151
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Reitsma M, Westerhout J, Wichers HJ, Wortelboer HM, Verhoeckx KCM. Protein transport across the small intestine in food allergy. Mol Nutr Food Res 2013; 58:194-205. [PMID: 24395537 DOI: 10.1002/mnfr.201300204] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 09/26/2013] [Accepted: 10/18/2013] [Indexed: 02/04/2023]
Abstract
In view of the imminent deficiency of protein sources for human consumption in the near future, new protein sources need to be identified. However, safety issues such as the risk of allergenicity are often a bottleneck, due to the absence of predictive, validated and accepted methods for risk assessment. The current strategy to assess the allergenic potential of proteins focuses mainly on homology, stability and cross-reactivity, although other factors such as intestinal transport might be of added value too. In this review, we present an overview of the knowledge of protein transport across the intestinal wall and the methods currently being used to measure this. A literature study reveals that protein transport in sensitised persons occurs para-cellularly with the involvement of mast cells, and trans-cellularly via enterocytes, while in non-sensitised persons micro-fold cells and enterocytes are considered most important. However, there is a lack of comparable systematic studies on transport of allergenic proteins. Knowledge of the multiple protein transport pathways and which model system can be useful to study these processes may be of added value in the risk assessment of food allergenicity.
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Affiliation(s)
- Marit Reitsma
- TNO, Zeist, The Netherlands; Food and Biobased Research, Wageningen University and Research Centre, The Netherlands
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152
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Gomez D, Sunyer JO, Salinas I. The mucosal immune system of fish: the evolution of tolerating commensals while fighting pathogens. FISH & SHELLFISH IMMUNOLOGY 2013; 35:1729-39. [PMID: 24099804 PMCID: PMC3963484 DOI: 10.1016/j.fsi.2013.09.032] [Citation(s) in RCA: 421] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Revised: 09/09/2013] [Accepted: 09/23/2013] [Indexed: 05/04/2023]
Abstract
The field of mucosal immunology research has grown fast over the past few years, and our understanding on how mucosal surfaces respond to complex antigenic cocktails is expanding tremendously. With the advent of new molecular sequencing techniques, it is easier to understand how the immune system of vertebrates is, to a great extent, orchestrated by the complex microbial communities that live in symbiosis with their hosts. The commensal microbiota is now seen as the "extended self" by many scientists. Similarly, fish immunologist are devoting important research efforts to the field of mucosal immunity and commensals. Recent breakthroughs on our understanding of mucosal immune responses in teleost fish open up the potential of teleosts as animal research models for the study of human mucosal diseases. Additionally, this new knowledge places immunologists in a better position to specifically target the fish mucosal immune system while rationally designing mucosal vaccines and other immunotherapies. In this review, an updated view on how teleost skin, gills and gut immune cells and molecules, function in response to pathogens and commensals is provided. Finally, some of the future avenues that the field of fish mucosal immunity may follow in the next years are highlighted.
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Affiliation(s)
- Daniela Gomez
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - J Oriol Sunyer
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Irene Salinas
- Center for Theoretical and Evolutionary Immunology (CETI), Department of Biology, MSC03 2020, University of New Mexico, Albuquerque, NM, 87131, USA
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153
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Funderburg NT, Stubblefield Park SR, Sung HC, Hardy G, Clagett B, Ignatz-Hoover J, Harding CV, Fu P, Katz JA, Lederman MM, Levine AD. Circulating CD4(+) and CD8(+) T cells are activated in inflammatory bowel disease and are associated with plasma markers of inflammation. Immunology 2013; 140:87-97. [PMID: 23600521 DOI: 10.1111/imm.12114] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2012] [Revised: 03/19/2013] [Accepted: 04/11/2013] [Indexed: 12/13/2022] Open
Abstract
Inflammatory bowel disease (IBD) is characterized by damage to the gut mucosa and systemic inflammation. We sought to evaluate the role of chronic inflammation on circulating T-cell activation in human subjects with Crohn's disease and ulcerative colitis. We studied 54 patients with IBD and 28 healthy controls. T-cell activation and cycling were assessed in whole blood samples by flow cytometry. Levels of lipopolysaccharide (LPS) were measured in serum by Limulus amoebocyte lysate assay, and plasma levels of inflammatory markers and LPS-binding proteins were measured by ELISA. The proportions of circulating CD4(+) and CD8(+) T lymphocytes in cycle (Ki67(+) ) are increased in patients with IBD compared with these proportions in controls. CD8(+) T cells from patients with IBD are also enriched for cells that expressed CD38 and HLA-DR, and proportions of these cells are related to plasma levels of interleukin-6 and C-reactive protein in these patients. Intracellular interleukin-2 and interferon-γ levels were elevated in resting and polyclonally activated CD4(+) and CD8(+) T cells in patients with IBD when compared with levels from healthy controls. Surprisingly, we did not find increased levels of LPS in the serum of patients with IBD. We did, however, find a signature of recent microbial translocation, as levels of LPS-binding protein are increased in the plasma of patients with IBD compared with plasma levels in healthy controls; LPS-binding protein levels are also directly related to proportions of CD38 HLA-DR-expressing CD4(+) and CD8(+) T cells. Local damage to the gastrointestinal tract in IBD may result in systemic inflammation and T-cell activation.
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Affiliation(s)
- Nicholas T Funderburg
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4952, USA
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154
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Thiesen S, Janciauskiene S, Uronen-Hansson H, Agace W, Högerkorp CM, Spee P, Håkansson K, Grip O. CD14(hi)HLA-DR(dim) macrophages, with a resemblance to classical blood monocytes, dominate inflamed mucosa in Crohn's disease. J Leukoc Biol 2013; 95:531-41. [PMID: 24212097 DOI: 10.1189/jlb.0113021] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Intestinal M play an important role in maintaining gut homeostasis. However, little is known about these cells, their precursors, and their role in intestinal inflammation. Here, we characterize the CD14(+) mononuclear cell populations in intestinal mucosa and blood in patients with CD. Among the LP CD14(+) M, we identified three distinct HLA-DR(+)-expressing subsets. Compared with uninflamed, inflamed mucosa contained a marked increase in the proportion of the CD14(hi)HLA-DR(dim) cellular subset. This subset resembled the classical blood monocytes with low CD16, HLA-DR, and CX3CR1 expression. Classical monocytes migrated efficiently toward CCL2 and released the highest levels of MMP-1 and proinflammatory cytokines when stimulated with immune complexes or LPS. Our findings strongly suggest that it is the classical and not the intermediate or nonclassical monocytes that are the precursors to the dominating intestinal CD14(hi)HLA-DR(dim) subset. This enhances our understanding of CD pathology and may provide new options in treatment.
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155
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156
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Lamont EA, Xu WW, Sreevatsan S. Host-Mycobacterium avium subsp. paratuberculosis interactome reveals a novel iron assimilation mechanism linked to nitric oxide stress during early infection. BMC Genomics 2013; 14:694. [PMID: 24112552 PMCID: PMC3832399 DOI: 10.1186/1471-2164-14-694] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 10/02/2013] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The initial interaction between host cell and pathogen sets the stage for the ensuing infection and ultimately determine the course of disease. However, there is limited knowledge of the transcripts utilized by host and pathogen and how they may impact one another during this critical step. The purpose of this study was to create a host-Mycobacterium avium subsp. paratuberculosis (MAP) interactome for early infection in an epithelium-macrophage co-culture system using RNA-seq. RESULTS Establishment of the host-MAP interactome revealed a novel iron assimilation system for carboxymycobactin. Iron assimilation is linked to nitric oxide synthase-2 production by the host and subsequent nitric oxide buildup. Iron limitation as well as nitric oxide is a prompt for MAP to enter into an iron sequestration program. This new iron sequestration program provides an explanation for mycobactin independence in some MAP strains grown in vitro as well as during infection within the host cell. Utilization of such a pathway is likely to aid MAP establishment and long-term survival within the host. CONCLUSIONS The host-MAP interactome identified a number of metabolic, DNA repair and virulence genes worthy for consideration as novel drug targets as well as future pathogenesis studies. Reported interactome data may also be utilized to conduct focused, hypothesis-driven research. Co-culture of uninfected bovine epithelial cells (MAC-T) and primary bovine macrophages creates a tolerant genotype as demonstrated by downregulation of inflammatory pathways. This co-culture system may serve as a model to investigate other bovine enteric pathogens.
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Affiliation(s)
- Elise A Lamont
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1971 Commonwealth Avenue, Saint Paul, MN 55108, USA
| | - Wayne W Xu
- Minnesota Supercomputing Institute, University of Minnesota, Saint Paul, MN 55108, USA
| | - Srinand Sreevatsan
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1971 Commonwealth Avenue, Saint Paul, MN 55108, USA
- Department of Veterinary Biomedical Sciences, University of Minnesota, Saint Paul, MN 55108, USA
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157
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Arató A. Milestones in understanding of the pathogenesis of immunmediated intestinal disorders. Development of their diagnosis and therapy. Orv Hetil 2013; 154:1512-23. [DOI: 10.1556/oh.2013.29710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In the last decades our knowledge has been enormously broadened about the structure and function of the gut associated lymphoid system. It was recognized how intricate and finely tuned connection exists between the gut bacterial flora and the intestinal mucosa. This subtle balance ensures mucosal homeostasis, which has a key role in organ defence against pathogens. However, at the same time this system makes possible the development of oral tolerance toward the commensals and the food antigens. In case of any disturbances in this finely tuned process, immunmediated intestinal disorders may easily develop. The first part of this paper reviews the structure and function of the mucosal immune system, while the second part surveys the pathogenesis, diagnosis and therapy of coeliac disease, inflammatory bowel disease and cow’s milk allergy induced enteropathy. Orv. Hetil., 2013, 154, 1512–1523.
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Affiliation(s)
- András Arató
- Semmelweis Egyetem, Általános Orvostudományi Kar I. Gyermekgyógyászati Klinika Budapest Bókay János u. 53. 1083
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158
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Comprehensive assessment of HIV target cells in the distal human gut suggests increasing HIV susceptibility toward the anus. J Acquir Immune Defic Syndr 2013; 63:263-71. [PMID: 23392465 DOI: 10.1097/qai.0b013e3182898392] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND Prevention of rectal HIV transmission is a high-priority goal for vaccines and topical microbicides because a large fraction of HIV transmissions occurs rectally. Yet, little is known about the specific target-cell milieu in the human rectum other than inferences made from the colon. METHODS We conducted a comprehensive comparative in situ fluorescence study of HIV target cells (CCR5-expressing T cells, macrophages, and putative dendritic cells) at 4 and 30 cm proximal of the anal canal in 29 healthy individuals, using computerized analysis of digitized combination stains. RESULTS Most strikingly, we find that more than 3 times as many CD68 macrophages express the HIV coreceptor CCR5 in the rectum than in the colon (P = 0.0001), and as such rectal macrophages seem biologically closer to the HIV-susceptible CCR5 phenotype in the vagina than the mostly HIV-resistant CCR5 phenotype in the colon. Putative CD209 dendritic cells are generally enriched in the colon compared with the rectum (P = 0.0004), though their CCR5 expression levels are similar in both compartments. CD3 T-cell densities and CCR5 expression levels are comparable in the colon and rectum. CONCLUSIONS Our study establishes the target-cell environment for HIV infection in the human distal gut and demonstrates in general terms that the colon and rectum are immunologically distinct anatomical compartments. Greater expression of CCR5 on rectal macrophages suggests that the most distal sections of the gut may be especially vulnerable to HIV infection. Our findings also emphasize that caution should be exercised when extrapolating data obtained from colon tissues to the rectum.
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159
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London A, Cohen M, Schwartz M. Microglia and monocyte-derived macrophages: functionally distinct populations that act in concert in CNS plasticity and repair. Front Cell Neurosci 2013; 7:34. [PMID: 23596391 PMCID: PMC3625831 DOI: 10.3389/fncel.2013.00034] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 03/18/2013] [Indexed: 11/25/2022] Open
Abstract
Functional macrophage heterogeneity is recognized outside the central nervous system (CNS), where alternatively activated macrophages can perform immune-resolving functions. Such functional heterogeneity was largely ignored in the CNS, with respect to the resident microglia and the myeloid-derived cells recruited from the blood following injury or disease, previously defined as blood-derived microglia; both were indistinguishably perceived detrimental. Our studies have led us to view the myeloid-derived infiltrating cells as functionally distinct from the resident microglia, and accordingly, to name them monocyte-derived macrophages (mo-MΦ). Although microglia perform various maintenance and protective roles, under certain conditions when they can no longer provide protection, mo-MΦ are recruited to the damaged CNS; there, they act not as microglial replacements but rather assistant cells, providing activities that cannot be timely performed by the resident cells. Here, we focus on the functional heterogeneity of microglia/mo-MΦ, emphasizing that, as opposed to the mo-MΦ, microglia often fail to timely acquire the phenotype essential for CNS repair.
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Affiliation(s)
- Anat London
- Department of Neurobiology, Weizmann Institute of Science Rehovot, Israel
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160
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Abstract
Gut mucosal surfaces separate the external environment from the internal sterile environment and so represent a first line of defence system. This barrier faces environments rich in pathogens that have developed effective mechanisms for colonisation of epithelial surfaces and invasion of mucosal tissues, but also harmless antigens such as food, airborne antigens or commensal bacterial flora. The latter represent the vast majority of the encountered antigens and require an appropriate response characterised by either ignorance or active suppression. However, for the former, a robust immune response is needed. Mucosae have developed a complex immune system that is capable of mounting an immune response against pathogenic antigens, while maintaining the required ignorance or active suppression against non-pathogenic antigens. Taking advantage of this knowledge, strategies have been devised to induce oral tolerance to antigens involved in experimental autoimmune disease or human conditions. It is now known that oral tolerance induces the up-regulation and activation of T cells with regulatory properties, a subtype of CD4⁺ T cells whose function is to regulate functions of other T lymphocytes to avoid excessive immune activation. Amongst them, the Th3 cells (cells that express the latency-associated peptide on the surface and secrete transforming growth factor β, a cytokine with immunoregulatory properties) are especially relevant in the induction of oral tolerance. Orally fed antigens seek to generate these types of cells in the treatment of autoimmune diseases in experimental animals or human subjects.
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161
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Abstract
At mucosal surfaces, phagocytes such as macrophages coexist with microbial communities; highly controlled regulation of these interactions is essential for immune homeostasis. Pattern-recognition receptors (PRRs) are critical in recognizing and responding to microbial products, and they are subject to negative regulation through various mechanisms, including downregulation of PRR-activating components or induction of inhibitors. Insights into these regulatory mechanisms have been gained through human genetic disease-association studies, in vivo mouse studies utilizing disease models or targeted gene perturbations, and in vitro and ex vivo human cellular studies examining phagocytic cell functions. Although mouse models provide an important approach to study macrophage regulation, human and mouse macrophages exhibit differences, which must be considered when extrapolating mouse findings to human physiology. This review discusses inhibitory regulation of PRR-induced macrophage functions and the consequences of dysregulation of these functions and highlights mechanisms that have a role in intestinal macrophages and in human macrophage studies.
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Affiliation(s)
- M Hedl
- Department of Internal Medicine, Yale University, New Haven, Connecticut, USA
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162
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Tissues use resident dendritic cells and macrophages to maintain homeostasis and to regain homeostasis upon tissue injury: the immunoregulatory role of changing tissue environments. Mediators Inflamm 2012; 2012:951390. [PMID: 23251037 PMCID: PMC3518145 DOI: 10.1155/2012/951390] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Accepted: 10/25/2012] [Indexed: 01/07/2023] Open
Abstract
Most tissues harbor resident mononuclear phagocytes, that is, dendritic cells and macrophages. A classification that sufficiently covers their phenotypic heterogeneity and plasticity during homeostasis and disease does not yet exist because cell culture-based phenotypes often do not match those found in vivo. The plasticity of mononuclear phagocytes becomes obvious during dynamic or complex disease processes. Different data interpretation also originates from different conceptual perspectives. An immune-centric view assumes that a particular priming of phagocytes then causes a particular type of pathology in target tissues, conceptually similar to antigen-specific T-cell priming. A tissue-centric view assumes that changing tissue microenvironments shape the phenotypes of their resident and infiltrating mononuclear phagocytes to fulfill the tissue's need to maintain or regain homeostasis. Here we discuss the latter concept, for example, why different organs host different types of mononuclear phagocytes during homeostasis. We further discuss how injuries alter tissue environments and how this primes mononuclear phagocytes to enforce this particular environment, for example, to support host defense and pathogen clearance, to support the resolution of inflammation, to support epithelial and mesenchymal healing, and to support the resolution of fibrosis to the smallest possible scar. Thus, organ- and disease phase-specific microenvironments determine macrophage and dendritic cell heterogeneity in a temporal and spatial manner, which assures their support to maintain and regain homeostasis in whatever condition. Mononuclear phagocytes contributions to tissue pathologies relate to their central roles in orchestrating all stages of host defense and wound healing, which often become maladaptive processes, especially in sterile and/or diffuse tissue injuries.
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163
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A single-amino-acid change in murine norovirus NS1/2 is sufficient for colonic tropism and persistence. J Virol 2012; 87:327-34. [PMID: 23077309 DOI: 10.1128/jvi.01864-12] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human norovirus (HuNoV) is the major cause of acute nonbacterial gastroenteritis worldwide but has no clear animal reservoir. HuNoV can persist after the resolution of symptoms, and this persistence may be essential for viral maintenance within the population. Many strains of the related murine norovirus (MNV) also persist, providing a tractable animal model for studying norovirus (NoV) persistence. We have used recombinant cDNA clones of representative persistent (CR6) and nonpersistent (CW3) strains to identify a domain within the nonstructural gene NS1/2 that is necessary and sufficient for persistence. Furthermore, we found that a single change of aspartic acid to glutamic acid in CW3 NS1/2 was sufficient for persistence. This same conservative change also caused increased growth of CW3 in the proximal colon, which we found to be a major tissue reservoir of MNV persistence, suggesting that NS1/2 determines viral tropism that is necessary for persistence. These findings represent the first identified function for NoV NS1/2 during infection and establish a novel model system for the study of enteric viral persistence.
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164
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Hunter AC, Elsom J, Wibroe PP, Moghimi SM. Polymeric particulate technologies for oral drug delivery and targeting: A pathophysiological perspective. Maturitas 2012; 73:5-18. [DOI: 10.1016/j.maturitas.2012.05.014] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 11/25/2022]
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165
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Hunter AC, Elsom J, Wibroe PP, Moghimi SM. Polymeric particulate technologies for oral drug delivery and targeting: a pathophysiological perspective. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8 Suppl 1:S5-20. [PMID: 22846372 DOI: 10.1016/j.nano.2012.07.005] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 05/25/2012] [Indexed: 01/01/2023]
Abstract
The oral route for delivery of pharmaceuticals is the most widely used and accepted. Nanoparticles and microparticles are increasingly being applied within this arena to optimize drug targeting and bioavailability. Frequently the carrier systems used are either constructed from or contain polymeric materials. Examples of these nanocarriers include polymeric nanoparticles, solid lipid nanocarriers, self-nanoemulsifying drug delivery systems and nanocrystals. It is the purpose of this review to describe these cutting edge technologies and specifically focus on the interaction and fate of these polymers within the gastrointestinal system.
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Affiliation(s)
- A Christy Hunter
- University of Manchester, Department of Pharmacy and Pharmaceutical Sciences, Stopford Building, Oxford Road, Manchester, M13 9PT, United Kingdom.
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166
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Moghimi SM, Parhamifar L, Ahmadvand D, Wibroe PP, Andresen TL, Farhangrazi ZS, Hunter AC. Particulate systems for targeting of macrophages: basic and therapeutic concepts. J Innate Immun 2012; 4:509-28. [PMID: 22722900 DOI: 10.1159/000339153] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 04/30/2012] [Indexed: 12/22/2022] Open
Abstract
Particulate systems in the form of liposomes, polymeric micelles, polymeric nano- and microparticles, and many others offer a rational approach for selective delivery of therapeutic agents to the macrophage from different physiological portals of entry. Particulate targeting of macrophages and intracellular drug release processes can be optimized through modifications of the drug carrier physicochemical properties, which include hydrodynamic size, shape, composition and surface characteristics. Through such modifications together with understanding of macrophage cell biology, targeting may be aimed at a particular subset of macrophages. Advances in basic and therapeutic concepts of particulate targeting of macrophages and related nanotechnology approaches for immune cell modifications are discussed.
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Affiliation(s)
- S M Moghimi
- Nanomedicine Laboratory, Centre for Pharmaceutical Nanotechnology and Nanotoxicology, University of Copenhagen, Copenhagen, Denmark.
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167
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Feng B, La JH, Schwartz ES, Gebhart GF. Irritable bowel syndrome: methods, mechanisms, and pathophysiology. Neural and neuro-immune mechanisms of visceral hypersensitivity in irritable bowel syndrome. Am J Physiol Gastrointest Liver Physiol 2012; 302:G1085-98. [PMID: 22403791 PMCID: PMC3362095 DOI: 10.1152/ajpgi.00542.2011] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Irritable bowel syndrome (IBS) is characterized as functional because a pathobiological cause is not readily apparent. Considerable evidence, however, documents that sensitizing proinflammatory and lipotoxic lipids, mast cells and their products, tryptases, enteroendocrine cells, and mononuclear phagocytes and their receptors are increased in tissues of IBS patients with colorectal hypersensitivity. It is also clear from recordings in animals of the colorectal afferent innervation that afferents exhibit long-term changes in models of persistent colorectal hypersensitivity. Such changes in afferent excitability and responses to mechanical stimuli are consistent with relief of discomfort and pain in IBS patients, including relief of referred abdominal hypersensitivity, upon intra-rectal instillation of local anesthetic. In the aggregate, these experimental outcomes establish the importance of afferent drive in IBS, consistent with a larger literature with respect to other chronic conditions in which pain is a principal complaint (e.g., neuropathic pain, painful bladder syndrome, fibromyalgia). Accordingly, colorectal afferents and the environment in which these receptive endings reside constitute the focus of this review. That environment includes understudied and incompletely understood contributions from immune-competent cells resident in and recruited into the colorectum. We close this review by highlighting deficiencies in existing knowledge and identifying several areas for further investigation, resolution of which we anticipate would significantly advance our understanding of neural and neuro-immune contributions to IBS pain and hypersensitivity.
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Affiliation(s)
- Bin Feng
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Jun Ho La
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Erica S. Schwartz
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - G. F. Gebhart
- Center for Pain Research, Department of Anesthesiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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168
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Weidenbusch M, Anders HJ. Tissue microenvironments define and get reinforced by macrophage phenotypes in homeostasis or during inflammation, repair and fibrosis. J Innate Immun 2012; 4:463-77. [PMID: 22507825 DOI: 10.1159/000336717] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 01/23/2012] [Indexed: 12/17/2022] Open
Abstract
Current macrophage phenotype classifications are based on distinct in vitro culture conditions that do not adequately mirror complex tissue environments. In vivo monocyte progenitors populate all tissues for immune surveillance which supports the maintenance of homeostasis as well as regaining homeostasis after injury. Here we propose to classify macrophage phenotypes according to prototypical tissue environments, e.g. as they occur during homeostasis as well as during the different phases of (dermal) wound healing. In tissue necrosis and/or infection, damage- and/or pathogen-associated molecular patterns induce proinflammatory macrophages by Toll-like receptors or inflammasomes. Such classically activated macrophages contribute to further tissue inflammation and damage. Apoptotic cells and an-tiinflammatory cytokines dominate in postinflammatory tissues which induce macrophages to produce more anti-inflammatory mediators. Similarly, tumor-associated macrophages also confer immunosuppression in tumor stroma. Insufficient parenchymal healing despite abundant growth factors pushes macrophages to gain a profibrotic phenotype and promote fibrocyte recruitment which both enforce tissue scarring. Ischemic scars are largely devoid of cytokines and growth factors so that fibrolytic macrophages that predominantly secrete proteases digest the excess extracellular matrix. Together, macrophages stabilize their surrounding tissue microenvironments by adapting different phenotypes as feed-forward mechanisms to maintain tissue homeostasis or regain it following injury. Furthermore, macrophage heterogeneity in healthy or injured tissues mirrors spatial and temporal differences in microenvironments during the various stages of tissue injury and repair.
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Affiliation(s)
- Marc Weidenbusch
- Medizinische Klinik IV, Klinikum der Universität München-LMU, München, Deutschland
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169
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170
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Harrison OJ, Maloy KJ. Innate immune activation in intestinal homeostasis. J Innate Immun 2011; 3:585-93. [PMID: 21912101 PMCID: PMC3224517 DOI: 10.1159/000330913] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 12/13/2022] Open
Abstract
Loss of intestinal immune regulation leading to aberrant immune responses to the commensal microbiota are believed to precipitate the chronic inflammation observed in the gastrointestinal tract of patients with inflammatory bowel diseases (IBD), Crohn's disease and ulcerative colitis. Innate immune receptors that recognize conserved components derived from the microbiota are widely expressed by both epithelial cells and leucocytes of the gastrointestinal tract and play a key role in host protection from infectious pathogens; yet precisely how pathogenic and commensal microbes are distinguished is not understood. Furthermore, aberrant innate immune activation may also drive intestinal pathology, as patients with IBD exhibit extensive infiltration of innate immune cells to the inflamed intestine, and polymorphisms in many innate immunity genes influence susceptibility to IBD. Thus, a balanced interaction between the microbiota and innate immune activation is required to maintain a healthy mutualistic relationship between the microbiota and the host, which when disturbed can result in intestinal inflammation.
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Affiliation(s)
- Oliver J Harrison
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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