Basement Membrane Research Articles

Histology, histochemistry and ultrastructure of cornea of domestic pigs (Sus scrofa domesticus).

A comprehensive light and ultrastructural examination of the cornea in Domestic Pigs (Sus scrofa domesticus) revealed four distinct layers: the anterior epithelium, corneal stroma, Descemet's membrane and endothelium. Although Bowman's layer was not distinctly identified through histology, histochemical analysis indicated the presence of a rudimentary Bowman's layer, possibly vestigial from evolution. Scanning electron microscopy of the outer corneal surface unveiled two cell types, characterized by micro-projections, with light cells exhibiting shorter, thicker projections compared to dark cells. Examination of the inner surface via scanning electron microscopy demonstrated an endothelial layer devoid of cilia and microvilli, yet faint round to oval elevations were observed, potentially representing cell nuclei. Transmission electron microscopy unveiled that basal cells of the anterior epithelium closely adhered to the basement membrane, featuring half desmosomes along the basal surface. These basal cells extensively interconnected through interdigitations and a few desmosomes. The superficial cell layer consisted of a few rows of closely attached flat cells, forming a leak-proof layer with zona occludens. The outermost cells of this layer displayed fine projections to enhance the surface area, facilitating tear film distribution. At lower magnification, Transmission electron microscopy of the corneal stroma revealed alternating light and dark bands, with light bands representing transverse sections of collagen fibril lamellae and dark bands corresponding to longitudinal or oblique sections. Spindle-shaped keratocytes (fibroblasts) were identified as the primary stromal cells, intermingled between the lamellae, and featured long processes in close contact with neighbouring keratocytes. Overall, the histomorphology of the pig cornea resembles that of the human cornea except indistinct Bowman's membrane. This detailed understanding of the normal corneal structure in pigs hold great significance for biomedical research, providing a valuable reference for studies involving this animal model.

Nanoliposomes Permeability in a Microfluidic Drug Delivery Platform across a 3D Hydrogel.

Nanoliposomes are nano-sized vesicles that can be used as drug delivery carriers with the ability to encapsulate both hydrophobic and hydrophilic compounds. Moreover, their lipid compositions facilitate their internalization by cells. However, the interaction between nanoliposomes and the membrane barrier of the human body is not well-known. If cellular tests and animal testing offer a solution, their lack of physiological relevance and ethical concerns make them unsuitable to properly mimic human body complexity. Microfluidics, which allows the environment of the human body to be imitated in a controlled way, can fulfil this role. However, existing models are missing the presence of something that would mimic a basal membrane, often consisting of a simple cell layer on a polymer membrane. In this study, we investigated the diffusion of nanoliposomes in a microfluidic system and found the optimal parameters to maximize their diffusion. Then, we incorporated a custom made GelMA with a controlled degree of substitution and studied the passage of fluorescently labeled nanoliposomes through this barrier. Our results show that highly substituted GelMA was more porous than lower substitution GelMA. Overall, our work lays the foundation for the incorporation of a hydrogel mimicking a basal membrane on a drug delivery microfluidic platform.

In Situ Structural Characterization of Cardiomyocyte Microenvironment by Multimodal STED Microscopy

Within the myocardium, cardiomyocytes reside in a complex and dynamic extracellular matrix (ECM) consisting of a basement membrane (BM) and interstitial matrix. The interactions between cardiomyocytes and the myocardial ECM play a critical role in maintaining cardiac geometry and function throughout cardiac development and in adult hearts. Understanding how the structural changes of the myocardial ECM affect cardiomyocyte function requires knowledge of pericellular structures. These structures are of a size beyond the resolution of conventional optical microscopy. Here, we demonstrated multi-scale and multi-aspect characterization of the cardiomyocyte microenvironment in myocardial tissue sections using multimodal stimulated emission depletion (STED) microscopy. Second harmonic generation and autofluorescence facilitated multiplexed imaging, enabling the interpretation of protein distribution in 3D. STED imaging modality revealed BM structures of cardiomyocytes and myocardial capillaries at the subdiffractional level. Moreover, meaningful measurements retrieved from acquired images, such as sarcomere length and capillary density, enabled quantitative assessment of myocardial structures.

The Balance Between Shear Flow and Extracellular Matrix in Ovarian Cancer-on-chip.

Ovarian cancer is the most lethal gynecologic cancer in developed countries. In the tumor microenvironment, the extracellular matrix (ECM) and flow shear stress are key players in directing ovarian cancer cells invasion. We use artificial ECM models based only on ECM proteins to build an ovarian tumor-on-chip to decipher the crosstalk between ECM and shear stress on the migratory behavior and cellular heterogeneity of ovarian tumor cells. This work shows that in the shear stress regime of the peritoneal cavity, the ECM plays a major role in driving individual or collective ovarian tumor cells migration. In the presence of basement membrane proteins, migration is more collective that on type I collagen regardless of shear stress. With increasing shear stress, individual cell migration was enhanced, while no significant impact on collective migration was measured. This highlights the central position that ECM and flow shear stress should hold in in vitro ovarian cancer models to deepen our understanding of cellular responses, and improve the development of ovarian cancer therapeutic platforms. In this frame, adding flow provides significant improvement in biological relevance over our previous work. Further steps for enhanced clinically relevance require not only multiple cell lines but patient-derived cells and sera. This article is protected by copyright. All rights reserved.

Monoclonal immunoglobulin deposition disease a spectrum? The treatment of an unusual biopsy presentation

Introduction: Monoclonal gammopathy of renal significance (MGRS) is characterized by clonal cell deposition of monoclonal immunoglobulin causing renal manifestations without overt malignancy. MIDD is a subtype of MGRS characterized by deposition of monoclonal light (LCDD), heavy chains (HCDD), or both (LHCDD) along the renal glomerular and tubular basement membranes. Virtually all organs can be involved, and if left untreated, MIDD can progress to MM and end stage renal disease. Although these patients classically did not receive treatment, current MIDD management is primarily focused on controlling the underlying clonal plasma cell disorder. Case description: We present a 56-year-old male with atypical MIDD treated successfully with plasma cell directed therapy consisting of daratumumab, cyclophosphamide, bortezomib, and dexamethasone (DARA-CYBOR-D). Despite a primary diagnosis of diabetic kidney disease, renal biopsy suggested myeloma-related MIDD based on linear immunofluorescent staining for IgG and kappa light chains along the tubular and glomerular basement membranes. Notably there were no electron dense deposits in the mesangium or tubular basement membranes typical to MIDD electron microscopy. Despite the presentation of MIDD on IF only, DARA-CYBOR-D treatment led to hematologic and renal improvement and remission from MIDD, with a GFR increase from 22 to 59 mL/min/BSA and a drop in urine protein from up to 9 to 0.6 g/dL. Conclusions: In conclusion, our case illustrates the efficacy of the DARA-CYBOR-D regimen in a patient with IF-only MIDD. We highlight the importance of obtaining a kidney biopsy when there are other potential causes for real decline and enhance our understanding of pathological and clinical spectrum of MIDD.

Detection of carbohydrate distribution in the testis of Aceh bull using periodic acid Schiff staining

Abstract Spermatogenesis that occurred in the seminiferous tubule of the testis requires various substances, one of which is carbohydrates. Data regarding carbohydrates distribution in the testis of Aceh bull is currently not available. The objective of this study is to determine the neutral carbohydrates distribution in the seminiferous tubule and interstitial tissue of Aceh bull testis using histochemical periodic acid Schiff (PAS) staining. Five pairs adult testis of Aceh bull were use and fixed in neutral buffered formalin 10% (immersion fixation), and then processed into histological preparation to be stained using PAS staining. A positive reaction on the presence of neutral carbohydrate in the testis indicated by magenta color in the specific cells and other components of testis. According microscopic observation, neutral carbohydrates found in the spermatogonium, spermatocyte, round spermatid, elongated spermatid, basal membrane, myoid peritubular cell, and cytoplasm of Sertoli cell in seminiferous tubule. Furthermore, the specific neutral carbohydrates were observed in the round spermatid with various expression, indicated that carbohydrates (glycoprotein) have an important role for acrosome formation in the round, elongating, and elongated spermatid during spermiogenesis to produce spermatozoa. Additionally, neutral carbohydrates were also found in the interstitial tissue of testis, including Leydig cell, fibrocyte, blood vessels, connective tissue, and tunica albuginea of testis. In conclusion, the presence of neutral carbohydrate in the testis of Aceh bull indicates that this substance is required to maintain spermatogenesis and tissue structure of the testis.

Role of connexin 43 in a rat model of periodontitis-induced renal injury.

This study aims to investigate the role of gap junction mediated by connexin 43 (Cx43) in renal injury induced by periodontitis in rats. Twelve SPF-grade Wistar male rats were divided into a control group and a periodontitis group by using a completely random number table method, with six rats in each group. The control group rats were not treated, while the periodontitis group rats were subjected to wire ligation of the neck of their bilateral maxillary first molars to construct a periodontitis model. After 8 weeks of modeling, the rats were examined for clinical indicators of the periodontium. micro-CT scanning of the maxilla reconstructed its 3D structure and analyzed the absorption of alveolar bone. Histopathological changes in periodontal and renal tissues were detected. MitoSOX red reagent was used to determine reactive oxygen species (ROS) content in renal tissues. A biochemical reagent kit was used to detect serum oxidative stress biomarkers. Real-time fluorescent quantitative-polymerase chain reaction (qRT-PCR) was employed to determine Cx43, nuclear factor kappa-B (NF-κB) , interleukin (IL)-1β, IL-6, BCL2-Associated X (Bax), B-lymphomatoma-2 gene (Bcl-2), and Caspase-3 mRNA were determined. Western blot analysis was used to detect Cx43, NF-κB, IL-1β, Bax, Bcl-2 and Caspase-3 protein. micro-CT 3D reconstruction showed significant bone resorption of the first molar alveolar bone in the periodontitis group rats and decreased height of the alveolar ridge. The distance from the enamel cementum boundary to the top of the alveolar ridge in the periodontitis group was significantly higher than that inthe control group. The histopathological results showed a large number of inflammatory cells that infiltrated the periodontal tissue of the periodontitis group, and the alveolar bone was significantly absorbed. Rats in the periodontitis group also exhibited mild thickening of the glomerular basement membrane, dilation of the Bowman's capsule, and destruction of the brush-like edge of the renal tubules in the renal tissue. The MitoSOX red staining results showed a significant increase in ROS content in the renal tissue of the periodontitis group. The biochemical test results showed that the levels of superoxide dismutase and glutathione in the serum of rats with periodontitis decreased, while that of malondialdehyde increased. The results of qRT-PCR and Western blot showed that the expression levels of Cx43, IL-1β, IL-6, Bax, Caspase-3 mRNA and Cx43, IL-1β, NF-κB, Bax, Caspase-3 proteins in the periodontitis group significantly increased compared with those in the control group, while the expression levels of Bcl-2 mRNA and protein decreased. Periodontitis may activate NF-κB signaling molecules by upregulating the expression of Cx43 in rat kidney tissues, leading to increased levels of inflammation and apoptosis and ultimately inducing kidney injury.

Associations of the Serum KL-6 with Severity and Prognosis in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease.

As a biomarker of alveolar-capillary basement membrane injury, Krebs von den Lungen-6 (KL-6) is involved in the occurrence and development of pulmonary diseases. However, the role of the KL-6 in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has yet to be elucidated. This prospective study was designed to clarify the associations of the serum KL-6 with the severity and prognosis in patients with AECOPD. This study enrolled 199 eligible AECOPD patients. Demographic data and clinical characteristics were recorded. Follow-up was tracked to evaluate acute exacerbation and death. The serum KL-6 concentration was measured via an enzyme-linked immunosorbent assay. Serum KL-6 level at admission was higher in AECOPD patients than in control subjects. The serum KL-6 concentration gradually elevated with increasing severity of AECOPD. Pearson and Spearman analyses revealed that the serum KL-6 concentration was positively correlated with the severity score, monocyte count and concentrations of C-reactive protein, interleukin-6, uric acid, and lactate dehydrogenase in AECOPD patients during hospitalization. A statistical analysis of long-term follow-up data showed that elevated KL-6 level at admission was associated with longer hospital stays, an increased risk of future frequent acute exacerbations, and increased severity of exacerbation in COPD patients. Serum KL-6 level at admission is positively correlated with increased disease severity, prolonged hospital stay and increased risk of future acute exacerbations in COPD patients. There are positive dose-response associations of elevated serum KL-6 with severity and poor prognosis in COPD patients. The serum KL-6 concentration could be a novel diagnostic and prognostic biomarker in AECOPD patients.

Well-controlled mucosal exudation of plasma proteins in airways with intact and regenerating epithelium.

Superficial, systemic microcirculations, distinct from the pulmonary circulation, supply the mucosae of human nasal and conducting airways. Non-injurious, inflammatory challenges of the airway mucosa cause extravasation without overt mucosal oedema. Instead, likely reflecting minimal increases in basolateral hydrostatic pressure, circulating proteins/peptides of all sizes are transmitted paracellularly across the juxtaposed epithelial barrier. Thus, small volumes of extravasated, unfiltered bulk plasma appear on the mucosal surface at nasal and bronchial sites of challenge. Importantly, the plasma-exuding mucosa maintains barrier integrity against penetrability of inhaled molecules. Thus, one-way epithelial penetrability, strict localization, and well-controlled magnitude and duration are basic characteristics of the plasma exudation response in human intact airways. Invivo experiments in human-like airways demonstrate that local plasma exudation is also induced by non-sanguineous removal of epithelium over an intact basement membrane. This humoral response results in a protective, repair-promoting barrier kept together by a fibrin-fibronectin net. Plasma exudation stops once the provisional barrier is substituted by a new cellular cover consisting of speedily migrating repair cells, which may emanate from all types of epithelial cells bordering the denuded patch. Exuded plasma on the surface of human airways reflects physiological microvascular-epithelial cooperation in first line mucosal defense at sites of intact and regenerating epithelium.

Fecal microbiome extract downregulates the expression of key proteins at the interface between airway remodelling and lung cancer pathogenesis in vitro

Lung cancer (LC) is the leading cause of cancer-related mortality, and it is caused by many factors including cigarette smoking. Despite numerous treatment strategies for LC, its five-year survival is still poor (<20 %), attributable to treatment resistance and lack of early diagnosis and intervention. Importantly, LC incidence is higher in patients affected by chronic respiratory diseases (CRDs) such as asthma and chronic obstructive pulmonary disorder (COPD), and LC shares with other CRDs common pathophysiological features including chronic inflammation, oxidative stress, cellular senescence, and airway remodelling. Remodelling is a complex process resulting from the aberrant activation of tissue repair secondary to chronic inflammation, oxidative stress, and tissue damage observed in the airways of CRD patients, and it is characterized by irreversible airway structural and functional alterations, concomitantly with tissue fibrosis, epithelial-to-mesenchymal transition (EMT), excessive collagen deposition, and thickening of the basement membrane. Many processes involved in remodelling, particularly EMT, are also fundamental for LC pathogenesis, highlighting a potential connection between CRDs and LC. This provides rationale for the development of novel treatment strategies aimed at targeting components of the remodelling pathways. In this study, we tested the in vitro therapeutic activity of rat fecal microbiome extract (FME) on A549 human lung adenocarcinoma cells. We show that treatment with FME significantly downregulates the expression of six proteins whose function is at the forefront between airway remodelling and LC development: Snail, SPARC, MUC-1, Osteopontin, MMP-2, and HIF-1α. The results of this study, if confirmed by further investigations, provide proof-of-concept for a novel approach in the treatment of LC, focused on tackling the airway remodelling mechanisms underlying the increased susceptibility to develop LC observed in CRD patients.

Protocol for correlation of histological risk assessment/scoring system with a depth of invasion in oral squamous cell carcinoma.

The commonest type of cancer in the head and neck region is oral squamous cell carcinoma (OSCC) due to its high rates of occurrence and mortality. The early diagnosis of oral cancer gives better prognosis. Brandwein-Gensler criteria predict the early stage of OSCC cases with a high risk of locoregional recurrence. To correlate Brandwein-Gensler criteria and depth of invasion of OSCC with three-year survival. In the study, This study will include 80 random histopathologically-diagnosed cases of OSCC. hematoxylin-eosin (HE)-stained section slides will be used to evaluate, Brandwein and Gensler criteria by three histopathologists in a blinded manner. The depth of invasion assessment will be done from the basement-membrane (BM), in regions where the BM has been lost, as well as from an illustrative line connecting the BM from the neighbouring epithelium to the point of deepest tumour invasion in the connective-tissue stroma with the help of a research microscope (Leica-DMLB2) in resected tissue specimens of OSCC cases. The present study will find the correlation between Brandwein-Gensler criteria and depth of invasion in OSCC in order to evaluate the locoregional recurrence in OSCC cases. In high-risk OSCC cases, there may be an increased depth of invasion in resected tissues. We hypothesized that the correlation between Brandwein-Gensler criteria and depth of invasion can be used as an independent predictor for locoregional recurrence in OSCC.

Clinical Implications and Molecular Features of Extracellular Matrix Networks in Soft Tissue Sarcomas.

The landscape of extracellular matrix (ECM) alterations in soft tissue sarcomas (STS) remains poorly characterized. We aimed to investigate the tumor ECM and adhesion signaling networks present in STS and their clinical implications. Proteomic and clinical data from 321 patients across 11 histological subtypes were analyzed to define ECM and integrin adhesion networks. Subgroup analysis was performed in leiomyosarcomas (LMS), dedifferentiated liposarcomas (DDLPS), and undifferentiated pleomorphic sarcomas (UPS). This analysis defined subtype-specific ECM profiles including enrichment of basement membrane proteins in LMS and ECM proteases in UPS. Across the cohort, we identified three distinct coregulated ECM networks which are associated with tumor malignancy grade and histological subtype. Comparative analysis of LMS cell line and patient proteomic data identified the lymphocyte cytosolic protein 1 cytoskeletal protein as a prognostic factor in LMS. Characterization of ECM network events in DDLPS revealed three subtypes with distinct oncogenic signaling pathways and survival outcomes. Evaluation of the DDLPS subtype with the poorest prognosis nominates ECM remodeling proteins as candidate antistromal therapeutic targets. Finally, we define a proteoglycan signature that is an independent prognostic factor for overall survival in DDLPS and UPS. STS comprise heterogeneous ECM signaling networks and matrix-specific features that have utility for risk stratification and therapy selection, which could in future guide precision medicine in these rare cancers.

Anti-GBM antibody in a patient with diabetic nephropathy; all that glitters is not gold.

We present the case of a 58-year-old male diabetic patient admitted to our department for a slight decrease in kidney function, with nephrotic range proteinuria, hematuria (16,000/ml) and positive anti-glomerular basement membrane antibodies. Kidney biopsy revealed diabetic nephropathy with no evidence of crescent formation or linear immunoglobulin deposits along the basement membrane. We discuss the various clinical settings involving positive anti-glomerular basement membrane in the absence of crescentic glomerulonephritis.

Investigating protease-mediated peptides of inflammation and tissue remodeling as biomarkers associated with flares in psoriatic arthritis.

Psoriatic arthritis (PsA) is an inflammatory arthritis associated with psoriasis. PsA disease involves flares, which are associated with increased joint inflammation and tissue remodeling. There is a need for identifying biomarkers related to PsA disease activity and flares to improve the management of PsA patients and decrease flares. The tissue turnover imbalance that occurs during the inflammatory and fibro-proliferative processes during flares leads to an increased degradation and/or reorganization of the extracellular matrix (ECM), where increased proteolysis plays a key role. Hence, protease-mediated fragments of inflammatory and tissue-remodeling components could be used as markers reflecting flares in PsA patients. A broad panel of protease-mediated biomarkers reflecting inflammation and tissue remodeling was measured in serum and synovial fluid (SF) obtained from PsA patients experiencing flares (acutely swollen joint[s], PsA-flare). In serum, biomarker levels assessed in PsA-flare patients were compared to controls and in early-diagnosed PsA patients not experiencing flares (referred to as PsA without flare). Furthermore, the biomarker levels assessed in SF from PsA-flare patients were compared to the levels in SF of osteoarthritis (OA) patients. In serum, levels of the PRO-C3 and C3M, reflecting formation and degradation of the interstitial matrix, were found significantly elevated in PsA-flare compared to controls and PsA without flare. The remodeling marker of the basement membrane, PRO-C4, was significantly elevated in PsA-flare compared to PsA without flare. The inflammation and immune cell activity related markers, CRPM, VICM, and CPa9-HNE were significantly elevated in PsA-flare patients compared to controls and PsA without flare. In addition, VICM (AUC = 0.71), CPa9-HNE (AUC = 0.89), CRPM (AUC = 0.76), and PRO-C3 (AUC = 0.86) showed good discriminatory performance for separating PsA-flare from PsA without flare. In SF, the macrophage activity marker, VICM, was significantly elevated whereas the type II collagen formation marker, PRO-C2, was significantly reduced in the PsA-flare compared to OA. The combination of five serum markers reflecting type III and IV collagen degradation (C3M and C4M, respectively), type III and VI collagen formation (PRO-C3 and PRO-C6, respectively), and neutrophil activity (CPa9-HNE) showed an excellent discriminatory performance (AUC = 0.98) for separating PsA-flare from PsA without flares. The serum biomarker panel of C3M, C4M, PRO-C3, PRO-C6, and CPa9-HNE reflecting synovitis, enthesitis, and neutrophil activity may serve as novel tool for quantitatively monitoring flares in PsA patients.

HIV1-Nef perturbs the integrity of blood testis barrier in rat model

ABSTRACT The blood-testis barrier is a specialized feature within the mammalian testis, located in close proximity to the basement membrane of seminiferous tubules. This barrier serves to divide the seminiferous epithelium into distinct basal and adluminal (apical) compartments. The selectivity of the BTB to foreign particles makes it a safe haven for the virus, and the high affinity of HIV for testis might lead to the vertical transmission of the virus. In the present study, recombinant HIV1-Nef (rNef) protein was injected intravenously to examine the effect of rNef on BTB. SD male rats received 250 µg and 500 µg of rNef along with 2% Evans blue dye within 1 ml through the tail vein. After 1 hour of perfusion, the animals were sacrificed for analysis. The dye migration assay and ELISA confirmed a significant impairment in the blood-testis barrier (BTB) and the manifestation of rNef in testes tissues, respectively. Moreover, a decline in the expression of tight junction proteins, including ZO1 and Occludin, was observed during rNef-induced BTB disruption. Overall, our findings demonstrated that rNef induces BTB disruption through various signaling events. At the site of ectoplasmic specialization of the seminiferous epithelium, the localization of cadherins was found to be disrupted, making the testis a vulnerable site. In conclusion, rNef perturbs the integrity of the blood-testis barrier in rat models; hence, it can also serve as a suitable model for studying the dynamics of the blood-testis barrier.

Basement Membranes, Brittlestar Tendons, and Their Mechanical Adaptability.

Basement membranes (BMs) are thin layers of extracellular matrix that separate epithelia, endothelia, muscle cells, and nerve cells from adjacent interstitial connective tissue. BMs are ubiquitous in almost all multicellular animals, and their composition is highly conserved across the Metazoa. There is increasing interest in the mechanical functioning of BMs, including the involvement of altered BM stiffness in development and pathology, particularly cancer metastasis, which can be facilitated by BM destabilization. Such BM weakening has been assumed to occur primarily through enzymatic degradation by matrix metalloproteinases. However, emerging evidence indicates that non-enzymatic mechanisms may also contribute. In brittlestars (Echinodermata, Ophiuroidea), the tendons linking the musculature to the endoskeleton consist of extensions of muscle cell BMs. During the process of brittlestar autotomy, in which arms are detached for the purpose of self-defense, muscles break away from the endoskeleton as a consequence of the rapid destabilization and rupture of their BM-derived tendons. This contribution provides a broad overview of current knowledge of the structural organization and biomechanics of non-echinoderm BMs, compares this with the equivalent information on brittlestar tendons, and discusses the possible relationship between the weakening phenomena exhibited by BMs and brittlestar tendons, and the potential translational value of the latter as a model system of BM destabilization.

Podocyte Pathogenic Bone Morphogenetic Protein-2 Pathway and Immune Cell Behaviors in Primary Membranous Nephropathy.

Primary membranous nephropathy (PMN) is one of the leading causes of end-stage renal disease, and the most frequent cause of massive proteinuria in nondiabetic adults, resulting in fatal complications. However, the underlying pathomechanisms of PMN remain largely unclear. Here, single-cell RNA sequencing is employed to analyze kidney biopsies from eleven PMN patients and seven healthy subjects. Profiling 44060 cells from patients allowed us to characterize the cellular composition and cell-type-specific gene expression in the PMN kidney. The complement-induced BMP2/pSMAD1/COL4 pathway is identified as the pathogenic pathway in podocytes, bridging two key events, i.e., complement system activation and glomerular basement membrane thickening in PMN. Augmented infiltration and activation of myeloid leukocytes and B lymphocytes are found, profiling delicate crosstalk of immune cells in PMN kidneys. Overall, these results provide valuable insights into the roles of podocytes and immune cells in PMN, and comprehensive resources toward the complete understanding of PMN pathophysiology.

The basement membrane regulates the cellular localization and the cytoplasmic interactome of Yes-Associated Protein (YAP) in mammary epithelial cells.

The Hippo pathway, a signaling cascade involved in the regulation of organ size and several other processes, acts as a conduit between extracellular matrix (ECM) cues and cellular responses. We asked whether the basement membrane (BM),a specialized ECM component known to induce quiescence and differentiation in mammary epithelial cells, would regulate the localization, activity, and interactome of YAP, a Hippo pathway effector. To address this question, we used a broad range of experimental approaches, including 2D and 3D cultures of both mouse and human mammary epithelial cells, as well as the developing mouse mammary gland. In contrast to malignant cells, nontumoral cells cultured with a reconstituted BM (rBM)displayed higher concentrations of YAP in the cytoplasm. Incidentally, when in the nucleus of rBM-treated cells, YAP resided preferentially at the nuclear periphery. In agreement with our cell culture experiments, YAP exhibited cytoplasmic predominance in ductal cells of developing mammary epithelia, where a denser BM is found. Conversely, terminal end bud (TEB)cells with a thinner BM displayed higher nucleus-to-cytoplasm ratios of YAP. Bioinformatic analysis revealed that genes regulated by YAP were overrepresented in the transcriptomes of microdissected TEBs. Consistently, mouse epithelial cells exposed to the rBM expressed lower levels of YAP-regulated genes, although the protein level of YAP and Hippo components were slightly altered by the treatment. Mass spectrometry analysis identified a differential set of proteins interacting with YAP in cytoplasmic fractions of mouse epithelial cells in the absence or presence of rBM. In untreated cells, YAP interactants were enriched in processes related to ubiquitin-mediated proteolysis, whereas in cells exposed to rBM YAP interactants were mainly key proteins related to amino acid, amino sugar, and carbohydrate metabolism. Collectively, we unraveled that the BM induces YAP translocation or retention in the cytoplasm of nontumoral epithelial cells and that in the cytoplasm YAP seems to undertake novel functions in metabolic pathways.

#2834 Analysis of cyst hetero- and homogeneity to unravel common pathways in autosomal dominant polycystic kidney disease

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease, with a prevalence of 1 in ca. 1000 individuals and accounting for 10% of the European dialysis population. It is most frequently (75-80%) caused by mutations in the PKD1 gene encoding Polycystin-1. Besides systemic manifestations such as liver cysts, hypertension and cardiac abnormalities, the most prominent phenotype is the gradual development of kidney cysts, leading to kidney enlargement and a decline in kidney function leading to end-stage kidney disease at an average age of ca. 50 years. The cysts arise from tubular epithelial cells in the nephron that start to dedifferentiate, proliferate and eventually secrete fluid into the cyst lumen promoting its swelling. This process is molecularly regulated by changes in Ca2+, cAMP, PKA and PI3K-Akt-mTOR signaling, among others. The renal cysts are further characterized by ciliary dysfunction, altered signal transduction, loss of polarity, apoptosis, mitochondrial abnormalities, metabolic reprogramming, inflammation, oxidative stress and epigenetic changes. However, the exact sequence of events and their relative importance in the process of cyst formation remains unclear. Therefore, we analyzed the transcriptomic cyst hetero- and homogeneity to identify the pathways that were different, but also shared among individual cysts. Method We performed RNA-Seq analysis on 40 individual cystic membranes of nephrectomized kidneys of 4 PKD1 patients. We included 4 samples of macroscopically healthy tissue from 2 ADPKD kidneys (histologically confirmed to have microcysts) and 4 samples from 4 healthy kidneys. Principal component, cluster and trajectory analysis was performed to explore cyst heterogeneity. Adjacent pieces of cystic membrane were analyzed for histology (H&amp;E, Sirius Red) or stained with FITC-tagged Lotus Tetragonolobus Lectin (LTL) or Dolichos Biflorus Agglutinin (DBA), a proximal and distal tubular marker, respectively. Results Although the cysts clearly separated from the healthy tissues in the analyses, there was also a distinct heterogeneity observed among the cysts that was independent of patient, gender, cyst size, location or fluid color. Pathway analysis revealed that these changes were characterized by a gradual increase of interstitial (remodeling) and inflammation markers, and a gradual decrease in differentiation markers (e.g. development, intercellular junctions, basement membrane) along the trajectory pseudotime. We could identify 6 clusters of cystic samples, with 2 clusters deviating from the main trajectory. With respect to tubular/epithelial dedifferentiation, the decrease in proximal tubular markers already occurred in microcystic tissue and was stronger compared to the other tubular segments. Consequently, none of the analyzed cystic membranes stained positive for LTL, while others showed clear staining for DBA. Microcysts on the other hand stained positive for LTL or DBA. Several cysts showed RNA marker expression of multiple tubular segments. Indeed, smaller macrocysts (diameter in the mm range) were lined by both LTL- and DBA-positive regions. Conclusion By analyzing transcriptomic hetero- and homogeneity among individual cysts, the molecular alterations in ADPKD progression can be tracked down and determined whether they occur similarly in all cysts or at different levels. Our data also suggest that loss of proximal tubular markers in macrocysts is more prominent compared to the decrease in distal markers. Finally, inner cyst walls can consist of cyst-lining cells of multiple origins.

#2108 Secondary amyloidosis in a cancer patient on pembrolizumab—an unusual finding

Abstract Background and Aims With the widening horizon of ICPIs in the management of oncological disorders, we require to remain vigilant of the possible iRAEs. We present a case report of secondary amyloidosis in at metastatic non-small cell lung carcinoma (NSCLC) patient treated with Pembrolizumab. We aim to describe the clinic-biological &amp; histopathological characteristics of ICPI-related kidney injury which may be beyond interstitial nephritis &amp; its response to treatment &amp; the role of kidney biopsy to define ICPI-related kidney injury. Treatment is challenging due to a paucity of relevant data, implicating further studies. Treatment with colchicine and steroids, tocilizumab in the setting of elevated interleukin-6 (IL6) levels have been reported in case series; unfortunately no appreciable renal benefit were noted. Method 77 year male, diabetic &amp; hypertensive on regular medication for &amp;gt;15 yr, reformed smoker (≈50 pack-years of cigarette) diagnosed with NSCLC (EGFR–wild type, PDL1–70%), received Pembrolizumab (13 cycles) &amp; Paclitaxel + Carboplatin &amp; was in remission. Follow up PET showed partial response—new lesions in brain. Gemcitabine added to the treatment &amp; had received 2 cycles, till hospitalization with febrile episode, decreased oral intake &amp; progressive edema. Clinical evaluation was non-contributory. Hematology &amp; biochemical evaluation (Table 1) showed raised serum creatinine 1.1 mg/dL (baseline 1 mg/dL), urinalysis—2+ protein, quantification showed 2.9295 g/24 h → 6.38 g/24 h (baseline uPCR-0.19 g/g). Abdominal ultrasound &amp; ECHO finding were not conclusive. Fundoscopy showed no evidence of proliferative diabetic or hypertensive retinopathy. Results Kidney Biopsy (Figure) was done. LM showed, few of 8 gloms with mild segmental mesangial expansion due to amorphous extracellular deposits which was PAS &amp; silver negative but showed congophilia (Fig. A,B,C,D). If negative for albumin, IgG, IgA, C3, C1q &amp; had 1+ granularity in the mesangium on IgM staining &amp; showed no light chain restriction in glomeruli &amp; tubular cast for kappa &amp; lambda. IHC (Fig. E) was positive for serum amyloid associated proteins. EM revealed minimal subendothelial &amp; mesangial expansion due to extracellular material organized into randomly arranged fine fibrils, &amp; no significant foot process effacement, electron dense deposits along the capillary basement membrane or within mesangium, glomerular basement membrane, thereby excluding possibility of light chain deposition disease. Conclusion Secondary amyloidosis with ICPI use has uncommonly &amp; with Pembrolizumab rarely been reported. Treatment is challenging due to paucity of literature. Hassan Izzedine et al. in their case series, on Pembrolizumab treated cancer patient [N = 676], showed 12 patients (7 men) (Incidence 1.77%) developed AKI (n = 10) &amp;/or Proteinuria (n = 2), median duration of use 9 months. All (n = 12) underwent renal biopsy, which showed AIN in 4, ATI in 5, MCD in 2. Recovery happened with withdrawal of drug coupled with corticosteroid. Reintroduction resulted in more severe recurrence of AIN in 1 patient only. Lapman et al. reported 1 case of secondary amyloidosis in cancer patients treated with Pembrolizumab. 42yr male Caucasian, had no reported chronic illness, except Asthma. Similarly developed significant proteinuria (Urine Pro 3+) &amp; AKI (Sr. Creat 1.58 mg/dl; Baseline 1.0 mg/dl) after 90 days of Pembrolizumab therapy. Under went 2 Kidney Biopsy–1st Biopsy revealed AA amyloid. AA amyloidosis was attributed to Pembrolizumab as repeat Bx revealed progressive deposits despite remission of malignancy, but his kidney disease progressed, and had to be initiation on maintenance hemodialysis. Stopping Pembrolizumab &amp; corticosteroids led to resolution of proteinuria in our patient too.