Fibrinogen and beta-amyloid association alters thrombosis and fibrinolysis: a possible contributing factor to Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder in which vascular pathology plays an important role. Since the beta-amyloid peptide (Abeta) is a critical factor in this disease, we examined its relationship to fibrin clot formation in AD. In vitro and in vivo experiments showed that fibrin clots formed in the presence of Abeta are structurally abnormal and resistant to degradation. Fibrin(ogen) was observed in blood vessels positive for amyloid in mouse and human AD samples, and intravital brain imaging of clot formation and dissolution revealed abnormal thrombosis and fibrinolysis in AD mice. Moreover, depletion of fibrinogen lessened cerebral amyloid angiopathy pathology and reduced cognitive impairment in AD mice. These experiments suggest that one important contribution of Abeta to AD is via its effects on fibrin clots, implicating fibrin(ogen) as a potential critical factor in this disease.

Gene regulation by gonadal hormone receptors underlies brain sex differences

Oestradiol establishes neural sex differences in many vertebrates1-3 and modulates mood, behaviour and energy balance in adulthood4-8. In the canonical pathway, oestradiol exerts its effects through the transcription factor oestrogen receptor-α (ERα)9. Although ERα has been extensively characterized in breast cancer, the neuronal targets of ERα, and their involvement in brain sex differences, remain largely unknown. Here we generate a comprehensive map of genomic ERα-binding sites in a sexually dimorphic neural circuit that mediates social behaviours. We conclude that ERα orchestrates sexual differentiation of the mouse brain through two mechanisms: establishing two male-biased neuron types and activating a sustained male-biased gene expression program. Collectively, our findings reveal that sex differences in gene expression are defined by hormonal activation of neuronal steroid receptors. The molecular targets we identify may underlie the effects of oestradiol on brain development, behaviour and disease.

Preoperative PROMIS Scores Predict Postoperative Outcomes After Primary ACL Reconstruction

Background:

PROMIS (Patient-Reported Outcomes Measurement Information System) scores in patients undergoing anterior cruciate ligament (ACL) reconstruction have not been fully described in the literature to date. The ability of preoperative patient-reported outcome scores to directly predict postoperative outcomes in patients who undergo primary ACL reconstruction is unknown.

Hypothesis:

Postoperative PROMIS physical function (PF), pain interference (PI), and depression (D) scores in patients who undergo ACL reconstruction will show improvement when compared with preoperative scores. Additionally, preoperative PROMIS PF, PI, and D scores will predict which patients will not achieve a minimal clinically important difference (MCID) postoperatively.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 233 patients who underwent primary ACL reconstruction between 2015 and 2016 and had completed PROMIS measures both preoperatively (within 60 days of surgery) and postoperatively (100-240 days after surgery) were included in this study. PROMIS PF, PI, and D scores were compared. Accuracy analyses were performed to determine whether preoperative PROMIS scores from each domain could predict postoperative achievement of MCID in the same domain. Cutoff scores were then calculated.

Results:

PROMIS PF, PI, and D scores all showed a significant improvement after ACL reconstruction (all P < .001). Preoperative scores from all 3 PROMIS domains showed a strong ability to predict clinically meaningful improvement, as defined by MCID, with areas under the receiver operating characteristic curve from 0.72 to 0.84. Optimal cutoffs for preoperative PROMIS scores showed that patients with a PF score of <42.5, PI score of >56.2, or D score of >44.8 were more likely to achieve MCID.

Conclusion:

PROMIS PF, PI, and D scores improved significantly in patients who underwent primary ACL reconstruction. Preoperative PROMIS PF, PI, and D scores were highly predictive of outcome in the early postoperative period. The reported cutoff scores showed high probability in predicting which patients would and would not achieve a clinically meaningful improvement.

The usefulness of MRI in evaluating menisci after meniscus repair

We reviewed magnetic resonance imaging (MRI) scans of 15 asymptomatic patients at 6 months to 1 year following meniscal repair procedures. All of the patients were found to have persistent MRI signals in the region of the repair. Nine of the 17 meniscal repairs in the 15 patients had persistent grade 3 signals. Arthrograms were performed on six patients (eight meniscal repairs). Seven of these postoperative menisci showed grade 3 signals on MRI. Only one meniscus was shown to have a complete tear by arthrogram. There were no false negative scans. The overall accuracy, defined as the percentage of postoperative menisci correctly diagnosed by MRI, was 38% (3/8). MRI is a useful preoperative diagnostic study following knee injury. This report demonstrates, however, that present MRI modalities are unable to distinguish between scar tissue of healed meniscal repairs and meniscal tears. Therefore, it is not a useful diagnostic tool in evaluating reinjury following successful meniscal repair.

Members of the high mobility group B protein family are dynamically expressed in embryonic neural stem cells

Neural Stem Cells (NSCs) are a distinct group of cells present in the embryonic and adult mammalian central nervous system (CNS) that are able to differentiate into neurons, astrocytes and oligodendrocytes. As NSC proliferation declines with age, factors that regulate this process need to be defined. To search for NSC regulatory factors, we performed a quantitative shotgun proteomics study that revealed that members of the High Mobility Group B (HMGB) family are highly expressed in NSCs. Using a neurosphere assay, we report the differential expression of HMGB 1, 2, 3, and 4 mRNAs in proliferating NSCs isolated from various time points during embryonic development, as well as the dynamic expression of HMGB1 and B2 mRNAs and proteins in differentiating embryonic NSCs. Expression of HMGB2 underwent the most dramatic changes during the developmental ages examined; as a result, we assessed its role in NSC proliferation and differentiation. We report the predominance of small diameter HMGB2-/- neurospheres in comparison to wild-type, which correlated with increased proliferation in these smaller HMGB2-/- neurospheres. Our data suggest that HMGB2 plays a regulatory role in NSC cell proliferation and maintenance pathways.

Culturing microglia from the neonatal and adult central nervous system

Microglia are the resident macrophage-like cells of the central nervous system (CNS) and, as such, have critically important roles in physiological and pathological processes such as CNS maturation in development, multiple sclerosis, and spinal cord injury. Microglia can be activated and recruited to action by neuronal injury or stimulation, such as axonal damage seen in MS or ischemic brain trauma resulting from stroke. These immunocompetent members of the CNS are also thought to have roles in synaptic plasticity under non-pathological conditions. We employ protocols for culturing microglia from the neonatal and adult tissues that are aimed to maximize the viable cell numbers while minimizing confounding variables, such as the presence of other CNS cell types and cell culture debris. We utilize large and easily discernable CNS components (e.g. cortex, spinal cord segments), which makes the entire process feasible and reproducible. The use of adult cells is a suitable alternative to the use of neonatal brain microglia, as many pathologies studied mainly affect the postnatal spinal cord. These culture systems are also useful for directly testing the effect of compounds that may either inhibit or promote microglial activation. Since microglial activation can shape the outcomes of disease in the adult CNS, there is a need for in vitro systems in which neonatal and adult microglia can be cultured and studied.

Podocyte-Parietal Epithelial Cell Interdependence in Glomerular Development and Disease

Podocytes and parietal epithelial cells (PECs) are among the few principal cell types within the kidney glomerulus, the former serving as a crucial constituent of the kidney filtration barrier and the latter representing a supporting epithelial layer that adorns the inner wall of Bowman's capsule. Podocytes and PECs share a circumscript developmental lineage that only begins to diverge during the S-shaped body stage of nephron formation-occurring immediately before the emergence of the fully mature nephron. These two cell types, therefore, share a highly conserved gene expression program, evidenced by recently discovered intermediate cell types occupying a distinct spatiotemporal gene expression zone between podocytes and PECs. In addition to their homeostatic functions, podocytes and PECs also have roles in kidney pathogenesis. Rapid podocyte loss in diseases, such as rapidly progressive GN and collapsing and cellular subtypes of FSGS, is closely allied with PEC proliferation and migration toward the capillary tuft, resulting in the formation of crescents and pseudocrescents. PECs are thought to contribute to disease progression and severity, and the interdependence between these two cell types during development and in various manifestations of kidney pathology is the primary focus of this review.

Arthroscopic medial meniscal repair in the athlete

Meniscal tears are common sports injuries. This article details the clinical evaluation of the athlete presenting with knee pain. Conservative (nonoperative) treatment and arthroscopic procedures are discussed.

Neurogenic to Gliogenic Fate Transition Perturbed by Loss of HMGB2

Mouse cortical development relies heavily on a delicate balance between neurogenesis and gliogenesis. The lateral ventricular zone produces different classes of excitatory pyramidal cells until just before birth, when the production of astroglia begins to prevail. Epigenetic control of this fate shift is of critical importance and chromatin regulatory elements driving neuronal or astroglial development play an vital role. Different classes of chromatin binding proteins orchestrate the transcriptional repression of neuronal-specific genes, while allowing for the activation of astrocyte-specific genes. Through proteomic analysis of embryonic neural progenitor cells (NPCs) our group had previously identified high mobility group B2 (HMGB2), a chromatin protein dynamically expressed throughout embryonic development. In the current study using cultures of perinatal NPCs from HMGB2+/+ and HMGB2-/- mice we discovered that vital elements of the polycomb group (PcG) epigenetic complexes polycomb repressive complexes 1 and 2 (PRC1/2) were downregulated during the differentiation process of HMGB2-null NPCs. These epigenetic changes led to downstream changes in specific histone modification levels, specifically the trimethylation of H3K27, and a subsequent shift in the perinatal neurogenesis to gliogenesis fate transition. Collectively these results demonstrate that chromatin binding proteins, such as HMGB2, can have significant effects on the epigenetic landscape of perinatal neural stem/progenitor cells.

Podocyte-specific KLF4 is required to maintain parietal epithelial cell quiescence in the kidney

Podocyte loss triggering aberrant activation and proliferation of parietal epithelial cells (PECs) is a central pathogenic event in proliferative glomerulopathies. Podocyte-specific Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor, is essential for maintaining podocyte homeostasis and PEC quiescence. Using mice with podocyte-specific knockdown of Klf4, we conducted glomerular RNA-sequencing, tandem mass spectrometry, and single-nucleus RNA-sequencing to identify cell-specific transcriptional changes that trigger PEC activation due to podocyte loss. Integration with in silico chromatin immunoprecipitation identified key ligand-receptor interactions, such as fibronectin 1 (FN1)–αVβ6, between podocytes and PECs dependent on KLF4 and downstream signal transducer and activator of transcription 3 (STAT3) signaling. Knockdown of Itgb6 in PECs attenuated PEC activation. Additionally, podocyte-specific induction of human KLF4 or pharmacological inhibition of downstream STAT3 activation reduced FN1 and integrin β 6 (ITGB6) expression and mitigated podocyte loss and PEC activation in mice. Targeting podocyte-PEC crosstalk might be a critical therapeutic strategy in proliferative glomerulopathies.

Localized pigmented villonodular synovitis presenting as a loose body in the knee

Localized pigmented villonodular synovitis is a rare condition of the knee that can present with symptoms suggesting internal derangement. We report a case of a patient who presented with signs and symptoms of a loose body in the knee. The lesion was treated with resection using arthroscopic cautery.

Clinically Depressed Patients Having Anterior Cruciate Ligament Reconstruction Show Improved but Inferior Rate of Achieving Minimum Clinically Important Difference for Patient-Reported Outcomes Measurement Information System Compared With Situationally Depressed or Nondepressed Patients

PURPOSE

To determine whether the preoperative diagnosis of depression predicted worse postoperative outcomes, including physical therapy (PT) compliance, return-to-sport, and patient-reported outcomes using the Patient-Reported Outcomes Measurement Information System (PROMIS) after anterior cruciate ligament (ACL) reconstruction.

METHODS

A multisurgeon series of consecutive patients who had undergone ACL reconstruction with minimum 2-year follow-up were included. Chart review was conducted to determine depression diagnosis status, demographic data, rehabilitation PT compliance, return to sports, and patient-reported outcome data using PROMIS. Patients who met the PROMIS threshold for mild depression but did not carry a clinical diagnosis of depression were classified as "situationally depressed."

RESULTS

Ninety-five of 115 consecutive patients (81%) met inclusion criteria with an average follow-up of 34 ± 1.9 months. Fourteen patients (15%) had a preoperative diagnosis of depression, whereas 21 (22%) were considered situationally depressed. Clinically depressed patients had a greater rate of PT noncompliance (33.2% ± 17.6% vs 21.9% ± 12.6%; P = .02) and a lower postoperative PROMIS Physical Function (50.8 ± 7.7 vs 57.8 ± 11.0; P = .03 compared with patients without depression. Situationally depressed patients had lower preoperative physical function (35.4 vs 42.5; P = .04) with no differences in postoperative outcomes scores compared to the non-depressed cohort.19/21 (90.5%) of situationally depressed patients had postoperative resolution of their depressive symptoms.

CONCLUSIONS

Situationally depressed patients without a clinical diagnosis of depression can expect significant improvements in both pain and function, as well as a resolution of their depressed mood based on PROMIS scores as they progress through recovery after ACL reconstruction. Clinically depressed patients also experience significant improvements; however, their rate of achieving the minimum clinically important difference for PROMIS outcomes may be less than their nondepressed or situationally depressed counterparts.

LEVEL OF EVIDENCE

III, prognostic comparative trial.

Multi-centre clinical investigation of indapamide in the United States: a review

Indapamide, a new indoline antihypertensive agent, has been the subject of a worldwide programme to develop this drug for general clinical use. The results are described of the multi-centre U.S. clinical programme demonstrating the effectiveness and tolerance of indapamide for the treatment of hypertension. All work was conducted under U.S. Federal Food and Drug Administration guidelines, and resulted recently in a New Drug Application. A total of 1891 subjects or patients participated in 27 separate studies conducted by 91 investigators. In controlled clinical trials comparing 2.5 mg indapamide once daily with 50 mg hydrochlorothiazide once daily for 40 weeks in patients with mild to moderate essential hypertension, indapamide produced a reduction of supine blood pressure of -9.5/-14.3 mmHg as compared with -7.6/-11.4 mmHg for hydrochlorothiazide. In combination with methyldopa, propranolol, clonidine, guanethidine and hydralazine, indapamide consistently produced a greater decrease in arterial pressure than did those agents given alone. Indapamide added to these step-care agents did not result in a meaningful increase in adverse reactions. Indapamide has been the subject of a long-term safety study in which over 100 hypertensive patients have been followed up for 2 years or longer. During this period of time, indapamide was well tolerated and remained effective. No biochemical, electrocardiographic or ophthalmological changes were associated with its use. Other studies with indapamide are discussed describing the systemic and renal haemodynamic effects, pharmacokinetic properties and special safety studies conducted with this agent. The use of indapamide in patients with hepatic or renal impairment is reviewed in detail.

Estradiol-induced changes in progesterone secretion by rabbit corpora lutea are associated with quantitative ultrastructural changes in luteal cells

In this study, we examined changes in luteal cell structure that accompany estradiol-altered progesterone production by the rabbit corpus luteum. To stimulate progesterone production, polydimethylsiloxane (Silastic) capsules containing 17 beta-estradiol were inserted sc into superovulated New Zealand White rabbits. Luteal progesterone production, assessed by measurement of progesterone in peripheral serum, was high after the estradiol-filled capsules were inserted, declined within 24 h after the capsules were removed, and increased within 32 h after reinsertion of the capsules. Stereological analyses at the light microscopic level revealed that the number of luteal cells and the volume of an average luteal cell did not differ significantly between estradiol-stimulated and estradiol-deprived rabbits over the time period employed. In contrast, stereological analyses at the electron microscopic level demonstrated that the surface areas of smooth endoplasmic reticulum and inner mitochondrial membrane declined with estradiol deprivation, but were restored by reimposition of estradiol stimulation. These changes in the surface area per cell of smooth endoplasmic reticulum and inner mitochondrial membrane were strongly correlated (r = 0.94 and r = 0.88, respectively) with changes in progesterone concentrations in peripheral serum. Changes in the surface area of lipid droplets per luteal cell also occurred, but were inversely correlated (r = -0.87) with progesterone levels. No significant changes were seen in the surface areas per cell of outer mitochondrial membrane or rough endoplasmic reticulum. These results demonstrate that estradiol stimulation and deprivation cause reversible quantitative changes in the rabbit luteal cell organelles known to be directly involved in progesterone biosynthesis. This leads to the conclusion that the steroidogenic activity of the luteal cell is tightly coupled to its subcellular structure.

Use of Area Deprivation Index to Predict Minimal Clinically Important Difference for Patient Reported Outcomes Measurement Information System After Arthroscopic Rotator Cuff Repair

BACKGROUND

Socioeconomic disparities correlate with worse outcomes after arthroscopic rotator cuff repair. However, use of a surrogate to describe socioeconomic disadvantage has been a challenge. The Area Deprivation Index (ADI) is a tool that encompasses 17 socioeconomic variables into a single metric based on census location.

HYPOTHESIS

Higher ADI would result in a worse minimal clinically important difference (MCID) for the Patient Reported Outcomes Measurement Information System (PROMIS) and have less improvement in range of motion (ROM) following arthroscopic rotator cuff repair (ARCR).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHOD

A retrospective review was performed for patients who underwent arthroscopic rotator cuff repair. Patients in the most socioeconomically disadvantaged quartile (ADIHigh) were compared with the least disadvantaged quartile (ADILow) in the ability to reach MCID. Demographic and surgical features were assessed for attainment of MCID.

RESULTS

In total 1382 patients were identified who underwent ARCR, of which a total of 306 patients met final inclusion criteria. A higher percentage of patients within the ADIHigh cohort identified as "Black" or "other" race and had government-issued insurance compared with the ADILow cohort (P < .05). The ADIHigh cohort had significantly worse postoperative forward flexion compared with the ADILow cohort (145.0°± 32.5° vs 156.3°± 23.4°; P = .001) despite starting with comparable preoperative ROM (P = .17). Logistic regression showed that ADI was the only variable significant for predicting achievement of MCID for all 3 PROMIS domains, with the ADIHigh cohort having significantly worse odds of achieving MCID Physical Function (odds ratio [OR], 0.31; P = .001), Pain Interference (OR, 0.21; P = .001), and Depression (OR, 0.28; P = .001). Meanwhile, age, sex, body mass index, and smoking history were nonsignificant. Moreover, "other" for race and Medicare insurance were significant for achievement of MCID Depression but not Physical Function or Pain Interference. Finally, ADI was the main feature for predictive logistic regression modeling.

CONCLUSION

ADI served as the only significant predictor for achieving MCID for all 3 PROMIS domains after arthroscopic rotator cuff repair. Patients who face high levels of socioeconomic disadvantage have lower rates of achieving MCID. In addition, patients with greater neighborhood disadvantage demonstrated significantly worse improvement in active forward flexion. Further investigation is required to understand the role of ADI on physical therapy compliance and to identify the barriers that prevent equitable postoperative care.

Effect of Insurance Reimbursement Status on Pre- and Postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Scores After Arthroscopic Rotator Cuff Repair

BACKGROUND

Previous studies reported inferior patient-reported outcomes (PROs) after arthroscopic rotator cuff repair for patients receiving workers' compensation (WC) relative to patients with commercial insurance. The extent to which alternative insurance reimbursement, including Medicaid and Medicare, influences outcomes after arthroscopic rotator cuff repair remains understudied.

HYPOTHESIS

Compared with patients with commercial insurance reimbursement, patients with WC or government-issued reimbursement would report lower pre- and postoperative Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (PF) scores, report higher pre- and postoperative PROMIS Depression (D) and Pain Interference (PI) scores, and experience smaller levels of improvement in all PROMIS domains with surgical intervention.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Demographic and surgical data were extracted from the medical record, and PROMIS domains were prospectively collected. Patients were divided into cohorts based on insurance reimbursement status. Differences between insurance-based cohorts for baseline variables, pre- and postoperative PROMIS scores, and change from baseline to final follow-up (delta) for PROMIS scores were evaluated using Kruskal-Wallis or chi-square tests. Mixed-effects linear regression models were performed to assess the influence of insurance while controlling for other variables. Survival analysis was performed to determine time to achieve minimal clinically important difference (MCID) for each PROMIS domain per cohort.

RESULTS

1252 patients underwent arthroscopic rotator cuff repair, met inclusion criteria, and completed PROMIS questionnaires. Statistically significant differences were noted in demographic variables including age (P < .001), sex (P < .001), ethnicity (P < .001), and body mass index (P < .001) between insurance-based cohorts. Unadjusted analysis revealed significantly higher PF scores and lower PI and D scores for the group with commercial insurance relative to those with Medicare, Medicaid, and WC at 6- and 12-month follow-up (P < .01 all comparisons), except for the Medicare versus commercial subcohort analysis for PI at 6 months (P = .28). These differences persisted for the Medicare, Medicaid, and WC groups (P < .03 all comparisons) after adjustment for confounding variables in linear regression.

CONCLUSIONS

The baseline characteristics of patients undergoing arthroscopic rotator cuff repair differed based on insurance reimbursement. Patients with commercial insurance reported improved physical function, decreased pain interference, and improved mood (less depression) relative to patients with government-issued and WC insurance, with maximum improvement 6 to 12 months postoperatively. There were few significant differences between insurance groups in change of PROMIS scores from preoperative to postoperative intervals, indicating that differences in the baseline demographic and surgical characteristics of these groups accounted for differences in response to surgery.

Arthroscopic subacromial decompression improved outcomes in situationally depressed patients compared to clinically depressed or nondepressed patients

Background

The purpose of this study is to evaluate patient reported outcomes after arthroscopic extensive débridement of the shoulder with subacromial decompression (SAD) for subacromial impingement using the Patient-Reported Outcomes Measurement Information System (PROMIS) system and evaluate if depression (Dep) (clinical or situational) impacts patients achieving a Minimal Clinically Important Difference (MCID).

Methods

Preoperative PROMIS Physical function (PF), Mood, and Dep scores were obtained at the closest date prior to arthroscopic rotator cuff repair and postoperative scores were collected at every clinical visit thereafter. Final PROMIS score used for data analysis was determined by the patients final PROMIS value between 90 to 180 days. Clinical Dep was determined by patients having a formal diagnosis of "Depression or Major Depressive Disorder" at the time of their surgery. Situationally depressed patients, those without a formal diagnosis yet exhibited symptomatic depressive symptoms, were classified by having a PROMIS-Dep cutoff scores larger than 52.5.

Results

A total of 136 patients were included for final statistical analysis. 13 patients had a clinical but not situational diagnosis of Dep, 86 patients were identified who had no instance of clinical or situational Dep (nondepressed). 35 patients were situationally depressed. All three cohorts demonstrated a significant improvement in postoperative PROMIS Dep, PI, and PF score relative to their preoperative value (P = .001). Situationally depressed patients achieved greater delta PROMIS-Dep compared to patients with major depressive disorder. Depressed patients had a higher chance of achieving MCID for PROMIS-Dep compared to nondepressed patients (P = .01). Logistic regression analysis demonstrated that underlying Dep did not alter the odds of obtaining MCID compared to nondepressed patients. Nonsmoking patients had significantly greater odds of achieving MCID for PF (P = .02).

Discussion

Patients improved after undergoing SAD regardless of underlying Dep or depressive symptoms. Depressed patients exhibited greater change in PROMIS scores compared to nondepressed patients. Smoking remains a risk factor for postoperative outcomes in patients undergoing SAD for subacromial impingement. Identifying and counseling patients with underlying depressive symptoms without a formal major depressive disorder diagnosis may lead to improved outcomes. These findings may help guide clinicians in deciding who would benefit the most from this procedure.

Single-Cell Spatial MIST for Versatile, Scalable Detection of Protein Markers

High-multiplex detection of protein biomarkers across tissue regions has been an attractive spatial biology approach due to significant advantages over traditional immunohistochemistry (IHC) methods. Different from most methods, spatial multiplex in situ tagging (MIST) transfers the spatial protein expression information to an ultrahigh-density, large-scale MIST array. This technique has been optimized to reach single-cell resolution by adoption of smaller array units and 30% 8-arm PEG polymer as transfer medium. Tissue cell nuclei stained with lamin B have been clearly visualized on the MIST arrays and are colocalized with detection of nine mouse brain markers. Pseudocells defined at 10 μm in size have been used to fully profile tissue regions including cells and the intercellular space. We showcased the versatility of our technology by successfully detecting 20 marker proteins in kidney samples with the addition of five minutes atop the duration of standard immunohistochemistry protocols. Spatial MIST is amenable to iterative staining and detection on the same tissue samples. When 25 proteins were co-detected on 1 mouse brain section for each round and 5 rounds were executed, an ultrahigh multiplexity of 125 proteins was obtained for each pseudocell. With its unique abilities, this single-cell spatial MIST technology has the potential to become an important method in advanced diagnosis of complex diseases.

A Small Molecule Agonist of Krüppel-Like Factor 15 in Proteinuric Kidney Disease

Key Points

A human podocyte-based high-throughput screen identified a novel agonist of Krüppel-like factor 15 (BT503), independent of glucocorticoid signaling. BT503 demonstrated renoprotective effects in three independent proteinuric kidney murine models. BT503 directly binds to inhibitor of nuclear factor kappa-B kinase subunit beta to inhibit NF-κB activation, which, subsequently restores Krüppel-like factor 15 under cell stress.

Background

Podocyte loss is the major driver of primary glomerular diseases such as FSGS. While systemic glucocorticoids remain the initial and primary therapy for these diseases, high-dose and chronic use of glucocorticoids is riddled with systemic toxicities. Krüppel-like factor 15 (KLF15) is a glucocorticoid-responsive gene, which is essential for the restoration of mature podocyte differentiation markers and stabilization of actin cytoskeleton in the setting of cell stress. Induction of KLF15 attenuates podocyte injury and glomerulosclerosis in the setting of cell stress.

Methods

A cell-based high-throughput screen with a subsequent structure–activity relationship study was conducted to identify novel agonists of KLF15 in human podocytes. Next, the agonist was tested in cultured human podocytes under cell stress and in three independent proteinuric models (LPS, nephrotoxic serum nephritis, and HIV-1 transgenic mice). A combination of RNA sequencing and molecular modeling with experimental validation was conducted to demonstrate the direct target of the agonist.

Results

The high-throughput screen with structure–activity relationship study identified BT503, a urea-based compound, as a novel agonist of KLF15, independent of glucocorticoid signaling. BT503 demonstrated protective effects in cultured human podocytes and in three independent proteinuric murine models. Subsequent molecular modeling with experimental validation shows that BT503 targets the inhibitor of nuclear factor kappa-B kinase complex by directly binding to inhibitor of nuclear factor kappa-B kinase subunit beta to inhibit canonical NF-κB signaling, which, in turn, restores KLF15 under cell stress, thereby rescuing podocyte loss and ameliorating kidney injury.

Conclusions

By developing and validating a cell-based high-throughput screen in human podocytes, we identified a novel agonist for KLF15 with salutary effects in proteinuric murine models through direct inhibition of inhibitor of nuclear factor kappa-B kinase subunit beta kinase activity.