Phenotypic heterogeneity in human genetic diseases: ultrasensitivity-mediated threshold effects as a unifying molecular mechanism.

Phenotypic heterogeneity is very common in genetic systems and in human diseases and has important consequences for disease diagnosis and treatment. In addition to the many genetic and non-genetic (e.g., epigenetic, environmental) factors reported to account for part of the heterogeneity, we stress the importance of stochastic fluctuation and regulatory network topology in contributing to phenotypic heterogeneity. We argue that a threshold effect is a unifying principle to explain the phenomenon; that ultrasensitivity is the molecular mechanism for this threshold effect; and discuss the three conditions for phenotypic heterogeneity to occur. We suggest that threshold effects occur not only at the cellular level, but also at the organ level. We stress the importance of context-dependence and its relationship to pleiotropy and edgetic mutations. Based on this model, we provide practical strategies to study human genetic diseases. By understanding the network mechanism for ultrasensitivity and identifying the critical factor, we may manipulate the weak spot to gently nudge the system from an ultrasensitive state to a stable non-disease state. Our analysis provides a new insight into the prevention and treatment of genetic diseases.

Emergence and Persistent Dominance of SARS-CoV-2 Omicron BA.2.3.7 Variant, Taiwan.

Since April 2022, waves of SARS-CoV-2 Omicron variant cases have surfaced in Taiwan and spread throughout the island. Using high-throughput sequencing of the SARS-CoV-2 genome, we analyzed 2,405 PCR-positive swab samples from 2,339 persons and identified the Omicron BA.2.3.7 variant as a major lineage within recent community outbreaks in Taiwan.

Salvia miltiorrhiza Extract and Individual Synthesized Component Derivatives Induce Activating-Transcription-Factor-3-Mediated Anti-Obesity Effects and Attenuate Obesity-Induced Metabolic Disorder by Suppressing C/EBPα in High-Fat-Induced Obese Mice.

Pharmacological studies indicate that Salvia miltiorrhiza extract (SME) can improve cardiac and blood vessel function. However, there is limited knowledge regarding the effects (exerted through epigenetic regulation) of SME and newly derived single compounds, with the exception of tanshinone IIA and IB, on obesity-induced metabolic disorders. In this study, we administered SME or dimethyl sulfoxide (DMSO) as controls to male C57BL/J6 mice after they were fed a high-fat diet (HFD) for 4 weeks. SME treatment significantly reduced body weight, fasting plasma glucose, triglyceride levels, insulin resistance, and adipogenesis/lipogenesis gene expression in treated mice compared with controls. Transcriptome array analysis revealed that the expression of numerous transcriptional factors, including activating transcription factor 3 (ATF3) and C/EBPα homologous protein (CHOP), was significantly higher in the SME group. ST32db, a novel synthetic derivative similar in structure to compounds from S. miltiorrhiza extract, ameliorates obesity and obesity-induced metabolic syndrome in HFD-fed wild-type mice but not ATF3-/- mice. ST32db treatment of 3T3-L1 adipocytes suppresses lipogenesis/adipogenesis through the ATF3 pathway to directly inhibit C/EBPα expression and indirectly inhibit the CHOP pathway. Overall, ST32db, a single compound modified from S. miltiorrhiza extract, has anti-obesity effects through ATF3-mediated C/EBPα downregulation and the CHOP pathway. Thus, SME and ST32db may reduce obesity and diabetes in mice, indicating the potential of both SME and ST32db as therapeutic drugs for the treatment of obesity-induced metabolic syndrome.

Emergent Roles of Circular RNAs in Metabolism and Metabolic Disorders.

Circular RNAs (circRNAs) are an emerging group of long non-coding RNAs (lncRNAs) and have attracted attention again according to the progress in high-throughput sequencing in recent years. circRNAs are genome transcripts produced from pre-messenger (m)RNA regions in a specific process called "back-splicing," which forms covalently closed continuous loops. Due to their lack of a 5' cap and 3' poly-adenylated tails, circRNAs are remarkably more stable than linear RNAs. Functionally, circRNAs can endogenously sponge to microRNAs, interact with RNA-binding proteins (RBPs), or translate themselves. Moreover, circRNAs can be expressed in cell type- or tissue-specific expression patterns. Therefore, they are proposed to play essential roles in fine-tuning our body's homeostasis by regulating transcription and translation processes. Indeed, there has been accumulating emergent evidence showing that dysregulation of circRNAs can lead to metabolic disorders. This study explored the current knowledge of circRNAs that regulate molecular processes associated with glucose and lipid homeostasis and related pathogeneses of metabolic disorders. We also suggest the potential role of circRNAs as disease biomarkers and therapeutic targets.

Alterations of bone markers in obese patients with type 2 diabetes after bariatric surgery: A meta-analysis and systemic review of randomized controlled trials and cohorts.

BACKGROUND: The aim of this study is to evaluate the alterations in bone mineral density and other surrogate markers for osteoporosis in obese patients with type 2 diabetes mellitus (T2DM) who received Roux-en-Y gastric bypass (RYGB) versus medical treatment as control. METHODS: We searched 4 electronic databases and reference lists of relevant studies for eligible research published before December, 2019. After quality assessment, eligible studies were synthesized for relevant outcomes, including lumbar spine bone mineral density (L-spine BMD) change, total hip BMD change, osteocalcin level, C-terminal telopeptide level, and parathyroid hormone level. RESULTS: Three randomized clinical trials and 2 observational studies concerning 307 total obese T2DM patients were included. Follow-up ranged from 12 to 60 months. Patients underwent RYGB surgery were associated with both higher L-spine BMD loss (mean difference: -2.90, 95% CI: -2.99∼-2.81, P < .00001) and total hip BMD loss (mean difference: -5.81, 95% CI: -9.22∼-2.40, P = .0008). As to biochemical markers of bone metabolism, we found significantly higher osteocalcin level in medical treatment (control) group compared with RYGB group (mean difference: 11.16, 95% CI: 8.57-13.75, P < .00001). However, higher C-terminal telopeptide level and parathyroid hormone level were noted in medical treatment group (control) compared with RYGB group (mean difference: 0.29, 95% CI: 0.11-0.48, P = .002; mean difference: 1.56, 95% CI: 0.84-2.27, P < .0001). CONCLUSIONS: RYGB surgery is associated with negative impact on bone metabolism and increase the risk of osteoporosis in obese patients with T2DM. We suggest that clinicians acknowledge the adverse effects of surgery and keep monitoring bone mineral components in post-RYGB populations. Further studies regarding the optimal amount of perioperative and postsurgical supplementation should be evaluated.

Inhibition of miR-155 potentially protects against lipopolysaccharide-induced acute lung injury through the IRF2BP2-NFAT1 pathway.

Sepsis-induced lung injury is a lethal complication with no effective treatment options, affecting millions of people worldwide. Oroxylin A (OroA) is a natural flavonoid with potent anticancer effects, but its modulating effect on inflammation through microRNAs (miRs) is not apparent. In this report, we investigated the target genes of the miR pathway mediated by OroA and assessed the potential for novel treatments of septic lung injury. An miR array screening and quantitative polymerase chain reaction identified that miR-155-5p could be a candidate regulated by OroA. Bioinformatics analysis indicated that interferon regulatory factor-2-binding protein-2 (IRF2BP2) might be a target of miR-155-5p, and this hypothesis was verified through reporter assays. In addition, an immunoprecipitation assay demonstrated that OroA increased the binding activity of IRF2BP2 to the nuclear factor of activated T-cells 1 (NFAT1), causing inducible nitric oxide synthase to cause an inflammatory reaction. Finally, the direct injection of short hairpin RNA (shRNA)-miR-155-5p into the bone marrow of mice ameliorated LPS-induced acute lung injury and inflammation in mice. Our results provide new mechanistic insights into the role of the OroA-induced miR-155-5p-IRF2BP2-NFAT1 axis in sepsis, demonstrating that direct bone marrow injection of lentivirus containing shRNA-155-5p could prove to be a potential future clinical application in alleviating sepsis-induced acute lung injury.

MicroRNAs as Biomarkers and Therapeutic Targets in Inflammation- and Ischemia-Reperfusion-Related Acute Renal Injury.

Acute kidney injury (AKI), caused mainly by ischemia-reperfusion, sepsis, or nephrotoxins (such as contrast medium), is identified by an abrupt decline in kidney function and is associated with high morbidity and mortality. Despite decades of efforts, the pathogenesis of AKI remains poorly understood, and effective therapies are lacking. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the posttranscriptional level to control cell differentiation, development, and homeostasis. Additionally, extracellular miRNAs might mediate cell-cell communication during various physiological and pathological processes. Recently, mounting evidence indicates that miRNAs play a role in the pathogenesis of AKI. Moreover, emerging research suggests that because of their remarkable stability in body fluids, microRNAs can potentially serve as novel diagnostic biomarkers of AKI. Of note, our previous finding that miR-494 is rapidly elevated in urine but not in serum provides insight into the ultimate role of urine miRNAs in AKI. Additionally, exosomal miRNAs derived from stem cells, known as the stem cell secretome, might be a potential innovative therapeutic strategy for AKI. This review aims to provide new data obtained in this field of research. It is hoped that new studies on this topic will not only generate new insights into the pathophysiology of urine miRNAs in AKI but also might lead to the precise management of this fatal disease.

Alteration autonomic control of cardiac function during hemodialysis predict cardiovascular outcomes in end stage renal disease patients.

Dialysis-induced hemodynamic instability has been associated with increased risk of cardiovascular (CV) mortality. However, the control mechanisms beneath the dynamic BP changes and cardiac function during hemodialysis and subsequent CV events are not known. We hypothesize that the impaired hemodynamic control can be prognostic indicators for subsequent CV events in end stage renal diseaes (ESRD) patients. To explore the association of hemodynamic parameters and CV events in hemodialysis patients, we enrolled ESRD patients who received chronic hemodialysis without documented atherosclerotic cardiovascular disease and hemodynamic parameters were continuously obtained from the impedance cardiography during hemodialysis. A total of 35 patients were enrolled. 16 patients developed hospitalized CV events. The statistical properties [coefficient of variance (standard deviation / mean value; CoV)] of hourly beat-to-beat dynamics of hemodynamic parameters were calculated. The CoV of stroke volume (SV) and cardiac index (CI) between the 1st and 2nd hour of dialysis were significantly increased in patients without CV events compared to those with CV events. Higher CoV of SVdiff and CIdiff were significantly correlated with longer CV event-free survival, and the area under the receiver operating characteristic (ROC) curve showed fair overall discriminative power (0.783 and 0.796, respectively). The responses of hemodynamic control mechanisms can be independent predictive indexes for lower hospitalized CV events, which implies that these patients who have better autonomic control systems may have better CV outcomes.

Green dialysate and gallbladder perforation in a peritoneal dialysis patients: a case report and literature review.

BACKGROUND: Gallbladder perforation is a rare but lethal condition and its diagnosis is usually difficult and delayed. Frequently, gallbladder rupture is associated with cholecystitis, but spontaneous perforation was ever described. However, spontaneous rupture of gallbladder has never been reported in patients underwent peritoneal dialysis. CASE PRESENTATION: We report a 62-year-old man who presented with abdominal pain for 2 days to clinic. Peritoneal dialysis-related peritonitis was diagnosed initially. It was followed by spontaneous gallbladder perforation with greenish dialysate. The patient was managed successfully by antibiotic treatment and primary closure of gallbladder perforation with external drainage. He recovered from this critical condition and stayed on dialysis. CONCLUSIONS: Early diagnosis and timely surgical intervention yields a good prognosis in PD patients with gallbladder perforation. Surgical intervention and antibiotic treatment are the mainstay of treatment. Both of them should take place promptly.

Lupus pneumonitis presenting with high titre of anti-Ro antibody.

Lupus pneumonitis carries high mortality and is a rare manifestation of systemic lupus erythematosus (SLE). However, it is difficult to diagnose and is often mistaken as pneumonia, alveolar haemorrhage, or organizing pneumonia. Previous studies demonstrated that serum anti-Ro antibodies are elevated more frequently in SLE patients with pneumonitis than in those without. We report a 21-year-old female who was newly diagnosed as having SLE with nephritis and who suddenly developed right lung opacity and rapidly progressed to severe hypoxaemia despite the use of broad-spectrum antibiotics. The serum titre of anti-Ro antibody was greater than 240 U/mL. She underwent lung biopsy and lupus pneumonitis was confirmed by the pathological findings. Subsequently, she showed a favourable response to plasma exchange, steroid pulse therapy, and mycophenolate mofetil (MMF) treatment. For SLE patients with pulmonary infiltrates, high degree of clinical suspicion of lupus pneumonitis is required and measurement of serum anti-Ro antibody may help to make the diagnosis.

Association Between Stroke Risk and Metformin Use in Hemodialysis Patients With Diabetes Mellitus: A Nested Case-Control Study.

BACKGROUND: Metformin use reduces the incidence and severity of stroke in patients with type 2 diabetes mellitus (DM). The benefits of metformin for stroke have not been examined in hemodialysis patients with DM. METHODS AND RESULTS: Using the National Health Insurance Research Database, we identified 17 760 patients with DM and new-onset hemodialysis between 2001 and 2013. Of these, 1898 patients hospitalized for either ischemic or hemorrhagic stroke were matched to 7592 control patients according to sex, age, and year of initial hemodialysis therapy by using incidence sampling. The association between metformin use and stroke risk was estimated using conditional logistic regression after adjustment for hemodialysis frequency, comorbidity, and prescribed medications. Metformin use was recorded before the date of stroke admission and the date of pseudostroke of the case and control patients, respectively. Results showed that hemodialysis patients with ischemic stroke were more likely to use metformin than the controls 1 year before the date of stroke admission (adjusted odds ratio: 1.64; 95% confidence interval, 1.32-2.04). The association was evident within 90 days before the index date (adjusted odds ratio: 1.81; 95% confidence interval, 1.27-2.60). The results were consistent with those of hemodialysis patients with hemorrhagic stroke. Metformin use remained a risk factor for stroke in patients treated with antihypertensive, sulfonylurea, and antiplatelet drugs. CONCLUSIONS: This nested case-control study is the first to show that metformin use is associated with stroke risk in hemodialysis patients with DM. We suggest that metformin should not be used by hemodialysis patients with DM.

Klotho May Ameliorate Proteinuria by Targeting TRPC6 Channels in Podocytes.

Klotho is a type-1 membrane protein predominantly produced in the kidney, the extracellular domain of which is secreted into the systemic circulation. Membranous and secreted Klotho protect organs, including the kidney, but whether and how Klotho directly protects the glomerular filter is unknown. Here, we report that secreted Klotho suppressed transient receptor potential channel 6 (TRPC6)-mediated Ca2+ influx in cultured mouse podocytes by inhibiting phosphoinositide 3-kinase-dependent exocytosis of the channel. Furthermore, soluble Klotho reduced ATP-stimulated actin cytoskeletal remodeling and transepithelial albumin leakage in these cells. Overexpression of TRPC6 by gene delivery in mice induced albuminuria, and exogenous administration of Klotho ameliorated the albuminuria. Notably, immunofluorescence and in situ hybridization revealed Klotho expression in podocytes of mouse and human kidney. Heterozygous Klotho-deficient CKD mice had aggravated albuminuria compared with that in wild-type CKD mice with a similar degree of hypertension and reduced clearance function. Finally, disrupting the integrity of glomerular filter by saline infusion-mediated extracellular fluid volume expansion increased urinary Klotho excretion. These results reveal a potential novel function of Klotho in protecting the glomerular filter, and may offer a new therapeutic strategy for treatment of proteinuria.

Inhibition of TRPC6 channels ameliorates renal fibrosis and contributes to renal protection by soluble klotho.

Fibrosis is an exaggerated form of tissue repair that occurs with serious damage or repetitive injury and ultimately leads to organ failure due to the excessive scarring. Increased calcium ion entry through the TRPC6 channel has been associated with the pathogenesis of heart and glomerular diseases, but its role in renal interstitial fibrosis is unknown. We studied this by deletion of Trpc6 in mice and found it decreased unilateral ureteral obstruction-induced interstitial fibrosis and blunted increased mRNA expression of fibrosis-related genes in the ureteral obstructed kidney relative to that in the kidney of wild-type mice. Administration of BTP2, a pyrazol derivative known to inhibit function of several TRPC channels, also ameliorated obstruction-induced renal fibrosis and gene expression in wild-type mice. BTP2 inhibited carbachol-activated TRPC3 and TRPC6 channel activities in HEK293 cells. Ureteral obstruction caused over a 10-fold increase in mRNA expression for TRPC3 as well as TRPC6 in the kidneys of obstructed relative to the sham-operated mice. The magnitude of protection against obstruction-induced fibrosis in Trpc3 and Trpc6 double knockout mice was not different from that in Trpc6 knockout mice. Klotho, a membrane and soluble protein predominantly produced in the kidney, is known to confer protection against renal fibrosis. Administration of soluble klotho significantly reduced obstruction-induced renal fibrosis in wild-type mice, but not in Trpc6 knockout mice, indicating that klotho and TRPC6 inhibition act in the same pathway to protect against obstruction-induced renal fibrosis. Thus klotho and TRPC6 may be pharmacologic targets for treating renal fibrosis.

Association between Use of Oral Anti-Diabetic Drugs and the Risk of Sepsis: A Nested Case-Control Study.

Although oral antidiabetic drugs (OADs) have been associated with immunomodulation in preclinical studies, little is still known about the association between the use of OADs and the risk of sepsis. Using a cohort of patients, extracted from Taiwan's National Health Insurance Research Database, with type 2 diabetes who were newly diagnosed between 2010 and 2012 and treated with OADs, we conducted a nested case-control study involving 43,015 cases (patients who were first hospitalized for sepsis) and 43,015 matched controls. Compared with non-use, metformin use was associated with a decreased risk of developing sepsis (adjusted odds ratio [OR] 0.80, 95% confidence interval [CI] 0.77-0.83, P < 0.001), but meglitinide (adjusted OR 1.32, 95% CI 1.25-1.40, P < 0.001) use was associated with the increased risk of developing sepsis. The risk for development of sepsis was also lower among current (adjusted OR 0.87, 95% CI 0.78-0.96) and recent (adjusted OR 0.83, 95% CI 0.73-0.94) thiazolidinedione users. Current or recent sulfonylurea use and dipeptidyl peptidase-4 inhibitor use were not significantly associated with the development of sepsis. Our results highlight the need to consider the potential pleiotropic effect of OADs against sepsis in addition to the lowering of blood glucose.

Association of hypoglycemia with incident chronic kidney disease in patients with type 2 diabetes: a nationwide population-based study.

This article aims to investigate the long-term risk of incident chronic kidney disease (CKD) in type 2 diabetes mellitus (T2DM) patients with hypoglycemia.This nationwide, population-based, propensity score (PS)-matched cohort study involved 2 cohorts: a hypoglycemic cohort and a matched cohort without hypoglycemia. Data from 1.3 million patients with newly diagnosed T2DM between 2000 and 2010 were extracted from Taiwan's National Health Insurance Research Database. Hypoglycemic events were collected using inpatient, outpatient, and emergency department diagnoses. Patients aged <20 years and those with previous histories of CKD were excluded. The association between hypoglycemia and subsequent CKD risk in patients with T2DM was examined using Cox regression analysis after PS matching.During the mean follow-up period of 4.2 years, a total of 15,036 (1.7 %) patients experienced at least 1 episode of hypoglycemia and 15,036 matched controls without hypoglycemia were identified among 906,368 eligible patients. The incidence rates of subsequent CKD were 26.1 and 14.8 events per 1000 person-years in the hypoglycemic and matched cohorts, respectively. The hazard ratio (HR) of hypoglycemia for incident CKD was 1.77 (95% confidence interval [CI], 1.63-1.92; P < 0.001). Compared with those without hypoglycemia, HRs for 1 to 3 and ≥4 episodes of hypoglycemia for CKD were 1.65 (95% CI, 1.50-1.81) and 1.75 (95% CI, 1.34-2.29), respectively (P for trend <0.001).Our study supports the association of hypoglycemia with CKD development among patients with T2DM, possibly in a dose-dependent relationship.

The waveform fluctuation and the clinical factors of the initial and sustained erythropoietic response to continuous erythropoietin receptor activator in hemodialysis patients.

OBJECTIVES: Erythropoiesis-stimulating agents (ESA) are the main treatment for anemia in hemodialysis (HD) patients. We evaluated factors determining the response after treatment of a new ESA (continuous erythropoietin erythropoietin receptor activator (CERA)). METHODS: 61 HD patients were classified by their response at two different timings. First, patients whose hematocrit (Hct) increased 1.5% in the first week were defined as initial responders (IR, n = 16). We compared several parameters between IR and the rest of the study subjects (non-IR, n = 45). Second, patients whose Hct increased 2% in the 4th week were defined as sustained responders (SR, n = 12), and we did a similar comparison. RESULTS: The Hct showed a waveform fluctuation. Compared with the rest, IR had significantly lower platelet counts and higher levels of ferritin, total protein, total bilirubin, and serum sodium, while SR had significantly lower levels of C-reactive protein and low-density lipoprotein (All P < 0.05). In comparison with the rest, higher Hct persisted for 10 weeks in SR but only for two separate weeks (the 1st and 7th week) in IR. CONCLUSIONS: The initial and sustained erythropoietic responses are independent from each other and are associated with different factors. Treatment focusing on these factors may improve the response.