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Teh YC, Chooi MY, Chong SZ. Behind the monocyte's mystique: uncovering their developmental trajectories and fates. DISCOVERY IMMUNOLOGY 2023; 2:kyad008. [PMID: 38567063 PMCID: PMC10917229 DOI: 10.1093/discim/kyad008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 05/11/2023] [Accepted: 07/17/2023] [Indexed: 04/04/2024]
Abstract
Monocytes are circulating myeloid cells that are derived from dedicated progenitors in the bone marrow. Originally thought of as mere precursors for the replacement of tissue macrophages, it is increasingly clear that monocytes execute distinct effector functions and may give rise to monocyte-derived cells with unique properties from tissue-resident macrophages. Recently, the advent of novel experimental approaches such as single-cell analysis and fate-mapping tools has uncovered an astonishing display of monocyte plasticity and heterogeneity, which we believe has emerged as a key theme in the field of monocyte biology in the last decade. Monocyte heterogeneity is now recognized to develop as early as the progenitor stage through specific imprinting mechanisms, giving rise to specialized effector cells in the tissue. At the same time, monocytes must overcome their susceptibility towards cellular death to persist as monocyte-derived cells in the tissues. Environmental signals that preserve their heterogenic phenotypes and govern their eventual fates remain incompletely understood. In this review, we will summarize recent advances on the developmental trajectory of monocytes and discuss emerging concepts that contributes to the burgeoning field of monocyte plasticity and heterogeneity.
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Affiliation(s)
- Ye Chean Teh
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
| | - Ming Yao Chooi
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
| | - Shu Zhen Chong
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, Republic of Singapore
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore
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Moghimi SM. Complement Propriety and Conspiracy in Nanomedicine: Perspective and a Hypothesis. Nucleic Acid Ther 2016; 26:67-72. [DOI: 10.1089/nat.2015.0587] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Seyed Moein Moghimi
- Centre for Pharmaceutical Nanotechnology and Nanotoxicology, University of Copenhagen, Copenhagen, Denmark
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Cooper DKC, Ekser B, Burlak C, Ezzelarab M, Hara H, Paris L, Tector AJ, Phelps C, Azimzadeh AM, Ayares D, Robson SC, Pierson RN. Clinical lung xenotransplantation--what donor genetic modifications may be necessary? Xenotransplantation 2012; 19:144-58. [PMID: 22702466 PMCID: PMC3775598 DOI: 10.1111/j.1399-3089.2012.00708.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Barriers to successful lung xenotransplantation appear to be even greater than for other organs. This difficulty may be related to several macro anatomic factors, such as the uniquely fragile lung parenchyma and associated blood supply that results in heightened vulnerability of graft function to segmental or lobar airway flooding caused by loss of vascular integrity (also applicable to allotransplants). There are also micro-anatomic considerations, such as the presence of large numbers of resident inflammatory cells, such as pulmonary intravascular macrophages and natural killer (NK) T cells, and the high levels of von Willebrand factor (vWF) associated with the microvasculature. We have considered what developments would be necessary to allow successful clinical lung xenotransplantation. We suggest this will only be achieved by multiple genetic modifications of the organ-source pig, in particular to render the vasculature resistant to thrombosis. The major problems that require to be overcome are multiple and include (i) the innate immune response (antibody, complement, donor pulmonary and recipient macrophages, monocytes, neutrophils, and NK cells), (ii) the adaptive immune response (T and B cells), (iii) coagulation dysregulation, and (iv) an inflammatory response (e.g., TNF-α, IL-6, HMGB1, C-reactive protein). We propose that the genetic manipulation required to provide normal thromboregulation alone may include the introduction of genes for human thrombomodulin/endothelial protein C-receptor, and/or tissue factor pathway inhibitor, and/or CD39/CD73; the problem of pig vWF may also need to be addressed. It would appear that exploration of every available therapeutic path will be required if lung xenotransplantation is to be successful. To initiate a clinical trial of lung xenotransplantation, even as a bridge to allotransplantation (with a realistic possibility of survival long enough for a human lung allograft to be obtained), significant advances and much experimental work will be required. Nevertheless, with the steadily increasing developments in techniques of genetic engineering of pigs, we are optimistic that the goal of successful clinical lung xenotransplantation can be achieved within the foreseeable future. The optimistic view would be that if experimental pig lung xenotransplantation could be successfully managed, it is likely that clinical application of this and all other forms of xenotransplantation would become more feasible.
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Affiliation(s)
- David K C Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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O'Dea KP, Wilson MR, Dokpesi JO, Wakabayashi K, Tatton L, van Rooijen N, Takata M. Mobilization and margination of bone marrow Gr-1high monocytes during subclinical endotoxemia predisposes the lungs toward acute injury. THE JOURNAL OF IMMUNOLOGY 2009; 182:1155-66. [PMID: 19124759 DOI: 10.4049/jimmunol.182.2.1155] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The specialized role of mouse Gr-1(high) monocytes in local inflammatory reactions has been well documented, but the trafficking and responsiveness of this subset during systemic inflammation and their contribution to sepsis-related organ injury has not been investigated. Using flow cytometry, we studied monocyte subset margination to the pulmonary microcirculation during subclinical endotoxemia in mice and investigated whether marginated monocytes contribute to lung injury in response to further septic stimuli. Subclinical low-dose i.v. LPS induced a rapid (within 2 h), large-scale mobilization of bone marrow Gr-1high monocytes and their prolonged margination to the lungs. With secondary LPS challenge, membrane TNF expression on these premarginated monocytes substantially increased, indicating their functional priming in vivo. Zymosan challenge produced small increases in pulmonary vascular permeability, which were markedly enhanced by the preadministration of low-dose LPS. The LPS-zymosan-induced permeability increases were effectively abrogated by pretreatment (30 min before zymosan challenge) with the platelet-activating factor antagonist WEB 2086 in combination with the phosphatidylcholine-phospholipase C inhibitor D609, suggesting the involvement of platelet-activating factor/ceramide-mediated pathways in this model. Depletion of monocytes (at 18 h after clodronate-liposome treatment) significantly attenuated the LPS-zymosan-induced permeability increase. However, restoration of normal LPS-induced Gr-1high monocyte margination to the lungs (at 48 h after clodronate-liposome treatment) resulted in the loss of this protective effect. These results demonstrate that mobilization and margination of Gr-1high monocytes during subclinical endotoxemia primes the lungs toward further septic stimuli and suggest a central role for this monocyte subset in the development of sepsis-related acute lung injury.
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Affiliation(s)
- Kieran P O'Dea
- Department of Anaesthetics, Pain Medicine and Intensive Care, Faculty of Medicine, Imperial College London, Chelsea and Westminster Hospital, London, United Kingdom
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Utkhede DR, Tilcock CP. Studies Upon the Toxicity of Polyethylene Glycol Coated Lipid Vesicles: Acute Hemodynamic Effects, Pyrogenicity and Complement Activation. J Liposome Res 2008. [DOI: 10.3109/08982109809039936] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Gamage LNA, Charavaryamath C, Swift TL, Singh B. Lung inflammation following a single exposure to swine barn air. J Occup Med Toxicol 2007; 2:18. [PMID: 18088427 PMCID: PMC2234408 DOI: 10.1186/1745-6673-2-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2007] [Accepted: 12/18/2007] [Indexed: 12/03/2022] Open
Abstract
Background Exposure to swine barn air is an occupational hazard. Barn workers following an eight-hour work shift develop many signs of lung dysfunction including lung inflammation. However, the in situ cellular and molecular mechanisms responsible for lung dysfunction induced following exposure to the barn air remain largely unknown. Specifically, the recruitment and role of pulmonary intravascular monocytes/macrophages (PIMMs), which increase host susceptibility for acute lung inflammation, remain unknown in barn air induced lung inflammation. We hypothesized that barn exposure induces recruitment of PIMMs and increases susceptibility for acute lung inflammation with a secondary challenge. Methods Sprague-Dawley rats were exposed either to the barn or ambient air for eight hours and were euthanized at various time intervals to collect blood, broncho-alveolar lavage fluid (BALF) and lung tissue. Subsequently, following an eight hour barn or ambient air exposure, rats were challenged either with Escherichia coli (E. coli) lipopolysaccharide (LPS) or saline and euthanized 6 hours post-LPS or saline treatment. We used ANOVA (P < 0.05 means significant) to compare group differences. Results An eight-hour exposure to barn air induced acute lung inflammation with recruitment of granulocytes and PIMMs. Granulocyte and PIMM numbers peaked at one and 48 hour post-exposure, respectively. Secondary challenge with E. coli LPS at 48 hour following barn exposure resulted in intense lung inflammation, greater numbers of granulocytes, increased number of cells positive for TNF-α and decreased amounts of TGF-β2 in lung tissues. We also localized TNF-α, IL-1β and TGF-β2 in PIMMs. Conclusion A single exposure to barn air induces lung inflammation with recruitment of PIMMs and granulocytes. Recruited PIMMs may be linked to more robust lung inflammation in barn-exposed rats exposed to LPS. These data may have implications of workers exposed to the barn air who may encounter secondary microbial challenge.
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Cantu E, Balsara KR, Li B, Lau C, Gibson S, Wyse A, Baig K, Gaca J, Gonzalez-Stawinski GV, Nichols T, Parker W, Davis RD. Prolonged function of macrophage, von Willebrand factor-deficient porcine pulmonary xenografts. Am J Transplant 2007; 7:66-75. [PMID: 17109734 DOI: 10.1111/j.1600-6143.2006.01603.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Porcine von Willebrand factor (vWF) activates human and primate platelets. Having determined the importance of pulmonary intravascular macrophages (PIMs) in pulmonary xenotransplantation, we evaluated whether, in the absence of PIMs, vWF might play a role in pulmonary xenograft dysfunction. Utilizing a left single-lung transplant model, baboons depleted of anti-alphaGal antibodies received lungs from either vWF-deficient (n = 2); MCP-expressing (n = 5); MCP PIM-depleted (n = 5); or vWF-deficient PIM-depleted swine (n = 3). Two out of three of the PIM-depleted, pvWF deficient grafts survived longer than any previously reported pulmonary xenografts, including PIM-depleted xenografts expressing human complement regulatory proteins. Depletion of PIM's from vWF-deficient lungs, like depletion of PIM's from hMCP lungs, resulted in abrogation of the coagulopathy associated with pulmonary xenotransplantation. Thus, in terms of pulmonary graft survival, control of adverse reactions involving pvWF appears to be equally or even more important than is complement regulation using hMCP expression. However, based on the rapid failure of PIM-sufficient, pvWF-deficient pulmonary xenografts, pVWF-deficient pulmonary xenografts appear to be particularly sensitive to macrophage-mediated damage. These data provide initial evidence that vWF plays a role in the 'delayed' (24 h) dysfunction observed in pulmonary xenotransplantation using PIM depleted hMCP organs.
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Affiliation(s)
- E Cantu
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Cantu E, Gaca JG, Palestrant D, Baig K, Lukes DJ, Gibson SE, Gonzalez-Stawinski GV, Olausson M, Parker W, Davis RD. Depletion of Pulmonary Intravascular Macrophages Prevents Hyperacute Pulmonary Xenograft Dysfunction. Transplantation 2006; 81:1157-64. [PMID: 16641602 DOI: 10.1097/01.tp.0000169758.57679.2a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recent years have brought dramatic progress in the field of xenotransplantation, with the development of transgenic swine and various other means of overcoming the rejection mediated by xenoreactive antibodies. Although progress has been rapid with kidney and heart xenografts, progress with pulmonary xenografts has lagged behind. Recent findings have suggested that donor pulmonary intravascular macrophages may play a critical role in the hyperacute dysfunction of pulmonary xenografts. METHODS The function of pulmonary xenografts from pigs depleted of pulmonary intravascular macrophages was compared with the function of xenografts from normal pigs. RESULTS Pulmonary xenografts from pigs from which pulmonary intravascular macrophages were depleted survived (23.5+/-0.9 hours) about five times longer than normal (macrophage sufficient) xenografts (4.4+/-1.41 hours) (P< 0.0001). At 21 hours post-reperfusion, the left pulmonary arterial flow was 225.0+/-34 ml/min in lungs depleted of pulmonary intravascular macrophages, whereas all normal xenografts had failed. CONCLUSIONS These findings indicate that donor macrophages play a critical role in pulmonary xenograft dysfunction. This finding has broad implications for xenotransplantation, suggesting that porcine macrophages might pose a barrier to the engraftment and function of a variety of porcine organ xenografts.
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Affiliation(s)
- Edward Cantu
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA
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Cantu E, Parker W, Platt JL, Duane Davis R. Pulmonary xenotransplantation: rapidly progressing into the unknown. Am J Transplant 2004; 4 Suppl 6:25-35. [PMID: 14871271 DOI: 10.1111/j.1600-6135.2004.0342.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
As one approach to circumventing the dire shortage of human lungs for transplantation, a handful of investigators have begun to probe the possibility of pulmonary xenotransplantation. The immunologic and perhaps physiologic barriers encountered by these investigators are considerable and progress in pulmonary xenotransplantation has lagged behind progress in cardiac and kidney xenotransplantation. However, during the last few years there have been substantial advances in the field of pulmonary xenotransplantation including, most noticeably, significant progress in attenuating hyperacute dysfunction. Progress has been made in understanding the barriers imposed by xenoreactive antibodies, complement, coagulation incompatibility and porcine pulmonary intravascular macrophages. Although our understanding of the barriers to pulmonary xenotransplantation is far from complete and the clinical application of pulmonary xenotransplantation is not yet in sight, current progress is fast paced. This progress provides a basis for future work and for a hope that the shortage of human lungs for transplantation will not always be a matter of life and death.
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Affiliation(s)
- Edward Cantu
- Department of Surgery, Duke University Medical Center, Durham, NC, USA.
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Gaca JG, Palestrant D, Lukes DJ, Olausson M, Parker W, Davis RD. Prevention of acute lung injury in swine: depletion of pulmonary intravascular macrophages using liposomal clodronate. J Surg Res 2003; 112:19-25. [PMID: 12873428 DOI: 10.1016/s0022-4804(03)00142-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Swine contain large numbers of pulmonary intravascular macrophages (PIMs) that mediate the physiological response observed in acute lung injury (ALI). As the hyperacute dysfunction observed in pulmonary xenotransplantation is similar to endotoxin-induced ALI, PIMs may play a critical role in pulmonary xenograft dysfunction. We used liposomal clodronate to eliminate the PIM population in a model of acute swine lung injury. MATERIALS AND METHODS Experimental swine (n = 6) received liposomal clodronate (1.25 g/10 kg) and control swine (n = 5) received saline containing liposomes before infusion of lipopolysaccharide (450 ng/kg). RESULTS Control swine demonstrated higher peak pulmonary artery pressures (41.8 +/- 2.2 versus 16.8 +/- 1.2 mm Hg; P < 0.0001) and higher peak pulmonary vascular resistances (1405 +/- 209 versus 353 +/- 81 dynes. s. cm(-5); P = 0.0016) in response to lipopolysaccharide infusion. Clodronate treated swine also had significantly lower serum levels of tumor necrosis factor-alpha, interleukin-6, and thrombin. CONCLUSIONS Liposomal clodronate effectively attenuates acute swine lung injury induced by endotoxin. This method of depletion of the PIM population presents a promising new treatment of swine lungs before xenotransplantation.
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Affiliation(s)
- Jeffrey G Gaca
- Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
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Cheng J, Glaser RM, Kruger-Grey H, White-Scharf ME, Cooper DKC, Thall AD. Promotion of xenogeneic hematopoietic chimerism in rodents by mononuclear phagocyte depletion. Xenotransplantation 2002; 9:402-9. [PMID: 12371936 DOI: 10.1034/j.1399-3089.2002.01112.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The successful establishment of tolerance toward pig tissues in primates through hematopoietic progenitor cell engraftment is restricted by the rapid disappearance of these cells in the recipient following infusion. We developed and tested the hypothesis that phagocytes of the reticuloendothelial system are responsible for the rapid clearance of infused pig hematopoietic cells using a mouse model. Mice received non-myeloablative conditioning and, on various days, were injected with medronate-encapsulated liposomes (M-L) or control blank liposomes, followed by the intravenous infusion of miniature swine hematopoietic cells. M-L were well-tolerated in mice (n=100) at levels that deplete mononuclear phagocytes. Depletion of mononuclear phagocytes in normal Balb/c mice as well as in severe combined immune deficient mice increased the accumulation of pig hematopoietic cells in the bone marrow (BM) by 10-fold when measured 24 h after the infusion of the cells. Colony-forming unit analysis showed an increased accumulation of pig hematopoietic progenitors in the BM of mice that were infused with medronate-liposomes. We conclude that depletion of mononuclear phagocytes by M-L has the potential to lower the barrier to the establishment of mixed chimerism and tolerance induction in xenotransplantation.
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Affiliation(s)
- J Cheng
- BioTransplant Inc., Charlestown, Massachusetts General Hospital, Boston, MA 02129, USA
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Knudsen E, Iversen PO, Van Rooijen N, Benestad HB. Macrophage-dependent regulation of neutrophil mobilization and chemotaxis during development of sterile peritonitis in the rat. Eur J Haematol 2002; 69:284-96. [PMID: 12460233 DOI: 10.1034/j.1600-0609.2002.02657.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pro-inflammatory cytokines attract leukocytes to inflamed tissues and activate them. Few attempts have been made to identify the sources of cytokines in vivo. We examined the importance of peritoneal macrophages in the mobilization and homing of neutrophils to a sterile peritonitis in the rat, with emphasis on their cytokine production. Macrophages, present in virtually all tissues, are known to be easily activated and to serve as an important source of cytokines. Flow cytometric analysis of cells stained intracellularly with tagged antibodies against various cytokines revealed that the peritoneal macrophages were stimulated to produce the following cytokines: interleukin (IL)-1beta, macrophage inflammatory protein-2 (MIP-2), and keratinocyte-derived cytokine (KC). High numbers of neutrophils, activated on arrival into the peritoneal cavity, also produced IL-1beta, whereas lower numbers contained interleukin-6, tumor necrosis factor-alpha, MIP-2, KC, and MIP-1alpha. This marked activation of peritoneal neutrophils was also reflected by increased surface expression of CD11b. On the other hand, peritoneal macrophages expressed high basal levels of CD11b, which were reduced 24 h after the onset of inflammation. In rats selectively depleted of macrophages by i.p. injection of liposome-containing clodronate, the massive influx of neutrophils to the peritoneal cavity was markedly reduced, as was the rapid mobilization of mature bone marrow neutrophils. Local macrophages are important both for the accumulation of neutrophils in the inflamed peritoneal cavity and for the early mobilization of neutrophils from the bone marrow. Macrophage-derived IL-1beta, MIP-2, and KC are possible mediators of neutrophil homing to inflamed tissues.
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Affiliation(s)
- Eirunn Knudsen
- Department of Physiology, Institute of Basic Medical Sciences, University of Oslo, Norway.
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Staub NC, Longworth KE, Serikov V, Jerome EH, Elsasser T. Detergent inhibits 70-90% of responses to intravenous endotoxin in awake sheep. J Appl Physiol (1985) 2001; 90:1788-97. [PMID: 11299269 DOI: 10.1152/jappl.2001.90.5.1788] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sheep have reactive pulmonary intravascular macrophages, which are essential for the marked pulmonary vascular response to infusions of small quantities of endotoxin. In another species with reactive pulmonary intravascular macrophages, horses, our laboratory found that an intravenous biosafe detergent, tyloxapol, inhibited some systemic and pulmonary responses to endotoxin (Longworth KE, Smith BL, Staub NC, Steffey EP, and Serikov V. Am J Vet Res 57: 1063-1066, 1996). We determined whether the same detergent would inhibit endotoxin responses in awake sheep. In 10 awake, instrumented sheep with chronic lung lymph fistulas, we did a control experiment by intravenously infusing 1 microg/kg Escherichia coli endotoxin. One week later, we gave 40 micromol/kg tyloxapol intravenously 1-4 h before infusing the same dose of endotoxin. In these paired studies, we compared pulmonary hemodynamics, lung lymph dynamics, body temperature, circulating leukocyte concentrations, and circulating tumor necrosis factor for 6 h. In all 10 sheep, tyloxapol blocked 80-90% of the pulmonary responses and 70-90% of the systemic responses. Tyloxapol is safe, inexpensive, easy to use, and effective immediately. It may be a clinically useful approach to contravening many of the effects of endotoxemia, in humans as well as animals.
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Affiliation(s)
- N C Staub
- Cardiovascular Research Institute, University of California, San Francisco 94143, USA
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Sone Y, Serikov VB, Staub NC. Intravascular macrophage depletion attenuates endotoxin lung injury in anesthetized sheep. J Appl Physiol (1985) 1999; 87:1354-9. [PMID: 10517763 DOI: 10.1152/jappl.1999.87.4.1354] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We recently showed that we can selectively and safely deplete most (average 85%) of the pulmonary intravascular macrophages in sheep by intravenously infusing liposomes containing dichloromethylene bisphosphonate. After a 1-h stable baseline, we made a 6-h comparison after a 30-min intravenous endotoxin infusion (1 microg/kg) between six anesthetized control lambs and six anesthetized lambs in which the intravascular macrophages had been depleted 24 h previously. Three of the control lambs had been macrophage depleted and allowed to recover their intravascular macrophage population for >/=2 wk. After depletion, both the early and late pulmonary arterial pressure rises were dramatically attenuated. Our main interest, however, was in the acute lung microvascular injury response. The early and late rises in lung lymph flow and the increase in lung lymph protein clearance (lymph flow x lymph-to-plasma protein concentration ratio) were >90% attenuated. We conclude the pulmonary intravascular macrophages are responsible for most of the endotoxin-induced pulmonary hypertension and increased lung microvascular leakiness in sheep, although the unavoidable injury of other intravascular macrophages by the depletion regime may also contribute something.
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Affiliation(s)
- Y Sone
- Cardiovascular Research Institute, University of California, San Francisco, California 94143, USA
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