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Abstract
Tumorigenesis has long been linked to the evasion of the immune system and the uncontrolled proliferation of transformed cells. The complement system, a major arm of innate immunity, is a key factor in the progression of cancer because many of its components have critical regulatory roles in the tumor microenvironment. For example, complement anaphylatoxins directly and indirectly inhibit antitumor T-cell responses in primary and metastatic sites, enhance proliferation of tumor cells, and promote metastasis and tumor angiogenesis. Many recent studies have provided evidence that cancer is able to hijack the immunoregulatory components of the complement system which fundamentally are tasked with protecting the body against abnormal cells and pathogens. Indeed, recent evidence shows that many types of cancer use C1q receptors (C1qRs) to promote tumor growth and progression. More importantly, most cancer cells express both C1q and its major receptors (gC1qR and cC1qR) on their surface which are essential for cell proliferation and survival. In this review, we discuss the ability of cancer to control and manipulate the complement system in the tumor microenvironment and identify possible therapeutic targets, including C1q and gC1qR.
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Affiliation(s)
- Danyaal Ain
- The Department of Medicine, Stony Brook University, 100 Nicholls Road, Stony Brook, NY 11794-8161, USA
| | - Talha Shaikh
- The Department of Medicine, Stony Brook University, 100 Nicholls Road, Stony Brook, NY 11794-8161, USA
| | - Samantha Manimala
- The Department of Medicine, Stony Brook University, 100 Nicholls Road, Stony Brook, NY 11794-8161, USA
| | - Berhane Ghebrehiwet
- The Department of Medicine, Stony Brook University, 100 Nicholls Road, Stony Brook, NY 11794-8161, USA
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Martinez APG, Abreu PAE, de Arruda Vasconcellos S, Ho PL, Ferreira VP, Saggu G, Barbosa AS, Isaac L. The Role of Properdin in Killing of Non-Pathogenic Leptospira biflexa. Front Immunol 2020; 11:572562. [PMID: 33240263 PMCID: PMC7683387 DOI: 10.3389/fimmu.2020.572562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 10/05/2020] [Indexed: 11/25/2022] Open
Abstract
Properdin (P) is a positive regulatory protein that stabilizes the C3 convertase and C5 convertase of the complement alternative pathway (AP). Several studies have suggested that properdin can bind directly to the surface of certain pathogens regardless of the presence of C3bBb. Saprophytic Leptospira are susceptible to complement-mediated killing, but the interaction of properdin with Leptospira spp. has not been evaluated so far. In this work, we demonstrate that properdin present in normal human serum, purified properdin, as well as properdin oligomers P2, P3, and P4, interact with Leptospira. Properdin can bind directly to the bacterial surface even in the absence of C3b. In line with our previous findings, AP activation was shown to be important for killing non-pathogenic L. biflexa, and properdin plays a key role in this process since this microorganism survives in P-depleted human serum and the addition of purified properdin to P-depleted human serum decreases the number of viable leptospires. A panel of pathogenic L.interrogans recombinant proteins was used to identify putative properdin targets. Lsa30, an outer membrane protein from L. interrogans, binds to unfractionated properdin and to a lesser extent to P2-P4 properdin oligomers. In conclusion, properdin plays an important role in limiting bacterial proliferation of non-pathogenic Leptospira species. Once bound to the leptospiral surface, this positive complement regulatory protein of the AP contributes to the formation of the C3 convertase on the leptospire surface even in the absence of prior addition of C3b.
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Affiliation(s)
| | | | - Silvio de Arruda Vasconcellos
- Laboratory of Bacterial Zoonoses, Faculty of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil
| | - Paulo Lee Ho
- Laboratory of Bacteriology, Butantan Institute, São Paulo, Brazil
| | - Viviana P Ferreira
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, United States
| | - Gurpanna Saggu
- Department of Medical Microbiology and Immunology, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, United States
| | | | - Lourdes Isaac
- Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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Santecchia I, Ferrer MF, Vieira ML, Gómez RM, Werts C. Phagocyte Escape of Leptospira: The Role of TLRs and NLRs. Front Immunol 2020; 11:571816. [PMID: 33123147 PMCID: PMC7573490 DOI: 10.3389/fimmu.2020.571816] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 09/16/2020] [Indexed: 12/21/2022] Open
Abstract
The spirochetal bacteria Leptospira spp. are causative agents of leptospirosis, a globally neglected and reemerging zoonotic disease. Infection with these pathogens may lead to an acute and potentially fatal disease but also to chronic asymptomatic renal colonization. Both forms of disease demonstrate the ability of leptospires to evade the immune response of their hosts. In this review, we aim first to recapitulate the knowledge and explore the controversial data about the opsonization, recognition, intracellular survival, and killing of leptospires by scavenger cells, including platelets, neutrophils, macrophages, and dendritic cells. Second, we will summarize the known specificities of the recognition or escape of leptospire components (the so-called microbial-associated molecular patterns; MAMPs) by the pattern recognition receptors (PRRs) of the Toll-like and NOD-like families. These PRRs are expressed by phagocytes, and their stimulation by MAMPs triggers pro-inflammatory cytokine and chemokine production and bactericidal responses, such as antimicrobial peptide secretion and reactive oxygen species production. Finally, we will highlight recent studies suggesting that boosting or restoring phagocytic functions by treatments using agonists of the Toll-like or NOD receptors represents a novel prophylactic strategy and describe other potential therapeutic or vaccine strategies to combat leptospirosis.
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Affiliation(s)
- Ignacio Santecchia
- Institut Pasteur, Microbiology Department, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France.,CNRS, UMR 2001 Microbiologie intégrative et Moléculaire, Paris, France.,INSERM, Equipe Avenir, Paris, France.,Université de Paris, Sorbonne Paris Cité, Paris, France
| | - María Florencia Ferrer
- Laboratorio de Virus Animales, Instituto de Biotecnología y Biología Molecular, CONICET-Universidad Nacional de La Plata, La Plata, Argentina
| | - Monica Larucci Vieira
- Departamento de Microbiologia, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil
| | - Ricardo Martín Gómez
- Laboratorio de Virus Animales, Instituto de Biotecnología y Biología Molecular, CONICET-Universidad Nacional de La Plata, La Plata, Argentina
| | - Catherine Werts
- Institut Pasteur, Microbiology Department, Unité Biologie et Génétique de la Paroi Bactérienne, Paris, France.,CNRS, UMR 2001 Microbiologie intégrative et Moléculaire, Paris, France
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Complement Resistance Assays. Methods Mol Biol 2020. [PMID: 32632870 DOI: 10.1007/978-1-0716-0459-5_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Like many other pathogens of medical importance, pathogenic Leptospira employ diverse strategies to circumvent Complement System activation. Under physiological conditions, this central humoral arm of innate immunity is tightly controlled by negative Complement regulatory proteins. However, upon infection, pathogenic microorganisms interfere with normal Complement host defense mechanisms by recruiting or mimicking Complement regulators and by secreting endogenous proteases or acquiring host's proteases that inactivate key Complement components. In this chapter, we describe in detail some of the most frequently used assays to evaluate Leptospira Complement resistance.
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Complement Evasion Strategies of Human Pathogenic Bacteria. Indian J Microbiol 2020; 60:283-296. [PMID: 32655196 DOI: 10.1007/s12088-020-00872-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 04/07/2020] [Indexed: 12/21/2022] Open
Abstract
Human pathogens need to overcome an elaborate network of host defense mechanisms in order to establish their infection, colonization, proliferation and eventual dissemination. The interaction of pathogens with different effector molecules of the immune system results in their neutralization and elimination from the host. The complement system is one such integral component of innate immunity that is critically involved in the early recognition and elimination of the pathogen. Hence, under this immune pressure, all virulent pathogens capable of inducing active infections have evolved immune evasive strategies that primarily target the complement system, which plays an essential and central role for host defense. Recent reports on several bacterial pathogens have elucidated the molecular mechanisms underlying complement evasion, inhibition of opsonic phagocytosis and cell lysis. This review aims to comprehensively summarize the recent findings on the various strategies adopted by pathogenic bacteria to escape complement-mediated clearance.
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Cytokine Profile in Early Infection by Leptospira interrogans in A/J Mice. J Immunol Res 2019; 2019:1892508. [PMID: 31687410 PMCID: PMC6800925 DOI: 10.1155/2019/1892508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/07/2019] [Accepted: 06/22/2019] [Indexed: 12/28/2022] Open
Abstract
Leptospirosis is considered a neglected disease with an estimated more than one million cases every year. Since rodents are at the same time the main reservoir and generally asymptomatic to Leptospira infection, understanding why some animal species are resistant and others are susceptible to this infection would shed some light in how to control this important zoonosis. The innate immune response against Leptospira is mainly dependent on phagocytosis and activation of the Complement System. In this context, cytokines may drive the early control of infection and the adaptive response. Since the Complement System is important to eliminate leptospires in vivo, we investigated if Complement C5 in A/J mice would modulate the cytokine production during infection by Leptospira interrogans serovar Kennewicki type Pomona Fromm (LPF). Thus, our aim was to investigate the systemic levels of pro- and anti-inflammatory cytokines during Leptospira infection in the blood, liver, lung, and kidney on the third and sixth days of infection in A/J C5+/+ and A/J C5-/- mice. Blood levels of TNF-α, IL-6, IFN-γ, and MCP-1 reached a peak on the third day. Although both mouse strains developed splenomegaly, similar histopathological alterations in the liver and the lung, levels of pro- and anti-inflammatory cytokines were different. A/J C5+/+ mice had higher levels of liver IL-10, IL-1β, IL-12p40, and IL-12p70 and kidney IL-1β, IL-12p40, and IL-12p70 on the sixth day of infection when compared to A/J C5-/- mice. Our results showed that in A/J genetic background, the Complement component C5 modulates a cytokine profile in the liver and kidney of infected mice, which may play a role in the control of disease progression.
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Caimano MJ, Groshong AM, Belperron A, Mao J, Hawley KL, Luthra A, Graham DE, Earnhart CG, Marconi RT, Bockenstedt LK, Blevins JS, Radolf JD. The RpoS Gatekeeper in Borrelia burgdorferi: An Invariant Regulatory Scheme That Promotes Spirochete Persistence in Reservoir Hosts and Niche Diversity. Front Microbiol 2019; 10:1923. [PMID: 31507550 PMCID: PMC6719511 DOI: 10.3389/fmicb.2019.01923] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/05/2019] [Indexed: 11/28/2022] Open
Abstract
Maintenance of Borrelia burgdorferi within its enzootic cycle requires a complex regulatory pathway involving the alternative σ factors RpoN and RpoS and two ancillary trans-acting factors, BosR and Rrp2. Activation of this pathway occurs within ticks during the nymphal blood meal when RpoS, the effector σ factor, transcribes genes required for tick transmission and mammalian infection. RpoS also exerts a 'gatekeeper' function by repressing σ70-dependent tick phase genes (e.g., ospA, lp6.6). Herein, we undertook a broad examination of RpoS functionality throughout the enzootic cycle, beginning with modeling to confirm that this alternative σ factor is a 'genuine' RpoS homolog. Using a novel dual color reporter system, we established at the single spirochete level that ospA is expressed in nymphal midguts throughout transmission and is not downregulated until spirochetes have been transmitted to a naïve host. Although it is well established that rpoS/RpoS is expressed throughout infection, its requirement for persistent infection has not been demonstrated. Plasmid retention studies using a trans-complemented ΔrpoS mutant demonstrated that (i) RpoS is required for maximal fitness throughout the mammalian phase and (ii) RpoS represses tick phase genes until spirochetes are acquired by a naïve vector. By transposon mutant screening, we established that bba34/oppA5, the only OppA oligopeptide-binding protein controlled by RpoS, is a bona fide persistence gene. Lastly, comparison of the strain 297 and B31 RpoS DMC regulons identified two cohorts of RpoS-regulated genes. The first consists of highly conserved syntenic genes that are similarly regulated by RpoS in both strains and likely required for maintenance of B. burgdorferi sensu stricto strains in the wild. The second includes RpoS-regulated plasmid-encoded variable surface lipoproteins ospC, dbpA and members of the ospE/ospF/elp, mlp, revA, and Pfam54 paralogous gene families, all of which have evolved via inter- and intra-strain recombination. Thus, while the RpoN/RpoS pathway regulates a 'core' group of orthologous genes, diversity within RpoS regulons of different strains could be an important determinant of reservoir host range as well as spirochete virulence.
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Affiliation(s)
- Melissa J. Caimano
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,*Correspondence: Melissa J. Caimano,
| | | | - Alexia Belperron
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jialing Mao
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Kelly L. Hawley
- Department of Pediatrics, UConn Health, Farmington, CT, United States,Division of Infectious Diseases and Immunology, Connecticut Children’s Medical Center, Hartford, CT, United States
| | - Amit Luthra
- Department of Medicine, UConn Health, Farmington, CT, United States
| | - Danielle E. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Christopher G. Earnhart
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Richard T. Marconi
- Department of Microbiology and Immunology, Virginia Commonwealth University Medical Center, Richmond, VA, United States
| | - Linda K. Bockenstedt
- Department of Internal Medicine, Section of Rheumatology, Allergy and Immunology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Jon S. Blevins
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Justin D. Radolf
- Department of Medicine, UConn Health, Farmington, CT, United States,Department of Pediatrics, UConn Health, Farmington, CT, United States,Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, United States,Department of Genetics and Genome Science, UConn Health, Farmington, CT, United States,Department of Immunology, UConn Health, Farmington, CT, United States
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