Biology subjects

Lother, A.

Publications and source records attributed to Lother, A..

3 recordsLinked to original sources

bioRxiv2023

Piezo1 stretch-activated channel activity differs between bone marrow-derived and cardiac tissue-resident macrophages

Macrophages (M{Phi}) play pivotal roles in tissue homeostasis and repair. Their mechanical environment recently emerged as a key modulator of various cell functions, and M{Phi} mechanosensitivity is likely to be critical for cellular activity in particular in a rhythmically contracting organ such as the heart. M{Phi}, in-vitro-differentiated from bone marrow (M{Phi}BM), form a popular cell model for research. This study explores the activity of stretch-activated ion channels (SAC) in murine M{Phi}BM and compares it to SAC activity in cardiac tissue-resident M{Phi} (M{Phi}TR). Our main findings are: i) M{Phi}BM and M{Phi}TR have stretch-induced currents, indicating expression of functional SAC at their plasma membrane; ii) the current profiles in M{Phi}BM and in M{Phi}TR show characteristics of cation non-selective SAC; iii) unlike in M{Phi}BM, Piezo1 ion channel activity at the plasma membrane of M{Phi}TR is not detectable, neither by assessing electrophysiological activity using the patch clamp technique, nor by measuring cytosolic calcium concentration upon perfusion with Yoda1, a Piezo1 channel agonist. In mature scars after ventricular cryoablation, stretch-induced current characteristics of M{Phi}TR are not significantly different compared to non-injured control tissue, even though scars are expected to contain a mix of pre-existing and circulation-recruited M{Phi}. This suggests that M{Phi} invading injured cardiac tissue either phenoconvert their mechanosensitivity from M{Phi}BM to M{Phi}TR, or that the in vitro differentiation protocols used to obtain M{Phi}BM generate cells that differ from M{Phi} recruited from the circulation during tissue repair in vivo. Further investigations will explore SAC identity in lineage-traced M{Phi} in scar tissue, and compare mechanosensitivity of circulating monocytes with that of M{Phi}BM. Key pointsO_LIM{Phi}BM and M{Phi}TR have stretch-induced currents, indicating expression of functional SAC at their plasma membrane; C_LIO_LIThe current profiles in M{Phi}BM and in M{Phi}TR show characteristics of cation non-selective SAC; C_LIO_LIUnlike in M{Phi}BM, Piezo1 ion channel activity at the plasma membrane of M{Phi}TR is not detectable C_LI

biophysics↗

bioRxiv2021

Enhanced FcγRIII/CD16 activation by discrete ligands as independent correlates of disease severity in COVID-19 patients

A dysregulated immune response with high levels of SARS-CoV-2 specific IgG antibodies characterizes patients with severe or critical COVID-19. Although a robust IgG response is traditionally considered to be protective, excessive triggering of activating Fc-gamma-receptors (Fc{gamma}Rs) could be detrimental and cause immunopathology. Here, we document that patients who develop soluble circulating IgG immune complexes (sICs) during infection are subject to enhanced immunopathology driven by Fc{gamma}R activation. Utilizing cell-based reporter systems we provide evidence that sICs are predominantly formed prior to a specific humoral response against SARS-CoV-2. sIC formation, together with increased afucosylation of SARS-CoV-2 specific IgG eventually leads to an enhanced CD16 (Fc{gamma}RIII) activation of immune cells reaching activation levels comparable active systemic lupus erythematosus (SLE) disease. Our data suggest a vicious cycle of escalating immunopathology driven by an early formation of sICs in predisposed patients. These findings reconcile the seemingly paradoxical findings of high antiviral IgG responses and systemic immune dysregulation in severe COVID-19. Clinical implicationsThe identification of sICs as drivers of an escalating immunopathology in predisposed patients opens new avenues regarding intervention strategies to alleviate critical COVID-19 progression. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=78 SRC="FIGDIR/small/449893v4_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@b4616corg.highwire.dtl.DTLVardef@682d1aorg.highwire.dtl.DTLVardef@16946cborg.highwire.dtl.DTLVardef@a6ef7d_HPS_FORMAT_FIGEXP M_FIG C_FIG A vicious cycle of immunopathology in COVID-19 patients is driven by soluble multimeric immune complexes (sICs). SARS-CoV-2 infection triggers sIC formation in prone individuals. Activation of Fc{gamma}RIII/CD16 expressing immune cells by sICs precedes a humoral response to SARS-CoV2 infection. sICs and infection add to IgG afucosylation, further enhancing Fc{gamma}RIII/CD16 activation by opsonized targets. High inflammation induces further sIC mediated immune cell activation ultimately leading to an escalating immunopathology.

immunology↗

bioRxiv2020

The landscape of SARS-CoV-2 RNA modifications

In 2019 the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the first documented cases of severe lung disease COVID-19. Since then, SARS-CoV-2 has been spreading around the globe resulting in a severe pandemic with over 500.000 fatalities and large economical and social disruptions in human societies. Gaining knowledge on how SARS-Cov-2 interacts with its host cells and causes COVID-19 is crucial for the intervention of novel therapeutic strategies. SARS-CoV-2, like other coronaviruses, is a positive-strand RNA virus. The viral RNA is modified by RNA-modifying enzymes provided by the host cell. Direct RNA sequencing (DRS) using nanopores enables unbiased sensing of canonical and modified RNA bases of the viral transcripts. In this work, we used DRS to precisely annotate the open reading frames and the landscape of SARS-CoV-2 RNA modifications. We provide the first DRS data of SARS-CoV-2 in infected human lung epithelial cells. From sequencing three isolates, we derive a robust identification of SARS-CoV-2 modification sites within a physiologically relevant host cell type. A comparison of our data with the DRS data from a previous SARS-CoV-2 isolate, both raised in monkey renal cells, reveals consistent RNA modifications across the viral genome. Conservation of the RNA modification pattern during progression of the current pandemic suggests that this pattern is likely essential for the life cycle of SARS-CoV-2 and represents a possible target for drug interventions.

genetics↗