Macrophage differentiation and function in health and disease

1、Macrophage differentiation and function in health and diseaseReview ArticleMacrophage differentiation and function in health and diseaseMakoto NaitoDivision of Cellular and Molecular Pathology,Department of Cellular Function,Niigata University Graduate School of Medical and Dental Sciences,Niigata,J

2、apanMacrophages exist in almost all animals.In some inverte-brates,mesenchymal cells,endothelial cells or?broblast-like cells can transform into macrophages.In vertebrates, primitive macrophages?rst develop in yolk sac hemato-poiesis and differentiate into fetal macrophages.Monocytes are differentia

3、ted from hematopoietic stem cells in the late stage of fetal hematopoietic organs and bone marrow. Macrophages serve as an effector in metabolism and host defense.Depletion of macrophages severely reduced biliru-bin production and host resistance to infection.Macroph-age scavenger receptors are invo

4、lved in host defense. Macrophage growth factors are critical for macrophage dif-ferentiation and function.In macrophage colony-stimulating factor(M-CSF)-de?cient osteopetrotic mice,monocytes, tissue macrophages and osteoclasts are de?cient. Granulocytemacrophage colony-stimulating factor(GM-CSF)-de?

5、cient mice develop alveolar proteinosis due to impaired surfactant catabolism by alveolar macrophages. Accumulation of glucocerebroside in macrophages due to the de?ciency of glucocerebrosidase in lysosomes pro-duces Gaucher cells.Macrophages in the arterial wall incor-porate chemically modi?ed low-

6、density lipoprotein(LDL) and transform into foam cells.Binding oxidized LDL to liver X receptor a(LXR a)upregulates the expression of its target genes,which act as cholesterol removers from macroph-ages.In?ammatory signals downregulate the expression of LXR a and enhance lipid accumulation.Thus,macr

7、ophages play a pivotal role in metabolism and host defense.Key words:atherosclerosis,Gaucher disease,GM-CSF,host defense,macrophages,M-CSF,ontogeny,phylogeny,scaven-ger receptor Macrophages are distributed throughout the body and exist in most tissues in various animals.The termmacrophagewas?rst use

8、d by Ellie Metchnikoff,the Nobel Prize winner of 1908.He introduced a rose thorn into star?sh larvae and observed amoeboid phagocytes around the intruder.He recognized the importance of phagocytosis in the general scheme of in?ammation.1,2More than a century has passed since his discovery of macroph

9、ages.It has since been dem-onstrated that macrophages are responsible for numerous metabolic,immunological,and in?ammatory processes under physiological and pathological conditions;but several questions remain on the origin,differentiation and function of macrophages.In this review,new aspects of ma

10、crophage differentiation and function are introduced with special reference to disor-ders caused by the dysregulation of macrophage function.MACROPHAGES IN PHYLOGENYEntamoeba,a protozoan parasite,is an ancient unicellular eukaryotic cell that shows active phagocytosis.Entamoeba histolytica is a path

11、ogenic parasite in human digestive organs.A nutrition type of Entamoeba possesses pseudopo-dia,lobopodia,?lopodia,reticulopodia and axopodia,struc-tures for movement and phagocytosis,and incorporated substances are digested in phagosomes,pinosomes,and lysosomes,which are acidi?ed by the action of pr

12、oton pump.3 Amebic erythrophagocytosis is characteristic of invasive amoebiasis,and fragment crystallizable(Fc)receptor-like protein,4phosphatidylserine receptor,115kDa protein against IgA,5and a112kDa adhesion molecule6on the cell membrane are suggested to be involved in erythrophagocy-tosis by amo

13、ebae,which also secrete several proteinases and incorporate and digest substances in the extracellular matrix.7,8These processes in the protozoan parasites are similar to those of macrophages,indicating that amoebae are a prototype of macrophages.Phagocytes exist in almost all the animal species.Var

14、ious terms are used to identify phagocytes,but the termCorrespondence:Makoto Naito,MD,PhD,Division of Cellular andMolecular Pathology,Department of Cellular Function,Niigata Uni-versity Graduate School of Medical and Dental Sciences,Asahimachi-dori1-757,Niigata951-8510,Japan.Email:mnaitomed.niigata-

15、u.ac.jpThis paper was presented at the96th Annual Meeting of theJapanese Society of Pathology,Osaka,Japan,2007,as the InvitedLecture(Japan Pathology Award)Received8October2007.Accepted for publication12November2007.?2008The AuthorJournal compilation?2008Japanese Society of PathologyPathology Interna

16、tional2008;58:143155doi:10.1111/j.1440-1827.2007.02203.xamoebocytesis the most frequent.In hydra,macrophages have not been con?rmed but ectodermal epithelial cells and endodermal epithelial cells show phagocytic activity,which plays an important role in graft rejection.9,10In mollusks only one type

17、of blood cell functions as phago-cytes.Fibroblasts in the connective tissue of the hemocoel wall of the land slug can transform into macrophages.11In these invertebrate animals the existence of hematopoietic stem cells is not con?rmed and macrophages are derived from endothelial cells and?broblasts.

18、In contrast,macroph-ages are derived from hematopoietic stem cells in verte-brates.Thus,the differentiation mechanism of macrophages in invertebrates and vertebrates appears to be different.MACROPHAGES IN ONTOGENYIn mouse embryos at9days of gestation,mononuclear cells are detected in the vascular lu

19、men of the yolk sac.12These mononuclear cells are round and possess a euchromatic nucleus with large nucleoli,a poorly developed Golgi appa-ratus,and abundant polyribosomes.Such immature cells rapidly differentiate into macrophages with more mature ultrastructural features.We designated the former i

20、mmature cellsprimitive macrophages,and the latter mature cells fetal macrophages.A transcription factor,PU.1,appears to be important for the differentiation of primitive macrophages into fetal macrophages.They are found in not only the vas-cular lumen but also the extravascular mesenchymal layer of

21、the yolk sac.13,14Primitive erythroblasts,primitive megakaryo-cytes and granulocyte/macrophage colony-forming cells are also produced in this primitive hematopoiesis.After the fetal cardiovascular system is connected with the vitelline and umbilical vessels,primitive macrophages are detected in the

22、hepatic sinusoid.These cells are suggested to have migrated from the yolk sac via the bloodstream.12,14 De?nitive hematopoietic cells appear during mammalian embryonic development in the aortagonadmesonephros region,and the microenvironment of this region also plays an important role in hematopoieti

23、c stem cell ontogeny.Thereaf-ter,primitive and fetal macrophages were found in various fetal tissues and the number of fetal macrophages in the liver increased with fetal age.Most macrophages expressed both the heme-degrading enzyme,heme oxygenase-1,and macrophage scavenger receptor.15Macrophages in

24、 fetal tissues have a high proliferative capacity.12,14The proliferative potential of fetal macrophages is important for their survival and for their colonization of fetal tissues via the bloodstream.Monocytes differentiate from hematopoietic stem cells. Macrophages in the in?ammatory foci are deriv

25、ed from monocytes that circulate in the blood and exude into in?am-matory lesions;but it has been shown that several tissue macrophages are derived from precursors different from monocytes.16Because the development of the monocytic cell lineage is incomplete in the early stage of fetal hematopoie-si

26、s,12,14primitive/fetal macrophages are considered to origi-nate from granulocytemacrophage colony-forming cells or earlier macrophage precursors,bypassing the monocytic cell series(Fig.1).MACROPHAGE DEPLETION AS A TOOL FORMACROPHAGE BIOLOGYThe macrophage depletion method is a simple but effective me

27、thod for analyzing the function of macrophages,and aFigure1Ontogeny of mouse mac-rophages.Primitive/fetal macrophagesoriginate from macrophage precursorsin yolk sac hematopoiesis and differen-tiate into fetal macrophages.Primitive/fetal macrophages circulate in the fetalcirculation and proliferate i

28、n hepatichematopoiesis.De?nitive hematopoi-etic cells appear in the aortagonadmesonephros(AGM)region.Somemacrophages in the fetal liver appearto be derived from hematopoieticstem cells in the AGM region.Themonocytic cell lineage develops inthe fetal liver and bone marrow.GM-CFC,granulocytemacrophage

29、colony-forming cells;HSC,hematopoi-etic stem cells;M f,macrophage.144M.Naito?2008The AuthorJournal compilation?2008Japanese Society of Pathologymethod using multilamellar liposomes encapsulating dichlo-romethylene diphosphonate(MDP)has been developed.17 Liposomes are selectively incorporated by macr

30、ophages, immediately transferred to lysosomes,and then MDP is released from liposomes into lysosomes by enzymatic digestion of the liposomal lipid layers.From4h after ingest-ing liposome-encapsulated MDP(lipo-MDP),macrophages in vivo and in vitro acquired the ultrastructural features of apoptosis,su

31、ch as condensed nuclear chromatin, nuclear fragmentation,cell shrinkage,and blebbing of the plasma membrane(Fig.2).17Macrophages incubated in medium containing lipo-MDP increased DNA fragmentation.These results imply that the intralysoso-mal accumulation of MDP generates signals to induce macrophage

32、 apoptosis.Lipo-MDP can eliminate various tissue macrophages by selecting a suitable administra-tion route.The i.v.administration of lipo-MDP depletes Kupffer cells in the liver and splenic macrophages. Intratracheal instillation of lipo-MDP can eliminate alveolar macrophages.Figure2(a)Macrophages u

33、ndergo apoptosis after phagocytosis of lipo-MDP.(b)Rat Kupffer cell containing several electron-lucent lipo-MDP in lysosomes(arrows).(c)Segmentation and fragmentation of a Kupffer cell.(d) Cultured macrophage with fragmented nuclei(arrow).(e)Gel electrophoresis of DNA extracted from apoptotic macrop

34、hages showing fragments of approximately185bp(lane1,control; lanes2,3,apoptotic macrophages). Lipo-MDP,liposome-encapsulated dichloromethylenediphosphonate.Figure5(a)Osteopetrotic(op/op) mice are toothless,have low body-weight and skeletal abnormalities,and are de?cient in tissue macrophages compare

35、d to normal littermates.(b) Percentage of tissue macrophages in op/op mice compared to normal litter-mates.BM,bone marrow,OC,osteo-clasts;s.c.,subcutaneoustissue.Figure6After daily macrophage colony-stimulating factor administra-tion to op/op mice,osteoclasts devel-oped and osteoclast numbers increa

36、sed in the bone of op/op mouse.(a)Tartrate-resistant acid phosphatase staining;(b)electron micrograph of osteoclasts(￥2000).aMacrophage differentiation and function145?2008The AuthorJournal compilation?2008Japanese Society of PathologyHost defenseWe ?rst examined the role of macrophages following pr

37、imary infection with Listeria monocytogenes (L.monocy-togenes ).18Kupffer cell-and splenic macrophage-depleted mice infected with a sublethal dose of L.monocytogenes died within 3days.Macrophage depletion resulted in marked increases in bacterial growth in the liver and spleen.The proliferation of L

38、.monocytogenes was observed in hepatocytes that underwent apoptosis.Rapid formation of abscesses was observed in the control mouse liver after L.monocytogenes infection,but there was less accumulation of neutrophils in the liver of Kupffer cell-depleted mice than in control mice.Thus,Kupffer cells p

39、rotect hepatocytes from L.monocytogenes infection (Fig.3).We also con?rmed that Kupffer cells protect hepa-tocytes from gut-derived stressors,including endotoxin,fol-lowing ischemiareperfusion.19Granulomas are units composed of macrophages and other immune cells to ?ght against pathogens.In Kupffer

40、cell-depleted mice the size and number of zymosan-induced granulomas in the liver were smaller than in untreated mice.20Expression of macrophage colony-stimulating factor (M-CSF),interleukin-1(IL-1),monocyte chemoattractant protein-1(MCP-1),tumor necrosis factor-a ,and interferon-g mRNA were enhance

41、d in the stage of granuloma formation inthe control mouse liver,whereas they were suppressed in Kupffer cell-depleted mice.Thus,Kupffer cells are indispens-able for granuloma formation and the production of various cytokines.Bilirubin metabolismHeme oxygenase 1,the heme-degrading enzyme in mac-ropha

42、ges,plays a key role in bilirubin metabolism,and is expressed in various tissue macrophages.In order to upregulate heme catabolism,heat-denatured red blood cells (h-RBC)were given i.v.21In the control rat liver,Kupffer cells constituted a major cellular component expressing heme oxygenase 1,while he

43、patocytes exhibited little expression.The levels of heme oxygenase 1expression in Kupffer cells were elevated immediately after injection of h-RBC.But in Kupffer cell-depleted livers the heme oxygenase 1-expressing cells were not detected even after h-RBC administration.In untreated control rats,tot

44、al bilirubin excre-tion increased approximately twofold at 5h after h-RBC administration.In contrast,Kupffer cell-depleting treatment decreased the level of bilirubin production even after admin-istration of h-RBC.These results suggest that Kupffer cells serve as an effector that upregulates heme-de

45、grading capac-ity and bilirubin production (Fig.4).Macrophage differentiationThis method is also effective to study macrophage differen-tiation after macrophage depletion.At 5days after complete depletion of Kupffer cells,small peroxidase-negative and acid-phosphatase weakly positive macrophages app

46、eared,increased in number,and differentiated into peroxidase-and acid-phosphatase-positive Kupffer cells.Repopulating small macrophages actively proliferated,and the number of Kupffer cells returned to the normal level by day 14.The numbers of macrophage precursors in the liver,as detected by the mo

47、no-clonal antibodies ER-MP20and ER-MP58,increased after macrophage depletion.ER-MP58-positive cells proliferated and differentiated into ER-MP20-positive cells and eventually into BM8-positive differentiated Kupffer cells in the liver.Bone-marrow-derived ER-MP58-positive cells were also detectable i

48、n the liver and differentiated into ER-MP20-positive cells,but they did not become BM8-positive mac-rophages.22These ?ndings imply that repopulating Kupffer cells are derived from a macrophage precursor pool in the liver rather than from bone marrow-derived monocytes.We then studied the repopulation

49、 of omental macrophages in mice depleted of macrophages following i.p.administration of lipo-MDP .As observed in the macrophage-depleted liver,macrophage precursors in the milky spots proliferated.TheseFigure 3(a )Survival of listeria-infected mice.Macrophage-depleted mice infected with a sublethal

50、dose of L.monocytogenes resulted in the death of the mice within 3days.(b )Schematic pre-sentation of histological changes in the liver of listeria-infected control mice and macrophage-depleted mice.18146M.Naito?2008The AuthorJournal compilation ?2008Japanese Society of Pathologymacrophage precursor

51、s moved to the omentum,and trans-formed into dendritic-shaped macrophages.Because M-CSF was found to be produced locally in milky spots after mac-rophage depletion,M-CSF appears to be an important factor in providing a microenvironment for the development and differentiation of omental macrophages.2

52、3ROLE OF MACROPHAGE GROWTH FACTORS INMACROPHAGE DIFFERENTIATIONMacrophage growth factors,including M-CSF,granulocytemacrophage colony-stimulating factor(GM-CSF)and IL-3 are important regulators of mononuclear phagocyte produc-tion and differentiation.Mice homozygous for the mutation osteopetrotic(op

53、/op mice)and GM-CSF-de?cient mice provide valuable information about the role of these factors.Macrophage colony-stimulating factorThe effects of M-CSF are mediated by the M-CSF receptor (M-CSFR),encoded by the c-fms proto-oncogene.24Osteo-petrotic(op/op)mice possess an inactivating mutation in the

54、coding region of the M-CSF gene and are devoid of detectable M-CSF.25,26These op/op mice are osteopetrotic27,28because of a marked de?ciency of osteoclasts.They are toothless,have low bodyweight,low growth rate,and skeletal abnormalities, and are de?cient in tissue macrophages(Fig.5).2830They also h

55、ave defects in both male and female fertility,neural development,the dermis,and synovial membranes.In op/op mice,osteoclasts appeared normal at birth;but osteoclast numbers fell within a few days after birth.31In adult op/op mice there were no multinuclear osteoclasts;but small numbers of mononuclea

56、r cells(so-calledpre-osteoclasts) were observed on the endosteal surface of bone.These pre-osteoclasts expressed tartrate-resistant acid phos-phatase and had ultrastructural features of immature osteo-clasts.After daily M-CSF administration in op/op mice, osteoclasts developed from the fusion of pre

57、-osteoclasts, and osteoclast numbers increased to the levels of normal littermates at3days(Fig.6).M-CSF administration also induced numerical increases of monocytes,pro-monocytes, and earlier precursor cells in bone marrow of the mutant mice.In op/op mice the tissue macrophages fell in number and we

58、re smaller than in normal littermates.Macrophages in op/op mice had various degrees of phagocytosis but the development of intracytoplasmic organelles and microvillous projections was poor.32After administration of M-CSF daily for2weeks,macrophages in op/op mice developed lysos-omes and microvillous

59、 projections.33The number of dendritic cells was similar to that in normal littermates and Birbeck granules in epidermal Langerhans cells were detected in op/op mice.These results indicate that the differentiation and maturation of tissue macrophages are mediated by M-CSF,but dendritic cell differentiation is con-trolled by other factor(s)than M-CSF,most probably by GM-CSF.34In young(46-week-old)op/