Mitochondrial ncRNA LDL-805 declines in alveolar epithelial type 2 cells of chronic obstructive pulmonary disease patients

Rationale

We showed that levels of a murine mitochondrial noncoding RNA, mito-ncR-LDL805 , increase in alveolar epithelial type 2 cells exposed to extracts from cigarette smoke. The transcripts translocate to the nucleus, upregulating nucleus-encoded mitochondrial genes and mitochondrial bioenergetics. This response is lost after chronic exposure to smoke in a mouse model of chronic obstructive pulmonary disease.

Objectives

To determine if mito-ncR-LDL805 plays a role in human disease, this study aimed to (i) identify the human homologue, (ii) test if the smoke-induced response occurs in human cells, (ii) determine causality between the subcellular localization of the transcript and increased mitochondrial bioenergetics, and (iii) analyze mito-ncR-LDL805 transcript levels in samples from patients with chronic obstructive pulmonary disease.

Methods

Levels and subcellular localization of the human homologue identified from an RNA transcript library were assessed in human alveolar epithelial type 2 cells exposed to smoke extract. Lipid nanoparticles were used for nucleus-targeted delivery of mito-ncR-LDL805 transcripts. Analyses included in situ hybridization, quantitative PCR, cell growth, and Seahorse mitochondrial bioenergetics assays.

Measurements and Main Results

The levels of human homologue transiently increased and the transcripts translocated to the nuclei in human cells exposed to smoke extract. Targeted nuclear delivery of transcripts increased mitochondrial bioenergetics. Alveolar cells from humans with chronic obstructive pulmonary disease had reduced levels of the mito-ncR-LDL805 .

Conclusions

mito-ncR-LDL805 mediates mitochondrial bioenergetics in murine and human alveolar epithelial type 2 cells in response to cigarette smoke exposure, but this response is likely lost in diseases associated with chronic smoking, such as chronic obstructive pulmonary disease, due to its diminished levels.

Impact

This study describes a novel mechanism by which epithelial cells in the lungs adapt to the mitochondrial stress triggered by exposure to cigarette smoke. We show that a noncoding RNA in mitochondria is upregulated and translocated to the nuclei of alveolar epithelial type 2 cells to trigger expression of genes that restore mitochondrial bioenergetics. Mitochondria function and levels of the noncoding RNA decrease under conditions that lead to chronic obstructive pulmonary disease, suggesting that the mitochondrial noncoding RNA can serve as potential therapeutic target to restore function to halt disease progression.

Surgical Repair Versus Stent for Esophageal Perforation: A Multi-institutional Database Analysis

BACKGROUND

Endoscopic esophageal stenting is used as an alternative to surgical repair for esophageal perforation. Multi-institutional studies supporting stenting are lacking. The purpose of this study was to compare the outcomes of surgical repair and esophageal stenting in patients with esophageal perforation using a nationally representative database. We hypothesized that mortality between these approaches would not be different.

METHODS

The Premier Healthcare Database was used to compare adult inpatients with esophageal perforation receiving either surgical repair or esophageal stenting from 2009 to 2019. Patients receiving intervention ≤7 days of admission were included in the analysis. Patients receiving both stent and repair on the same day were excluded. The composite outcome of interest was death or discharge to hospice. Logistic regression was used to evaluate independent predictors of death or hospice, adjusting for comorbidities.

RESULTS

There were 2543 patients with esophageal perforation identified who received repair (1314 [51.7%]) or stenting (1229 [48.3%]). Stenting increased from 7.0% in 2009 to 78.1% in 2019. Patients receiving repair were more likely to be female and White and had fewer Elixhauser comorbidities. Death or discharge to hospice was more common after stent (134/1314 [10.2%] repair vs 199/1229 [16.2%] stent; P < .001); however, after adjustment for comorbidities, logistic regression suggested that death or hospice discharge was similar between approaches (stent vs repair: odds ratio, 1.074; 95% CI, 0.81-1.42; P = .622). Hospital length of stay was shorter after stenting (stent vs repair coefficient, -4.09; P < .001).

CONCLUSIONS

In patients with esophageal perforation, the odds for death or discharge to hospice were similar for esophageal stenting compared with surgical repair.

Retrograde signaling by a mtDNA-encoded non-coding RNA preserves mitochondrial bioenergetics

Alveolar epithelial type II (AETII) cells are important for lung epithelium maintenance and function. We demonstrate that AETII cells from mouse lungs exposed to cigarette smoke (CS) increase the levels of the mitochondria-encoded non-coding RNA, mito-RNA-805, generated by the control region of the mitochondrial genome. The protective effects of mito-ncR-805 are associated with positive regulation of mitochondrial energy metabolism, and respiration. Levels of mito-ncR-805 do not relate to steady-state transcription or replication of the mitochondrial genome. Instead, CS-exposure causes the redistribution of mito-ncR-805 from mitochondria to the nucleus, which correlated with the increased expression of nuclear-encoded genes involved in mitochondrial function. These studies reveal an unrecognized mitochondria stress associated retrograde signaling, and put forward the idea that mito-ncRNA-805 represents a subtype of small non coding RNAs that are regulated in a tissue- or cell-type specific manner to protect cells under physiological stress.

Decision analysis supports the use of drain amylase-based enhanced recovery method after esophagectomy

Postesophagectomy anastomotic leak is a common postsurgical complication. The current standard method of detecting leak is esophagram usually late in the postoperative period. Perianastomotic drain amylase level had shown promising results in early detection anastomosis leak. Previous studies have shown that postoperative day 4 amylase level is more specific and sensitive than esophagram. The purpose of this study is to determine if implementing a drain amylase-based screening method for anastomotic leak can reduce length of stay and hospital cost relative to a traditional esophagram-based pathway. The drain amylase protocol we propose uses postoperative day 4 drain amylase level to direct the initiation of PO intake and discharge. We designed a decision analysis tree using TreeAge Pro software to compare the drain amylase-based screening method to the standard of care, the esophagram. We performed a retrospective review of postesophagectomy patients from a tertiary academic medical center (University hospital Cleveland medical center) where amylase level was measured routinely postoperatively. The patients were separated into amylase-based pathway group and the standard of care group based on their postop management. The length of stay, costs, complications, and leak rate of these two groups were used to inform the decision analysis tree. In the base-case analysis, the decision analysis demonstrated that an amylase-based screening method can reduce the hospital stay by one day and reduced costs by ∼$3,000 compared to esophagram group. To take the variability of the data into consideration, we performed a Monte Carlo simulation. The result showed again a median saving of 0.71 days and ∼$2,500 per patient in hospital cost. A ballistic sensitivity analysis was performed to show that the sensitivity of postoperative day 4 amylase level in detecting a leak was the most important factor in the model. We conclude that implementing an amylase-based screening method for anastomotic leak in postesophagectomy patient can significantly reduce hospital cost and length of stay. This study demonstrates a novel protocol to improve postesophagectomy care. Based on this result, we believe a prospective multicenter study is appropriate.

Medium-term follow up of pulmonary autograft aortic valve replacement: technical advances and echocardiographic follow up

BACKGROUND AND AIM OF THE STUDY

The Ross procedure (aortic valve replacement (AVR) with pulmonary autograft and pulmonary homograft replacement of pulmonary valve) was developed as a durable aortic valve substitute that avoids the need for anticoagulation and provides young patients with a long-lasting aortic valve substitute. Our seven-year follow up echocardiography data are reviewed.

METHODS

Between May 1993 and March 2000, 40 adult patients (28 males, 12 females; mean age 33.3 years) underwent the Ross procedure at the Brigham and Women's Hospital for congenital aortic stenosis (n = 6), aortic insufficiency (n = 17) and mixed disease (n = 17). All patients had aortic root replacement with the pulmonary autograft and had no regurgitation after operation. Postoperative evaluation was conducted by transthoracic echocardiography, office visit and/or telephone interview. NYHA functional class, aortic and pulmonary valve function and aortic root dimensions were evaluated.

RESULTS

One patient died postoperatively as a result of a low output state related to global left ventricular dysfunction. Four patients (10%) developed pulmonary homograft stenosis with a peak gradient >40mmHg; and six developed mild pulmonary stenosis. One patient had aortic insufficiency seven years postoperatively that required valve replacement. Eight patients developed mild dilatation (>37 mm) of the neoaortic root, and five of these had aortic insufficiency. One patient required transplantation at 40 months for restrictive cardiomyopathy.

CONCLUSION

The Ross procedure is an effective means of AVR that can be accomplished with low perioperative morbidity and mortality if certain technical modifications are carried out. In this series of 40 patients with mid-term follow up, a significant number developed moderate pulmonary trunk stenosis, though echo characterization demonstrated good valve function.

Femtosecond dynamics of the forbidden carotenoid S1 state in light-harvesting complexes of purple bacteria observed after two-photon excitation

Time-resolved excited-state absorption intensities after direct two-photon excitation of the carotenoid S(1) state are reported for light-harvesting complexes of purple bacteria. Direct excitation of the carotenoid S(1) state enables the measurement of subsequent dynamics on a fs time scale without interference from higher excited states, such as the optically allowed S(2) state or the recently discovered dark state situated between S(1) and S(2). The lifetimes of the carotenoid S(1) states in the B800-B850 complex and B800-B820 complex of Rhodopseudomonas acidophila are 7+/-0.5 ps and 6+/-0.5 ps, respectively, and in the light-harvesting complex 2 of Rhodobacter sphaeroides approximately 1.9+/-0.5 ps. These results explain the differences in the carotenoid to bacteriochlorophyll energy transfer efficiency after S(2) excitation. In Rps. acidophila the carotenoid S(1) to bacteriochlorophyll energy transfer is found to be quite inefficient (phi(ET1) <28%) whereas in Rb. sphaeroides this energy transfer is very efficient (phi(ET1) approximately 80%). The results are rationalized by calculations of the ensemble averaged time constants. We find that the Car S(1) --> B800 electronic energy transfer (EET) pathway ( approximately 85%) dominates over Car S(1) --> B850 EET ( approximately 15%) in Rb. sphaeroides, whereas in Rps. acidophila the Car S(1) --> B850 EET ( approximately 60%) is more efficient than the Car S(1) --> B800 EET ( approximately 40%). The individual electronic couplings for the Car S(1) --> BChl energy transfer are estimated to be approximately 5-26 cm(-1). A major contribution to the difference between the energy transfer efficiencies can be explained by different Car S(1) energy gaps in the two species.