Effects of airway smooth muscle contraction and inflammation on lung tissue compliance

There are renewed interests in using the parameter K of Salazar-Knowles' equation to assess lung tissue compliance. K either decreases or increases when the lung's parenchyma stiffens or loosens, respectively. However, whether K is affected by other common features of respiratory diseases, such as inflammation and airway smooth muscle (ASM) contraction, is unknown. Herein, male C57BL/6 mice were treated intranasally with either saline or lipopolysaccharide (LPS) at 1 mg/Kg to induce pulmonary inflammation. They were then subjected to either a multiple or a single-dose challenge with methacholine to activate ASM to different degrees. A quasi-static pressure-driven partial pressure-volume maneuver was performed before and after methacholine. The Salazar-Knowles' equation was then fitted to the deflation limb of the P-V loop to obtain K, as well as the parameter A, an estimate of lung volume (inspiratory capacity). The fitted curve was also used to derive the quasi-static elastance (Est) at 5 cmH2O. The results demonstrate that LPS and both methacholine challenges increased Est. LPS also decreased A, but did not affect K. In contradistinction, methacholine decreased both A and K in the multiple-dose challenge, while it decreased K but not A in the single-dose challenge. These results suggest that LPS increases Est by reducing the open lung volume (A) and without affecting tissue compliance (K), while methacholine increases Est by decreasing tissue compliance with or without affecting lung volume. We conclude that lung tissue compliance, assessed using the parameter K of Salazar-Knowles' equation, is insensitive to inflammation but sensitive to ASM contraction.

Myofascial Tissue and Depression

Background The myofascial system plays a fundamental role in the mechanics of the body, in body tension regulation and the etiology of pathological states like chronic pain. Moreover, it contains contractile elements and preliminary evidence suggests that its properties are linked to psychological factors. The aim of the present research was to investigate characteristics of the myofascial tissue in patients with Major Depressive Disorder (MDD) and to examine whether the state of the myofascial tissue causally affects pathopsychological processes in MDD. Methods In Study 1, stiffness and elasticity of the myofascial tissue of 40 inpatients suffering from MDD measured with a tissue compliance meter were compared with those of 40 matched never-depressed participants. In Study 2, 69 MDD patients were randomly assigned to single-session self-myofascial release intervention (SMRI) or a placebo intervention. Effects on memory bias and affect were investigated. Results Results showed that MDD patients displayed heightened stiffness and reduced elasticity of the myofascial tissue and that patients in the SMRI group showed a reduced negative memory bias and more positive affect compared to patients in the placebo condition. Conclusions The preliminary results of our studies indicate that the myofascial tissue might be part of a dysfunctional body-mind dynamic that maintains MDD.

Transcriptome and proteome dynamics of cervical remodeling in the mouse during pregnancy

During gestation, the female reproductive tract must maintain pregnancy while concurrently preparing for parturition. Here, we explore the transitions in gene expression and protein turnover (fractional synthesis rates [FSR]) by which the cervix implements a transition from rigid to compliant. Shifts in gene transcription to achieve immune tolerance and alter epithelial cell programs begin in early pregnancy. Subsequently, in mid-to-late pregnancy transcriptional programs emerge that promote structural reorganization of the extracellular matrix (ECM). Stable isotope labeling revealed a striking slowdown of overall FSRs across the proteome on gestation day 6 that reverses in mid-to-late pregnancy. An exception was soluble fibrillar collagens and proteins of collagen assembly, which exhibit high turnover in non-pregnant cervix compared to other tissues and FSRs that continue throughout pregnancy. This finding provides a mechanism to explain how cross-linked collagen is replaced by newly synthesized, less-cross-linked collagens, which allows increased tissue compliance during parturition. The rapid transition requires a reservoir of newly synthesized, less cross-linked collagens, which is assured by the high FSR of soluble collagens in the cervix. These findings suggest a previously unrecognized form of “metabolic flexibility” for ECM in the cervix that underlies rapid transformation in compliance to allow parturition.

An update to the Monro–Kellie doctrine to reflect tissue compliance after severe ischemic and hemorrhagic stroke

High intracranial pressure (ICP) can impede cerebral blood flow resulting in secondary injury or death following severe stroke. Compensatory mechanisms include reduced cerebral blood and cerebrospinal fluid volumes, but these often fail to prevent raised ICP. Serendipitous observations in intracerebral hemorrhage (ICH) suggest that neurons far removed from a hematoma may shrink as an ICP compliance mechanism. Here, we sought to critically test this observation. We tracked the timing of distal tissue shrinkage (e.g. CA1) after collagenase-induced striatal ICH in rat; cell volume and density alterations (42% volume reduction, 34% density increase; p < 0.0001) were highest day one post-stroke, and rebounded over a week across brain regions. Similar effects were seen in the filament model of middle cerebral artery occlusion (22% volume reduction, 22% density increase; p ≤ 0.007), but not with the Vannucci-Rice model of hypoxic-ischemic encephalopathy (2.5% volume increase, 14% density increase; p ≥ 0.05). Concerningly, this ‘tissue compliance’ appears to cause sub-lethal damage, as revealed by electron microscopy after ICH. Our data challenge the long-held assumption that ‘healthy’ brain tissue outside the injured area maintains its volume. Given the magnitude of these effects, we posit that ‘tissue compliance’ is an important mechanism invoked after severe strokes.

Influence of quantified dry cupping on soft tissue compliance in athletes with myofascial pain syndrome

Purpose This study aimed to develop a quantitative dry cupping system that can monitor negative pressure attenuation and soft tissue pull-up during cupping to quantify soft tissue compliance. Methods Baseball players with myofascial pain syndrome were recruited to validate the benefits of cupping therapy. Nine of 40 baseball players on the same team were diagnosed with trapezius myofascial pain syndrome; another nine players from the same team were recruited as controls. All participants received cupping with a negative pressure of 400 mmHg for 15 minutes each time, twice a week, for 4 weeks. Subjective perception was investigated using upper extremity function questionnaires, and soft tissue compliance was quantified objectively by the system. Results During the 15-minute cupping procedure, pressure attenuation in the normal group was significantly greater than that in the myofascial group (p = 0.017). The soft tissue compliance in the normal group was significantly higher than that in the myofascial group (p = 0.050). Moreover, a 4-week cupping intervention resulted in an obvious increase in soft tissue lift in the myofascial pain group (p = 0.027), although there was no statistical difference in the improvement of soft tissue compliance. Shoulder (p = 0.023) and upper extremity function (p = 0.008) were significantly improved in both groups, but there was no significant difference between the two groups. Conclusion This quantitative cupping monitoring system could immediately assess tissue compliance and facilitate the improvement of soft tissues after cupping therapy. Hence, it can be used in athletes to improve their functional recovery and maintain soft tissues health during the off-season period.

Abstract 16880: Exosomes From Dilated Cardiomyocytes Activate Fibrosis

In dilated cardiomyopathy (DCM), exaggerated fibrosis reduces tissue compliance and accelerates the progression to heart failure. However, the mechanisms for fibrotic remodeling in DCM are not well understood. Exosomes are small extracellular vesicles that function as intercellular messengers. Our hypothesis is that exosomes from hypertrophic stimulated DCM cardiomyocytes activate fibrosis in the heart. We utilized iPSCs reprogrammed from DCM patients and healthy control individuals (CTL) to differentiate them into cardiomyocytes (iCMs). iCMs were stimulated by Angiotensin II, and conditioned media were collected to isolate exosomes thereafter. Fibroblasts were treated with CTL-exosomes and DCM-exosomes respectively in vitro. Meanwhile, we injected exosomes into the mouse hearts in vivo. Fibrotic markers and protein expression were examined by western blot and histology. Additionally, we also analyzed the microRNA profiles in the DCM-exosomes and CTL-exosomes by small RNA sequencing. The microRNAs expressions in exosomes were also confirmed by RT-PCR. We found DCM exosomes treatment significantly upregulated extracellular matrix proteins expressions in fibroblasts. Collagen I, collagen III, and CTGF were significantly upregulated in DCM exosomes treatment group compared to CTL exosomes treatment group. Intramyocardial injection of DCM exosomes into wild type mice (CD-1) caused impaired ejection fraction after 7 days compared to CTL exosomes injection (DCM = 51.5 ± 6.21%*, CTL =64.6 ± 3.99%; * = P < 0.05). Picro sirius red staining for extracellular matrix showed significant increase of fibrosis in DCM exosome injection group, compared to CTL exosomes and PBS group (DCM = 3.08 ± 0.24%*, CTL = 0.087 ± 0.02%, PBS = 0.053 ± 0.01%; * = P < 0.05). Next-generation sequencing of these exosomes exhibited upregulation of a group microRNAs in the DCM exosomes. microRNA-103a upregulation was confirmed in DCM exosomes. Overexpression microRNA-103a resulted in fibroblast activation and upregulation of Col I, Col III, and CTGF expression in vitro. Our findings uncovered a critical role for exosomal microRNA (microRNA-103a) mediating pathological fibrotic remodeling in DCM.

Elastin levels are higher in healing tendons than in intact tendons and influence tissue compliance

ABSTRACTElastic fibers containing elastin play an important role in tendon functionality, but the knowledge on presence and function of elastin during tendon healing is limited. The aim of this study was to investigate elastin content and distribution in intact and healing Achilles tendons and to understand how elastin influence the viscoelastic properties of tendons. The right Achilles tendon was completely transected in 81 Sprague-Dawley rats. Elastin content was quantified in intact and healing tendons (7, 14, and 28 days post-surgery) and elastin distribution was visualized by immunohistochemistry. Degradation of elastin by elastase incubation was used to study the role of elastin on viscoelastic properties. Mechanical testing was either performed as a cyclic test (20x 10 N) or as a creep test. We found significantly higher levels of elastin in healing tendons at all time-points compared to intact tendons (4% in healing tendons 28 days post-surgery vs 2% in intact tendons). The elastin was more widely distributed throughout the extracellular matrix in the healing tendons in contrast to the intact tendon where the distribution was not so pronounced. Elastase incubation reduced the elastin levels by approximately 30% and led to a 40-50% reduction in creep. This reduction was seen in both intact and healing tendons. Our results show that healing tendons contain more elastin and is more compliable than intact tendons. The role of elastin in tendon healing and tissue compliance indicate a protective role of elastic fibers to prevent re-injuries during early tendon healing.PLAIN LANGUAGE SUMMARYTendons transfer high loads from muscles to bones during locomotion. They are primarily made by the protein collagen, a protein that provide strength to the tissues. Besides collagen, tendons also contain other building blocks such as e.g. elastic fibers. Elastic fibers contain elastin and elastin is important for the extensibility of the tendon. When a tendon is injured and ruptured the tissue heals through scar formation. This scar tissue is different from a normal intact tendon and it is important to understand how the tendons heal. Little is known about the presence and function of elastin during healing of tendon injuries. We have shown, in animal experiments, that healing tendons have higher amounts of elastin compared to intact tendons. The elastin is also spread throughout the tissue. When we reduced the levels of this protein, we discovered altered mechanical properties of the tendon. The healing tendon can normally extend quite a lot, but after elastin removal this extensibility was less obvious. The ability of the healing tissue to extend is probably important to protect the tendon from re-injuries during the first months after rupture. We therefore propose that the tendons heal with a large amount of elastin to prevent re-ruptures during early locomotion.

p19Arf Exacerbates Cigarette Smoke-Induced Pulmonary Dysfunction

Senescent cells accumulate in tissues during aging or pathological settings. The semi-genetic or pharmacological targeting of senescent cells revealed that cellular senescence underlies many aspects of the aging-associated phenotype and diseases. We previously reported that cellular senescence contributes to aging- and disease-associated pulmonary dysfunction. We herein report that the elimination of Arf-expressing cells ameliorates cigarette smoke-induced lung pathologies in mice. Cigarette smoke induced the expression of Ink4a and Arf in lung tissue with concomitant increases in lung tissue compliance and alveolar airspace. The elimination of Arf-expressing cells prior to cigarette smoke exposure protected against these changes. Furthermore, the administration of cigarette smoke extract lead to pulmonary dysfunction, which was ameliorated by subsequent senescent cell elimination. Collectively, these results suggest that senescent cells are a potential therapeutic target for cigarette smoking-associated lung disease.

Mathematical Relationship Between Palpation Forces and Displacement Associated With Restriction

Based on the clinical data, a mathematical model was developed that characterized the palpation forces and the associated deformation/displacement of the surface of the body when osteopathic clinicians examine the low back or lumbar spine region. The purpose of this work was to better understand the haptic perception of clinicians who use palpation to assist in their assessment of patients with low back pain. Clinicians use palpation to identify areas of reduced tissue compliance thought to be associated with restriction of segmental vertebral motion. Using existing experimental data generated by multiple clinicians examining human volunteers, palpation forces and associated displacements were modeled by using three key variables: stiffness, damping, and inertia of the system. Of the total number of force application cycles analyzed, 92% had a goodness of fit, R2, that was better than 95% (R2≥ 0.95). When comparing the experimental data to the response of the three-parameter force/displacement mathematical model, the mathematical model delivered an accurate representation of palpation forces and displacements. A normalized stiffness difference (NSD) was generated to compare to clinician assessments. Recommendations for design specifications of a palpation-training device were suggested.