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Cytotoxic T lymphocytes (CTLs) use immune synapses to destroy infected or transformed target cells. Although the mechanisms governing synapse assembly have been studied extensively, little is known about how this interface dissociates, which is a critical step that both frees the CTL to search for additional prey and enables the phagocytosis of target corpses. Here, we applied time-lapse imaging to explore the basis for synapse dissolution and found that it occurred concomitantly with the cytoskeletal contraction of apoptotic targets. Genetic and pharmacological disruption of apoptotic contraction indicated that it was necessary for CTL dissociation. Furthermore, acute stimulation of contractile forces triggered the release of live targets, demonstrating that contraction is sufficient to drive the response. Finally, mechanically amplifying apoptotic contractility promoted faster CTL detachment and serial killing. Collectively, these results establish a biophysical basis for synapse dissolution and highlight the importance of mechanosensory feedback in the regulation of cell-cell interactions.

The impact of the intratumoral microbiome on immune checkpoint inhibitor (ICI) efficacy in patients (pts) with non-small cell lung cancer (NSCLC) is unknown. In preclinical studies, the presence of lung intratumoral Escherichia was associated with a proinflammatory tumor microenvironment and decreased metastases within lung tissue. We sought to detect intratumoral bacteria in pts with advanced NSCLC using hybrid capture-based, next generation sequencing (NGS). We studied 849 pts treated with ICI-based therapy who underwent NGS at our center. We extracted unmapped reads from BAM files, and these were queried for bacteria (blastn alignment using the NCBI database). Putative environmental contaminants were subtracted from the analysis using “no template” controls (n=2,539) to exclude possible artifactual false positives. A custom E.Coli fluorescence in situ hybridization (FISH) probe was used to visualize Escherichia within the tumors after co-registration with H&E. In 849 pts, a median of 30 bacterial reads was detected per sample (inter-quartile range (18-85)). Among 68 pts with paired primary/metastatic samples, the bacterial spectra were similar in both sites, suggesting that tumor resident bacteria might travel with cancer cells to distant sites. Antibiotic use within 30 days of tumor sampling was associated with decreased intratumoral bacterial diversity (p=0.023 by Inverse Simpson, p=0.038 by Shannon). Intratumoral Escherichia was associated with better PFS (HR 0.78, 95% CI 0.62-0.98, p=0.036), and OS (HR 0.74, 95% CI 0.58-0.95, p=0.017) in pts treated with single-agent ICI, but not combination Chemo/ICI. In a multivariable model adjusting for prognostic features in NSCLC including PD-L1 tumor proportion score, the presence of intratumoral Escherichia was associated with better PFS (p=0.040) and OS (p=0.045) upon single-agent ICI therapy. Escherichia appeared to be intracellular based on co-registration of FISH staining and serial H&E sections. These findings warrant further investigation of the possible inter-relationships between intratumoral Escherichia, tumor immune micro-environment, and ICI therapeutic outcomes. Citation Format: Arielle Elkrief, Anita S. Bowman, Ayyuce Begum Bektas, Wenfei Kang, Katia Manova-Todorova, Jacklynn V. Egger, Hira Rizvi, Daniel Kelly, Eric Chan, Eric Rosiek, Fan Ning, Gregory J. Riely, Álvaro Quintanal Villalonga, Snjezana Dogan, Umesh Bhanot, Mithat Gonen, Matthew D. Hellmann, Adam J. Schoenfeld, Charles M. Rudin, Marc Ladanyi, Chad M. Vanderbilt. Intratumoral Escherichia is associated with response to single-agent immune checkpoint inhibition in patients with advanced non-small cell lung cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5185.

Dry state preservation at ambient temperatures (lyopreservation) is a biomimetic alternative to low temperature stabilization (cryopreservation) of biological materials. Lyopreservation is hypothesized to rely upon the creation of a glassy environment, which is commonly observed in desiccation-tolerant organisms. Non-uniformities in dried samples have been indicated as one of the reasons for instability in storage outcome. The current study presents a simple, fast, and uniform surface tension based technique that can be implemented for lyopreservation of mammalian cells. The technique involves withdrawing cells attached to rigid substrates to be submerged in a solution of lyoprotectant and then withdrawing the samples at a specific rate to an inert environment. This creates a uniform thin film of desiccated lyoprotectant due to sudden change of surface tension. The residual moisture contents at different locations in the desiccated film was quantified using a spatially resolved Raman microspectroscopy technique. Post-desiccation cellular viability and growth are quantified using fluorescent microscopy and dye exclusion assays. Cellular injury following desiccation is evaluated by bioenergetic quantification of metabolic functions using extracellular flux analysis and by a Raman microspectroscopic analysis of change in membrane structure. The technique developed here addresses an important bottleneck of lyoprocessing which requires the fast and uniform desiccation of cellular samples.