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Helmholtz Munich

Staab-Weijnitz Lab

Collagen biosynthesis and maturation in lung fibrosis

Our work aims at unravelling the contributions of the extracellular matrix (ECM) on the regulation of dynamic cell circuits, on environmental barrier immunity and on immunometabolic programming.

Our work aims at unravelling the contributions of the extracellular matrix (ECM) on the regulation of dynamic cell circuits, on environmental barrier immunity and on immunometabolic programming..

ECM - Extracellular Matrix

The extracellular matrix (ECM) is a ubiquitous complex glycoprotein network, which provides a scaffold for cellular support and migration and a mechanical barrier in all tissue types and compartments including the lung. In addition, the ECM governs cell behavior and function by virtue of distinct biomechanical and molecular cues. Its components as well as ECM-modifying factors are secreted by multiple cell types including lung epithelial cells, lung fibroblasts, and immune cells. Hence, the ECM underlies constant remodeling and is drastically changed in chronic lung disease.

Picture: Nuclei (blue) and secreted extracellular matrix deposits (red)

Collagen - the main ECM component

Collagen is the main ECM component in virtually all tissues. There are at least 28 different collagen types, which are sub-classified in seven categories, based on their heterogeneous supramolecular structures. In addition, collagen chains are heavily modified by an intracellular protein machinery prior to secretion, as well as further processed, modified, and cross-linked by enzymatic and non-enzymatic events in the extracellular space. Given the high abundance of collagen and the drastic changes in disease, it is of critical importance to decipher how changes in collagen composition and post-translational modification (PTM) patterns affect adhesion, migration and function of cells in normal physiology, in the context of environmental injury, and in lung disease.

Picture: Immunofluorescent staining of a normal human lung section for type IV collagen (green)

Scientists at Staab-Weijnitz Lab

Natalia Cabeza Boeddinghaus

Technical Assistant (TA)

Ashesh Chakraborty

Doctoral Student (PhD)

Elisabeth Hennen

Senior Technical Assistant

Marie Zöller

PhD Student

Publications

2022, Scientific Article in American Journal of Respiratory Cell and Molecular Biology

An inhibitory function of TRPA1 channels in TGF-β1-driven fibroblast to myofibroblast differentiation.

Transient receptor potential ankyrin 1 (TRPA1) is a non-selective Ca2+ permeable cation channel, which was originally cloned from human lung fibroblasts (HLFs). TRPA1-mediated Ca2+ entry is evoked by exposure to several chemicals, including allyl isothiocyanate (AITC), and a protective effect of TRPA1 activation in the development of cardiac fibrosis has been proposed. Yet, the function of TRPA1 in transforming growth factor β1 (TGF-β1)-driven fibroblast to myofibroblast differentiation and the development of pulmonary fibrosis remains elusive. TRPA1 expression and function was analyzed in cultured primary HLFs, and mRNA levels were significantly reduced after adding TGF-β1. Expression of genes encoding fibrosis markers, e.g. alpha smooth muscle actin (ACTA2), plasminogen activator inhibitor 1 (SERPINE1), fibronectin (FN1) and type I collagen (COL1A1) was increased after siRNA-mediated down-regulation of TRPA1-mRNA in HLFs. Moreover, AITC-induced Ca2+ entry in HLFs was decreased after TGF-β1 treatment and by application of TRPA1 siRNAs, while AITC treatment alone did not reduce cell viability or enhanced apoptosis. Most interestingly, AITC-induced TRPA1 activation augmented ERK1/2 phosphorylation, which might inhibit TGF-β-receptor signaling. Our results suggest an inhibitory function of TRPA1 channels in TGF-β1-driven fibroblast to myofibroblast differentiation. Therefore, activation of TRPA1 channels might be protective during the development of pulmonary fibrosis in patients.

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2022, Scientific Article in Frontiers in Cellular and Infection Microbiology

Effects of immunophilin inhibitors and non-immunosuppressive analogs on coronavirus replication in human infection models.

Rationale: Human coronaviruses (HCoVs) seriously affect human health by causing respiratory diseases ranging from common colds to severe acute respiratory diseases. Immunophilins, including peptidyl-prolyl isomerases of the FK506-binding protein (FKBP) and the cyclophilin family, are promising targets for pharmaceutical inhibition of coronavirus replication, but cell-type specific effects have not been elucidated. FKBPs and cyclophilins bind the immunosuppressive drugs FK506 and cyclosporine A (CsA), respectively. Methods: Primary human bronchial epithelial cells (phBECs) were treated with CsA, Alisporivir (ALV), FK506, and FK506-derived non-immunosuppressive analogs and infected with HCoV-229E. RNA and protein were assessed by RT-qPCR and immunoblot analysis. Treatment with the same compounds was performed in hepatoma cells (Huh-7.5) infected with HCoV-229E expressing Renilla luciferase (HCoV-229E-RLuc) and the kidney cell line HEK293 transfected with a SARS-CoV-1 replicon expressing Renilla luciferase (SARS-CoV-1-RLuc), followed by quantification of luminescence as a measure of viral replication. Results: Both CsA and ALV robustly inhibited viral replication in all models; both compounds decreased HCoV-229E RNA in phBECs and reduced luminescence in HCoV-229E-RLuc-infected Huh7.5 and SARS-CoV-1-RLuc replicon-transfected HEK293. In contrast, FK506 showed inconsistent and less pronounced effects in phBECs while strongly affecting coronavirus replication in Huh-7.5 and HEK293. Two non-immunosuppressive FK506 analogs had no antiviral effect in any infection model. Conclusion: The immunophilin inhibitors CsA and ALV display robust anti-coronaviral properties in multiple infection models, including phBECs, reflecting a primary site of HCoV infection. In contrast, FK506 displayed cell-type specific effects, strongly affecting CoV replication in Huh7.5 and HEK293, but inconsistently and less pronounced in phBECs.

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2022, Scientific Article in Archives of Toxicology

TRPM7 restrains plasmin activity and promotes transforming growth factor-β1 signaling in primary human lung fibroblasts.

Sustained exposure of the lung to various environmental or occupational toxins may eventually lead to pulmonary fibrosis, a devastating disease with no cure. Pulmonary fibrosis is characterized by excessive deposition of extracellular matrix (ECM) proteins such as fibronectin and collagens. The peptidase plasmin degrades the ECM, but protein levels of the plasmin activator inhibitor-1 (PAI-1) are increased in fibrotic lung tissue, thereby dampening plasmin activity. Transforming growth factor-β1 (TGF-β1)-induced activation of SMAD transcription factors promotes ECM deposition by enhancing collagen, fibronectin and PAI-1 levels in pulmonary fibroblasts. Hence, counteracting TGF-β1-induced signaling is a promising approach for the therapy of pulmonary fibrosis. Transient receptor potential cation channel subfamily M Member 7 (TRPM7) supports TGF-β1-promoted SMAD signaling in T-lymphocytes and the progression of fibrosis in kidney and heart. Thus, we investigated possible effects of TRPM7 on plasmin activity, ECM levels and TGF-β1 signaling in primary human pulmonary fibroblasts (pHPF). We found that two structurally unrelated TRPM7 blockers enhanced plasmin activity and reduced fibronectin or PAI-1 protein levels in pHPF under basal conditions. Further, TRPM7 blockade strongly inhibited fibronectin and collagen deposition induced by sustained TGF-β1 stimulation. In line with these data, inhibition of TRPM7 activity diminished TGF-β1-triggered phosphorylation of SMAD-2, SMAD-3/4-dependent reporter activation and PAI-1 mRNA levels. Overall, we uncover TRPM7 as a novel supporter of TGF-β1 signaling in pHPF and propose TRPM7 blockers as new candidates to control excessive ECM levels under pathophysiological conditions conducive to pulmonary fibrosis.

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2022, Scientific Article in Cells

FK506-binding protein 11 is a novel plasma cell-specific antibody folding catalyst with increased expression in idiopathic pulmonary fibrosis.

Antibodies are central effectors of the adaptive immune response, widespread used therapeutics, but also potentially disease-causing biomolecules. Antibody folding catalysts in the plasma cell are incompletely defined. Idiopathic pulmonary fibrosis (IPF) is a fatal chronic lung disease with increasingly recognized autoimmune features. We found elevated expression of FK506-binding protein 11 (FKBP11) in IPF lungs where FKBP11 specifically localized to antibodyproducing plasma cells. Suggesting a general role in plasma cells, plasma cell-specific FKBP11 expression was equally observed in lymphatic tissues, and in vitro B cell to plasma cell differentiation was accompanied by induction of FKBP11 expression. Recombinant human FKBP11 was able to refold IgG antibody in vitro and inhibited by FK506, strongly supporting a function as antibody peptidyl-prolyl cis-trans isomerase. Induction of ER stress in cell lines demonstrated induction of FKBP11 in the context of the unfolded protein response in an X-box-binding protein 1 (XBP1)-dependent manner. While deficiency of FKBP11 increased susceptibility to ER stressmediated cell death in an alveolar epithelial cell line, FKBP11 knockdown in an antibody-producing hybridoma cell line neither induced cell death nor decreased expression or secretion of IgG antibody. Similarly, antibody secretion by the same hybridoma cell line was not affected by knockdown of the established antibody peptidyl-prolyl isomerase cyclophilin B. The results are consistent with FKBP11 as a novel XBP1-regulated antibody peptidyl-prolyl cis-trans isomerase and indicate significant redundancy in the ER-resident folding machinery of antibody-producing hybridoma cells.

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2022, Review in Cells

Emerging roles of airway epithelial cells in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease with incompletely understood aetiol-ogy and limited treatment options. Traditionally, IPF was believed to be mainly caused by repetitive injuries to the alveolar epithelium. Several recent lines of evidence, however, suggest that IPF equally involves an aberrant airway epithelial response, which contributes significantly to disease development and progression. In this review, based on recent clinical, high-resolution imaging, genetic, and single-cell RNA sequencing data, we summarize alterations in airway structure, function, and cell type composition in IPF. We furthermore give a comprehensive overview on the genetic and mecha-nistic evidence pointing towards an essential role of airway epithelial cells in IPF pathogenesis and describe potentially implicated aberrant epithelial signalling pathways and regulation mechanisms in this context. The collected evidence argues for the investigation of possible therapeutic avenues targeting these processes, which thus represent important future directions of research.

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Contact

PD Dr. Claudia Staab-Weijnitz

Team Leader