Biology subjects

Lotz, M. K.

Publications and source records attributed to Lotz, M. K..

4 recordsLinked to original sources

bioRxiv2026

DRG meningeal tertiary lymphoid structures are regulated by B cells as a pronociceptive locus after peripheral nerve injury

B cell-derived IgG in the dorsal root ganglia (DRG) drives neuropathic pain after peripheral nerve injury (PNI), but the site of B cell organization is unclear. Here, PNI induced leukocyte clusters in the DRG meninges, enveloped by lymphatic endothelium and apposed to high endothelial venules. These clusters resemble tertiary lymphoid structures (TLSs) with germinal center-like features, including germinal center B cells and plasma cells, and follicular dendritic and follicular helper T cells. Single-cell RNA sequencing revealed enrichment of germinal center B cells in the DRG meninges after PNI. Germinal center B cells regulate TLS organization: TLSs were absent after deletion of Ezh2 from germinal center-experienced B cells. Intrathecal CD20 monoclonal antibody to locally deplete B cells also disrupted TLS organization. Conversely, intrathecal B cell transfer to B cell-deficient (muMT) mice was sufficient for TLS organization after PNI. Allodynia did not develop when TLS organization was disordered. Similar TLSs formed in pig DRG after tail docking and in human donors with chronic pain, where B cell receptor clonotype analysis confirmed functional maturity. Together, these data establish that germinal center B cells are required for TLS organization, and that disrupting this process abolishes the development of neuropathic pain after PNI.

neuroscience↗

bioRxiv2026

Extracellular Sulfatase Regulation of BMP-7 and FGF-2 Signaling in Human Articular Chondrocytes

We performed a new set of experiments to confirm findings reported in our previous publication regarding the role of Sulf-1 and Sulf-2 in regulating BMP-7 and FGF-2 signaling in human articular chondrocytes. Using primary chondrocytes from five independent human donors, we examined the effects of Sulf knockdown on Smad1/5 and Erk1/2 phosphorylation. Sulf-1 and Sulf-2 knockdown consistently reduced BMP-7-induced Smad1/5 phosphorylation and enhanced FGF-2-induced Erk1/2 phosphorylation. Although the magnitude of Erk1/2 activation was somewhat lower than originally reported, the direction and statistical significance of the effects were preserved. These results confirm the original conclusions and support the role of Sulfs as dual regulators of BMP-7 and FGF-2 signaling pathways in human chondrocytes.

cell biology↗

bioRxiv2026

3'tRNAAsp(GTC)-derived fragment links inflammation to post-transcriptional reprogramming in chondrocytes during osteoarthritis.

ObjectiveTransfer RNA-derived fragments (tRFs) belong to an emerging class of small non-coding RNAs that dynamically respond to metabolic stressors and drive different pathological processes, yet their role in osteoarthritis (OA) remains poorly explored. We aimed to define the tRF landscape in OA and investigate the function of 3tRFAsp(GTC) in chondrocyte stress adaptation and translational control. MethodsEx vivo, cartilage specimens from OA patients (n=6) and healthy donors (n=7) were analyzed by small RNA sequencing to define disease-associated tRF signatures. In vitro, primary chondrocytes derived from OA patients were treated with lipopolysaccharide (LPS) to mimic inflammatory environment of OA, used for small RNA sequencing (n=3) and validation analysis (n=6). Functional studies in C28/I2 chondrocytes included antisense oligonucleotide-mediated 3tRFAsp(GTC) inhibition, AGO2-RNA immunoprecipitation (RIP), polysome profiling, stress granule (SG) immunofluorescence, and differential protein analysis. Computational target prediction and pathway enrichment were used to explore tRF-mediated regulatory networks. ResultsBoth OA cartilage and LPS-treated chondrocytes displayed upregulation of 3tRFAsp(GTC) and 5tRFGlu(CTC), indicating a shared inflammatory tRF signature. Predicted targets of upregulated tRFs were enriched in stress-adaptive, proteostasis, and translational control pathways, whereas downregulated tRFs modulated mitochondrial processes. Silencing 3tRFAsp(GTC) inhibited LPS-induced COX2 and MMP13 expression, prevented ER stress, and blocked SG assembly. RIP confirmed selective recruitment of 3tRFAsp(GTC) into AGO2 complexes. Polysome profiling revealed association with 40S ribosomal subunit, mediating translational arrest and influencing selective mRNA expression. Conclusion3tRFAsp(GTC) emerges as a regulator linking inflammation to translational control and SG dynamics in OA. tRFs thus could represent novel therapeutic targets in OA disease.

biochemistry↗

bioRxiv2020

The TAT Protein Transduction Domain as an Intra-articular Drug-Delivery Technology

ObjectiveIntra-articular drug delivery holds great promise for the treatment of joint diseases such as osteoarthritis. The objective of this study was to evaluate the TAT peptide transduction domain (TAT-PTD) as a potential intra-articular drug delivery technology for synovial joints. DesignExperiments examined the ability of TAT conjugates to associate with primary chondrocytes and alter cellular function both in vitro and in vivo. Further experiments examined the ability of the TAT-PTD to bind to human osteoarthritic cartilage. ResultsThe results show that the TAT-PTD associates with chondrocytes, is capable of delivering siRNA for chondrocyte gene knockdown, and that the recombinant enzyme TAT-Cre is capable of inducing in vivo genetic recombination within the knee joint in a reporter mouse model. Lastly, binding studies show that osteoarthritic cartilage preferentially uptakes the TAT-PTD from solution. ConclusionsThe results suggest that the TAT-PTD is a promising delivery strategy for intra-articular therapeutics.

bioengineering↗