A Low-Cost Method of Ciliary Beat Frequency Measurement Using iPhone and MATLAB: Rabbit Study

Comparing region of interest selection and whole-field analysis for measurement of ciliary beat frequency in high-speed video analysis

BACKGROUND

Ciliary beat frequency (CBF) is crucial in mucociliary clearance. High-speed video analysis (HSVA) is commonly used to measure CBF but lacks standardization. We compared visual observation and computer-assisted calculation using fast Fourier transformation (FFT) in freshly collected bronchial ciliary epithelial cells and cultured cells.

METHODS

Bronchial epithelial cells were obtained from 12 patients who required bronchoscopic examination. Eighty-five videos of ciliary movement of freshly collected and cultured cells were recorded and used to calculate CBF using manual observation, region of interest (ROI) selection, and whole-field analysis.

RESULTS

CBF measured by the ROI selection method strongly correlated with that measured using manual observation, especially in freshly collected cells. However, 27.8% of the manual observation method values were doubled in the ROI selection method, probably because a round trip of cilia was calculated as two cycles and needed to be corrected to 1/2 value. Upon increasing the number of ROIs, the results of the ROI selection method came closer to that of WFA.

CONCLUSIONS

Computer-assisted calculation using FFT can aid in measuring CBF; however, current methods require visual confirmation. Further automated evaluation techniques are needed to establish more standardized and generalized CBF measurement methods using HSVA.

Dysregulation of TMEM16A impairs oviductal transport of embryos

Ectopic pregnancy is an acute abdominalgia in obstetrics and gynecology, especially in fallopian tubal pregnancy. The ion channel protein transmembrane protein 16A (TMEM16A) is widely distributed in various tissues, even in the oviduct. In this study, we showed that TMEM16A was expressed in the human fallopian tube and was upregulated in patients with tubal pregnancy. By measuring isolated fallopian tube tissues, we found that TMEM16A was involved in regulating not only the contraction of muscle strips but also the beat frequency of cilia. In addition, pharmacological activation or inhibition of TMEM16A could lead to retention of embryos in oviducts. Moreover, the embryos in oviducts were delayed in development and some of them had malformations and deletions. The total number of embryos in the oviducts and uterus was significantly less than that of the control group. Furthermore, we detected changes in the level of m6A methylation, where the relevant writers and readers were reduced in tubal tissues from tubal pregnancies. In m6A mRNA methylation, writers catalyze the addition of methyl groups to cytosine residues and readers bind to the methyl groups and affect gene translation. In human fallopian tube epithelial cell line FTE187, we found that interference with methyltransferase 3 (METTL3) expression increased TMEM16A, suggesting that TMEM16A might be regulated by m6A methylation. In general, our study revealed a novel regulatory point for embryo transport and development, introducing a new role for the diagnosis and treatment of tubal pregnancy.NEW & NOTEWORTHY The ion channel protein TMEM16A is expressed in the epithelium and smooth muscle of the human fallopian tube and is upregulated in patients with tubal pregnancy. TMEM16A is involved in regulating the smooth muscle contraction and the cilia beating. Dysregulated TMEM16A may result in embryo retention in the oviduct and delayed early embryo development. Our study reveals a new regulatory point for embryo transport and development.

Assessing motile cilia coverage and beat frequency in mammalian in vitro cell culture tissues

Cilia density, distribution and beating frequency are important properties of airway epithelial tissues. These parameters are critical in diagnosing primary ciliary dyskinesia and examining in vitro models, including those derived from induced pluripotent stem cells. Video microscopy can be used to characterize these parameters, but most tools available at the moment are limited in the type of information they can provide, usually only describing the ciliary beat frequency of very small areas, while requiring human intervention and training for their use. We propose a novel and open-source method to fully characterize cilia beating frequency and motile cilia coverage in an automated fashion without user intervention. We demonstrate the ability to differentiate between different coverage densities, identifying even small patches of cilia in a larger field of view, and to fully characterize the cilia beating frequency of all moving areas. We also show that the method can be used to combine multiple fields of view to better describe a sample without relying on small pre-selected regions of interest. This is released with a simple graphical user interface for file handling, enabling a full analysis of individual fields of view in a few minutes on a typical personal computer.

Quantifying cilia beat frequency using high-speed video microscopy: Assessing frame rate requirements when imaging different ciliated tissues

Motile cilia are found in numerous locations throughout our body and play a critical role in various physiological processes. The most commonly used method to assess cilia motility is to quantify cilia beat frequency (CBF) via video microscopy. However, a large heterogeneity exists within published literature regarding the framerate used to image cilia motility for calculating CBF. The aim of this study was to determine the optimal frame rate required to image cilia motility for CBF assessment, and if the Nyquist theorem may be used to set this rate. One‐second movies of cilia were collected at >600 fps from mouse airways and ependyma at room‐temperature or 37°C. Movies were then down‐sampled to 30–300 fps. CBF was quantified for identical cilia at different framerates by either manual counting or automated MATLAB script. Airway CBF was significantly impaired in 30 fps movies, while ependymal CBF was significantly impaired in both 60 and 30 fps movies. Pairwise comparison showed that video framerate should be at least 150 fps to accurately measure CBF, with minimal improvement in CBF accuracy in movies >150 fps. The automated script was also found to be less accurate for measuring CBF in lower fps movies than manual counting, however, this difference disappeared in higher framerate movies (>150 fps). In conclusion, our data suggest the Nyquist theorem is unreliable for setting sampling rate for CBF measurement. Instead, sampling rate should be 3–4 times faster than CBF for accurate CBF assessment. Especially if CBF calculation is to be automated.

CiliarMove: new software for evaluating ciliary beat frequency helps find novel mutations by a Portuguese multidisciplinary team on primary ciliary dyskinesia

Evaluation of ciliary beat frequency (CBF) performed by high-speed videomicroscopy analysis (HVMA) is one of the techniques required for the correct diagnosis of primary ciliary dyskinesia (PCD). Currently, due to lack of open-source software, this technique is widely performed by visually counting the ciliary beatings per a given time-window. Our aim was to generate open-source, fast and intuitive software for evaluating CBF, validated in Portuguese PCD patients and healthy volunteers. Nasal brushings collected from 17 adult healthy volunteers and 34 PCD-referred subjects were recorded using HVMA. Evaluation of CBF was compared by two different methodologies: the new semi-automated computer software CiliarMove and the manual observation method using slow-motion movies. Clinical history, nasal nitric oxide and transmission electron microscopy were performed for diagnosis of PCD in the patient group. Genetic analysis was performed in a subset (n=8) of suspected PCD patients. The correlation coefficient between the two methods was R2=0.9895. The interval of CBF values obtained from the healthy control group (n=17) was 6.18-9.17 Hz at 25°C. In the PCD-excluded group (n=16), CBF ranged from 6.84 to 10.93 Hz and in the PCD group (n=18), CBF ranged from 0 to 14.30 Hz. We offer an automated open-source programme named CiliarMove, validated by the manual observation method in a healthy volunteer control group, a PCD-excluded group and a PCD-confirmed group. In our hands, comparisons between CBF intervals alone could discern between healthy and PCD groups in 78% of the cases.

A Novel Approach for the Automatic Estimation of the Ciliated Cell Beating Frequency

The qualitative and quantitative evaluation of nasal epithelial cells is interesting in chronic infectious and inflammatory pathologies of the nose and sinuses. Among the cells of the population of the nasal mucosa, ciliated cells are particularly important. In fact, the observation of these cells is essential to investigate primary ciliary dyskinesia, a rare and severe disease associated with other serious diseases such as respiratory diseases, situs inversus, heart disease, and male infertility. Biopsy or brushing of the ciliary mucosa and assessment of ciliary function through measurements of the Ciliary Beating Frequency (CBF) are usually required to facilitate diagnosis. Therefore, low-cost and easy-to-use technologies devoted to measuring the ciliary beating frequency are desirable. We have considered related works in this field and noticed that up to date an actually usable system is not available to measure and monitor CBF. Moreover, performing this operation manually is practically unfeasible or demanding. For this reason, we designed BeatCilia, a low cost and easy-to-use system, based on image processing techniques, with the aim of automatically measuring CBF. This system performs cell Region of Interest (RoI) detection basing on dense optical flow computation of cell body masking, focusing on the cilia movement and taking advantage of the structural characteristics of the ciliated cell and CBF estimation by applying a fast Fourier transform to extract the frequency with the peak amplitude. The experimental results show that it offers a reliable and fast CBF estimation method and can efficiently run on a consumer-grade smartphone. It can support rhinocytologists during cell observation, significantly reducing their efforts.

ORKAMBI-Mediated Rescue of Mucociliary Clearance in Cystic Fibrosis Primary Respiratory Cultures Is Enhanced by Arginine Uptake, Arginase Inhibition, and Promotion of Nitric Oxide Signaling to the Cystic Fibrosis Transmembrane Conductance Regulator Channel

ORKAMBI, a combination of the corrector, lumacaftor, and the potentiator, ivacaftor, partially rescues the defective processing and anion channel activity conferred by the major cystic fibrosis-causing mutation, F508del, in in vitro studies. Clinically, the improvement in lung function after ORKAMBI treatment is modest and variable, prompting the search for complementary interventions. As our previous work identified a positive effect of arginine-dependent nitric oxide signaling on residual F508del-Cftr function in murine intestinal epithelium, we were prompted to determine whether strategies aimed at increasing arginine would enhance F508del-cystic fibrosis transmembrane conductance regulator (CFTR) channel activity in patient-derived airway epithelia. Now, we show that the addition of arginine together with inhibition of intracellular arginase activity increased cytosolic nitric oxide and enhanced the rescue effect of ORKAMBI on F508del-CFTR-mediated chloride conductance at the cell surface of patient-derived bronchial and nasal epithelial cultures. Interestingly, arginine addition plus arginase inhibition also enhanced ORKAMBI-mediated increases in ciliary beat frequency and mucociliary movement, two in vitro CF phenotypes that are downstream of the channel defect. This work suggests that strategies to manipulate the arginine-nitric oxide pathway in combination with CFTR modulators may lead to improved clinical outcomes. SIGNIFICANCE STATEMENT: These proof-of-concept studies highlight the potential to boost the response to cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulators, lumacaftor and ivacaftor, in patient-derived airway tissues expressing the major CF-causing mutant, F508del-CFTR, by enhancing other regulatory pathways. In this case, we observed enhancement of pharmacologically rescued F508del-CFTR by arginine-dependent, nitric oxide signaling through inhibition of endogenous arginase activity.

A Nanosensor Toolbox for Rapid, Label-Free Measurement of Airway Surface Liquid and Epithelial Cell Function

Ciliated lung epithelial cells and the airway surface liquid (ASL) comprise one of the body's most important protective systems. This system is finely tuned, and perturbations to ASL rheology, ASL depth, ASL pH, the transepithelial potential, and the cilia beat frequency are all associated with disease pathology. Further, these apparently distinct properties interact with each other in a complex manner. For example, changes in ASL rheology can result from altered mucin secretion, changes in ASL pH, or changes in ASL depth. Thus, one of the great challenges in trying to understand airway pathology is that the properties of the ASL/epithelial cell system need to be assessed near-simultaneously and without perturbing the sample. Here, we show that nanosensor probes mounted on a scanning ion conductance microscope make this possible for the first time, without any need for labeling. We also demonstrate that ASL from senescence-retarded human bronchial epithelial cells retains its native properties. Our results demonstrate that by using a nanosensor approach, it is possible to pursue faster, more accurate, more coherent, and more informative studies of ASL and airway epithelia in health and disease.

Effects of pelvic endometriosis and adenomyosis on ciliary beat frequency and muscular contractions in the human fallopian tube

BACKGROUND

Pelvic endometriosis (EM) and adenomyosis (AM) have different effects on the fallopian tube. This study aimed to assess the transport capability of the fallopian tube in women with pelvic EM or AM.

METHODS

Twenty women with uterine leiomyoma (control group), 20 with adenomyosis without pelvic EM (AM group) and 35 with pelvic EM without AM (EM group) were included. EM cases were further divided into the tubal EM and non-tubal EM subgroups. Ciliary beat frequency (CBF), percentage of ciliated cells, and smooth muscle contraction were measured.

RESULTS

CBFs of the ampulla in EM cases were significantly lower than those of control and AM cases; CBFs of the ampulla and isthmus in tubal EM cases were significantly lower than those of the control group and non-tubal EM subgroup. In both the ampulla and isthmus segment, percentages of ciliated cells in EM patients were significantly lower than those of AM and control patients; the tubal EM subgroup showed significantly lower values than the control group and non-tubal EM subgroup. Amplitude-to-weight ratios of longitudinal muscular contractility in EM cases were significantly lower than control values; tubal EM cases showed significantly lower values than controls and the non-tubal EM subgroup. Contraction frequencies in EM cases were significantly lower than those of control and AM cases, in both longitudinal and circular muscles; tubal EM cases showed significantly lower values than controls and the non-tubal EM subgroup.

CONCLUSION

EM with tubal EM damaged transport function of the fallopian tube, to varying degrees, whereas tubal function in EM without tubal EM and in AM is not altered.