Catherine Godson

Subclinical CKD (sCKD) represents an under-recognised phase of renal vulnerability in which structural injury and impaired physiological adaptability precede detectable changes in serum creatinine, eGFR, or albuminuria. Current diagnostic frameworks rely heavily on static biomarkers that lack sensitivity at higher GFR ranges, leaving a substantial “blind spot” in early disease detection. Renal functional reserve (RFR), the increase in GFR in response to a metabolic or physiological stressor, offers a dynamic assessment of kidney health that may reveal latent renal dysfunction before overt CKD manifests. This review discusses the physiological basis, methodological approaches, and emerging clinical applications of RFR testing. Protein ingestion and intravenous amino acid infusion are the most established stimuli, eliciting coordinated vasodilatory and neurohormonal responses that transiently augment GFR. Measurement techniques range from gold-standard exogenous filtration markers to more pragmatic tools such as creatinine clearance, cystatin C, and Doppler ultrasound–based assessments; each carries advantages and limitations that have historically impeded standardization and broader clinical uptake. Evidence across multiple clinical contexts demonstrates that blunted RFR frequently accompanies early renal injury despite preserved eGFR and normoalbuminuria. RFR has also shown promise for perioperative risk stratification and may help identify individuals at heightened susceptibility to nephrotoxic exposures or hemodynamic stress. Despite its potential, RFR implementation remains constrained by protocol heterogeneity, labour-intensive measurement methods, and limited reproducibility. Future priorities include the development of standardized, feasible protocols and validation in large prospective cohorts. RFR represents a promising tool to close the diagnostic gap in sCKD, offering a path toward earlier detection, personalized intervention, and more proactive kidney health management.

BACKGROUND: Defective macrophage efferocytosis is a key driver of chronic nonresolving inflammation in dyslipidemia-associated diseases, such as obesity and atherosclerosis. However, the mechanism by which intracellular lipid accumulation impairs macrophage efferocytosis remains unclear. We hypothesized that lipid-induced endoplasmic reticulum (ER) stress mediates defective macrophage efferocytosis. METHODS: Bone marrow–derived macrophages were exposed to 7-ketocholesterol or palmitate to induce ER stress, and efferocytosis was quantified by measuring uptake of fluorescently labeled apoptotic cells with microscopy and flow cytometry. Key pathways were interrogated with pharmacological inhibitors, siRNA (silencing RNA), and in vivo models, including obese mice and in Ldlr ^−/− mice with hematopoietic-specific deletion of TRIB3 (Tribbles pseudokinase-3). Human relevance was assessed by testing efferocytosis in macrophages from individuals carrying the TRIB3 Q84R coronary artery disease risk variant (rs2295490) and by examining carotid endarterectomy samples. RESULTS: Activation of the ATF4 (activating transcription factor 4) branch of the ER stress pathway in lipid-loaded foamy macrophages led to upregulation of TRIB3, which triggered the downregulation of Rab27a, resulting in impaired focal exocytosis of intracellular membrane pools towards nascent, apoptotic cell–containing phagosomes. The resultant delay in phagosome closure stalled efferocytosis. In obese mice, this impairment was reversed using an ER stress–relieving chemical chaperone and via macrophage-specific knockdown of ATF4 or TRIB3. In atherosclerotic mice, hematopoietic cell–specific deletion of TRIB3 led to increased lesional efferocytosis, decreased plaque necrosis, and increased collagen, which are characteristic of stable plaques. In humans, TRIB3 expression was higher in vulnerable regions of carotid plaques, and macrophages from individuals carrying the gain-of-function TRIB3 Q84R risk variant expressed more TRIB3 and displayed decreased efferocytosis. CONCLUSIONS: Lipid-induced ER stress impairs macrophage efferocytosis via activation of the ATF4-TRIB3-Rab27a signaling axis, leading to exacerbated plaque necrosis. Targeted disruption of TRIB3 signaling in macrophages represents a novel therapeutic approach to promote efferocytosis and stabilize atherosclerotic plaques.

BACKGROUND: Neutrophil extracellular traps (NETs) contribute to atherosclerosis progression and are linked to adverse clinical outcomes such as myocardial infarction and stroke. Although the triggers of NET formation in plaques are known, the mechanisms governing DNase-mediated NET clearance and how these are disrupted during atherosclerosis remain unclear. Moreover, the consequences of impaired NET clearance on disease progression are not known. METHODS: Low-density lipoprotein receptor knockout ( Ldlr ^{−/ −} ) mice with hematopoietic cell–specific deletion of DNase1 and DNase1L3 were fed a Western-type diet for 16 weeks to examine the impact of loss of DNase activity and the subsequent NET accumulation on advanced atherosclerosis. The effect of NETs on macrophage efferocytosis was examined in vitro and in the mouse peritoneal cavity and atherosclerotic plaque in vivo. To identify the signaling pathway impairing the NET-induced DNase response, in vitro assays were performed using selective endoplasmic reticulum stress pathway inhibitors, and the findings were validated in murine and human atherosclerotic tissues. RESULTS: Lack of DNase secretion by macrophages led to accumulation of NETs in local tissues, including atherosclerotic plaques. Persisting NETs in turn promoted cleavage of the efferocytosis receptor MerTK (c-mer proto-oncogene tyrosine kinase), resulting in defective macrophage efferocytosis and increased atherosclerotic plaque necrosis. In vitro screening identified endoplasmic reticulum stress–induced activation of the PERK (protein kinase R–like endoplasmic reticulum kinase)–ATF (activating transcription factor) 4 signaling axis in atherogenic macrophages as a key driver of impaired DNase secretion, leading to delayed NET clearance and their pathological persistence. Treatment of human atherosclerotic plaques and Ldlr ^−/− mice with integrated stress response inhibitor, a selective PERK inhibitor, restored vascular DNase secretion and facilitated NET clearance. CONCLUSIONS: Macrophages play a key role in clearing NETs from tissues. Endoplasmic reticulum stress suppresses macrophage DNase secretion, leading to NET accumulation in atherosclerotic plaques, which triggers efferocytosis impairment and plaque progression. Targeting the PERK-ATF4 axis to restore DNase release and NET clearance represents a promising therapeutic strategy to promote plaque stabilization.

Background: Diabetic heart disease may eventually lead to heart failure, a leading cause of mortality in diabetic individuals. The lack of effective treatments for diabetes-induced heart failure may result from a failure to address the underlying pathological processes, including chronic, low-grade inflammation. Previous studies have reported that lipoxin A₄ (LXA₄), known to promote resolution of inflammation, attenuates diabetes-induced atherosclerosis, but its impact on diabetic hearts has not been sought. Thus, we aimed to determine whether LXA₄ therapeutic treatment attenuates diabetes-induced cardiac pathology. Methods: Six-week-old male apolipoprotein E-deficient (ApoE^−/−) mice were followed for 16 weeks after injection of streptozotocin (STZ, 55 mg/kg/day, i.p. for 5 days) to induce type-1 diabetes (T1DM). Treatment with LXA₄ (5 μg/kg, i.p.) or vehicle (0.02% ethanol, i.p.) was administered twice weekly for the final 6 weeks. One week before endpoint, echocardiography was performed within a subset of mice from each group. At the end of the study, mice were euthanized with sodium pentobarbital (100 mg/kg i.p.) and hearts were collected for ex vivo analysis, including histological assessment, gene expression profiling by real-time PCR and protein level measurement by western blot. Results: As expected diabetic mice showed a significant elevation in plasma glycated hemoglobin (HbA_1c) and glucose levels, along with reduced body weight. Vehicle-treated diabetic mice exhibited increased cardiac inflammation, macrophage content, and an elevated ratio of M1-like to M2-like macrophage markers. In addition, myocardial fibrosis, cardiomyocytes apoptosis and hypertrophy (at the genetic level) were evident, with echocardiography revealing early signs of left ventricular (LV) diastolic dysfunction. Treatment with LXA₄ ameliorated diabetes-induced cardiac inflammation, pro-inflammatory macrophage polarization and cardiac remodeling (especially myocardial fibrosis and cardiomyocytes apoptosis), with ultimate improvement in cardiac function. Of note, this improvement was independent of glucose control. Conclusions: These findings demonstrated that LXA₄ treatment attenuated the extent of cardiac inflammation in diabetic hearts, resulting in limited cardiac remodeling and improved LV diastolic function. This supports further exploration of LXA₄-based therapy for the management of diabetic heart disease. The recent development of stable LXA₄ mimetics holds potential as a novel strategy to treat cardiac dysfunction in diabetes, paving the way for innovative and more effective therapeutic strategies. Graphical

Key Points: We have identified a transcriptional signature of 93 genes associated with CKD severity and progression. Protein 4.1, ezrin, radixin, moesin domain-containing protein 3 gene expression is reduced in the context of more severe kidney disease and in individuals who go on to develop progressive disease. Protein 4.1, ezrin, radixin, moesin domain-containing protein 3 interacts with proteins of the cell cytoskeleton and cell-cell junctions in proximal tubule epithelial cells. Background: Currently, there are limited methods to link disease severity and risk of disease progression in CKD. To better understand this potential relationship, we interrogated the renal transcriptomic profile of individuals with CKD with measures of CKD severity and identified protein 4.1, ezrin, radixin, moesin-domain containing protein 3 (FRMD3) as a candidate gene for follow-up study. Methods: RNA-sequencing was used to profile the transcriptome of CKD biopsies from the North Dublin Renal BioBank, the results of which were correlated with clinical parameters. The potential function of FRMD3 was explored by interrogating the FRMD3 interactome and assessing the effect of lentiviral mediated FRMD3 knock down on human renal proximal tubule epithelial cells by assessing cell viability, metabolic activity, and structural markers. Results: We identified a subset of 93 genes which are significantly correlated with eGFR and percentage tubulointerstitial fibrosis at time of biopsy and with CKD progression 5 years postbiopsy. These results were validated against transcriptomic data from an external cohort of 432 nephrectomy samples. One of the top-ranking genes from this subset, FRMD3, has previously been associated with the risk of developing diabetic kidney disease. Interrogating the interactome of FRMD3 in tubule epithelial cells revealed interactions with cytoskeletal components of cell-cell junctions. Knockdown of FRMD3 expression in tubule epithelial cells resulted in increased proapoptotic activity within the cells, as well as dysregulation of E-Cadherin. Conclusions: We have identified a panel of kidney-specific transcripts correlated with severity and progression of kidney disease, and from this, we have identified a possible role for FRMD3 in tubule cell structure and health.

Introduction: Cardiovascular disease (CVD) is responsible for over 30% of mortality worldwide. CVD arises from the complex influence of molecular, clinical, social, and environmental factors. Despite the growing number of autosomal genetic variants contributing to CVD, the cause of most CVDs is still unclear. Mitochondria are crucial in the pathophysiology, development and progression of CVDs; the impact of mitochondrial DNA (mtDNA) variants and mitochondrial haplogroups in the context of CVD has recently been highlighted.Aims: We investigated the role of genetic variants in both mtDNA and nuclear-encoded mitochondrial genes (NEMG) in CVD, including coronary artery disease (CAD), hypertension, and serum lipids in the UK Biobank, with sub-group analysis for diabetes.Methods: We investigated 371,542 variants in 2,527 NEMG, along with 192 variants in 32 mitochondrial genes in 381,994 participants of the UK Biobank, stratifying by presence of diabetes.Results: Mitochondrial variants showed associations with CVD, hypertension, and serum lipids. Mitochondrial haplogroup J was associated with CAD and serum lipids, whereas mitochondrial haplogroups T and U were associated with CVD. Among NEMG, variants within Nitric Oxide Synthase 3 (NOS3) showed associations with CVD, CAD, hypertension, as well as diastolic and systolic blood pressure. We also identified Translocase Of Outer Mitochondrial Membrane 40 (TOMM40) variants associated with CAD; Solute carrier family 22 member 2 (SLC22A2) variants associated with CAD and CVD; and HLA-DQA1 variants associated with hypertension. Variants within these three genes were also associated with serum lipids.Conclusion: Our study demonstrates the relevance of mitochondrial related variants in the context of CVD. We have linked mitochondrial haplogroup U to CVD, confirmed association of mitochondrial haplogroups J and T with CVD and proposed new markers of hypertension and serum lipids in the context of diabetes. We have also evidenced connections between the etiological pathways underlying CVDs, blood pressure and serum lipids, placing NOS3, SLC22A2, TOMM40 and HLA-DQA1 genes as common nexuses.

Increased albuminuria indicates underlying glomerular pathology and is associated with worse renal disease outcomes, especially in diabetic kidney disease. Many single nucleotide polymorphisms (SNPs), associated with albuminuria, could be potentially useful to construct polygenic risk scores (PRSs) for kidney disease. We investigated the diagnostic accuracy of SNPs, previously associated with albuminuria-related traits, on albuminuria and renal injury in the UK Biobank population, with a particular interest in diabetes. Multivariable logistic regression was used to evaluate the influence of 91 SNPs on urine albumin-to-creatinine ratio (UACR)-related traits and kidney damage (any pathology indicating renal injury), stratifying by diabetes. Weighted PRSs for microalbuminuria and UACR from previous studies were used to calculate the area under the receiver operating characteristic curve (AUROC). CUBN-rs1801239 and DDR1-rs116772905 were associated with all the UACR-derived phenotypes, in both the overall and non-diabetic cohorts, but not with kidney damage. Several SNPs demonstrated different effects in individuals with diabetes compared to those without. SNPs did not improve the AUROC over currently used clinical variables. Many SNPs are associated with UACR or renal injury, suggesting a role in kidney dysfunction, dependent on the presence of diabetes in some cases. However, individual SNPs or PRSs did not improve the diagnostic accuracy for albuminuria or renal injury compared to standard clinical variables.

Inflammation and its timely resolution are critical to ensure effective host defense and appropriate tissue repair after injury and or infection. Chronic, unresolved inflammation typifies many prevalent pathologies. The key mediators that initiate and drive the inflammatory response are well defined and targeted by conventional anti-inflammatory therapeutics. More recently, there is a growing appreciation that specific mediators, including arachidonate-derived lipoxins, are generated in self-limiting inflammatory responses to promote the resolution of inflammation and endogenous repair mechanisms without compromising host defense. We discuss the proresolving biological actions of lipoxins and recent efforts to harness their therapeutic potential through the development of novel, potent lipoxin mimetics generated via efficient, modular stereoselective synthetic pathways. We consider the evidence that lipoxin mimetics may have applications in limiting inflammation and reversing fibrosis and the underlying mechanisms.