Biology subjects

Petricca, L.

Publications and source records attributed to Petricca, L..

8 recordsLinked to original sources

bioRxiv2026

Synovial lining expressed mechanosensor PIEZO1 drives inflammation-permissive macrophage phenotypes and joint inflammation

Synovial tissue-resident macrophages regulate immune homeostasis within the joint, but can adopt an inflammation-permissive phenotype that promotes immune cell infiltration in rheumatoid arthritis (RA). Understanding the factors that drive this phenotypic switch may help prevent the localisation of inflammation in the joints of individuals at-risk of RA. We identified the mechanosensitive ion channel PIEZO1 as a potential regulator of lining-layer synovial tissue macrophage (STM) function. PIEZO1 was highly expressed in homeostatic, tissue resident TREM2pos lining-layer STMs and in its pathogenic chemokine producing TREM2low phenotype that characterises the hyperplastic lining-layer in active RA. Intra-articular injection of a PIEZO1 agonist in mice induced neutrophil and monocyte infiltration, whereas inhibition of PIEZO1 signalling restored the protective macrophage phenotype. Thus, mechanosensing via PIEZO1 is a defining feature of the joint lining-layer, and its aberrant activation by mechanical stress may lead to the localisation of inflammation within the joint, facilitating a transition from asymptomatic autoimmunity of at-risk RA to clinical disease.

immunology↗

bioRxiv2025

The ontogeny of myeloid-stromal synovial tissue niches in rheumatoid arthritis.

Recent single-cell multi-omic and spatial analyses of synovial biopsies have transformed our understanding of myeloid cell-driven mechanisms underlying human joint pathology and tissue homeostasis in Rheumatoid arthritis (RA). However, the developmental trajectories of synovial tissue macrophage (STM) subsets in humans remain poorly understood, due in part to the lack of models that faithfully replicate synovial tissue niches. This hinders the exploration of the therapeutic potential of targeting specific synovial myeloid cell clusters. Using multi-omics analyses of synovial tissue from an allogeneic bone marrow transplant recipient, we show that joint-specific tissue-resident STM subsets, including both health- and disease-associated clusters, can derive from peripheral blood monocytes. Analysis of embryonic synovial joints revealed that macrophage localization and maturation in the joints are preceded by local stromal niche specialisation, indicating that synovial fibroblasts (FLS) provide tissue-specific instructive cues to STM precursors. To elucidate human STM developmental trajectories, we established a SNP-based fate-tracking human synovial organoid system by embedding distinct blood-derived myeloid precursors, together with FLS clusters from RA synovial biopsies and endothelial cells, into 3D structures. These organoids reproduced key synovial tissue features, including lining and sublining architecture and stromal-myeloid cell cluster composition. Importantly, they supported differentiation of all resident STM subsets: homeostatic lining TREM2pos macrophages, their pathogenic TREM2lowSPP1pos counterparts that characterize the RA hyperplastic lining, and both homeostatic and RA-associated perivascular LYVE1pos STM clusters, all traced to monocytic precursors. In summary, we show that development of STM subsets is driven by fibroblast-conditioned spatial niches. We have established a novel, tractable ex vivo platform to dissect the niche-specific cues driving homeostatic versus pathogenic phenotypic clusters. One Sentence SummaryHuman tissue-resident STMs develop from monocytes under the guidance of cues from FLS within discrete spatial locations.

immunology↗

bioRxiv2025

Modulation of huntingtin S421 phosphorylation in a Huntington's disease mouse model and its detection in nonhuman primate cerebrospinal fluid

Huntingtons disease (HD) is a progressive neurodegenerative disease caused by the pathologic expansion of a CAG repeat in the first exon of the huntingtin (HTT) gene, resulting in a huntingtin (HTT) protein with an expanded polyglutamine (polyQ) tract. Phosphorylation at residue S421 (pS421) is one of the post-translational modifications proposed to influence the biology of wild-type and mutant (m)HTT, such as HTT stability and clearance, HTT subcellular localization, mHTT toxicity, and regulation of HTT function in axonal transport. However, the detection and quantification of S421-HTT phosphorylation in relevant biological contexts have remained challenging and the consequences of pS421 in HD pathogenesis remains unclear. Here we report the development of a novel ultrasensitive immunoassay enabling the specific and sensitive detection of pS421-HTT in a variety of biologically relevant contexts. With this assay we conducted a longitudinal assessment of pS421 levels in tissues from a mouse model of HD to investigate the relationship between S421 phosphorylation and phenotypic progression. We also identified PRKACA, the cAMP-regulated catalytic subunit of PKA, as a kinase capable of phosphorylating S421-HTT, demonstrating its ability to regulate endogenous pS421 in human cells. Finally, we exploited the sensitivity of the assay to detect endogenous pS421-HTT in cerebrospinal fluid (CSF) from nonhuman primates, showing for the first time that phosphorylation at S421-HTT can be detected in this bio-fluid. These reagents and assay will enable investigation of the biological consequence and the relevance of pS421 in the natural history of HD.

neuroscience↗

bioRxiv2024

Distinct tissue-niche localization and function of synovial tissue myeloid DC subsets in health, and in active and remission Rheumatoid Arthritis

Current rheumatoid arthritis (RA) treatments do not restore immune tolerance. Investigating dendritic cell (DC) populations in human synovial tissue (ST) may reveal pathways to re-instate tolerance in RA. With single-cell and spatial-transcriptomics of synovial tissue biopsies, validated by micro co-culture systems, we identified condition and niche-specific myeloid DC clusters with distinct differentiation trajectories and functions. Healthy synovium contains a unique tolerogenic AXLpos DC2 cluster in the superficial sublining layer. In active RA, a macrophage-rich lining-layer niche becomes populated with inflammatory DC3 clusters that specifically activate memory CCL5pos TEM and CCL5posCXCL13pos TPH, promoting synovitis. In the sublining lymphoid niche, CCR7pos DC2 mReg specifically interact with naive-T-cells, potentially driving the local expansion of new effector T-cells. Sustained remission sees the resolution of these niches but lacks the recovery of tolerogenic AXLpos DC2, indicating latent potential for disease flare. A human RA disease-flare model showed that the activation of blood predecessor of ST-DC3 clusters precedes the onset of inflammation in joints. Therapeutic strategies targeting pathogenic ST-DC3 clusters, or reinstating tolerogenic AXLpos DC2, may restore immune homeostasis in RA. In briefDeconstruction of human RA synovium, using single-cell spatial transcriptomics and micro-culture systems, reveals distinct neighbourhoods within the synovial architecture across health, and RA patients with active disease or sustained remission. Discrete niches are identified that contain distinct myeloid DC clusters that differ in frequency, differentiation trajectories, and effector functions. HighlightsO_LIHuman RA synovium exhibits condition and niche specific myeloid DC clusters that vary in their tissue differentiation trajectories and functions. C_LIO_LIST-CD14pos DC3 (iDC3) support inflammatory CCL5pos TEM and CCL5pos TPH cell activation in the hyperplastic lining layer. C_LIO_LIST-CCR7pos DC2 (mReg), driven by MIR155, interact with naive-T-cells in sublining lymphoid niches. C_LIO_LIA specific inflammatory signature of blood predecessors of ST-DC3s predict flare in RA. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/600758v1_ufig1.gif" ALT="Figure 1"> View larger version (74K): org.highwire.dtl.DTLVardef@27ab01org.highwire.dtl.DTLVardef@4be238org.highwire.dtl.DTLVardef@1f10734org.highwire.dtl.DTLVardef@1102056_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

IKBKB reduces huntingtin aggregation by phosphorylating Serine 13 via a non-canonical IKK pathway

N-terminal phosphorylation at residues T3 and S13 is believed to have important beneficial implications for the biological and pathological properties of mutant huntingtin, where IKBKB was identified as a candidate regulator of huntingtin N-terminal phosphorylation. The paucity of mechanistic information on IKK pathways, together with the lack of sensitive methods to quantify endogenous huntingtin phosphorylation, prevented detailed study of the role of IKBKB in Huntingtons disease. Using novel ultrasensitive assays, we demonstrate that IKBKB can regulate endogenous S13 huntingtin phosphorylation in a manner dependent on its kinase activity and known regulators. We found that the ability of IKBKB to phosphorylate endogenous huntingtin S13 is mediated through a non-canonical IRF3-mediated IKK-pathway, distinct from the established involvement of IKBKB in mutant huntingtins pathological mechanisms mediated via the canonical pathway. Furthermore, increased huntingtin S13 phosphorylation by IKBKB resulted in decreased aggregation of mutant huntingtin in cells, again dependent on its kinase activity. These findings point to a non-canonical IKK-pathway linking S13 huntingtin phosphorylation to the pathological properties of mutant huntingtin aggregation, thought to be significant to Huntingtons disease.

neuroscience↗

bioRxiv2022

Comparative analysis of total alpha-synuclein (αSYN) immunoassays reveals that they do not capture the diversity of modified αSYN proteoforms

BackgroundThe development of therapeutics for Parkinsons disease (PD) requires the establishment of biomarker assays to enable stratifying patients, monitoring disease progression and assessing target engagement. Attempts to develop diagnostic assays based on detecting levels of the -synuclein (SYN) protein, a central player in the pathogenesis of PD, have yielded inconsistent results. ObjectiveTo determine whether the three commercial kits that have been extensively used for total SYN quantification in human biological fluids (from Euroimmun, MSD, and Biolegend) are capable of capturing the diversity and complexity of relevant SYN proteoforms. MethodsWe investigated and compared the ability of the different assays to detect the diversity of SYN proteoform using a library of SYN proteins that compromise the majority of disease-relevant SYN variants and post-translational modification. ResultsOur findings showed that none of the three tested immunoassays accurately capture the totality of relevant SYN species and are unable to recognize most disease-associated C-terminally truncated variants of SYN. Moreover, several N-terminal truncations and phosphorylation/nitration differentially modify the level of SYN detection and recovery by different immunoassays, and a CSF matrix effect was observed for most of the SYN proteoforms analyzed by the three immunoassays. ConclusionsOur results showed that these immunoassays do not capture the totality of the relevant SYN species and therefore may not be appropriate tools to provide an accurate measure of total SYN levels in samples containing modified forms of the protein. This highlights the need for next-generation SYN immunoassays that capture the diversity of SYN proteoforms.

neuroscience↗

bioRxiv2020

Dose-dependent and disease-modifying effects of striatal infusion of cholesterol in Huntington's disease

A variety of pathophysiological mechanisms are implicated in Huntingtons disease (HD). Among them, reduced cholesterol biosynthesis has been detected in the HD mouse brain from pre-symptomatic stages, leading to diminished cholesterol synthesis, particularly in the striatum. In addition, systemic injection of cholesterol-loaded brain-permeable nanoparticles ameliorates synaptic and cognitive function in a transgenic mouse model of HD. To identify an appropriate treatment regimen and gain mechanistic insights into the beneficial activity of exogenous cholesterol in the HD brain, we employed osmotic mini-pumps to infuse three escalating doses of cholesterol directly into the striatum of HD mice in a continuous and rate-controlled manner. All tested doses prevented cognitive decline, while amelioration of disease-related motor defects was dose-dependent. In parallel, we found morphological and functional recovery of synaptic transmission involving both excitatory and inhibitory synapses of striatal medium spiny neurons. The treatment also enhanced endogenous cholesterol biosynthesis and clearance of mutant Huntingtin aggregates. These results indicate that cholesterol infusion to the striatum can exert a dose-dependent, disease-modifying effect and may be therapeutically relevant in HD.

neuroscience↗

bioRxiv2019

TBK1 regulates autophagic clearance of soluble mutant huntingtin and inhibits aggregation/toxicity in different models of Huntington's disease

Phosphorylation of the N-terminal domain of the Huntingtin (HTT) protein (at T3, S13, and S16) has emerged as a key regulator of HTT stability, clearance, localization, aggregation and toxicity. Herein, we report the discovery and validation of a kinase, TANK-binding kinase 1 (TBK1), that specifically and efficiently phosphorylates both wild-type and mutant full-length or N-terminal fragments of HTT in vitro (S13/S16) and in cell/ neuronal cultures (S13). We show that overexpression of TBK1 in mammalian cells, primary neurons and a Caenorhabditis elegans model of Huntingtons Disease (HD) increases mutant HTTex1 phosphorylation, lowers its levels, increases its nuclear localization and significantly reduces its aggregation and cytotoxicity. Our mechanistic studies demonstrate that the TBK1-mediated neuroprotective effects are due to phosphorylation-dependent inhibition of mutant HTTex1 aggregation and an increase in autophagic flux. These findings suggest that upregulation and/or activation of TBK1 represents a viable strategy for the treatment of HD. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/869586v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1368abeorg.highwire.dtl.DTLVardef@1cecff4org.highwire.dtl.DTLVardef@b6b7c5org.highwire.dtl.DTLVardef@1daf53d_HPS_FORMAT_FIGEXP M_FIG Graphical abstract C_FIG

neuroscience↗