Cilia Research Articles

Strongly Truncated Dnaaf4 Plays a Conserved Role in Drosophila Ciliary Dynein Assembly as Part of an R2TP-Like Co-Chaperone Complex With Dnaaf6.

Axonemal dynein motors are large multi-subunit complexes that drive ciliary movement. Cytoplasmic assembly of these motor complexes involves several co-chaperones, some of which are related to the R2TP co-chaperone complex. Mutations of these genes in humans cause the motile ciliopathy, Primary Ciliary Dyskinesia (PCD), but their different roles are not completely known. Two such dynein (axonemal) assembly factors (DNAAFs) that are thought to function together in an R2TP-like complex are DNAAF4 (DYX1C1) and DNAAF6 (PIH1D3). Here we investigate the Drosophila homologues, CG14921/Dnaaf4 and CG5048/Dnaaf6. Surprisingly, Drosophila Dnaaf4 is truncated such that it completely lacks a TPR domain, which in human DNAAF4 is likely required to recruit HSP90. Despite this, we provide evidence that Drosophila Dnaaf4 and Dnaaf6 proteins can associate in an R2TP-like complex that has a conserved role in dynein assembly. Both are specifically expressed and required during the development of the two Drosophila cell types with motile cilia: mechanosensory chordotonal neurons and sperm. Flies that lack Dnaaf4 or Dnaaf6 genes are viable but with impaired chordotonal neuron function and lack motile sperm. We provide molecular evidence that Dnaaf4 and Dnaaf6 are required for assembly of outer dynein arms (ODAs) and a subset of inner dynein arms (IDAs).

Kartagener Syndrome: A Case Report

Kartagener syndrome (KS) is a rare autosomal recessive disorder characterized by a clinical triad of situs inversus, chronic sinusitis, and bronchiectasis. Impaired ciliary motility due to abnormal ciliary structure or function is the main pathophysiological problem in KS. A 38-year-old woman presented to our outpatient clinic with a productive cough, fever, and shortness of breath for 1 month. She has had recurrent episodes of respiratory tract infections since childhood. Clinical investigations revealed situs inversus, sinusitis, and bronchiectasis. She was diagnosed with KS and treated with antibiotics, mucolytics, bronchodilators, and chest physiotherapy. Patients with KS present with chronic recurrent respiratory tract infections due to ineffective mucociliary clearance. Early diagnosis is important to improve prognosis. The main goals in the management of KS are to prevent the progression of the disease, preserve pulmonary function, and improve quality of life.

Kif9 is an active kinesin motor required for ciliary beating and proximodistal patterning of motile axonemes.

Most motile cilia have a stereotyped structure of nine microtubule outer doublets and a single central pair of microtubules. The central pair of microtubules are surrounded by a set of proteins, termed the central pair apparatus. A specific kinesin, Klp1 projects from the central pair and contributes to ciliary motility in Chlamydomonas. The vertebrate ortholog, Kif9, is required for beating in mouse sperm flagella, but the mechanism of Kif9/Klp1 function remains poorly defined. Here, using Xenopus epidermal multiciliated cells, we show that Kif9 is necessary for ciliary motility and the proper distal localization of not only central pair proteins, but also radial spokes and dynein arms. In addition, single-molecule assays in vitro reveal that Xenopus Kif9 is a long-range processive motor, although it does not mediate long-range movement in ciliary axonemes in vivo. Together, our data suggest that Kif9 is integral for ciliary beating and is necessary for proper axonemal distal end integrity.

Spef1/CLAMP binds microtubules and actin-based structures and regulates cell migration and epithelia cell polarity.

During migration, cells invade, repair, and create barriers leading to the formation of new cellular contacts in target tissues. Cell migration requires many proteins that collectively form the cytoskeleton. The main cytoskeletal elements are actin filaments, microtubules (MTs), and intermediate filaments. These structures work in concert with a large number of accessory proteins that contribute in a variety of ways to regulate filament assembly and turnover, to alter the configuration or arrangement of filaments by bundling or crosslinking, to link the cytoskeleton to other structures in the cell, such as membranes and junctions, and to transport cargo along the filaments. Sperm flagella protein-1 (Spef1), also designated calponin homology and microtubules-associated protein (CLAMP), is a multifunctional protein that interacts with cytoskeletal structures, including MTs, actin filaments, and focal adhesions in epithelia. In this review, we outline Spef1/CLAMP structure and expression in several cellular models. The function of Spef1/CLAMP in flagellar and ciliary motility, MT-binding and stability, regulation of planar cell polarity, and potential contribution to the maintenance of actin-based structures, such as lamellipodia and filopodia during cell migration, are also discussed.

A Young Bangladeshi Boy with Primary Ciliary Dyskinesia (Kartagener’s Syndrome): A Rare Case

Kartagener’s syndrome, an autosomal recessive inherited disorder, is a subgroup of primary ciliary dyskinesias (PCD). This genetic disorder manifests from early life which distinguishes it from acquired mucociliary disorders. Kartagener’s syndrome presents as a classical triad of situs inversus, sinusitis and bronchiectasis occurring majorly due to impaired ciliary motility. A 16 year-old boy from Fulbaria, Mymensingh with left sided consolidation for 1 month and recurrent episodes of nasal congestion and lower respiratory tract infection (LRTI) since his childhood. Clinical and imaging findings revealed left sided consolidation, chronic sinusitis, bronchiectasis, dextrocardia, and situs inversus. He was treated with orally administered antibiotics, bronchodilators, mucolytics, and chest physiotherapy. He was symptomatically better with the above therapy, and started on a long-term low-dose prophylactic antibiotic. As there is no easy, reliable non-invasive diagnostic test for Kartagener’s syndrome and the correct diagnosis is often delayed by years, it may cause chronic respiratory problems with reduced quality of life. Genetic counseling and fertility issues should be addressed once Kartagener’s syndrome is diagnosed.
 CBMJ 2022 January: vol. 11 no. 01 P: 56-60

Key gene network related to primary ciliary dyskinesia in hippocampus of patients with Alzheimer’s disease revealed by weighted gene co-expression network analysis

BackgroundAlzheimer’s disease (AD) is closely related to aging, showing an increasing incidence rate for years. As one of the main brain regions involved in AD, hippocampus has been extensively studied due to its association with many human diseases. However, little is known about its association with primary ciliary dyskinesia (PCD).Material and MethodsThe microarray data of hippocampus on AD were retrieved from the Gene Expression Omnibus (GEO) database to construct the co-expression network by weighted gene co-expression network analysis (WGCNA). The gene network modules associated with AD screened with the common genes were further annotated based on Gene Ontology (GO) database and enriched based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The protein-protein interaction (PPI) network was constructed based on STRING database to identify the hub genes in the network.ResultsGenes involved in PCD were identified in the hippocampus of AD patients. Functional analysis revealed that these genes were mainly enriched in ciliary tissue, ciliary assembly, axoneme assembly, ciliary movement, microtubule based process, microtubule based movement, organelle assembly, axoneme dynamin complex, cell projection tissue, and microtubule cytoskeleton tissue. A total of 20 central genes, e.g., DYNLRB2, ZMYND10, DRC1, DNAH5, WDR16, TTC25, and ARMC4 were identified as hub genes related to PCD in hippocampus of AD patients.ConclusionOur study demonstrated that AD and PCD have common metabolic pathways. These common pathways provide novel evidence for further investigation of the pathophysiological mechanism and the hub genes suggest new therapeutic targets for the diagnosis and treatment of AD and PCD.SubjectsBioinformatics, Cell Biology, Molecular Biology, Neurology.

Reactivation of Demembranated Cell Models in <em>Chlamydomonas reinhardtii</em>

Since the historical experiment on the contraction of glycerinated muscle by adding ATP, which Szent-Györgyi demonstrated in the mid-20th century, in vitro reactivation of demembranated cells has been a traditional and potent way to examine cell motility. The fundamental advantage of this experimental method is that the composition of the reactivation solution may be easily changed. For example, a high-Ca2+ concentration environment that occurs only temporarily due to membrane excitation in vivo can be replicated in the lab. Eukaryotic cilia (a.k.a. flagella) are elaborate motility machinery whose regulatory mechanisms are still to be clarified. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism in the research field of cilia. The reactivation experiments using demembranated cell models of C. reinhardtii and their derivatives, such as demembranated axonemes of isolated cilia, have significantly contributed to understanding the molecular mechanisms of ciliary motility. Those experiments clarified that ATP energizes ciliary motility and that various cellular signals, including Ca2+, cAMP, and reactive oxygen species, modulate ciliary movements. The precise method for demembranation of C. reinhardtii cells and reactivation of the cell models is described here.

In vivo visualization and analysis of ciliary motion in allergic rhinitis models induced by ovalbumin.

Due to the lack of an assessment approach, the image of in vivo nasal ciliary motion of allergic rhinitis (AR) has never been captured and analyzed to date. Here, we have used an optimized approach to analyze the nasal ciliary function in vivo in AR rats. The digital microscopy system, a method for direct observation of ciliary motion in a living AR rat model, was applied to visualize and measure ciliary motion in vivo, including ciliary beat frequency (CBF) and ciliary beat distance (CBD). The AR rat model was established by ovalbumin sensitization. Comparisons of nasal ciliary motion in vivo between the experimental group (ovalbumin sensitization, allergen, or histamine) and the control group were analyzed. In the living rat model of allergic rhinitis, CBF and CBD decreased to 57.8 and 73.1% of the control group, respectively, but were restored after administration of chlorpheniramine maleate. Ovalbumin (OVA) significantly inhibited the ciliary motion of normal mucosa in vivo. However, responding to the OVA challenge, the ciliary motion of OVA-sensitized mucosa would not decrease further and stay at a stable level. Histamine stimulated in vivo ciliary motion quickly within 30 min, but afterward, the ciliary motion gradually decreased below the baseline. These results have clarified that in vivo ciliary motion was impaired by nasal mucosal sensitization, and this impairment was most likely related to allergen challenge and histamine. In addition, the short-term stimulation and long-term inhibition effects of histamine on in vivo ciliary motion were first reported in this study.

Influence of metachronal ciliary wave motion on peristaltic flow of nanofluid model of synovitis problem

In this article, we have considered the effect of metachronal ciliary wave motion on the peristaltic flow of the Buongiorno nanofluid model for the synovitis problem. This study is additionally limited by the assumption of a low Reynolds number and lubrication theory approximations. An internal energy generation is also taken into account. Shear-thinning (model I) and shear-thickening (model II) for the concentration fluids are considered. The obtained dimensionless rheological equation is solved by using the homotopy perturbation Sumudu transformation method. The influence of various physical parameters on the dimensionless velocity, pressure rise, temperature, volume fraction, multi-sinusoidal waves, triangular waves, and streamlines has been analyzed. A trapping phenomenon is thoroughly examined. It is observed from the investigation that the shear-thinning (model I) and shear-thickening (model II) have completely distinct characteristics. The synovial fluid parameter shows opposite behavior on velocity and pressure rise profiles for models I and II, whereas the multi-sinusoidal wave and triangular wave forms retain the same shape of the waves as in the pressure gradient. These models can be used to treat rheumatoid arthritis as synovial fluids are present in joints. Fluid transfer in biological organs is improved by metachronal ciliary motion. Patients with rheumatoid arthritis can be treated with nanoparticles and ciliary motion. It is primarily due to their biocompatibility, low toxicity, and controlled release as well as their capacity to boost bioavailability and bioactivity of treatments and enable targeting the injured joints through the use of nanoparticles. In the limited scenario, the current work is in good accord with the earlier research, and it is analyzed through a graph.

Ciliary central apparatus structure reveals mechanisms of microtubule patterning.

A pair of extensively modified microtubules form the central apparatus (CA) of the axoneme of most motile cilia, where they regulate ciliary motility. The external surfaces of both CA microtubules are patterned asymmetrically with large protein complexes that repeat every 16 or 32 nm. The composition of these projections and the mechanisms that establish asymmetry and longitudinal periodicity are unknown. Here, by determining cryo-EM structures of the CA microtubules, we identify 48 different CA-associated proteins, which in turn reveal mechanisms for asymmetric and periodic protein binding to microtubules. We identify arc-MIPs, a novel class of microtubule inner protein, that bind laterally across protofilaments and remodel tubulin structure and lattice contacts. The binding mechanisms utilized by CA proteins may be generalizable to other microtubule-associated proteins. These structures establish a foundation to elucidate the contributions of individual CA proteins to ciliary motility and ciliopathies.

Cryo-EM structure of an active central apparatus

Accurately regulated ciliary beating in time and space is critical for diverse cellular activities, which impact the survival and development of nearly all eukaryotic species. An essential beating regulator is the conserved central apparatus (CA) of motile cilia, composed of a pair of microtubules (C1 and C2) associated with hundreds of protein subunits per repeating unit. It is largely unclear how the CA plays its regulatory roles in ciliary motility. Here, we present high-resolution structures of Chlamydomonas reinhardtii CA by cryo-electron microscopy (cryo-EM) and its dynamic conformational behavior at multiple scales. The structures show how functionally related projection proteins of CA are clustered onto a spring-shaped scaffold of armadillo-repeat proteins, facilitated by elongated rachis-like proteins. The two halves of the CA are brought together by elastic chain-like bridge proteins to achieve coordinated activities. We captured an array of kinesin-like protein (KLP1) in two different stepping states, which are actively correlated with beating wave propagation of cilia. These findings establish a structural framework for understanding the role of the CA in cilia.

Analysis of the diagnosis of Japanese patients with primary ciliary dyskinesia using a conditional reprogramming culture.

Primary ciliary dyskinesia (PCD) is diagnosed through multiple methods, including transmission electron microscopy (TEM), a high-speed video microscopy analysis (HSVA), immunofluorescence (IF), and genetic testing. A primary cell culture has been recommended to avoid the misdiagnosis of secondary ciliary dyskinesia derived from infection or inflammation and improve diagnostic accuracy. However, primary cells fail to differentiate into ciliated cells through repeated passages. The conditional reprogramming culture (CRC) method, a combination of a Rho-kinase inhibitor and fibroblast feeder cells, has been applied to cystic fibrosis. The goal of this study was to evaluate the value of CRC in diagnosing PCD in Japanese patients. Eleven patients clinically suspected of having PCD were included. Airway epithelial cells were obtained from an endobronchial forceps biopsy and cultured at the air-liquid interface (ALI) combined with CRC. Ciliary movement, ultrastructure, and mutated ciliary protein evaluation were performed using HSVA, TEM, and IF, respectively. Genetic testing was performed on some patients. CRC yielded dense and well-differentiated ciliated cells with a high success rate (∼90%). In patients with PCD, the ciliary ultrastructure phenotype (outer dynein arm defects or normal ultrastructure) and IF findings (absence of the mutated ciliary protein) were confirmed after CRC. In DNAH11-mutant cases with normal ultrastructure by TEM, the HSVA revealed stiff and hyperfrequent ciliary beating with low bending capacity in CRC-expanded cells, thereby supporting the diagnosis. CRC could be a potential tool for improving diagnostic accuracy and contributing to future clinical and basic research in PCD.

Simultaneous visualization of flow fields and oxygen concentrations to unravel transport and metabolic processes in biological systems

SummaryFrom individual cells to whole organisms, O2 transport unfolds across micrometer- to millimeter-length scales and can change within milliseconds in response to fluid flows and organismal behavior. The spatiotemporal complexity of these processes makes the accurate assessment of O2 dynamics via currently available methods difficult or unreliable. Here, we present “sensPIV,” a method to simultaneously measure O2 concentrations and flow fields. By tracking O2-sensitive microparticles in flow using imaging technologies that allow for instantaneous referencing, we measured O2 transport within (1) microfluidic devices, (2) sinking model aggregates, and (3) complex colony-forming corals. Through the use of sensPIV, we find that corals use ciliary movement to link zones of photosynthetic O2 production to zones of O2 consumption. SensPIV can potentially be extendable to study flow-organism interactions across many life-science and engineering applications.

Spectrum of Genetic Variants in a Cohort of 37 Laterality Defect Cases.

Laterality defects are defined by the perturbed left–right arrangement of organs in the body, occurring in a syndromal or isolated fashion. In humans, primary ciliary dyskinesia (PCD) is a frequent underlying condition of defective left–right patterning, where ciliary motility defects also result in reduced airway clearance, frequent respiratory infections, and infertility. Non-motile cilia dysfunction and dysfunction of non-ciliary genes can also result in disturbances of the left–right body axis. Despite long-lasting genetic research, identification of gene mutations responsible for left–right patterning has remained surprisingly low. Here, we used whole-exome sequencing with Copy Number Variation (CNV) analysis to delineate the underlying molecular cause in 35 mainly consanguineous families with laterality defects. We identified causative gene variants in 14 families with a majority of mutations detected in genes previously associated with PCD, including two small homozygous CNVs. None of the patients were previously clinically diagnosed with PCD, underlining the importance of genetic diagnostics for PCD diagnosis and adequate clinical management. Identified variants in non-PCD-associated genes included variants in PKD1L1 and PIFO, suggesting that dysfunction of these genes results in laterality defects in humans. Furthermore, we detected candidate variants in GJA1 and ACVR2B possibly associated with situs inversus. The low mutation detection rate of this study, in line with other previously published studies, points toward the possibility of non-coding genetic variants, putative genetic mosaicism, epigenetic, or environmental effects promoting laterality defects.

E2f4 is required for intestinal and otolith development in zebrafish.

E2f4 is a multifunctional transcription factor that is essential for many cellular processes. Although the role of E2f4 during cell cycle progression has been investigated in great detail, less is known about E2f4 during embryonic development. Here, we investigated the role of E2f4 during zebrafish development. Zebrafish e2f4 mutants displayed ectopic otolith formation due to abnormal ciliary beating in the otic vesicle. The beating defects of motile cilia were caused by abnormal expression of ciliary motility genes. The expression of two genes, lrrc23 and ccdc151, were significantly decreased in the absence of E2f4. In addition to that, e2f4 mutants also displayed growth retardation both in the body length and body weightand mostly died at around 6 months old. Although food intake was normal in the mutants, we found that the microvilli of the intestinal epithelia were significantly affected in the mutants. Finally, the intestinal epithelia of e2f4 mutants also displayed reduced cell proliferation, together with an increased level of cell apoptosis. Our data suggested a tissue-specific role of E2f4 during zebrafish development, which is distinct from the traditional views of this protein as a transcription repressor.

Targeting mucin hypersecretion in COVID-19 therapy.

Targeting mucin hypersecretion in COVID-19 therapy.

On the Asymptotic Boundary Condition at the Free-Fluid/Porous-Medium Interface in Periciliary Layer due to the Ciliary Movement

The purpose of this study is to study the movement of the periciliary (PCL) fluid due to the ciliary locomotion. In this research, because the bundle of cilia is considered instead of a single cilium, Stokes–Brinkman equations in a macroscopic scale are employed to find the velocity of the PCL fluid. When the cilia are perpendicular to the horizontal plane, the PCL consists of only the cilia. The inclination of cilia (cilia make an angle θ θ < 90 ∘ to the horizontal plane) results in two different domains in the PCL, the regions comprising and not comprising cilia. The main objective of this study is to determine the appropriate boundary conditions of the velocity between these two regions where the PCL fluid is moved by self-propelled cilia rather than the pressure gradient. A matched asymptotic expansion method is applied to the Stokes–Brinkman equations to determine the constraints. Two boundary conditions at the interface are obtained and the velocity of the PCL fluid at the top of PCL can be used to be the boundary conditions at the bottom of the mucus layer to determine the velocity of mucus. This model can help engineers to build devices to treat patients who have problem with the respiratory system. Applications include modeling fluid flow through filters such as engine filter and rice fields.

DMBT1 is upregulated in cystic fibrosis, affects ciliary motility, and is reduced by acetylcysteine

BackgroundCystic fibrosis (CF) is the most common genetic disorder in the Caucasian population. Despite remarkable improvements in morbidity and mortality during the last decades, the disease still limits survival and reduces quality of life of affected patients. Moreover, CF still represents substantial economic burden for healthcare systems. Inflammation and infection already start in early life and play important roles in pulmonary impairment. The aim of this study is to analyze the potential role of DMBT1, a protein with functions in inflammation, angiogenesis, and epithelial differentiation, in CF.ResultsImmunohistochemically DMBT1 protein expression was upregulated in lung tissues of CF patients compared to healthy controls. Additionally, pulmonary expression of Dmbt1 was approximately 6-fold increased in an established transgenic mouse model of CF-like lung disease (ENaC tg) compared to wild-type mice as detected by qRT-PCR. Since acetylcysteine (ACC) has been shown to reduce inflammatory markers in the airways, its potential influence on DMBT1 expression was analyzed. A549 cells stably transfected with an expression plasmid encoding the largest (8kb) DMBT1 variant (DMBT1+ cells) or an empty vector control (DMBT1- cells) and incubated with ACC both showed significantly reduced DMBT1 concentrations in the culture medium (p = 0.0001). To further elucidate the function of DMBT1 in pulmonary airways, respiratory epithelial cells were examined by phase contrast microscopy. Addition of human recombinant DMBT1 resulted in altered cilia motility and irregular beat waves (p < 0.0001) suggesting a potential effect of DMBT1 on airway clearance.ConclusionsDMBT1 is part of inflammatory processes in CF and may be used as a potential biomarker for CF lung disease and a potential tool to monitor CF progression. Furthermore, DMBT1 has a negative effect on ciliary motility thereby possibly compromising airway clearance. Application of ACC, leading to reduced DMBT1 concentrations, could be a potential therapeutic option for CF patients.

Limitations of Nasal Nitric Oxide Measurement for Diagnosis of Primary Ciliary Dyskinesia with Normal Ultrastructure.

Rationale: Primary ciliary dyskinesia (PCD) is a heterogeneous, multisystem disorder characterized by defective ciliary beating. Diagnostic guidelines of the American Thoracic Society and European Respiratory Society recommend measurement of nasal nitric oxide (nNO) for PCD diagnosis. Several studies demonstrated low nNO production rates in PCD individuals, but underlying causes remain elusive. Objectives: To determine nNO production rates in a well-characterized PCD cohort, including subgroup analyses with regard to ultrastructural and ciliary beating phenotypes. Methods: This study included 301 individuals assessed according to European Respiratory Society guidelines. Diagnostic cutoffs for nNO production rates for this study cohort and subgroups with normal and abnormal ultrastructure were determined. Diagnostic accuracy was also tested for the widely used 77 nl/min cutoff in this study cohort. The relationship between nNO production rates and ciliary beat frequencies (CBFs) was evaluated. Results: The study cohort comprised 180 individuals with definite PCD diagnosis, including 160 individuals with genetic diagnosis, 16 individuals with probable PCD diagnosis, and 105 disease controls. The 77 nl/min nNO cutoff showed a test sensitivity of 0.92 and specificity of 0.86. Test sensitivity was lower (0.85) in the subgroup of 47 PCD individuals with normal ultrastructure compared with 133 PCD individuals with abnormal ultrastructure (0.95). The optimal diagnostic cutoff for the nNO production rate for the whole study cohort was 69.8 nl/min (sensitivity, 0.92; specificity, 0.89); however, it was 107.8 nl/min (sensitivity, 0.89; specificity, 0.78) for the subgroup of PCD with normal ultrastructure. PCD individuals with normal ultrastructure compared with abnormal ultrastructure showed higher ciliary motility. Consistently, PCD individuals with higher CBFs showed higher nNO production rates. In addition, laterality defects occurred less frequently in PCD with normal ultrastructure. Conclusions: Measurements of nNO below the widely used 77 nl/min cutoff are less sensitive in detecting PCD individuals with normal ultrastructure. Our findings indicate that higher nNO production in this subgroup with a higher cutoff for the nNO production rate (107.8 nl/min) and higher residual ciliary motility is dependent on the underlying molecular PCD defect. Higher nNO production rates, higher residual CBFs, and the lower prevalence of laterality defects hamper diagnosis of PCD with normal ultrastructure. Adjusting the cutoff of nNO production rate to 107.8 nl/min might promote diagnosing PCD with normal ultrastructure.

Crenotherapy as a Complementary and Integrative Treatment for Chronic Rhinosinusitis: A Systematic Review and Discussion of Current Evidence Limitations.

Chronic rhinosinusitis (CRS) is a common condition that affects patients' quality of life. Standard treatments for CRS have known side effects and variable efficacy rates. Thus, complementary and integrative (CIM) treatments for CRS such as crenotherapy, which utilizes high mineral content water or vapor as an inhalation therapy, are of continued interest. To summarize and evaluate the current research investigating crenotherapy's therapeutic potential and clinical outcomes for the treatment of CRS. Systematic review and qualitative analysis. A systematic review was performed, with a comprehensive search strategy applied to 6 databases from inception to March 2021: CINAHL, Cochrane, Embase, PubMed, Scopus, and Web of Science. Studies with at least 10 patients, which investigated crenotherapy as the sole or adjunctive treatment for CRS in humans were included. In total, 10 articles out of 756 were included. Of these, 6 were randomized controlled trials. The remaining four articles were non-randomized prospective cohort studies. Six studies assessed clinical symptoms in response to crenotherapy, and there were unanimous improvements in Visual Analog Scale (VAS), Sino-Nasal Outcome Test-20 (SNOT-20), and other quality of life metrics. The studies that assessed inflammatory markers, cytology, or other measures showed significant improvement in neutrophil count, spores, ciliary motility, IgE, and manometry. Minimal to no adverse events were reported across all 10 studies. There is limited data to support crenotherapy's effectiveness in treating patients with CRS. However, published studies suggest that for certain patients crenotherapy can both improve CRS symptoms and objective measures of nasociliary function with minimal side effects. Findings must be interpreted with caution due to study heterogeneity, inconsistent use of standard CRS definitions and outcomes measures, as well as other study design flaws. Given these results, as well as a growing interest in CIM, crenotherapy treatments for CRS deserve further investigation.