Scattering-Based Light-Sheet Microscopy Imaging of Human Papillomavirus-Associated Squamous Lesions of the Anal Canal: A Proof-of-Principle Study.

Demand for anal cancer screening is expected to rise following the recent publication of the Anal Cancer-HSIL Outcomes Research trial, which showed that treatment of high-grade squamous intraepithelial lesions significantly reduces the rate of progression to anal cancer. While screening for human papillomavirus-associated squamous lesions in the cervix is well established and effective, this is less true for other sites in the lower anogenital tract. Current anal cancer screening and prevention rely on high-resolution anoscopy with biopsies. This procedure has a steep learning curve for providers and may cause patient discomfort. Scattering-based light-sheet microscopy (sLSM) is a novel imaging modality with the potential to mitigate these challenges through real-time, microscopic visualization of disease-susceptible tissue. Here, we report a proof-of-principle study that establishes feasibility of dysplasia detection using an sLSM device. We imaged 110 anal biopsy specimens collected prospectively at our institution's dysplasia clinic (including 30 nondysplastic, 40 low-grade squamous intraepithelial lesion, and 40 high-grade squamous intraepithelial lesion specimens) and found that these optical images are highly interpretable and accurately recapitulate histopathologic features traditionally used for the diagnosis of human papillomavirus-associated squamous dysplasia. A reader study to assess diagnostic accuracy suggests that sLSM images are noninferior to hematoxylin and eosin images for the detection of anal dysplasia (sLSM accuracy = 0.87; hematoxylin and eosin accuracy = 0.80; P = .066). Given these results, we believe that sLSM technology holds great potential to enhance the efficacy of anal cancer screening by allowing accurate sampling of diagnostic tissue at the time of anoscopy. While the current imaging study was performed on ex vivo biopsy specimens, we are currently developing a handheld device for in vivo imaging that will provide immediate microscopic guidance to high-resolution anoscopy providers.

Does cholesterol suppress the antimicrobial peptide induced disruption of lipid raft containing membranes?

The activity of antimicrobial peptides has been shown to depend on the composition of the target cell membrane. The bacterial selectivity of most antimicrobial peptides has been attributed to the presence of abundant acidic phospholipids and the absence of cholesterol in bacterial membranes. The high amount of cholesterol present in eukaryotic cell membranes is thought to prevent peptide-induced membrane disruption by increasing the cohesion and stiffness of the lipid bilayer membrane. While the role of cholesterol on an antimicrobial peptide-induced membrane disrupting activity has been reported for simple, homogeneous lipid bilayer systems, it is not well understood for complex, heterogeneous lipid bilayers exhibiting phase separation (or "lipid rafts"). In this study, we show that cholesterol does not inhibit the disruption of raft-containing 1,2-dioleoyl-sn-glycero-3-phosphocholine:1,2-dipalmitoyol-sn-glycero-3-phosphocholine model membranes by four different cationic antimicrobial peptides, MSI-78, MSI-594, MSI-367 and MSI-843 which permeabilize membranes. Conversely, the presence of cholesterol effectively inhibits the disruption of non-raft containing 1,2-dioleoyl-sn-glycero-3-phosphocholine or 1,2-dipalmitoyol-sn-glycero-3-phosphocholine lipid bilayers, even for antimicrobial peptides that do not show a clear preference between the ordered gel and disordered liquid-crystalline phases. Our results show that the peptide selectivity is not only dependent on the lipid phase but also on the presence of phase separation in heterogeneous lipid systems.

HAI-1 is an independent predictor of lung cancer mortality and is required for M1 macrophage polarization.

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death worldwide. Though immune checkpoint inhibitors (ICIs) have revolutionized lung cancer therapy in recent years, there are several factors limiting the therapeutic efficacy of ICI-based immunotherapy in lung cancer. Recent evidence suggests that one such mechanism is the phenotypic shift of tumor-infiltrating macrophages away from an anti-tumor M1 phenotype and towards an anti-inflammatory and tumor-permissive M2 phenotype. Though this phenomenon is well documented, the means through which the lung tumor microenvironment (TME) usurps macrophage function are poorly described. Hepatocyte growth factor (HGF) is a known driver of both lung cancer pathobiology as well as M2 polarization, and its signaling is antagonized by the tumor suppressor gene HAI-1 (SPINT1). Using a combination of genomic databases, primary NSCLC specimens, and in vitro models, we determined that patients with loss of HAI-1 have a particularly poor prognosis, hallmarked by increased HGF expression and an M2-dominant immune infiltrate. Similarly, conditioned media from HAI-1-deficient tumor cells led to a loss of M1 and increased M2 polarization in vitro, and patient NSCLC tissues with loss of HAI-1 showed a similar loss of M1 macrophages. Combined, these results suggest that loss of HAI-1 is a potential means through which tumors acquire an immunosuppressive, M2-dominated TME, potentially through impaired M1 macrophage polarization. Hence, HAI-1 status may be informative when stratifying patients that may benefit from therapies targeting the HGF pathway, particularly as an adjuvant to ICI-based immunotherapy.