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Rodriguez Galvan JJ, de Vries M, Belblidia S, Fisher A, Prescott RA, Crosse KM, Mangel WF, Duerr R, Dittmann M. In-silico docking platform with serine protease inhibitor (SERPIN) structures identifies host cysteine protease targets with significance for SARS-CoV-2. bioRxiv 2024:2022.11.18.517133. [PMID: 36415456 PMCID: PMC9681043 DOI: 10.1101/2022.11.18.517133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Serine Protease Inhibitors (SERPINs) regulate protease activity in various physiological processes such as inflammation, cancer metastasis, angiogenesis, and neurodegenerative diseases. However, their potential in combating viral infections, where proteases are also crucial, remains underexplored. This is due to our limited understanding of SERPIN expression during viral-induced inflammation and of the SERPINs' full spectrum of target proteases. Here, we demonstrate widespread expression of human SERPINs in response to respiratory virus infections, both in vitro and in vivo , alongside classical antiviral effectors. Through comprehensive in-silico docking with full-length SERPIN and protease 3D structures, we confirm known inhibitors of specific proteases; more importantly, the results predict novel SERPIN-protease interactions. Experimentally, we validate the direct inhibition of key proteases essential for viral life cycles, including the SERPIN PAI-1's capability to inhibit select cysteine proteases such as cathepsin L, and the serine protease TMPRSS2. Consequently, PAI-1 suppresses spike maturation and multi-cycle SARS-CoV-2 replication. Our findings challenge conventional notions of SERPIN selectivity, underscore the power of in-silico docking for SERPIN target discovery, and offer potential therapeutic interventions targeting host proteolytic pathways to combat viruses with urgent unmet therapeutic needs. SIGNIFICANCE Serine protease inhibitors (SERPINs) play crucial roles in various physiological processes, including viral infections. However, our comprehension of the full array of proteases targeted by the SERPIN family has traditionally been limited, hindering a comprehensive understanding of their regulatory potential. We developed an in-silico docking platform to identify new SERPIN target proteases expressed in the respiratory tract, a critical viral entry portal. The platform confirmed known and predicted new targets for every SERPIN examined, shedding light on previously unrecognized patterns in SERPIN selectivity. Notably, both key proteases for SARS-CoV-2 maturation were among the newly predicted targets, which we validated experimentally. This underscores the platform's potential in uncovering targets with significance in viral infections, paving the way to define the full potential of the SERPIN family in infectious disease and beyond.
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Prescott RA, Pankow AP, de Vries M, Crosse KM, Patel RS, Alu M, Loomis C, Torres V, Koralov S, Ivanova E, Dittmann M, Rosenberg BR. A comparative study of in vitro air-liquid interface culture models of the human airway epithelium evaluating cellular heterogeneity and gene expression at single cell resolution. Respir Res 2023; 24:213. [PMID: 37635251 PMCID: PMC10464153 DOI: 10.1186/s12931-023-02514-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 08/17/2023] [Indexed: 08/29/2023] Open
Abstract
BACKGROUND The airway epithelium is composed of diverse cell types with specialized functions that mediate homeostasis and protect against respiratory pathogens. Human airway epithelial (HAE) cultures at air-liquid interface are a physiologically relevant in vitro model of this heterogeneous tissue and have enabled numerous studies of airway disease. HAE cultures are classically derived from primary epithelial cells, the relatively limited passage capacity of which can limit experimental methods and study designs. BCi-NS1.1, a previously described and widely used basal cell line engineered to express hTERT, exhibits extended passage lifespan while retaining the capacity for differentiation to HAE. However, gene expression and innate immune function in BCi-NS1.1-derived versus primary-derived HAE cultures have not been fully characterized. METHODS BCi-NS1.1-derived HAE cultures (n = 3 independent differentiations) and primary-derived HAE cultures (n = 3 distinct donors) were characterized by immunofluorescence and single cell RNA-Seq (scRNA-Seq). Innate immune functions were evaluated in response to interferon stimulation and to infection with viral and bacterial respiratory pathogens. RESULTS We confirm at high resolution that BCi-NS1.1- and primary-derived HAE cultures are largely similar in morphology, cell type composition, and overall gene expression patterns. While we observed cell-type specific expression differences of several interferon stimulated genes in BCi-NS1.1-derived HAE cultures, we did not observe significant differences in susceptibility to infection with influenza A virus and Staphylococcus aureus. CONCLUSIONS Taken together, our results further support BCi-NS1.1-derived HAE cultures as a valuable tool for the study of airway infectious disease.
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Affiliation(s)
- Rachel A Prescott
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Alec P Pankow
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Maren de Vries
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Keaton M Crosse
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Roosheel S Patel
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Mark Alu
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Cynthia Loomis
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Victor Torres
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Sergei Koralov
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Ellie Ivanova
- Department of Pathology, NYU Grossman School of Medicine, New York, NY, 10016, USA
| | - Meike Dittmann
- Department of Microbiology, NYU Grossman School of Medicine, New York, NY, 10016, USA.
| | - Brad R Rosenberg
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.
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Prescott RA, Pankow AP, de Vries M, Crosse K, Patel RS, Alu M, Loomis C, Torres V, Koralov S, Ivanova E, Dittmann M, Rosenberg BR. A comparative study of in vitro air-liquid interface culture models of the human airway epithelium evaluating cellular heterogeneity and gene expression at single cell resolution. bioRxiv 2023:2023.02.27.530299. [PMID: 36909601 PMCID: PMC10002689 DOI: 10.1101/2023.02.27.530299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
The airway epithelium is composed of diverse cell types with specialized functions that mediate homeostasis and protect against respiratory pathogens. Human airway epithelial cultures at air-liquid interface (HAE) are a physiologically relevant in vitro model of this heterogeneous tissue, enabling numerous studies of airway disease 1â€"7 . HAE cultures are classically derived from primary epithelial cells, the relatively limited passage capacity of which can limit experimental methods and study designs. BCi-NS1.1, a previously described and widely used basal cell line engineered to express hTERT, exhibits extended passage lifespan while retaining capacity for differentiation to HAE 5 . However, gene expression and innate immune function in HAE derived from BCi-NS1.1 versus primary cells have not been fully characterized. Here, combining single cell RNA-Seq (scRNA-Seq), immunohistochemistry, and functional experimentation, we confirm at high resolution that BCi-NS1.1 and primary HAE cultures are largely similar in morphology, cell type composition, and overall transcriptional patterns. While we observed cell-type specific expression differences of several interferon stimulated genes in BCi-NS1.1 HAE cultures, we did not observe significant differences in susceptibility to infection with influenza A virus and Staphylococcus aureus . Taken together, our results further support BCi-NS1.1-derived HAE cultures as a valuable tool for the study of airway infectious disease.
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Affiliation(s)
| | - Alec P. Pankow
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai
| | - Maren de Vries
- Department of Microbiology, NYU Grossman School of Medicine
| | - Keaton Crosse
- Department of Microbiology, NYU Grossman School of Medicine
| | - Roosheel S. Patel
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai
| | - Mark Alu
- Department of Pathology, NYU Grossman School of Medicine
| | - Cynthia Loomis
- Department of Pathology, NYU Grossman School of Medicine
| | - Victor Torres
- Department of Microbiology, NYU Grossman School of Medicine
| | - Sergei Koralov
- Department of Pathology, NYU Grossman School of Medicine
| | - Ellie Ivanova
- Department of Pathology, NYU Grossman School of Medicine
| | - Meike Dittmann
- Department of Microbiology, NYU Grossman School of Medicine
| | - Brad R. Rosenberg
- Department of Microbiology, The Icahn School of Medicine at Mount Sinai
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Perelman SS, James DBA, Boguslawski KM, Nelson CW, Ilmain JK, Zwack EE, Prescott RA, Mohamed A, Tam K, Chan R, Narechania A, Pawline MB, Vozhilla N, Moustafa AM, Kim SY, Dittmann M, Ekiert DC, Bhabha G, Shopsin B, Planet PJ, Koralov SB, Torres VJ. Genetic variation of staphylococcal LukAB toxin determines receptor tropism. Nat Microbiol 2021; 6:731-745. [PMID: 33875847 PMCID: PMC8597016 DOI: 10.1038/s41564-021-00890-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 03/11/2021] [Indexed: 02/02/2023]
Abstract
Staphylococcus aureus has evolved into diverse lineages, known as clonal complexes (CCs), which exhibit differences in the coding sequences of core virulence factors. Whether these alterations affect functionality is poorly understood. Here, we studied the highly polymorphic pore-forming toxin LukAB. We discovered that the LukAB toxin variants produced by S. aureus CC30 and CC45 kill human phagocytes regardless of whether CD11b, the previously established LukAB receptor, is present, and instead target the human hydrogen voltage-gated channel 1 (HVCN1). Biochemical studies identified the domain within human HVCN1 that drives LukAB species specificity, enabling the generation of humanized HVCN1 mice with enhanced susceptibility to CC30 LukAB and to bloodstream infection caused by CC30 S. aureus strains. Together, this work advances our understanding of an important S. aureus toxin and underscores the importance of considering genetic variation in characterizing virulence factors and understanding the tug of war between pathogens and the host.
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Affiliation(s)
- Sofya S Perelman
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - David B A James
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kristina M Boguslawski
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Chase W Nelson
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Juliana K Ilmain
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Erin E Zwack
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Rachel A Prescott
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Adil Mohamed
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Kayan Tam
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Rita Chan
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Apurva Narechania
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
| | - Miranda B Pawline
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Medicine, Division of Infectious Diseases, New York University Grossman School of Medicine, New York, NY, USA
| | - Nikollaq Vozhilla
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Ahmed M Moustafa
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Sang Y Kim
- Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA
- Office of Collaborative Sciences, NYU Grossman School of Medicine, New York, NY, USA
| | - Meike Dittmann
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
| | - Damian C Ekiert
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
| | - Gira Bhabha
- Skirball Institute of Biomolecular Medicine and Department of Cell Biology, New York University Grossman School of Medicine, New York, NY, USA
| | - Bo Shopsin
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA
- Department of Medicine, Division of Infectious Diseases, New York University Grossman School of Medicine, New York, NY, USA
| | - Paul J Planet
- Institute for Comparative Genomics, American Museum of Natural History, New York, NY, USA
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sergei B Koralov
- Department of Pathology, New York University Grossman School of Medicine, New York, NY, USA
| | - Victor J Torres
- Department of Microbiology, New York University Grossman School of Medicine, New York, NY, USA.
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de Vries M, Mohamed AS, Prescott RA, Valero-Jimenez AM, Desvignes L, O’Connor R, Steppan C, Devlin JC, Ivanova E, Herrera A, Schinlever A, Loose P, Ruggles K, Koralov SB, Anderson AS, Binder J, Dittmann M. A comparative analysis of SARS-CoV-2 antivirals in human airway models characterizes 3CL pro inhibitor PF-00835231 as a potential new treatment for COVID-19. bioRxiv 2021:2020.08.28.272880. [PMID: 32869028 PMCID: PMC7457613 DOI: 10.1101/2020.08.28.272880] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent of Coronavirus Disease 2019 (COVID-19). There is a dire need for novel effective antivirals to treat COVID-19, as the only approved direct-acting antiviral to date is remdesivir, targeting the viral polymerase complex. A potential alternate target in the viral life cycle is the main SARS-CoV-2 protease 3CLpro (Mpro). The drug candidate PF-00835231 is the active compound of the first anti-3CLpro regimen in clinical trials. Here, we perform a comparative analysis of PF-00835231, the pre-clinical 3CLpro inhibitor GC-376, and the polymerase inhibitor remdesivir, in alveolar basal epithelial cells modified to express ACE2 (A549+ACE2 cells). We find PF-00835231 with at least similar or higher potency than remdesivir or GC-376. A time-of-drug-addition approach delineates the timing of early SARS-CoV-2 life cycle steps in A549+ACE2 cells and validates PF-00835231's early time of action. In a model of the human polarized airway epithelium, both PF-00835231 and remdesivir potently inhibit SARS-CoV-2 at low micromolar concentrations. Finally, we show that the efflux transporter P-glycoprotein, which was previously suggested to diminish PF-00835231's efficacy based on experiments in monkey kidney Vero E6 cells, does not negatively impact PF-00835231 efficacy in either A549+ACE2 cells or human polarized airway epithelial cultures. Thus, our study provides in vitro evidence for the potential of PF-00835231 as an effective SARS-CoV-2 antiviral and addresses concerns that emerged based on prior studies in non-human in vitro models.
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Affiliation(s)
- Maren de Vries
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
| | - Adil S Mohamed
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
| | - Rachel A Prescott
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York 10016, USA
| | - Ana M Valero-Jimenez
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
| | - Ludovic Desvignes
- Department of Medicine, New York University Grossman School of Medicine, New York 10016, USA
- Office of Science & Research, NYU Langone Health, New York 10016, USA
| | | | | | - Joseph C Devlin
- Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York 10016, USA
- Institute of Systems Genetics, New York University Grossman School of Medicine, New York 10016, USA
| | - Ellie Ivanova
- Department of Pathology, New York University Grossman School of Medicine, New York 10016, USA
| | - Alberto Herrera
- Department of Pathology, New York University Grossman School of Medicine, New York 10016, USA
| | - Austin Schinlever
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
- Vilcek Institute of Graduate Biomedical Sciences, New York University Grossman School of Medicine, New York 10016, USA
| | - Paige Loose
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
| | - Kelly Ruggles
- Institute of Systems Genetics, New York University Grossman School of Medicine, New York 10016, USA
| | - Sergei B Koralov
- Department of Pathology, New York University Grossman School of Medicine, New York 10016, USA
| | | | - Joseph Binder
- Pfizer Oncology Research and Development, San Diego, CA 92128, USA
| | - Meike Dittmann
- Department of Microbiology, New York University Grossman School of Medicine, New York 10016, USA
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Verma S, Prescott RA, Ingano L, Nickerson KP, Hill E, Faherty CS, Fasano A, Senger S, Cherayil BJ. The YrbE phospholipid transporter of Salmonella enterica serovar Typhi regulates the expression of flagellin and influences motility, adhesion and induction of epithelial inflammatory responses. Gut Microbes 2020; 11:526-538. [PMID: 31829769 PMCID: PMC7527071 DOI: 10.1080/19490976.2019.1697593] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
serovar Typhi is the etiologic agent of typhoid fever, a major public health problem in the developing world. Moving toward and adhering to the intestinal epithelium represents key initial steps of infection by S. Typhi. We examined the role of the S. Typhi yrbE gene, which encodes an inner membrane phospholipid transporter, in these interactions with epithelial cells. Disruption of yrbE resulted in elevated expression of flagellin and a hypermotile phenotype. It also significantly reduced the ability of S. Typhi to adhere to the HeLa epithelial cell line and to polarized primary epithelial cells derived from human ileal organoids. Interestingly, the yrbE-deficient strain of S. Typhi induced higher production of interleukin-8 from the primary human ileal epithelial cell monolayers compared to the wild-type bacteria. Deletion of the flagellin gene (fliC) in the yrbE-deficient S. Typhi inhibited motility and attenuated interleukin-8 production, but it did not correct the defect in adhesion. We also disrupted yrbE in S. Typhimurium. In contrast to the results in S. Typhi, the deficiency of yrbE in S. Typhimurium had no significant effect on flagellin expression, motility or adhesion to HeLa cells. Correspondingly, the lack of yrbE also had no effect on association with the intestine or the severity of intestinal inflammation in the mouse model of S. Typhimurium infection. Thus, our results point to an important and serovar-specific role played by yrbE in the early stages of intestinal infection by S. Typhi.
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Affiliation(s)
- Smriti Verma
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Rachel A. Prescott
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Laura Ingano
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Kourtney P. Nickerson
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Emily Hill
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Christina S. Faherty
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Alessio Fasano
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Stefania Senger
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Bobby J. Cherayil
- Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, USA,Department of Pediatrics, Harvard Medical School, Boston, MA, USA,CONTACT Bobby J. Cherayil Mucosal Immunology and Biology Research Center, Department of Pediatrics, Massachusetts General Hospital, Boston, MA, USA
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Orren A, Prescott RA. Bf F1 and C22 gene frequencies in patients with insulin dependent diabetes mellitus (IDDM) from three South African populations. ACTA ACUST UNITED AC 2008; 22:385-8. [PMID: 6558983 DOI: 10.1111/j.1399-0039.1983.tb02270.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
African (59), Coloured (140) and White (71) IDDM patients were allotyped for Bf and C2. In Africans and Coloureds, unlike Whites, no strong associations with Bf Fl and C22 were observed.
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Prescott RA, Potter PC. Allergenicity and cross-reactivity of buffalo grass (Stenotaphrum secundatum). S Afr Med J 2001; 91:237-43. [PMID: 11291423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
BACKGROUND In the subtropical climate of South Africa, grasses of the subfamily Panicoideae are predominant. Bermuda grass has previously been shown to be an important local allergen, and immunoglobulin E (IgE) epitopes of Bermuda grass extracts are known to be distinct from those of the Pooid pollen extracts. Following our demonstration of sensitivity in 43% of patients grass-allergic to the Panicoid, Kikuyu grass, we have studied the closely related buffalo grass, Stenotaphrum secundatum, indigenous to the Western Cape region, the east coast of Africa and the oceanic islands such as Mauritius; and Eragrostis, another common indigenous grass with a wide distribution. OBJECTIVE To partially characterise the allergens of buffalo pollen, and examine its immunological relationships with local common grasses such as Eragrostis and Kikuyu. METHODS Grass-allergic patients were evaluated clinically, and skin prick tests (SPTs) and radio-allergosorbent tests (RASTs) to Bermuda and grass mix were performed. Sera of timothy grass-sensitive patients from Belgium were also included in this study. Pollen extract from buffalo grass was characterised by specific IgE binding by means of immunoblotting and enzyme-linked immunosorbent assay (ELISA). Cross-reactivity between the grasses was studied by means of inhibition of IgE binding. RESULTS More than 90% of grass-sensitive patients were found to have IgE antibodies to Buffalo and Eragrostis pollen. Inhibition of ELISA and immunoblots revealed that extracts of these grass pollens could significant inhibit IgE binding to the local grass pollens, Kikuyu, buffalo, Eragrostis and Bermuda on solid phase, but 100% inhibition was never achieved, indicating that cross-reactive but also unique epitopes are present. We also identified a subset of patients with negative RASTs to Bermuda, and minimal inhibition by Bermuda pollen extract. CONCLUSION Buffalo and Eragrostis are important aeroallergens in the Cape, dispersed during the long dry, windy summer. Our data suggest that the local grasses are major sensitisers, and that South African diagnostic panels should include extracts of buffalo and Eragrostis grasses.
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Affiliation(s)
- R A Prescott
- Allergology Unit, Department of Immunology, University of Cape Town
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