Murine Pro-Inflammatory Responses to Acute and Sustained Intermittent Hypoxia: Implications for Obstructive Sleep Apnea Research.

OBJECTIVES: Obstructive sleep apnea (OSA) is characterized by chronic systemic inflammation; however, the mechanisms underlying these pathologic consequences are incompletely understood. Our objective was to determine the effects of short- versus long-term exposure to intermittent hypoxia (IH) on pro-inflammatory mediators within vulnerable organs impacted by OSA. STUDY DESIGN: Experimental animal study. METHODS: A total of 8-10 week old C57BL/6J mice were exposed to normoxic or IH conditions for 7 days (short-term) or 6 weeks (long-term) under 12 h light, 12 h dark cycles. After exposure, multiple tissues were collected over a 24 h period. These tissues were processed and evaluated for gene expression and protein levels of pro-inflammatory mediators from peripheral tissues. RESULTS: We observed a global decrease in immune response pathways in the heart, lung, and liver compared with other peripheral organs after short-term exposure to IH. Although there were tissue-specific alterations in the gene expression of pro-inflammatory mediators, with down-regulation in the lung and up-regulation in the heart, we also observed reduced protein levels of pro-inflammatory mediators in the serum, lung, and heart following short-term exposure to IH. Long-term exposure to IH resulted in an overall increase in the levels of inflammatory mediators in the serum, lung, and heart. CONCLUSIONS: We demonstrated novel, longitudinal changes in the inflammatory cascade in a mouse model of OSA. The duration of exposure to IH led to significant variability of inflammatory responses within blood and cardiopulmonary tissues. Our findings further elucidate how inflammatory responses change over the course of the disease in vulnerable organs. LEVEL OF EVIDENCE: NA Laryngoscope, 134:S1-S11, 2024.

Obstructive sleep apnea in a mouse model is associated with tissue-specific transcriptomic changes in circadian rhythmicity and mean 24-hour gene expression.

Intermittent hypoxia (IH) is a major clinical feature of obstructive sleep apnea (OSA). The mechanisms that become dysregulated after periods of exposure to IH are unclear, particularly in the early stages of disease. The circadian clock governs a wide array of biological functions and is intimately associated with stabilization of hypoxia-inducible factors (HIFs) under hypoxic conditions. In patients, IH occurs during the sleep phase of the 24-hour sleep-wake cycle, potentially affecting their circadian rhythms. Alterations in the circadian clock have the potential to accelerate pathological processes, including other comorbid conditions that can be associated with chronic, untreated OSA. We hypothesized that changes in the circadian clock would manifest differently in those organs and systems known to be impacted by OSA. Using an IH model to represent OSA, we evaluated circadian rhythmicity and mean 24-hour expression of the transcriptome in 6 different mouse tissues, including the liver, lung, kidney, muscle, heart, and cerebellum, after a 7-day exposure to IH. We found that transcriptomic changes within cardiopulmonary tissues were more affected by IH than other tissues. Also, IH exposure resulted in an overall increase in core body temperature. Our findings demonstrate a relationship between early exposure to IH and changes in specific physiological outcomes. This study provides insight into the early pathophysiological mechanisms associated with IH.

Integration of genome-scale data identifies candidate sleep regulators.

STUDY OBJECTIVES: Genetics impacts sleep, yet, the molecular mechanisms underlying sleep regulation remain elusive. In this study, we built machine learning models to predict sleep genes based on their similarity to genes that are known to regulate sleep. METHODS: We trained a prediction model on thousands of published datasets, representing circadian, immune, sleep deprivation, and many other processes, using a manually curated list of 109 sleep genes. RESULTS: Our predictions fit with prior knowledge of sleep regulation and identified key genes and pathways to pursue in follow-up studies. As an example, we focused on the NF-κB pathway and showed that chronic activation of NF-κB in a genetic mouse model impacted the sleep-wake patterns. CONCLUSION: Our study highlights the power of machine learning in integrating prior knowledge and genome-wide data to study genetic regulation of complex behaviors such as sleep.

An in silico genome-wide screen for circadian clock strength in human samples.

MOTIVATION: Years of time-series gene expression studies have built a strong understanding of clock-controlled pathways across species. However, comparatively little is known about how 'non-clock' pathways influence clock function. We need a strong understanding of clock-coupled pathways in human tissues to better appreciate the links between disease and clock function. RESULTS: We developed a new computational approach to explore candidate pathways coupled to the clock in human tissues. This method, termed LTM, is an in silico screen to infer genetic influences on circadian clock function. LTM uses natural variation in gene expression in human data and directly links gene expression variation to clock strength independent of longitudinal data. We applied LTM to three human skin and one melanoma datasets and found that the cell cycle is the top candidate clock-coupled pathway in healthy skin. In addition, we applied LTM to thousands of tumor samples from 11 cancer types in the TCGA database and found that extracellular matrix organization-related pathways are tightly associated with the clock strength in humans. Further analysis shows that clock strength in tumor samples is correlated with the proportion of cancer-associated fibroblasts and endothelial cells. Therefore, we show both the power of LTM in predicting clock-coupled pathways and classify factors associated with clock strength in human tissues. AVAILABILITY AND IMPLEMENTATION: LTM is available on GitHub (https://github.com/gangwug/LTMR) and figshare (https://figshare.com/articles/software/LTMR/21217604) to facilitate its use. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

duper is a null mutation of Cryptochrome 1 in Syrian hamsters.

The duper mutation is a recessive mutation that shortens the period length of the circadian rhythm in Syrian hamsters. These animals show a large phase shift when responding to light pulses. Limited genetic resources for the Syrian hamster (Mesocricetus auratus) presented a major obstacle to cloning duper. This caused the duper mutation to remain unknown for over a decade. In this study, we did a de novo genome assembly of Syrian hamsters with long-read sequencing data from two different platforms, Pacific Biosciences and Oxford Nanopore Technologies. Using two distinct ecotypes and a fast homozygosity mapping strategy, we identified duper as an early nonsense allele of Cryptochrome 1 (Cry1) leading to a short, unstable protein. CRY1 is known as a highly conserved component of the repressive limb of the core circadian clock. The genome assembly and other genomic datasets generated in this study will facilitate the use of the Syrian hamster in biomedical research.

Intermittent Hypoxia Alters the Circadian Expression of Clock Genes in Mouse Brain and Liver.

At least one-third of adults in the United States experience intermittent hypoxia (IH) due to health or living conditions. The majority of these adults suffer with sleep breathing conditions and associated circadian rhythm disorders. The impact of IH on the circadian clock is not well characterized. In the current study, we used an IH mouse model to understand the impact of IH on the circadian gene expression of the canonical clock genes in the central (the brain) and peripheral (the liver) tissues. Gene expression was measured using a Quantitative Reverse Transcription Polymerase Chain Reaction (qRT-PCR). CircaCompare was used to evaluate the differential rhythmicity between normoxia and IH. Our observations suggested that the circadian clock in the liver was less sensitive to IH compared to the circadian clock in the brain.

Integrative Profiling of T790M-Negative EGFR-Mutated NSCLC Reveals Pervasive Lineage Transition and Therapeutic Opportunities.

PURPOSE: Despite the established role of EGFR tyrosine kinase inhibitors (TKIs) in EGFR-mutated NSCLC, drug resistance inevitably ensues, with a paucity of treatment options especially in EGFR T790M-negative resistance. EXPERIMENTAL DESIGN: We performed whole-exome and transcriptome analysis of 59 patients with first- and second-generation EGFR TKI-resistant metastatic EGFR-mutated NSCLC to characterize and compare molecular alterations mediating resistance in T790M-positive (T790M+) and -negative (T790M-) disease. RESULTS: Transcriptomic analysis revealed ubiquitous loss of adenocarcinoma lineage gene expression in T790M- tumors, orthogonally validated using multiplex IHC. There was enrichment of genomic features such as TP53 alterations, 3q chromosomal amplifications, whole-genome doubling and nonaging mutational signatures in T790M- tumors. Almost half of resistant tumors were further classified as immunehot, with clinical outcomes conditional on immune cell-infiltration state and T790M status. Finally, using a Bayesian statistical approach, we explored how T790M- and T790M+ disease might be predicted using comprehensive genomic and transcriptomic profiles of treatment-naïve patients. CONCLUSIONS: Our results illustrate the interplay between genetic alterations, cell lineage plasticity, and immune microenvironment in shaping divergent TKI resistance and outcome trajectories in EGFR-mutated NSCLC. Genomic and transcriptomic profiling may facilitate the design of bespoke therapeutic approaches tailored to a tumor's adaptive potential.

Short-term exposure to intermittent hypoxia leads to changes in gene expression seen in chronic pulmonary disease.

Obstructive sleep apnea (OSA) results from episodes of airway collapse and intermittent hypoxia (IH) and is associated with a host of health complications. Although the lung is the first organ to sense changes in oxygen levels, little is known about the consequences of IH to the lung hypoxia-inducible factor-responsive pathways. We hypothesized that exposure to IH would lead to cell-specific up- and downregulation of diverse expression pathways. We identified changes in circadian and immune pathways in lungs from mice exposed to IH. Among all cell types, endothelial cells showed the most prominent transcriptional changes. Upregulated genes in myofibroblast cells were enriched for genes associated with pulmonary hypertension and included targets of several drugs currently used to treat chronic pulmonary diseases. A better understanding of the pathophysiologic mechanisms underlying diseases associated with OSA could improve our therapeutic approaches, directing therapies to the most relevant cells and molecular pathways.

Genomic landscape of lung adenocarcinoma in East Asians.

Lung cancer is the world's leading cause of cancer death and shows strong ancestry disparities. By sequencing and assembling a large genomic and transcriptomic dataset of lung adenocarcinoma (LUAD) in individuals of East Asian ancestry (EAS; n = 305), we found that East Asian LUADs had more stable genomes characterized by fewer mutations and fewer copy number alterations than LUADs from individuals of European ancestry. This difference is much stronger in smokers as compared to nonsmokers. Transcriptomic clustering identified a new EAS-specific LUAD subgroup with a less complex genomic profile and upregulated immune-related genes, allowing the possibility of immunotherapy-based approaches. Integrative analysis across clinical and molecular features showed the importance of molecular phenotypes in patient prognostic stratification. EAS LUADs had better prediction accuracy than those of European ancestry, potentially due to their less complex genomic architecture. This study elucidated a comprehensive genomic landscape of EAS LUADs and highlighted important ancestry differences between the two cohorts.

PI3K Catalytic Subunits α and ß Modulate Cell Death and IL-6 Secretion Induced by Talc Particles in Human Lung Carcinoma Cells.

Hydrated magnesium silicate (or "talc" particles) is a sclerosis agent commonly used in the management of malignant pleural effusions, a common symptom of metastatic diseases, including lung cancers. However, the direct effects of talc particles to lung carcinoma cells, which can be found in the malignant pleural effusion fluids from patients with lung cancer, are not fully understood. Here, we report a study of the signaling pathways that can modulate the cell death and IL-6 secretion induced by talc particles in human lung carcinoma cells. We found that talc-sensitive cells have higher mRNA and protein expression of PI3K catalytic subunits α and ß. Further experiments confirmed that modulation (inhibition or activation) of the PI3K pathway reduces or enhances cellular sensitivity to talc particles, respectively, independent of the inflammasome. By knocking down specific PI3K isoforms, we also confirmed that both PI3Kα and -ß mediate the observed talc effects. Our results suggest a novel role of the PI3K pathway in talc-induced cell death and IL-6 secretion in lung carcinoma cells. These cellular events are known to drive fibrosis, and thus further studies of the PI3K pathway may provide a better understanding of the mechanisms of talc sclerosis in the malignant pleural space.

Clonal MET Amplification as a Determinant of Tyrosine Kinase Inhibitor Resistance in Epidermal Growth Factor Receptor-Mutant Non-Small-Cell Lung Cancer.

PURPOSE: Mesenchymal epithelial transition factor ( MET) activation has been implicated as an oncogenic driver in epidermal growth factor receptor ( EGFR)-mutant non-small-cell lung cancer (NSCLC) and can mediate primary and secondary resistance to EGFR tyrosine kinase inhibitors (TKI). High copy number thresholds have been suggested to enrich for response to MET inhibitors. We examined the clinical relevance of MET copy number gain (CNG) in the setting of treatment-naive metastatic EGFR-mutant-positive NSCLC. PATIENTS AND METHODS: MET fluorescence in situ hybridization was performed in 200 consecutive patients identified as metastatic treatment-naïve EGFR-mutant-positive. We defined MET-high as CNG greater than or equal to 5, with an additional criterion of MET/centromeric portion of chromosome 7 ratiο greater than or equal to 2 for amplification. Time-to-treatment failure (TTF) to EGFR TKI in patients identified as MET-high and -low was estimated by Kaplan-Meier method and compared using log-rank test. Multiregion single-nucleotide polymorphism array analysis was performed on 13 early-stage resected EGFR-mutant-positive NSCLC across 59 sectors to investigate intratumoral heterogeneity of MET CNG. RESULTS: Fifty-two (26%) of 200 patients in the metastatic cohort were MET-high at diagnosis; 46 (23%) had polysomy and six (3%) had amplification. Median TTF was 12.2 months (95% CI, 5.7 to 22.6 months) versus 13.1 months (95% CI, 10.6 to 15.0 months) for MET-high and -low, respectively ( P = .566), with no significant difference in response rate regardless of copy number thresholds. Loss of MET was observed in three of six patients identified as MET-high who underwent postprogression biopsies, which is consistent with marked intratumoral heterogeneity in MET CNG observed in early-stage tumors. Suboptimal response (TTF, 1.0 to 6.4 months) to EGFR TKI was observed in patients with coexisting MET amplification (five [3.2%] of 154). CONCLUSION: Although up to 26% of TKI-naïve EGFR-mutant-positive NSCLC harbor high MET CNG by fluorescence in situ hybridization, this did not significantly affect response to TKI, except in patients identified as MET-amplified. Our data underscore the limitations of adopting arbitrary copy number thresholds and the need for cross-assay validation to define therapeutically tractable MET pathway dysregulation in EGFR-mutant-positive NSCLC.

A database of tissue-specific rhythmically expressed human genes has potential applications in circadian medicine.

The discovery that half of the mammalian protein-coding genome is regulated by the circadian clock has clear implications for medicine. Recent studies demonstrated that the circadian clock influences therapeutic outcomes in human heart disease and cancer. However, biological time is rarely given clinical consideration. A key barrier is the absence of information on tissue-specific molecular rhythms in the human body. We have applied the cyclic ordering by periodic structure (CYCLOPS) algorithm, designed to reconstruct sample temporal order in the absence of time-of-day information, to the gene expression collection of 13 tissues from 632 human donors. We identified rhythms in gene expression across the body; nearly half of protein-coding genes were shown to be cycling in at least 1 of the 13 tissues analyzed. One thousand of these cycling genes encode proteins that either transport or metabolize drugs or are themselves drug targets. These results provide a useful resource for studying the role of circadian rhythms in medicine and support the idea that biological time might play a role in determining drug response.

Bystander CD8+ T cells are abundant and phenotypically distinct in human tumour infiltrates.

Various forms of immunotherapy, such as checkpoint blockade immunotherapy, are proving to be effective at restoring T cell-mediated immune responses that can lead to marked and sustained clinical responses, but only in some patients and cancer types1-4. Patients and tumours may respond unpredictably to immunotherapy partly owing to heterogeneity of the immune composition and phenotypic profiles of tumour-infiltrating lymphocytes (TILs) within individual tumours and between patients5,6. Although there is evidence that tumour-mutation-derived neoantigen-specific T cells play a role in tumour control2,4,7-10, in most cases the antigen specificities of phenotypically diverse tumour-infiltrating T cells are largely unknown. Here we show that human lung and colorectal cancer CD8+ TILs can not only be specific for tumour antigens (for example, neoantigens), but also recognize a wide range of epitopes unrelated to cancer (such as those from Epstein-Barr virus, human cytomegalovirus or influenza virus). We found that these bystander CD8+ TILs have diverse phenotypes that overlap with tumour-specific cells, but lack CD39 expression. In colorectal and lung tumours, the absence of CD39 in CD8+ TILs defines populations that lack hallmarks of chronic antigen stimulation at the tumour site, supporting their classification as bystanders. Expression of CD39 varied markedly between patients, with some patients having predominantly CD39- CD8+ TILs. Furthermore, frequencies of CD39 expression among CD8+ TILs correlated with several important clinical parameters, such as the mutation status of lung tumour epidermal growth factor receptors. Our results demonstrate that not all tumour-infiltrating T cells are specific for tumour antigens, and suggest that measuring CD39 expression could be a straightforward way to quantify or isolate bystander T cells.

Noise in the Vertebrate Segmentation Clock Is Boosted by Time Delays but Tamed by Notch Signaling.

Taming cell-to-cell variability in gene expression is critical for precise pattern formation during embryonic development. To investigate the source and buffering mechanism of expression variability, we studied a biological clock, the vertebrate segmentation clock, controlling the precise spatiotemporal patterning of the vertebral column. By counting single transcripts of segmentation clock genes in zebrafish, we show that clock genes have low RNA amplitudes and expression variability is primarily driven by gene extrinsic sources, which is suppressed by Notch signaling. We further show that expression noise surprisingly increases from the posterior progenitor zone to the anterior segmentation and differentiation zone. Our computational model reproduces the spatial noise profile by incorporating spatially increasing time delays in gene expression. Our results, suggesting that expression variability is controlled by the balance of time delays and cell signaling in a vertebrate tissue, will shed light on the accuracy of natural clocks in multi-cellular systems and inspire engineering of robust synthetic oscillators.

Elucidating the genomic architecture of Asian EGFR-mutant lung adenocarcinoma through multi-region exome sequencing.

EGFR-mutant lung adenocarcinomas (LUAD) display diverse clinical trajectories and are characterized by rapid but short-lived responses to EGFR tyrosine kinase inhibitors (TKIs). Through sequencing of 79 spatially distinct regions from 16 early stage tumors, we show that despite low mutation burdens, EGFR-mutant Asian LUADs unexpectedly exhibit a complex genomic landscape with frequent and early whole-genome doubling, aneuploidy, and high clonal diversity. Multiple truncal alterations, including TP53 mutations and loss of CDKN2A and RB1, converge on cell cycle dysregulation, with late sector-specific high-amplitude amplifications and deletions that potentially beget drug resistant clones. We highlight the association between genomic architecture and clinical phenotypes, such as co-occurring truncal drivers and primary TKI resistance. Through comparative analysis with published smoking-related LUAD, we postulate that the high intra-tumor heterogeneity observed in Asian EGFR-mutant LUAD may be contributed by an early dominant driver, genomic instability, and low background mutation rates.

Gastrodia elata modulates amyloid precursor protein cleavage and cognitive functions in mice.

Gastrodia elata (Tianma) is a traditional Chinese medicine often used for the treatment of headache, convulsions, hypertension, and cardiovascular diseases. The vasodilatory actions of Tianma led us to investigate its specific effects on memory and learning as well as on Alzheimer's disease (AD)-related signaling. We conducted a radial arm water maze analysis and the novel object recognition test to assess the cognitive functions of Tianma-treated mice. Our data show that Tianma enhances cognitive functions in mice. Further investigations revealed that Tianma enhances the α-secretase-mediated proteolytic processing of the amyloid precursor protein (App) that precludes the amyloid-ß peptide production and supports the non-amyloidogenic processing of App which is favorable in AD treatment. We hypothesize that Tianma promotes cognitive functions and neuronal survival by inhibiting ß-site App-cleaving enzyme 1 activity and promoting the neuroprotective α-secretase activity.