Toxoplasma gondii infection triggers ongoing inflammation mediated by increased intracellular Cl concentration in airway epithelium

Published:November 02, 2022DOI:


      • T. gondii secretes cysteine proteases to degrade CFTR expressed in airway epithelial cells.
      • Degradation of CFTR triggers airway inflammation via Cl-SGK1-NF-κB signaling.
      • T. gondii up-regulated PDE4 to evoke a sustained elevation in [Cl]i and ongoing inflammation.
      • Allicin exerted anti-Toxoplasma properties by reconstructing intracellular Cl homeostasis.


      Toxoplasma gondii is a widespread parasitic protozoan causing toxoplasmosis including pulmonary toxoplasmosis. As the first line of host defense, airway epithelial cells play critical roles in orchestrating pulmonary innate immunity. However, the mechanism underlying the airway inflammation induced by the T. gondii infection remains largely unclear. This study demonstrated that after infection with T. gondii, the major anion channel located in the apical membranes of airway epithelial cells, cystic fibrosis transmembrane conductance regulator (CFTR), was degraded by the parasite-secreted cysteine proteases. The intracellular Cl concentration ([Cl]i) was consequently elevated, leading to activation of nuclear factor-κB (NF-κB) signaling via serum/glucocorticoid regulated kinase 1. Furthermore, the heightened [Cl]i and activated NF-κB signaling could be sustained in a positive feedback regulatory manner resulting from decreased intracellular cAMP level through NF-κB-mediated up-regulation of phosphodiesterase 4. Conversely, the sulfur-containing compound allicin conferred anti-inflammatory effects on pulmonary toxoplasmosis by decreasing [Cl]i via activation of CFTR. These results suggest that the intracellular Cl dynamically modulated by T. gondii mediates sustained airway inflammation, which provides a potential therapeutic target against pulmonary toxoplasmosis.

      Graphical abstract



      [Cl−]i (intracellular Cl− concentration), ANO1 (anoctamin 1), ASL (airway surface liquid), CaCC (Ca2+-activated Cl− channel), CFTR (cystic fibrosis transmembrane conductance regulator), CP (cysteine protease), eGFP (enhanced green fluorescent protein), hAECs (human airway epithelial cells), HE (hematoxylin and eosin), IκB (inhibitor of NF-κB), IFN-γ (interferon-γ), IL (interleukin), ISC (short-circuit current), KO (knockout), mAECs (mouse airway epithelial cells), MOI (multiplicity of infection), NF-κB (nuclear factor-κB), PDE4 (phosphodiesterase 4), SD (standard deviation), SGK1 (serum/glucocorticoid regulated kinase 1), Sup (supernatant), Th (T helper), TLR (Toll-like receptor), TNF-α (tumor necrosis factor-α)
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        • Pittman KJ
        • Knoll LJ
        Long-term relationships: the complicated interplay between the host and the developmental stages of Toxoplasma gondii during acute and chronic infections.
        Microbiol Mol Biol Rev. 2015; 79: 387-401
        • Flegr J
        • Prandota J
        • Sovičková M
        • Israili ZH
        Toxoplasmosis - a global threat. Correlation of latent toxoplasmosis with specific disease burden in a set of 88 countries.
        PLoS One. 2014; 9: e90203
        • Almeria S
        • Dubey JP
        Foodborne transmission of Toxoplasma gondii infection in the last decade. An overview.
        Res Vet Sci. 2021; 135: 371-385
        • Teutsch SM
        • Juranek DD
        • Sulzer A
        • Dubey JP
        • Sikes RK
        Epidemic toxoplasmosis associated with infected cats.
        N Engl J Med. 1979; 300: 695-699
        • Eriz MS
        Atenea. 2007; 363: 145-158
        • Motta JPS
        • Cleinman IB
        • Bruno LP
        An immunocompetent young man with diffuse pulmonary infiltrates.
        Breathe. 2020; 16200165
        • Dubey JP
        History of the discovery of the life cycle of Toxoplasma gondii.
        Int J Parasitol. 2009; 39: 877-882
        • Smith JL
        Documented outbreaks of toxoplasmosis: Transmission of Toxoplasma gondii to humans.
        J Food Prot. 1993; 56: 630-639
        • Dubey JP
        Toxoplasmosis in humans (Homo sapiens).
        Toxoplasmosis of animals and humans. 2nd edition. CRC Press, 2009
        • Pomeroy C
        • Filice GA
        Pulmonary toxoplasmosis: A review.
        Clin Infect Dis. 1992; 14: 863-870
        • Dunay IR
        • Gajurel K
        • Dhakal R
        • Liesenfeld O
        • Montoya JG
        Treatment of toxoplasmosis : historical perspective, animal.
        Clin Microbiol Infect. 2018; 31e00057-17
        • Voynow JA
        • Mengr BKR
        Mucins, mucus, and sputum.
        Chest. 2009; 135: 505-512
        • Song Y
        • Namkung W
        • Nielson DW
        • Lee JW
        • Finkbeiner WE
        • Verkman AS
        Airway surface liquid depth measured in ex vivo fragments of pig and human trachea: Dependence on Na+ and Cl channel function.
        Am J Physiol - Lung Cell Mol Physiol. 2009; 297: L1131-L1140
        • Xu JB
        • Lu SJ
        • Ke LJ
        • Qiu ZE
        • Chen L
        • Zhang HL
        • et al.
        Trichomonas vaginalis infection impairs anion secretion in vaginal epithelium.
        PLoS Negl Trop Dis. 2021; 15e0009319
        • Savant AP
        • McColley SA
        Cystic fibrosis year in review 2019: Section 2 pulmonary disease and infections.
        Pediatr Pulmonol. 2020;
        • Wong XM
        • Younger S
        • Peters CJ
        • Jan YN
        • Jan LY
        Subdued, a TMEM16 family Ca2+-activated Cl channel in Drosophila melanogaster with an unexpected role in host defense.
        Elife. 2013; 2e00862
        • Zhang YL
        • Chen PX
        • Guan WJ
        • Guo HM
        • Qiu ZE
        • Xu JW
        • et al.
        Increased intracellular Cl concentration promotes ongoing inflammation in airway epithelium article.
        Mucosal Immunol. 2018; 11: 1149-1157
        • Guo HM
        • Gao JM
        • Luo YL
        • Wen YZ
        • Zhang YL
        • Hide G
        • et al.
        Infection by Toxoplasma gondii, a severe parasite in neonates and AIDS patients, causes impaired anion secretion in airway epithelia.
        Proc Natl Acad Sci U S A. 2015; 112: 4435-4440
        • Pena HFJ
        • Ferreira MN
        • Gennari SM
        • de Andrade HF
        • Meireles LR
        • Galisteo AJ
        Toxoplasma gondii isolated from a Brazilian patient with rare pulmonary toxoplasmosis has a novel genotype and is closely related to Amazonian isolates.
        Parasitol Res. 2021; 120: 1109-1113
        • Bajnok J
        • Tarabulsi M
        • Carlin H
        • Bown K
        • Southworth T
        • Dungwa J
        • et al.
        High frequency of infection of lung cancer patients with the parasite Toxoplasma gondii.
        ERJ Open Res. 2019; 500143-2018
        • Yarovinsky F
        Innate immunity to Toxoplasma gondii infection.
        Nat Rev Immunol. 2014; 14: 109-121
        • Lu YN
        • Zhao XD
        • Xu X
        • Piao J
        • Aosai F
        • Li YB
        • et al.
        Arctigenin exhibits hepatoprotective activity in Toxoplasma gondii-infected host through HMGB1/TLR4/NF-κB pathway.
        Int Immunopharmacol. 2020; 84106539
        • Sangaré LO
        • Yang N
        • Konstantinou EK
        • Lu D
        • Mukhopadhyay D
        • Young LH
        • et al.
        Toxoplasma GRA15 activates the NF-κB pathway through interactions with TNF receptor-associated factors.
        MBio. 2019; 10e00808-19
        • Guiton PS
        • Sagawa JM
        • Fritz HM
        • Boothroyd JC
        An in vitro model of intestinal infection reveals a developmentally regulated transcriptome of Toxoplasma sporozoites and a NF-κB-like signature in infected host cells.
        PLoS One. 2017; 12e0173018
        • Pilewski JM
        • Frizzell RA
        Role of CFTR in airway disease.
        Physiol Rev. 1999; 79: 215-255
        • Anderson MP
        • Gregory RJ
        • Thompson S
        • Souza DW
        • Paul S
        • Mulligan RC
        • et al.
        Demonstration that CFTR is a chloride channel by alteration of its anion selectivity.
        Science. 1991; 253: 202-205
        • Stauber T
        • Jentsch TJ
        Chloride in vesicular trafficking and function.
        Annu Rev Physiol. 2013; : 453-477
        • Hasegawa H
        • Skach W
        • Baker O
        • Calayag MC
        • Lingappa V
        • Verkman AS
        A multifunctional aqueous channel formed by CFTR.
        Science. 1992; 258: 1477-1479
        • Stratford FLL
        • Pereira MMC
        • Becq F
        • McPherson MA
        • Dormer RL
        Benzo(c)quinolizinium drugs inhibit degradation of ΔF508-CFTR cytoplasmic domain.
        Biochem Biophys Res Commun. 2003; 300: 524-530
        • Que X
        • Engel JC
        • Ferguson D
        • Wunderlich A
        • Tomavo S
        • Reed SL
        Cathepsin Cs are key for the intracellular survival of the protozoan parasite, Toxoplasma gondii.
        J Biol Chem. 2007; 282: 4994-5003
        • Lang F
        • Voelkl J
        Therapeutic potential of serum and glucocorticoid inducible kinase inhibition.
        Expert Opin Investig Drugs. 2013; 22: 701-714
        • Michalski JM
        • Golden G
        • Ikari J
        • Rennard SI
        PDE4: A novel target in the treatment of chronic obstructive pulmonary disease.
        Clin Pharmacol Ther. 2012; 91: 134-142
        • Banner KH
        • Trevethick MA
        PDE4 inhibition: A novel approach for the treatment of inflammatory bowel disease.
        Trends Pharmacol Sci. 2004; 25: 430-436
        • Cavallito CJ
        • Bailey JH
        Allicin, the antibacterial principle of Allium sativum. I. Isolation, physical properties and antibacterial action.
        J Am Chem Soc. 1944; 66: 1950-1951
        • Dai J
        • Chen Y
        • Jiang F
        Allicin reduces inflammation by regulating ROS/NLRP3 and autophagy in the context of A. fumigatus infection in mice.
        Gene. 2020; 762145042
        • Wang X
        • Zhang C
        • Chen C
        • Guo Y
        • Meng X
        • Kan C
        Allicin attenuates lipopolysaccharide-induced acute lung injuryin neonatal rats via the PI3K/Akt pathway.
        Mol Med Rep. 2018; 17: 6777-6783
        • Shen N
        • Cheng A
        • Qiu M
        • Zang G
        Allicin improves lung injury induced by sepsis via regulation of the toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MYD88)/nuclear factor kappa B (NF-κB) pathway.
        Med Sci Monit. 2019; 25: 2567-2576
        • Peng Y
        • Jiang Y
        • Ou H
        • Xing W
        • Yang M
        • Gao M
        Role of autophagy in ameliorating sepsis-induced acute lung injury by allicinin in mice.
        J Cent South Univ (Medical Sci). 2017; 42: 899-905
        • Cui T
        • Liu W
        • Chen S
        • Yu C
        • Li Y
        • Zhang JY
        Antihypertensive effects of allicin on spontaneously hypertensive rats via vasorelaxation and hydrogen sulfide mechanisms.
        Biomed Pharmacother. 2020; 128110240
        • Qiu ZE
        • Xu JB
        • Chen L
        • Huang ZX
        • Lei TL
        • Huang ZY
        • et al.
        Allicin facilitates airway surface liquid hydration by activation of CFTR.
        Front Pharmacol. 2022; 13890284
        • Rodriguez JB
        • Szajnman SH
        New antibacterials for the treatment of toxoplasmosis; A patent review.
        Expert Opin Ther Pat. 2012; 22: 311-333
        • Wohlfert EA
        • Blader IJ
        • Wilson EH
        Brains and brawn: Toxoplasma infections of the central nervous system and skeletal muscle.
        Trends Parasitol. 2017; 33: 519-531
        • Carruthers VB
        Proteolysis and Toxoplasma invasion.
        Int J Parasitol. 2006; 36: 595-600
        • Siqueira-Neto JL
        • Debnath A
        • McCall LI
        • Bernatchez JA
        • Ndao M
        • Reed SL
        • et al.
        Cysteine proteases in protozoan parasites.
        PLoS Negl Trop Dis. 2018; 12e0006512
        • Hutson SL
        • Wheeler KM
        • McLone D
        • Frim D
        • Penn R
        • Swisher CN
        • et al.
        Patterns of hydrocephalus caused by congenital Toxoplasma gondii infection associate with parasite genetics.
        Clin Infect Dis. 2015; 61: 1831-1834
        • Khan K
        • Khan W
        Congenital toxoplasmosis: An overview of the neurological and ocular manifestations.
        Parasitol Int. 2018; 67: 715-721
        • Patel AJ
        • Raol VH
        • Jea A
        Rare association between cystic fibrosis, Chiari I malformation, and hydrocephalus in a baby: A case report and review of the literature.
        J Med Case Rep. 2011; 5366
        • Hollenhorst MI
        • Richter K
        • Fronius M
        Ion transport by pulmonary epithelia.
        J Biomed Biotechnol. 2011; 2011174306
        • Toczyłowska-Mamińska R
        • Dołowy K
        Ion transporting proteins of human bronchial epithelium.
        J Cell Biochem. 2012; 113: 426-432
        • Valdivieso ÁG
        • Santa-Coloma TA
        The chloride anion as a signalling effector.
        Biol Rev. 2019; 94: 1839-1856
        • Harari Y
        • Russell DA
        • Castro GA
        Anaphylaxis-mediated epithelial Cl secretion and parasite rejection in rat intestine.
        J Immunol. 1987; 138: 1250-1255
        • Xu JB
        • Zhang YL
        • Huang J
        • Lu SJ
        • Sun Q
        • Chen PX
        • et al.
        Increased intracellular Cl concentration mediates Trichomonas vaginalis-induced inflammation in the human vaginal epithelium.
        Int J Parasitol. 2019; 49: 697-704
        • Lang F
        • Böhmer C
        • Palmada M
        • Seebohm G
        • Strutz-Seebohm N
        • Vallon V
        (Patho)physiological significance of the serum- and glucocorticoid- inducible kinase isoforms.
        Physiol Rev. 2006; 86: 1151-1178
        • Waerntges S
        • Klingel K
        • Weigert C
        • Fillon S
        • Buck M
        • Schleicher E
        • et al.
        Excessive transcription of the human serum and glucocorticoid dependent kinase hSGK1 in lung fibrosis.
        Cell Physiol Biochem. 2002; 12: 135-142
        • Gan W
        • Li T
        • Ren J
        • Li C
        • Liu Z
        • Yang M
        Serum–glucocorticoid-regulated kinase 1 contributes to mechanical stretch-induced inflammatory responses in cardiac fibroblasts.
        Mol Cell Biochem. 2018; 445: 67-78
        • Lister K
        • Autelitano DJ
        • Jenkins A
        • Hannan RD
        • Sheppard KE
        Cross talk between corticosteroids and alpha-adrenergic signalling augments cardiomyocyte hypertrophy: A possible role for SGK1.
        Cardiovasc Res. 2006; 70: 555-565
        • Das S
        • Aiba T
        • Rosenberg M
        • Hessler K
        • Xiao C
        • Quintero PA
        Pathological role of serum- and glucocorticoid-regulated kinase 1 in adverse ventricular remodeling.
        Circulation. 2012; 126: 2208-2219
        • Voelkl J
        • Lin Y
        • Alesutan I
        • Ahmed MSE
        • Pasham V
        • Mia S
        • et al.
        Sgk1 sensitivity of Na+/H+ exchanger activity and cardiac remodeling following pressure overload.
        Basic Res Cardiol. 2012; 107236
        • Hansen BF
        Pathology of the heart in AIDS: A study of 60 consecutive autopsies.
        APMIS. 1992; 100: 273-279
        • Dambaeva S
        • Bilal M
        • Schneiderman S
        • Germain A
        • Fernandez E
        • Kwak-Kim J
        • et al.
        Decidualization score identifies an endometrial dysregulation in samples from women with recurrent pregnancy losses and unexplained infertility.
        F&S Reports. 2021; 2: 95-103
        • El-Tantawy N
        • Taman A
        • Shalaby H
        Toxoplasmosis and female infertility: Is there a co-relation?.
        Am J Epidemiol Infect Dis. 2014; 2: 29-32
        • Fallahi S
        • Rostami A
        • Nourollahpour Shiadeh M
        • Behniafar H
        • Paktinat S
        An updated literature review on maternal-fetal and reproductive disorders of Toxoplasma gondii infection.
        J Gynecol Obstet Hum Reprod. 2018; 47: 133-140
        • Colinot DL
        • Garbuz T
        • Bosland MC
        • Wang L
        • Rice SE
        • Sullivan Jr WJ
        • et al.
        The common parasite Toxoplasma gondii induces prostatic inflammation and microglandular hyperplasia in a mouse model.
        Prostate. 2017; 77: 1066-1075
        • Hsien Lai S
        • Zervoudakis G
        • Chou J
        • Gurney ME
        • Quesnelle KM
        PDE4 subtypes in cancer.
        Oncogene. 2020; 39: 3791-3802
        • Page CP
        Phosphodiesterase inhibitors for the treatment of asthma and chronic obstructive pulmonary disease.
        Int Arch Allergy Immunol. 2014; 165: 152-164
        • Lugnier C
        Cyclic nucleotide phosphodiesterase (PDE) superfamily: A new target for the development of specific therapeutic agents.
        Pharmacol Ther. 2006; 109: 366-398
        • Sunke R
        • Bankala R
        • Thirupataiah B
        • Ramarao EVVS
        • Kumar JS
        • Doss HM
        • et al.
        InCl3 mediated heteroarylation of indoles and their derivatization via CH activation strategy: Discovery of 2-(1H-indol-3-yl)-quinoxaline derivatives as a new class of PDE4B selective inhibitors for arthritis and/or multiple sclerosis.
        Eur J Med Chem. 2019; 174: 198-215
        • Afifi MA
        • Al-Rabia MW
        The immunomodulatory effects of rolipram abolish drug-resistant latent phase of Toxoplasma gondii infection in a murine model.
        J Microsc Ultrastruct. 2015; 3: 86-91
        • Neal LM
        • Knoll LJ
        Toxoplasma gondii profilin promotes recruitment of Ly6Chi CCR2+ inflammatory monocytes that can confer resistance to bacterial infection.
        PLoS Pathog. 2014; 10e1004203
        • Wagner A
        • Förster-Waldl E
        • Garner-Spitzer E
        • Schabussova I
        • Kundi M
        • Pollak A
        • et al.
        Immunoregulation by Toxoplasma gondii infection prevents allergic immune responses in mice.
        Int J Parasitol. 2009; 39: 465-472
        • Fenoy I
        • Giovannoni M
        • Batalla E
        • Martin V
        • Frank FM
        • Piazzon I
        • et al.
        Toxoplasma gondii infection blocks the development of allergic airway inflammation in BALB/c mice.
        Clin Exp Immunol. 2009; 155: 275-284
        • Harris JC
        • Cottrell SL
        • Plummer S
        • Lloyd D.
        Antimicrobial properties of Allium sativum (garlic).
        Appl Microbiol Biotechnol. 2001; 57: 282-286
        • Lun ZR
        • Burri C
        • Menzinger M
        • Kaminsky R
        Antiparasitic activity of diallyl trisulfide (Dasuansu) on human and animal pathogenic protozoa (Trypanosoma sp., Entamoeba histolytica and Giardia lamblia) in vitro.
        Ann Soc Belg Med Trop. 1994; 74: 51-59
        • Rahman MS.
        Allicin and other functional active components in garlic: Health benefits and bioavailability.
        Int J Food Prop. 2007; 10: 245-268
        • Gruhlke MCH
        • Slusarenko AJ
        The biology of reactive sulfur species (RSS).
        Plant Physiol Biochem. 2012; 59: 98-107
        • Reiter J
        • Levina N
        • Van Der Linden M
        • Gruhlke M
        • Martin C
        • Slusarenko AJ
        Diallylthiosulfinate (Allicin), a volatile antimicrobial from garlic (Allium sativum), kills human lung pathogenic bacteria, including MDR strains, as a vapor.
        Molecules. 2017; 221711
        • Atmaca HT
        • Gazyagci AN
        • Canpolat S
        • Kul O
        Hepatic stellate cells increase in Toxoplasma gondii infection in mice.
        Parasit Vectors. 2013; 6135
        • Pope SM
        • Lässer C
        Toxoplasma gondii infection of fibroblasts causes the production of exosome-like vesicles containing a unique array of mRNA and miRNA transcripts compared to serum starvation.
        J Extracell Vesicles. 2013; 222484
        • Chen PX
        • Zhang YL
        • Xu JW
        • Yu MH
        • Huang JH
        • Zhao L
        • et al.
        Sodium tanshinone IIA sulfonate stimulated Cl secretion in mouse trachea.
        PLoS One. 2017; 12e0178226