Biomedical subjects

Silvia Armelloni

Publications and source records attributed to Silvia Armelloni.

4 recordsLinked to original sources

PubMed2026

Single-section multiplex spatial proteomics of immune microenvironments in kidney transplantation.

Characterizing kidney disease is challenged by marked cellular heterogeneity and limited tissue availability from renal biopsies. Conventional diagnostic workflows rely on multiple serial sections for parallel staining, increasing tissue consumption, sampling bias, and loss of spatial information, thereby constraining molecular characterization within intact tissue architecture. High-plex spatial proteomics may overcome these limitations by enabling comprehensive molecular profiling on a single section. Here, we present and evaluate a high-plex cyclic immunofluorescence imaging workflow (MACSima™, Miltenyi Biotec) applied to kidney transplant biopsies, including BK virus nephropathy (BKVN) and focal segmental glomerulosclerosis (FSGS), to characterize spatial immune organization with a focus on complement system components. Feasibility and subcellular resolution were first assessed in a lupus nephritis section, demonstrating compatibility with diagnostic immune panels and preservation of tissue morphology. A 48-marker multiplex panel interrogating immunity, oxidative stress, senescence, and fibrosis was then applied to BKVN samples, including paired pre- and post-treatment biopsies, revealing distinct proteomic patterns and dynamic changes following therapy. In FSGS, a glomerulus-focused panel identified spatially resolved innate and adaptive immune signatures, including complement-related patterns supporting exploratory analysis of glomerular immune architecture. Structural, nuclear, membrane, and phosphorylated signaling markers enabled precise delineation of renal compartments and assessment of cellular states such as proliferation, DNA damage, and pathway activation. The workflow also supported detection of extracellular vesicles in cultured renal cells, highlighting its versatility. Overall, this approach provides a robust, tissue-sparing platform for integrated spatial and molecular profiling of renal biopsies, reducing sampling bias while enabling discovery-level phenotyping from a single section. This unified strategy is particularly suited to kidney transplantation, where diagnosis, therapeutic decision-making, and longitudinal monitoring are closely interconnected.

Kidney Transplantation↗

PubMed2006

Glomerular podocytes contain neuron-like functional synaptic vesicles.

Although patients with chronic renal failure are increasing worldwide, many aspects of kidney biology remain to be elucidated. Recent research has uncovered several molecular properties of the glomerular filtration barrier, in which podocytes, highly differentiated, ramified cells that enwrap the glomerular basement membrane, have been reported to be mainly responsible for filter's selectivity. We previously described that podocytes express Rab3A, a GTPase restricted to cell types that are capable of highly regulated exocytosis, such as neuronal cells. Here, we first demonstrate by a proteomic study that Rab3A in podocytes coimmmunoprecipitates with molecules once thought to be synapse specific. We then show that podocytes possess structures resembling synaptic vesicles, which contain glutamate, coexpress Rab3A and synaptotagmin 1, and undergo spontaneous and stimulated exocytosis and recycling, with glutamate release. Finally, from the results of a cDNA microarray study, we describe the presence of a series of neuron- and synapse-specific molecules in normal human glomeruli and confirm the glomerular protein expression of both metabotropic and ionotropic glutamate receptors. These data point toward a synaptic-like mechanism of communication among glomerular cells, which perfectly fits with the molecular composition of the glomerular filter and puts in perspective several previous observations, proposing a different working hypothesis for understanding glomerular signaling dynamics.

Animals↗

PubMed2003

Glomerular podocytes possess the synaptic vesicle molecule Rab3A and its specific effector rabphilin-3a.

Several recent studies have focused on similarities between glomerular podocytes and neurons because the two cells share a specialized cytoskeletal organization and several expression-restricted proteins, such as nephrin and synaptopodin. In neurons, the small guanosine triphosphatase Rab3A and its effector rabphilin-3A form a complex required for the correct docking of synaptic vesicles to their target membrane. Because rabphilin-3A binds in neurons to cytoskeletal proteins also important for podocyte homeostasis, and the complex rabphilin-3A-Rab3A has been demonstrated in neurons and neuroendocrine cells, the aim of our work was to investigate their possible expression and regulation in podocytes. Normal kidneys from mouse, rat, and human were studied by immunohistochemistry, Western blotting, and reverse transcriptase-polymerase chain reaction to evaluate the expression of Rab3A and rabphilin-3A. Double-staining immunohistochemistry and immunogold electron microscopy were then used to precisely localize the two proteins at the cellular and subcellular levels. Rab-3A and rabphilin-3A regulations in disease were then analyzed in growth hormone-transgenic mice, a well established model of focal and segmental glomerulosclerosis, and in human biopsies from proteinuric patients. Our results demonstrated that rabphilin-3A and Rab3A are present in normal mouse, rat, and human kidneys, with an exclusively glomerular expression and a comma-like pattern of positivity along the glomerular capillary wall, suggestive for podocyte staining. Co-localization of both molecules with synaptopodin confirmed their presence in podocytes. By immunogold electron microscopy both proteins were found around vesicles contained in podocyte foot processes. Their expression was increased in growth hormone-transgenic mice compared to their wild-type counterpart, and in a subset of biopsies from proteinuric patients. Our data, demonstrating the presence of two synaptic proteins in podocytes, further supports similarities between cytoskeletal and vesicular organization of podocytes and neurons. The altered expression observed in mouse and human proteinuric diseases suggests a possible role for these molecules in glomerulopathies.

Adaptor Proteins, Signal Transducing↗

PubMedDate not supplied

CD20-positive infiltrates in human membranous glomerulonephritis.

Membranous glomerulonephritis (MGN), histologically defined by subepithelial immune deposits, is the most common cause of nephrotic syndrome in Caucasian adults. The current hypothesis of the underlying disease mechanism postulates production of antibodies against podocyte-derived antigens. Respective antigens could be demonstrated in different animal models and recently in human neonatal MGN. Further support for this hypothesis was generated by the response of human MGN to therapeutic B cell depletion by rituximab. However, the role of B cells in this disease is not well defined. In this study, the interstitial expression of CD20 mRNA was determined in 31 MGN patients and controls (tumor nephrectomies (n = 4), minimal change disease (MCD, n = 10) and focal segmental glomerulosclerosis (n = 6)). CD20 mRNA expression was significantly higher in MGN patients compared to controls. By immunohistochemistry, a focal or diffuse interstitial B cell infiltration could be detected in MGN patients (n = 63), which was absent or minimal in patients with MCD (n = 11). These data suggest an involvement of B cells in the pathogenesis of MGN, possibly as antigen-presenting cells. Further studies should investigate the potential to predict the response to therapeutic B cell depletion by intrarenal CD20 quantification, a potential diagnostic basis for the selection of a specific therapy currently evolving for renal disease.

Antigens, CD20↗