreasing the risk of chronic kidney disease (CKD) development in such patients remain unclear.

METHODS

We retrospectively analysed the data of 37,117 patients with hypertension (≥55 years old) from the National Health Insurance Research Database during 1 January 2001 to 31 December 2012. After a 1:1 propensity score matching by the year of diagnosis, we divided the patients into vaccinated (n = 15,961) and unvaccinated groups (n = 21,156).

RESULTS

In vaccinated group, significantly higher prevalence of comorbidities such as diabetes, cerebrovascular disease, dyslipidemia, heart and liver disease were observed compared with unvaccinated group. After adjusting age, sex, comorbidities, medications (anti-hypertensive agents, metformin, aspirin and statin), level of urbanization and monthly incomes, significantly lower risk of CKD occurrence was observed among vaccinated patients in influenza season, non-influenza season and all season (Adjusted hazard ratio [aHR]: 0.39, 95% confidence level [C.I.]: 0.33-0.46; 0.38, 95% C.I.: 0.31-0.45; 0.38, 95% C.I.: 0.34-0.44, respectively). The risk of hemodialysis significantly decreased after vaccination (aHR: 0.40, 95% C.I.: 0.30-0.53; 0.42, 95% C.I.: 0.31-0.57; 0.41, 95% C.I.: 0.33-0.51, during influenza season, non-influenza season and all season). In sensitivity analysis, patients with different sex, elder and non-elder age, with or without comorbidities and with or without medications had significant decreased risk of CKD occurrence and underwent hemodialysis after vaccination. Moreover, the potential protective effect appeared to be dose-dependent.

CONCLUSIONS

Influenza vaccination decreases the risk of CKD among patients with hypertension and also decrease the risk of receiving renal replacement therapy. Its potential protective effects are dose-dependent and persist during both influenza and noninfluenza seasons.

Renal and Inflammatory Proteins as Biomarkers of Diabetic Kidney Disease and Lupus Nephritis

Current methods for differentiation of kidney disease types are unspecific and may be invasive. Thus, there is a need for development of new biomarkers of kidney disorders that are specific and less invasive. In this study, we analyzed serum samples of diabetic kidney disease (DKD) and lupus nephritis (LN) patients to identify biomarkers of these two disorders. Serum samples were analyzed by Simple Plex assays. We calculated the area under the curve (AUC) as well as receiver operating characteristics (ROC) to obtain the sensitivity and specificity and other biomarker-related variables of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), interleukin- (IL-) 18, Lipocalin-2/NGAL, epidermal growth factor (EGF), u-Plasminogen Activator (uPA), and C-reactive protein (CRP) as potential biomarkers. Protein levels of ASC, IL-18, EGF, and Lipocalin-2/NGAL were higher in DKD and LN patients when compared to controls, whereas only uPA was elevated in DKD patients and CRP in LN patients. As determined by the AUC, of the six analytes studied, EGF (AUC = 0.9935), Lipocalin-2/NGAL (0.9554), ASC (0.7666), and uPA (0.7522) are reliable biomarkers of DKD, whereas EGF (1.000), Lipocalin-2/NGAL (0.9412), uPA (0.7443), and IL-18 (0.7384) are more reliable for LN. The biomarkers analyzed can differentiate between healthy and affected individuals. However, there was no difference between the levels of these biomarkers in DKD vs LN. Thus, although these biomarkers cannot be used to categorize patients between DKD and LN, they are useful as biomarkers of renal pathology.

Pioglitazone Ameliorates Acute Endotoxemia-Induced Acute on Chronic Renal Dysfunction in Cirrhotic Ascitic Rats

Endotoxemia-activated tumor necrosis factor (TNFα)/nuclear factor kappa B (NFκB) signals result in acute on chronic inflammation-driven renal dysfunction in advanced cirrhosis. Systemic activation of peroxisome proliferator-activated receptor gamma (PPARγ) with pioglitazone can suppress inflammation-related splanchnic and pulmonary dysfunction in cirrhosis. This study explored the mechanism and effects of pioglitazone treatment on the abovementioned renal dysfunction in cirrhotic rats. Cirrhotic ascitic rats were induced with renal dysfunction by bile duct ligation (BDL). Then, 2 weeks of pioglitazone treatment (Pio, PPAR gamma agonist, 12 mg/kg/day, using the azert osmotic pump) was administered from the 6th week after BDL. Additionally, acute lipopolysaccharide (LPS, Escherichia coli 0111:B4; Sigma, 0.1 mg/kg b.w, i.p. dissolved in NaCl 0.9%) was used to induce acute renal dysfunction. Subsequently, various circulating, renal arterial and renal tissue pathogenic markers were measured. Cirrhotic BDL rats are characterized by decreased mean arterial pressure, increased cardiac output and portal venous pressure, reduced renal arterial blood flow (RABF), increased renal vascular resistance (RVR), increased relative renal weight/hydroxyproline, downregulated renal PPARγ expression, upregulated renal inflammatory markers (TNFα, NFκB, IL-6, MCP-1), increased adhesion molecules (VCAM-1 and ICAM-1), increased renal macrophages (M1, CD68), and progressive renal dysfunction (increasing serum and urinary levels of renal injury markers (lipocalin-2 and IL-18)). In particular, acute LPS administration induces acute on chronic renal dysfunction (increasing serum BUN/creatinine, increasing RVR and decreasing RABF) by increased TNFα-NFκB-mediated renal inflammatory markers as well as renal M1 macrophage infiltration. In comparison with the BDL+LPS group, chronic pioglitazone pre-treatment prevented LPS-induced renal pathogenic changes in the BDL-Pio+LPS group. Activation of systemic, renal vessel and renal tissue levels of PPARγ by chronic pioglitazone treatment has beneficial effects on the endotoxemia-related TNFα/NFκB-mediated acute and chronic renal inflammation in cirrhosis. This study revealed that normalization of renal and renal arterial levels of PPARγ effectively prevented LPS-induced acute and chronic renal dysfunction in cirrhotic ascitic rats.

Intestinal SIRT1 Deficiency-Related Intestinal Inflammation and Dysbiosis Aggravate TNFα-Mediated Renal Dysfunction in Cirrhotic Ascitic Mice

In advanced cirrhosis, the TNFα-mediated intestinal inflammation and bacteria dysbiosis are involved in the development of inflammation and vasoconstriction-related renal dysfunction. In colitis and acute kidney injury models, activation of SIRT1 attenuates the TNFα-mediated intestinal and renal abnormalities. This study explores the impacts of intestinal SIRT1 deficiency and TNFα-mediated intestinal abnormalities on the development of cirrhosis-related renal dysfunction. Systemic and renal hemodynamics, intestinal dysbiosis [cirrhosis dysbiosis ratio (CDR) as marker of dysbiosis], and direct renal vasoconstrictive response (renal vascular resistance (RVR) and glomerular filtration rate (GFR)) to cumulative doses of TNFα were measured in bile duct ligated (BDL)-cirrhotic ascitic mice. In SIRT1^IEC-KO-BDL-ascitic mice, the worsening of intestinal dysbiosis exacerbates intestinal inflammation/barrier dysfunction, the upregulation of the expressions of intestinal/renal TNFα-related pathogenic signals, higher TNFα-induced increase in RVR, and decrease in GFR in perfused kidney. In intestinal SIRT1 knockout groups, the positive correlations were identified between intestinal SIRT1 activity and CDR. Particularly, the negative correlations were identified between CDR and RVR, with the positive correlation between CDR and GFR. In mice with advanced cirrhosis, the expression of intestinal SIRT1 is involved in the linkage between intestinal dysbiosis and vasoconstriction/hypoperfusion-related renal dysfunction through the crosstalk between intestinal/renal TNFα-related pathogenic inflammatory signals.

Inflammation and Trajectory of Renal Function in Community-Dwelling Older Adults

OBJECTIVES

To examine the hypothesis that the inflammatory state of aging is a risk factor for accelerated renal function (RF) decline using inflammatory biomarkers and RF measures collected over 9 years of follow-up in relatively healthy individuals enrolled in the Invecchiare in Chianti study.

DESIGN

Longitudinal.

SETTING

Community.

PARTICIPANTS

Individuals aged 60 and older with baseline estimated glomerular filtration rate (eGFR) of 60 mL/min per 1.73 m² and greater and no diabetes mellitus (DM) (N = 687).

MEASURES

eGFR, as a proxy for RF, was determined using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation at baseline and 3-, 6-, and 9-year follow-up. Incident chronic kidney disease (CKD) was defined as new-onset eGFR less than 60 mL/min per 1.73 m² at each follow-up. Predictors included baseline and time-dependent inflammatory biomarkers: soluble tumor necrosis factor alpha receptors (sTNFα-R1 and -R2), interleukin (IL)-6, IL-18, IL-1β, IL-1 receptor antagonist, and high-sensitivity C-reactive protein.

RESULTS

Higher baseline sTNFα-R1 was significantly associated with lower eGFR over 9 years, independent of DM or blood pressure (baseline: β^ = -0.39, P = .001; 3-year: β^ = -0.26, P = .001; 6-year: β^ = -0.36, P = .001; 9-year: β^ = -0.47, P = .001). The rate of TNFα-R1 change was significantly associated with rate of eGFR change (β^ = -0.18, P = .001). Baseline sTNFα-R1 predicted incident CKD (per 1-standard deviation increment: 3-year: relative risk (RR) = 1.3, 95% confidence interval (CI) = 1.1-1.5; 6-year: RR = 1.5, 95% CI = 1.1-2.2; 9-year RR = 1.6, 95% CI = 1.1-2.2). Similar results were found for sTNFα-R2.

CONCLUSION

Baseline TNFα-R levels and their rates of change were significantly associated with RF decline and incident CKD in older adults independent of DM or blood pressure.

Severity of coronary artery disease is an independent risk factor for decline in kidney function

BACKGROUND AND AIM

Chronic kidney disease (CKD) and cardiovascular disease are closely interrelated and the presence of one condition synergistically affects the prognosis of the other, in a negative manner. There are surprisingly very few data on the relationship between baseline coronary artery disease (CAD) severity and subsequent decline in kidney function. We aimed to evaluate for the first time whether baseline coronary artery lesion severity predicts the decline in kidney function.

MATERIALS AND METHODS

The study population was derived from a series of consecutive patients presenting with stable angina pectoris or angina equivalents, who underwent coronary angiography. SYNTAX score for each patient was calculated to define severity of CAD. Change in kidney function was defined by calculating the rates of change in eGFR.

RESULTS

Among the 823 patients included in our study, the mean age was 59.2±10.7years, 78.4% were males, and 32% had diabetes. The mean baseline eGFR was 87.3±24.9ml/min/1.73m(2) and the median Syntax score was 14 (IQR=10-20). The median length of follow-up was 2.75years (IQR=2.42-3.50). The mean yearly change for eGFR in the entire study population was 4.06 (95% CI: 3.59-4.51)ml/min/1.73m(2). A higher Syntax score was associated with a significantly faster decline in eGFR in all (unadjusted and adjusted) models. During the follow-up, 103 patients developed CKD. A higher Syntax score, analyzed both as continuous and categorical variable, was associated with incident CKD in all models.

CONCLUSION

We have demonstrated for the first time that severity of CAD is an independent risk factor for the decline in kidney function. Studies are needed to highlight the potential mechanisms regarding the association between severity of CAD and decline in kidney function.

The long noncoding RNA landscape in hypoxic and inflammatory renal epithelial injury

Long noncoding RNAs (lncRNAs) are emerging as key species-specific regulators of cellular and disease processes. To identify potential lncRNAs relevant to acute and chronic renal epithelial injury, we performed unbiased whole transcriptome profiling of human proximal tubular epithelial cells (PTECs) in hypoxic and inflammatory conditions. RNA sequencing revealed that the protein-coding and noncoding transcriptomic landscape differed between hypoxia-stimulated and cytokine-stimulated human PTECs. Hypoxia- and inflammation-modulated lncRNAs were prioritized for focused followup according to their degree of induction by these stress stimuli, their expression in human kidney tissue, and whether exposure of human PTECs to plasma of critically ill sepsis patients with acute kidney injury modulated their expression. For three lncRNAs (MIR210HG, linc-ATP13A4-8, and linc-KIAA1737-2) that fulfilled our criteria, we validated their expression patterns, examined their loci for conservation and synteny, and defined their associated epigenetic marks. The lncRNA landscape characterized here provides insights into novel transcriptomic variations in the renal epithelial cell response to hypoxic and inflammatory stress.

From the periphery to the brain: Lipocalin-2, a friend or foe?

Lipocalin-2 (LCN2) is an acute-phase protein that, by binding to iron-loaded siderophores, acts as a potent bacteriostatic agent in the iron-depletion strategy of the immune system to control pathogens. The recent identification of a mammalian siderophore also suggests a physiological role for LCN2 in iron homeostasis, specifically in iron delivery to cells via a transferrin-independent mechanism. LCN2 participates, as well, in a variety of cellular processes, including cell proliferation, cell differentiation and apoptosis, and has been mostly found up-regulated in various tissues and under inflammatory states, being its expression regulated by several inducers. In the central nervous system less is known about the processes involving LCN2, namely by which cells it is produced/secreted, and its impact on cell proliferation and death, or in neuronal plasticity and behaviour. Importantly, LCN2 recently emerged as a potential clinical biomarker in multiple sclerosis and in ageing-related cognitive decline. Still, there are conflicting views on the role of LCN2 in pathophysiological processes, with some studies pointing to its neurodeleterious effects, while others indicate neuroprotection. Herein, these various perspectives are reviewed and a comprehensive and cohesive view of the general function of LCN2, particularly in the brain, is provided.