A Review: Expression of Aquaporins in Otitis Media

Does Helicobacter pylori have a role in the pathogenesis of otitis media with effusion, or is it a fallacy??

PURPOSE

Helicobacter pylori, causing chronic systemic infection, may colonize in middle ear milieu and conduce to effusion collection. Many investigations on relationship between pathogenesis of otitis media with effusion (OME) and Helicobacter pylori yielded conflicting results. We investigated Helicobacter pylori presence in effusion and adenoid samples of children having OME and in middle ear and adenoid samples of children with healthy middle ears to elucidate its role on OME pathogenesis.

METHODS

This prospective case-control study included 300 patients aged 1-12 years. One-hundred effusion samples collected from 100 children undergoing ventilation tube insertion and adenoidectomy due to chronic OME and adenoid hypertrophy formed study group, and 100 adenoid samples collected from adenoids of these children formed Group-1. One-hundred healthy-looking middle ear irrigation solutions collected from 100 children undergoing cochlear implantation formed Group-2. One-hundred adenoid samples collected from 100 children having no effusion and only undergoing adenoidectomy formed Group-3. After DNA isolation of samples, Helicobacter pylori 16 S rRNA and 23 S rRNA gene for clarithromycin-resistance were investigated by real time-polymerase chain reaction (Rt-PCR).

RESULTS

The median age of 300 children was 5, and 179 were boys and 121 were girls. Helicobacter pylori was detected by Rt-PCR in none (%0) of the 400 samples (200 middle ear, 200 adenoid).

CONCLUSION

In this largest sample-size study utilizing updated molecular methods to date, negative results indicate that Helicobacter pylori does not play role as an active pathogen in polymicrobiality of OME, and adenoids do not serve as a reservoir for Helicobacter pylori in this process.

Exploring Aquaporins in Human Studies: Mechanisms and Therapeutic Potential in Critical Illness

Aquaporins (AQPs) are membrane proteins facilitating water and other small solutes to be transported across cell membranes. They are crucial in maintaining cellular homeostasis by regulating water permeability in various tissues. Moreover, they regulate cell migration, signaling pathways, inflammation, tumor growth, and metastasis. In critically ill patients, such as trauma, sepsis, and patients with acute respiratory distress syndrome (ARDS), which are frequently encountered in intensive care units (ICUs), water transport regulation is crucial for maintaining homeostasis, as dysregulation can lead to edema or dehydration, with the latter also implicating hemodynamic compromise. Indeed, AQPs are involved in fluid transport in various organs, including the lungs, kidneys, and brain, where their dysfunction can exacerbate conditions like ARDS, acute kidney injury (AKI), or cerebral edema. In this review, we discuss the implication of AQPs in the clinical entities frequently encountered in ICUs, such as systemic inflammation and sepsis, ARDS, AKI, and brain edema due to different types of primary brain injury from a clinical perspective. Current and possible future therapeutic implications are also considered.

Aquaporins: Potential Targets in Inflammatory Diseases

Inflammation involves a long chain of molecular reactions and cellular activity designed to repair tissue damaged by various causes. The inflammatory process and its complex mechanisms have recently become a focus of interest for many researchers. After the onset of inflammation, various adverse conditions that initiate the inflammatory response need to be addressed; however, failure to limit the inflammatory reaction may result in the damage or destruction of host cells. Therefore, inflammatory reactions play a role in many diferent diseases. Aquaporins (AQPs), commonly referred to as water channels, are protein channels responsible for forming pores in the membranes of biological cells. Their main function is to aid in the movement of water between cells. Aquaporins not only regulate transepithelial fluid transport across membranes but also play a role in regulating essential events crucial for the inflammatory response. Aquaporins have been shown in many studies to have important roles in inflammatory diseases. This clearly indicates that AQPs may be potential targets for inflammatory diseases. This review summarizes the research to date on the structure and function of AQPs and provides an update on the relationship between AQPs and various human inflammatory diseases.

Aquaporins and diseases pathogenesis: From trivial to undeniable involvements, a disease-based point of view

Aquaporins (AQPs), as transmembrane proteins, were primarily identified as water channels with the ability of regulating the transmission of water, glycerol, urea, and other small-sized molecules. The classic view of AQPs involvement in therapeutic plan restricted them and their regulators into managing only a narrow spectrum of the diseases such as diabetes insipidus and the syndrome of inappropriate ADH secretion. However, further investigations performed, especially in the third millennium, has found that their cooperation in water transmission control can be manipulated to handle other burden-imposing diseases such as cirrhosis, heart failure, Meniere's disease, cancer, bullous pemphigoid, eczema, and Sjögren's syndrome.

Human Aquaporins: Functional Diversity and Potential Roles in Infectious and Non-infectious Diseases

Aquaporins (AQPs) are integral membrane proteins and found in all living organisms from bacteria to human. AQPs mainly involved in the transmembrane diffusion of water as well as various small solutes in a bidirectional manner are widely distributed in various human tissues. Human contains 13 AQPs (AQP0-AQP12) which are divided into three sub-classes namely orthodox aquaporin (AQP0, 1, 2, 4, 5, 6, and 8), aquaglyceroporin (AQP3, 7, 9, and 10) and super or unorthodox aquaporin (AQP11 and 12) based on their pore selectivity. Human AQPs are functionally diverse, which are involved in wide variety of non-infectious diseases including cancer, renal dysfunction, neurological disorder, epilepsy, skin disease, metabolic syndrome, and even cardiac diseases. However, the association of AQPs with infectious diseases has not been fully evaluated. Several studies have unveiled that AQPs can be regulated by microbial and parasitic infections that suggest their involvement in microbial pathogenesis, inflammation-associated responses and AQP-mediated cell water homeostasis. This review mainly aims to shed light on the involvement of AQPs in infectious and non-infectious diseases and potential AQPs-target modulators. Furthermore, AQP structures, tissue-specific distributions and their physiological relevance, functional diversity and regulations have been discussed. Altogether, this review would be useful for further investigation of AQPs as a potential therapeutic target for treatment of infectious as well as non-infectious diseases.

Expression, Distribution and Role of Aquaporins in Various Rhinologic Conditions

Aquaporins (AQPs) are water-specific membrane channel proteins that regulate cellular and organismal water homeostasis. The nose, an organ with important respiratory and olfactory functions, is the first organ exposed to external stimuli. Nose-related topics such as allergic rhinitis (AR) and chronic rhinosinusitis (CRS) have been the subject of extensive research. These studies have reported that mechanisms that drive the development of multiple inflammatory diseases that occur in the nose and contribute to the process of olfactory recognition of compounds entering the nasal cavity involve the action of water channels such as AQPs. In this review, we provide a comprehensive overview of the relationship between AQPs and rhinologic conditions, focusing on the current state of knowledge and mechanisms that link AQPs and rhinologic conditions. Key conclusions include the following: (1) Various AQPs are expressed in both nasal mucosa and olfactory mucosa; (2) the expression of AQPs in these tissues is different in inflammatory diseases such as AR or CRS, as compared with that in normal tissues; (3) the expression of AQPs in CRS differs depending on the presence or absence of nasal polyps; and (4) the expression of AQPs in tissues associated with olfaction is different from that in the respiratory epithelium.

Decreased expression of autophagy markers in culture-positive patients with chronic otitis media

Objective

Abnormal autophagy plays a role in the pathogenesis of various diseases. This study aimed to evaluate associations between the clinical manifestations of chronic otitis media (COM) and expression of autophagy markers.

Methods

Associations between presence of bacteria, otorrhea, and conductive and sensorineural hearing loss and levels of autophagy-related mRNAs were investigated in 47 patients with COM.

Results

Autophagy-related mRNAs were detected in all inflammatory tissues of COM patients. LC3-II showed the highest level of expression, followed by Beclin-1, P13KC3, Rubicon, and mTOR. Beclin-1 mRNA levels were significantly lower in culture-positive than in culture-negative patients.

Conclusion

Autophagy is involved in the pathogenesis of COM. The finding that expression of autophagy markers, especially Beclin-1, was lower in culture-positive than in culture-negative patients suggested that these markers are closely associated with the clinical features of COM.

Expression of aquaporins in inner ear disease

The inner ear is responsible for hearing and balance and consists of a membranous labyrinth within a bony labyrinth. The balance structure is divided into the otolith organ that recognizes linear acceleration and the semicircular canal that is responsible for rotational movement. The cochlea is the hearing organ. The external and middle ear are covered with skin and mucosa, respectively, and the space is filled with air, whereas the inner ear is composed of endolymph and perilymph. The inner ear is a fluid-filled sensory organ composed of hair cells with cilia on the upper part of the cells that convert changes in sound energy and balance into electric energy through the hair cells to transmit signals to the auditory nerve through synapses. Aquaporins (AQPs) are a family of transmembrane proteins present in all species that can be roughly divided into three subfamilies according to structure and function: 1) classical AQP, 2) aquaglyceroporin, and 3) superaquaporin. Currently, the subfamily of mammalian species is known to include 13 AQP members (AQP0-AQP12). AQPs have a variety of functions depending on their structure and are related to inner ear diseases such as Meniere's disease, sensorineural hearing loss, and presbycusis. Additional studies on the relationship between the inner ear and AQPs may be helpful in the diagnosis and treatment of inner ear disease. Laryngoscope, 130:1532-1539, 2020.

Comparative Analysis of the aquaporin Gene Family in 12 Fish Species

Simple Summary

Aquaporins (Aqps) are a group of membrane proteins. In this study, 166 Aqp genes were identified in 12 fish species. Gene organization, motif distribution, recombination, and selection pressure were performed to investigate their evolutionary characteristics. In addition, expression profiles of Aqps were also examined under pathogens infection and organophosphorus pesticide stress. This study will provide a useful reference for further functional study.

Abstract

Aquaporins (Aqps) are a class of water channel proteins that play key roles in many physiological functions and cellular processes. Here, we analyzed 166 putative Aqp genes in 12 fish species and divided them into four groups. Gene organization and motif distribution analyses suggested potentially conserved functions in each group. Several recombination events were identified in some members, which accelerate their divergence in evolution. Furthermore, a few positive selection sites were identified, and mutations at these sites could alter the stability of Aqp proteins. In addition, expression profiles of some Aqp genes under pathogen infection and organophosphorus pesticide stress were also investigated. The result implied that several Aqp genes may affect different immune responses and osmoregulation. This study provides a comparative analysis of the fish Aqp gene family to facilitate further functional analyses.