Respiratory diseases

Breathing ion channels.

Ion channels and transporters involved in respiratory diseases

Respiratory disease is a growing medical issue due to lifestyle, environmental and genetic factors, with research ongoing to find treatments for asthma, cough, chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and cystic fibrosis (CF). Ion channels are potential therapeutic targets for several respiratory diseases, which include purinergic receptors to treat chronic cough and the CFTR channel expressed in lung airway epithelium for CF. The role of ion channels and transporters in viral respiratory disease has also been highlighted by the recent COVID-19 pandemic, where they facilitate viral entry and replication, whilst also playing a role in the immune response and inflammation.

From CFTR to viroporins

Ion channels in chronic cough and CFTR

Chronic cough is one of the major reasons for GP visits in the US. In recent years, P2X3 ionotropic receptors have been implicated in respiratory hyperactivity seen in asthma and chronic cough. Several P2X3 inhibitors have reached clinical trials for chronic and refractory cough, although adverse effects on taste sensation have been reported and it is hoped that more selective drugs will reduce these side effects. In addition, some voltage-gated Na+ channels such as NaV1.3 and NaV1.7  are attractive targets for cough therapeutics due to their presence on sensory and vagal nerves.

Cystic Fibrosis is a rare fatal hereditary lung disease. Mutations in the cystic fibrosis conductance regulator (CFTR) in airway epithelia affect electrolyte transport, mucus obstruction, neutrophilic inflammation and bacterial infection, leading to chronic lung disease and premature mortality. Another potential target for the treatment of CF is TMEM16A, a calcium-activated chloride channel expressed in airway surface epithelium as well as in submucosal glands and goblet cells. Recently, a positive modulator of TMEM16A was shown to enhance anion and fluid secretion from cystic fibrosis patients. This target mechanism presents a novel approach to treat a wide range of cystic fibrosis patients and other respiratory disorders.

Online data analysis of CFTR expressing CHO cells as recorded on SyncroPatch 384, using one NPC-384 (multi-hole, 8 holes per well) patch clamp chip. Three hundred and eighty-four small color-coded pictures as seen in the upper left part display 384 recordings. One highlighted experiment is displayed at the bottom, 16 selected experiments are displayed on the right. Graphs show current amplitudes of CFTR activated by external forskolin (10 µM; white region), potentiation by increasing concentrations of genistein (1, 10, 100 µM; blue regions), and full block by 300 µM glibenclamide (grey region).

Ion channels in respiratory viral infections and immunity

The recent COVID-19 pandemic in 2020 - 2022 has highlighted the importance of ion channels in viral entry into human cells, viral replication and anti-viral immunity. For example, viroporins are small integral membrane ion channels essential for the life cycle of a diverse range of RNA and DNA viruses. Viroporins are potential drug targets for the block of viral replication and the spread of infection, with examples including envelope E protein cation channel in SARS CoV-2, M2 proton channel in influenza virus, polio virus 2B Ca2+ channel, and the hepatitis virus p7 proton channel. On the other hand, two pore channels (TPC) have been shown to play a key role in Ebola virus infection. In endosomal membranes they are responsible for entry of Ebola virus and may provide a therapeutic target as an antiviral for Ebola virus and other filoviruses.

Ca2+-release activated calcium (CRAC) channels are required for the differentiation and function of T lymphocytes, thus providing immunity to infection, as well as mediating inflammation and preventing autoimmunity. Therefore, CRAC inhibitors could be novel therapeutics for autoimmune or inflammatory conditions. For example, the CRAC channel blocker, CM4620-IE, from CalciMedica has recently entered Phase II clinical trials to prevent a cytokine storm in COVID-19 patients. Additionally, volume-regulated anion channels (VRAC) have been shown to play a crucial role in anti-viral immunity via cGAMP transmission between cells mediated by these ion channels.


Recordings of LRRC8 from wild type (WT) and LRRC8A-/- knockout (KO) HaCaT keratinocytes measured on the Patchliner. Shown are current responses to a voltage ramp protocol in isotonic and hypotonic solution and the corresponding timecourse of the experiment from the two groups of cells.

Transporters in respiratory viral transmission

In addition to ion channels, some transporters have also been implicated in virus recognition and infection. The sodium-dependent neutral amino acid transporter B0AT1 is a protein that mediates epithelial resorption of neutral amino acids across the apical membrane in the kidney and intestine.  Recently it has been shown that the angiotensin-converting enzyme 2 (ACE2) and B0AT1 protein form a complex for recognition of the SARS-CoV-2 virus, thereby playing a role in coronavirus recognition and infection.

B0AT1 expressed in  CHO cell membranes was activated on the SURFE2R 96. (A) Activation buffer containing leucine was used to induce electrical currents. The presence of both leucine and Na+ were required to activate B0AT1. (B) Testing of stereoselectivity of B0AT1 membranes demonstrated a preference for l-leucine. (C) When B0AT1 was not expressed, no currents were recorded. (D) Dependence of leucine transport on decreasing Na+ concentrations.

Gerbeth-Kreul C., et al., SLAS Discovery. (2021)

Ion channels and transporters in respiratory diseases

Chronic cough
P2X3, NaV1.3, NaV1.7
Cystic Fibrosis
Autoimmune/ inflammatory conditions
Viral entry, replication and immunity
Viroporins, TPC, VRAC, B0AT1

Assay platforms for

respiratory disease research

Automated patch clamp,
transporter assays and bilayers

Automated patch clamp platforms are well suited to study ion channels involved in respiratory diseases. Purinergic P2X receptors can be recorded using the Port-a-Patch, Patchliner and SyncroPatch 384, taking advantage of the fast external solution exchange. Block of P2X3 and P2X2/3 receptors by gefapixant has been shown on the Port-a-Patch in a paper published in the British Journal of Pharmacology in 2019. The Patchliner is routinely used in cystic fibrosis research to record the CFTR and F508del-CFTR using fluoride-free internal solution (Billet, A., et al., Front. Pharmacol. (2017); Becq F., et al., Eur. Resp. J. (2021). The use of internal exchange on the Patchliner and internal perfusion on the SyncroPatch 384 can be used to activate currents with Ca2+ or cAMP on the inside of the cell after whole-cell access has been achieved.

Transporters involved in viral recognition and immunity can be recorded on the SURFE2R N1 and at higher throughput on the SURFE2R 96 instruments and recombinant viral proteins such as viroporins can be reconstituted into bilayers and recorded on the Orbit mini and Orbit 16 TC. The Vesicle Prep Pro can be used to make giant unilamellar vesicles for expression of viral proteins and transporters for further studies.

How can we help you?

Contact our specialist Dr. Cecilia George (HQ Senior Sales Manager SURFE2R / Senior Scientist ). Cecilia is delighted to help you: