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Bessho S, Grando KCM, Kyrylchuk K, Miller A, Klein-Szanto AJ, Zhu W, Gallucci S, Tam V, Tükel Ç. Systemic exposure to bacterial amyloid curli alters the gut mucosal immune response and the microbiome, exacerbating Salmonella-induced arthritis. Gut Microbes 2023; 15:2221813. [PMID: 37317012 PMCID: PMC10269392 DOI: 10.1080/19490976.2023.2221813] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 05/30/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023] Open
Abstract
The Salmonella biofilm-associated amyloid protein, curli, is a dominant instigator of systemic inflammation and autoimmune responses following Salmonella infection. Systemic curli injections or infection of mice with Salmonella Typhimurium induce the major features of reactive arthritis, an autoimmune disorder associated with Salmonella infection in humans. In this study, we investigated the link between inflammation and microbiota in exacerbating autoimmunity. We studied C57BL/6 mice from two sources, Taconic Farms and Jackson Labs. Mice from Taconic Farms have been reported to have higher basal levels of the inflammatory cytokine IL - 17 than do mice from Jackson Labs due to the differences in their microbiota. When we systemically injected mice with purified curli, we observed a significant increase in diversity in the microbiota of Jackson Labs mice but not in that of the Taconic mice. In Jackson Labs, mice, the most striking effect was the expansion of Prevotellaceae. Furthermore, there were increases in the relative abundance of the family Akkermansiaceae and decreases in families Clostridiaceae and Muribaculaceae in Jackson Labs mice. Curli treatment led to significantly aggravated immune responses in the Taconic mice compared to Jackson Labs counterparts. Expression and production of IL - 1β, a cytokine known to promote IL - 17 production, as well as expression of Tnfa increased in the gut mucosa of Taconic mice in the first 24 hours after curli injections, which correlated with significant increases in the number of neutrophils and macrophages in the mesenteric lymph nodes. A significant increase in the expression of Ccl3 in colon and cecum of Taconic mice injected with curli was detected. Taconic mice injected with curli also had elevated levels of inflammation in their knees. Overall, our data suggest that autoimmune responses to bacterial ligands, such as curli, are amplified in individuals with a microbiome that promote inflammation.
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Affiliation(s)
- Shingo Bessho
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | - Kaitlyn C. M. Grando
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | - Kathrine Kyrylchuk
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | - Amanda Miller
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | | | - Wenhan Zhu
- Department of Pathology Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Stefania Gallucci
- Division of Innate Immunity, Department of Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Vincent Tam
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
| | - Çagla Tükel
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, USA
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Nicastro LK, de Anda J, Jain N, Grando KCM, Miller AL, Bessho S, Gallucci S, Wong GCL, Tükel Ç. Assembly of ordered DNA-curli fibril complexes during Salmonella biofilm formation correlates with strengths of the type I interferon and autoimmune responses. PLoS Pathog 2022; 18:e1010742. [PMID: 35972973 PMCID: PMC9380926 DOI: 10.1371/journal.ppat.1010742] [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] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 07/14/2022] [Indexed: 11/23/2022] Open
Abstract
Deposition of human amyloids is associated with complex human diseases such as Alzheimer’s and Parkinson’s. Amyloid proteins are also produced by bacteria. The bacterial amyloid curli, found in the extracellular matrix of both commensal and pathogenic enteric bacterial biofilms, forms complexes with extracellular DNA, and recognition of these complexes by the host immune system may initiate an autoimmune response. Here, we isolated early intermediate, intermediate, and mature curli fibrils that form throughout the biofilm development and investigated the structural and pathogenic properties of each. Early intermediate aggregates were smaller than intermediate and mature curli fibrils, and circular dichroism, tryptophan, and thioflavin T analyses confirmed the establishment of a beta-sheet secondary structure as the curli conformations matured. Intermediate and mature curli fibrils were more immune stimulatory than early intermediate fibrils in vitro. The intermediate curli was cytotoxic to macrophages independent of Toll-like receptor 2. Mature curli fibrils had the highest DNA content and induced the highest levels of Isg15 expression and TNFα production in macrophages. In mice, mature curli fibrils induced the highest levels of anti-double-stranded DNA autoantibodies. The levels of autoantibodies were higher in autoimmune-prone NZBWxF/1 mice than wild-type C57BL/6 mice. Chronic exposure to all curli forms led to significant histopathological changes and synovial proliferation in the joints of autoimmune-prone mice; mature curli was the most detrimental. In conclusion, curli fibrils, generated during biofilm formation, cause pathogenic autoimmune responses that are stronger when curli complexes contain higher levels of DNA and in mice predisposed to autoimmunity. Amyloid curli is an extracellular component of the biofilms of enteric bacteria like Salmonella and E. coli. During biofilm development, curli binds to extracellular DNA to form complexes that stimulate the immune system. Using complimentary techniques, we discovered that curli amyloids undergo changes in their physical and pathogenic properties throughout the development of the biofilm, polymerizing from early intermediate and intermediate to mature curli fibrils. While all three curli conformations activated TLR2, they bound different amounts of DNA that positively correlate with the complexity of the amyloids and their ability to induce type I IFNs and pro-inflammatory cytokines, and accelerate the onset of anti-dsDNA autoantibodies in autoimmune-prone mice. Synchrotron x-ray diffraction results suggest that DNA is organized by the beta sheet motif of curli monomers into a spatially periodic lattice that can amplify immune activation. Intermediate curli complexes were the only form that also showed cytotoxicity in macrophages independent of TLR2 and they induced higher levels of IL-1b, a cytokine involved in cell death. In mice prone to autoimmunity, the intermediate and mature curli/DNA induced also joint inflammation. Overall, the maturation of curli-DNA complexes through biofilm development stimulated distinct immune responses influenced by DNA content and promoted autoimmune features in mice.
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Affiliation(s)
- Lauren K. Nicastro
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Jaime de Anda
- Department of Bioengineering, California Nano Systems Institute, University of California, Los Angeles, California, United States of America
| | - Neha Jain
- Department of Bioscience and Bioengineering, Indian Institute of Technology, Jodhpur, India
| | - Kaitlyn C. M. Grando
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Amanda L. Miller
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Shingo Bessho
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Stefania Gallucci
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Gerard C. L. Wong
- Department of Bioengineering, California Nano Systems Institute, University of California, Los Angeles, California, United States of America
| | - Çagla Tükel
- Center for Microbiology and Immunology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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