HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Okuda, M. Articles by Nishikawa, S.-i. Search for Related Content PubMed PubMed Citation Articles by Okuda, M. Articles by Nishikawa, S.-i.

Distinct Activities of Stromal Cells Involved in the Organogenesis of Lymph Nodes and Peyer’s Patches¹

Masato Okuda^*,, Atsushi Togawa^*, Hiromi Wada and Shin-ichi Nishikawa^2,*

^* Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, Kobe, Japan; and Department of Thoracic Surgery, Faculty of Medicine, Kyoto University, Kyoto, Japan

	Abstract

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 
It is now well established that the interaction between "inducer" cells of hemopoietic origin and "organizer" cells of mesenchymal lineage is involved in the organogenesis of lymph node (LN) and Peyer’s patch (PP). Organizer cells are defined by the expression of VCAM-1 and ICAM-1 and the production of homeostatic chemokines. However, several studies suggested the presence of a diversity among these cells from different lymphoid tissues. Thus, we attempted to define the difference of organizer cells of LN and PP in terms of gene expression profile. Microarray analyses of organizer cells revealed that these cells isolated from embryonic mesenteric LN expressed higher levels of genes that are related to inflammation, tissue remodeling, and development of mesenchymal lineage compared with those from PP. Several transcription factors related to epithelial-mesenchymal interactions were also up-regulated in organizer cells from LN. These results indicate that organizer cells in LN and PP are indeed distinct and suggest that the organizer cells in LN are at a more activated stage than those in PP.

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 
Unlike the lymphopoietic tissues such as thymus that emerged simultaneously with the evolution of the acquired immune system, peripheral lymphoid tissues (PLT)³ such as lymph node (LN) and Peyer’s patch (PP) appeared late along with the evolution of the mammals. This evolutionary difference is indeed reflected by the cellular mechanisms underlying the organogenesis of these old and new tissues (1). The induction of the thymus anlage exploits a morphogenic process that is common for most organs, such as the ingression of epithelial structure and epithelial-mesenchymal interaction (2, 3), whereas cells of hemopoietic lineage that are rarely involved in usual organogenesis play a role in the induction of the PLT (4). The bone formation would be another example of the organogenesis regulated by cells of hemopoietic lineage, because osteoclasts arise from macrophage precursors in bone marrow (5). With respect to PLT formation, previous studies including ours indicated that the hemopoietic cells that express IL-7R and ₄₇ integrin are commonly required for both LN and PP organogenesis (6, 7, 8). Because of this feature, these hemopoietic cells are now designated as the inducer of PLT organogenesis.

During the initial stage of PLT organogenesis, the inducer cells and surrounding mesenchymal components form a mutually interacting unit driving PLT organogenesis. We showed that the active compartment of mesenchymal cells involved in PP organogenesis is specified as cells that express both VCAM-1 and ICAM-1. Indeed, this population turned out to express a series of molecules that are essential for PP organogenesis, and thus was designated as the PP organizer (4). In subsequent studies, we showed that VCAM-1/ICAM-1 double-positive (DP) cells were also present in the LN. More recently, Cupedo et al. (9) investigated in detail this DP population in the LN and showed that DP cell is the population that expresses receptor activator for NF-B ligand (RANKL) that is essential for LN organogenesis. This paper also reported the presence of two distinct types of double-positive cells—one expressed both ICAM-1 and VCAM-1 at a high level (DP^high), whereas the other expressed both molecules at an intermediate level (DP^med)—and demonstrated that the proportion of each of the two DP populations was different between mesenteric LN (MLN) and peripheral LN. This study was thus the first demonstration of the presence of a diversity of DP organizer population among PLT and raised a possibility that this diversity might be responsible for the difference in the molecular requirements for PLT organogenesis. For instance, IL-7R and receptor activator for NF-B (RANK) signal are required differentially for PP and LN organogenesis, respectively; it is plausible that the expression level of ligands for these receptors, such as IL-7 and RANKL, respectively, in organizer cell population may differ among the organs (8, 10, 11, 12).

The aim of this study was to define the difference in the DP organizer population between PP and LN. Our results showed that DP^high populations in LN and PP are indeed completely distinct populations, although both belong to the mesenchymal cell lineage.

	Materials and Methods

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 
Mice

Pregnant C57BL/6J mice were purchased from Japan SLC. Noon of the day when the vaginal plug was found was designated as 0.5 days postcoitus. All animal experimental plans were reviewed and approved by the Institutional Animal Experiment Review Board.

Antibodies

For flow cytometry analyses, the following Abs were used: allophycocyanin-Cy7 anti-CD45 (30-F11) and FITC anti-ICAM-1 (3E2) were purchased from BD Pharmingen (San Jose, CA). Anti-VCAM-1 (M/K-2) was purified and labeled with allophycocyanin in our laboratory. RANKL on the cell surface was detected with biotin anti-mouse TRANCE (IK22/5; eBioscience) followed by streptavidin PE (BD Pharmingen). Biotin anti-rat IgG2a isotype control (eBR2a; eBioscience) was used as a negative control.

Flow cytometry

Embryonic organs were dissected under stereomicroscope and dissociated by dispase (Invitrogen Life Technologies) incubation for 15 min at 37°C. After gentle pipetting, dissociated cells were washed with HBSS containing 20% FCS and DNase (Sigma-Aldrich). Cells were filtered through nylon mesh to remove large clumps, washed, and stained with mAbs as described. These cells were analyzed or sorted by FACSAria (BD Biosciences).

Microarray analysis

GeneChip murine genome U74v2 arrays (Affymetrix) were used to identify genes differentially expressed in CD45^–VCAM-1^highICAM-1^high organizer cell population from MLN and PP compared with the negative control population (CD45^–VCAM-1^–ICAM-1^–). RNA sample preparation, array hybridization, array washing, and scanning were performed according to the manufacturer’s protocol. Ten micrograms of total RNA was extracted from the sorted cells with TRIzol reagent (Invitrogen Life Technologies). Double-stranded cDNA was synthesized in two steps using the Superscript Choice System (Invitrogen Life Technologies) and the reverse transcription primer T7-(dT)₂₄ (GE Healthcare Bio-Sciences). Subsequently, biotin-labeled cRNA was synthesized using the BioArray RNA Transcript labeling Kit (Affymetrix). Biotin-labeled cRNA was fragmented in a 40-µl reaction mixture containing 40 mM Tris-acetate (pH 8.1), 100 mM potassium acetate, and 30 mM magnesium acetate, and incubated at 94°C for 35 min, and then hybridized onto the MGU74v2 series of arrays and scanned according to the manufacturer’s protocol. Data were analyzed further using D-CHIP (http://www.dchip.org).

Immunohistochemistry

Whole-mount immunostaining was performed as previously described with slight modifications. In brief, excised guts were incubated in fixing solution (4% paraformaldehyde in PBS) for 30 min at 4°C. After washing three times in PBS each for 30 min at 4°C, specimens were dehydrated by incubating 30 min each with 50, 75, 100, 100% methanol in PBS at 4°C. To block endogenous peroxidase, the fixed specimens were bleached (methanol to 30% H₂O₂, 20:1) for 30 min at room temperature. For staining, the dehydrated specimens were first blocked by incubating twice in PBSMT (2% skim milk and 0.1% Triton X-100 in PBS) for 1 h at room temperature, incubated with PBSMT containing 0.5 µg/ml anti-VCAM-1 mAb (clone 429; BD Pharmingen) overnight at 4°C. After washing five times in PBSMT each for 1 h at 4°C, the primary Ab was detected by incubating 1 µg/ml HRP-conjugated goat anti-rat Ig Ab (BioSource International) overnight at 4°C. After extensive washing with more than five exchanges of PBSMT, including the final washes in PBST (0.1% Triton X-100 in PBS) three times for 20 min each at room temperature, specimens were soaked in PBST containing 0.05% NiCl₂ and 250 mg/ml diaminobenzidine for 20 min, and H₂O₂ was added to 0.01%. The enzymatic reaction was allowed to proceed until the desired color intensity was reached, and the specimens were rinsed three or four times in PBST. Finally, the specimens were dehydrated and the solution was exchanged to glycerol before being photographed.

Real-time quantitative RT-PCR

Total RNA was purified using TRIzol. First-strand cDNA was synthesized from 2 µg of total RNA using oligo(dT) primers, random hexamers, and SuperScript II (Invitrogen Life Technologies). Primers were designed using assay design center in Universal ProbeLibrary site (https://www.roche-applied-science.com). Designs were based on publicly available sequences. Real-time RT-PCR analysis was performed on ABI PRISM 7500 Sequence Detection System using the SYBR Green PCR Master Mix (GE Healthcare Bio-Sciences). The PCR consisted of 12.5 µl of SYBR Green PCR Master Mix, 10 µM forward and reverse primers, and 10 µl of 1/2-diluted template cDNA in a total volume of 25 µl. Cycling was performed using the default conditions of the ABI 7500 SDS Software 1.2: 2 min at 50°C, 10 min at 95°C, followed by 40 rounds of 15 s at 95°C and 1 min at 60°C. The relative expression of each gene was normalized against GAPDH. Sequences for each primer pair are listed in Table I.

	Results

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

Previous studies showed that both RANK and its ligand RANKL were essential signal mediators for LN organogenesis, whereas they were dispensable for PP organogenesis, which requires IL-7R signaling instead (8, 10, 11, 12). In addition, a line of evidence suggests that the inducer cells that are involved in the induction of PP and LN organogenesis represent almost identical lineage, or at least share common features, and can react to both RANKL and IL-7 to express lymphotoxin (LT) ₁₂ (6, 11). From these results, it is plausible that the factor that determines the nature of signals for activating inducers in PP and LN is the diversity among the organizer cell population (13).

To explore the diversity of organizer cell populations in LN and PP, we examined the expression pattern of VCAM-1 and ICAM-1 in MLN and PP of embryonic day 17.5 (E17.5) embryos. Consistent with the previous study of Cupedo et al. (9), both ICAM-1^highVCAM-1^high (DP^high) and ICAM-1^medVCAM-1^med (DP^med) populations were present in MLN, whereas only a small population of DP^med cells was present in PP. However, this difference in the composition of organizer populations may not represent the inherent difference between LN and PP, because DP^med cells increase during neonatal development (Fig. 1A). This result was confirmed histologically, because a gradation in VCAM-1 staining was observed in the day 4 PP, whereas the staining was more monotonous in E17.5 PP (Fig. 1B) (14, 15). Nonetheless, we confirmed the result of Cupedo et al. showing that there are two types of DP cells; one is DP^high and the other is DP^med. Our results further showed that composition of those two populations varies over the developmental stages of each organ as well as among organs.

View larger version (57K): [in this window] [in a new window]   FIGURE 1. Organizer cells in PLT. Single-cell suspensions of whole mesenteries or whole intestines from embryonic (E17.5) or neonatal (P4) C57BL/6 mice were prepared and analyzed by FACS analysis. Each CD45-negative population from either organ was stained by anti-VCAM-1 and anti-ICAM-1 Abs. A, R1, R2, and R3 populations represent the VCAM-1highICAM-1high, VCAM-1medICAM-1med, and VCAM-1–ICAM-1– cells, respectively. B, Intestines from E17.5 embryo or P4 neonates were stained with anti-VCAM-1 Ab by whole-mount immunohistochemistry.

We next sought to determine the cell surface expression of RANK and RANKL in each organizer population by flow cytometry analysis (6, 16). RANK expression could not be detected in any of the organizer populations, be it DP^med or DP^high (data not shown). In contrast, the surface expression of RANKL was detected in the DP^high population of MLN but not that of PP, whereas the DP^med population in either tissue did not express RANKL (Fig. 2). This result suggests that the DP^high organizer cells in MLN are distinct from those in PP, and is consistent with the notion that the differential activity of the organizers, particularly the DP^high population, is responsible for the difference in the signals used for the activation of the inducer cells.

View larger version (36K): [in this window] [in a new window]   FIGURE 2. Cell surface expression of RANKL on organizer cells. Each organizer cell population described in Fig. 1 was analyzed for its cell surface expression level of RANKL. Cells were stained with anti-RANKL Ab and analyzed by FACS (blue line). Anti-rat IgG isotype control was used as a negative control (red line).

To further define the difference in the DP^high organizer populations between LN and PP, we compared the gene expression profile of these two populations by DNA microarray analysis. DP^high cells were FACS sorted from either whole mesentery or whole intestine of E17.5 embryos, which includes MLN or PP, respectively (Fig. 3). VCAM-1^lowICAM-1^low cells from the whole mesentery were also sorted to use as a negative control. Purity of sorted cells was confirmed by the analysis of sorted cell samples. Cell sorting was repeated until the total cell number reached up to >10⁴. Total RNA isolated from the pooled cells was amplified and used for the hybridization with Affymetrix chips. The same experiments were repeated twice and the lists of genes that showed >2-fold difference in both experiments in their expression levels between PP and MLN are presented (supplemental Tables I–VI).⁴ Because the genes that we have detected in the previous section were also included in these lists, they may represent to a significant extent the difference of two cell populations. From these lists, genes whose functional role was described to a significant extent by the gene ontology in Mouse Genome Informatics website (http://www.informatics.jax.org/) were extracted and categorized in Tables II and III.

View larger version (43K): [in this window] [in a new window]   FIGURE 3. Cell sorting of organizer cell population. Single-cell suspensions of E17.5 and P4 mesenteries or intestines were stained with anti-CD45, anti-VCAM-1, and anti-ICAM-1 Abs. CD45–VCAM-1highICAM-1high population from both tissues were FACS sorted. CD45–VCAM-1–ICAM-1– cells from mesenteries were also sorted to use as a negative control. Purity of the sorting process was assessed by the analysis of the postsort samples.

Using the lists, we first focused on the difference in two organizer populations in terms of the expression of genes involved in the cell-cell interaction, including cell adhesion molecules, cytokines, chemokines, and other proteins. Of note, MLN expressed significantly higher levels of a variety of cytokines and chemokines than PP, including RANKL, IL-6, IL-7, CCL7, CXCL1, and CCL11. In contrast, only CCL21 was expressed higher in PP than in MLN. Considering previous studies showing that some ILs and chemokines are induced in mesenchymal cells particularly by inflammation, the feature of MLN organizer cells suggests that they are at the activated state (17, 18, 19).

In addition, MLN organizers expressed molecules that have been shown to be expressed inducibly during the differentiation of various mesenchymal cell lineages. Matrix metalloproteinase 8 and tetranectin are implicated in the tissue remodeling process such as the bone formation, nephroblastoma overexpressed gene is implicated as immediate-early protein involved in cell growth regulation, and retinol binding protein 4 is a secretory protein induced in adipocytes (20, 21, 22, 23). This observation is also consistent with the notion that MLN organizer represents a more active state in some ways than peripheral LN organizer.

To confirm this observation from the microarray analysis, we performed quantitative RT-PCR analyses of those molecules. As expected, both VCAM-1 and ICAM-1 were expressed in either DP^high population. However, although its surface expression could not be detected, a low level of RANKL mRNA expression was detected in DP^high population of PP by RT-PCR, even though its expression level was lower than that in the DP^high population of MLN. Interestingly, IL-7 expression was significantly higher in the DP^high population of MLN than that of PP. In contrast, the expression level of homeostatic chemokines, including CXCL13, CCL19, and CCL21 was higher in PP than in MLN (Fig. 4A) (24, 25). Other cytokines were also expressed in a higher level in the DP^high population of MLN than that of PP (Fig. 4B).

View larger version (34K): [in this window] [in a new window]   FIGURE 4. Quantitative RT-PCR analyses of genes expressed in organizer cells. The expression levels of genes that are known to be expressed in organizer cells were compared between DPhigh populations from E17.5 and P4 mesenteries and intestines. A, Relative expression level compared with that of GAPDH is shown. B, The expression level of cytokines, chemokines, and transcription factors that were significantly overexpressed in MLN by microarray analyses was confirmed.

Expression of transcription regulators

The above results strongly suggest that organizer populations are distinct between PP and MLN. We next compared two organizer populations in terms of the expression of transcription regulators. We could not notice a specific signature in the function of genes that were expressed higher in PP organizer cells. In contrast, the list of genes that are expressed higher in MLN organizers contains some interesting features. Many genes listed such as Meox2, GATA6, Lhx8, Prrx1, Egr2 have been implicated in various settings in which mesenchymal cell lineages play a role in the morphogenesis (26, 27). Previous gene knockout studies indicated that Meox2, Lhx8, and Prrx1 were involved in the development of skeletal tissues. Meox2 null mutant shows a severe defect in the formation of skeletal muscles, and mutations of Lhx8 and Prrx1 resulted in cleft palate (28, 29, 30, 31). This difference of gene expression profile was confirmed by quantitative RT-PCR (Fig. 4B). In embryo, Meox2, Lhx8, and Prrx1 were only expressed in DP^high population of MLN. Although expression of these genes became detectable in DP^high population of PP over time, their expression levels remain significantly lower than that of MLN.

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 
How mesenchymal cells that look relatively homogeneous in morphology are able to be involved in enormously diverse processes of morphogenesis is one of the most important questions in developmental biology. A common mechanism unraveled by previous studies is the transformation of a limited portion of mesenchymal cells to the activated state with the ability to regulate the subsequent process of morphogenesis. One typical example of this process has been visualized as a mesenchymal cell condensation at the site of morphogenesis (32, 33). Development of various molecular markers indicated that the condensed mesenchymal cells were indeed distinct from surrounding cells. PLT are another example in which the mesenchymal cells involved in organogenesis have been distinguished by the expression of specific molecular markers. At an early stage of PP organogenesis, we demonstrated that mesenchymal cells that are distinguished from surrounding cells by the coexpression of VCAM-1 and ICAM-1 play the organizer role in subsequent organogenic process (16). Likewise, DP⁺ mesenchymal cells are also found in developing LN, indicating a common mechanism for both PLT. This result thus strongly suggested the involvement of the common mesenchymal subsets in the organogenesis of both PP and LN. To verify this possibility was the major aim of this study.

The heterogeneity of mesenchymal cells in PLT has been suggested by a previous study by Cupedo et al. (9). In this study, they identified the existence of two mesenchymal populations, one expressing a medium level of VCAM-1 and ICAM-1 (DP^dull) and the other expressing a high level of both molecules (DP^high). Although the proportion of the two DP populations markedly varies among LN of different regions, not much difference was detected within DP^high populations. Interestingly, the proportion of DP^dull population is similarly low as those in the PLT in the study of Cupedo et al. However, we think that this difference reflects the developmental stage rather than the permanent feature of each PLT. As shown in Fig. 1, the proportion of DP^dull population in PP increases along with its postnatal development. Indeed, two distinct intensities of VCAM-1 staining are detected at P4, whereas VCAM-1 is expressed relatively homogeneously in the embryonic PP anlagen. Thus, as suggested by a previous study of Cupedo et al., it is likely that two mesenchymal components play distinct roles in PLT embryogenesis.

With respect to DP^high population, our study demonstrated for the first time the presence of diversity in the DP^high organizers between PP and MLN. The most significant difference is the specific expression of RANKL on MLN DP^high organizers. This result is consistent with the previous study by Cupedo et al. showing its expression in LN mesenchymal cells. Moreover, this may partly account for the specific requirement of RANK signaling in LN organogenesis. In addition, the expression level of some inducible chemokines such as CCL7, CCL11, or CXCL1 is markedly higher in DP^high organizers in MLN than those in PP (34, 35, 36). Likewise, the expression of IL-6 and IL-7 are higher in MLN than in PP. Considering that these molecules are secreted upon stimulation, these results suggest that the organizer of MLN is at a more activated state those in PP. We have shown that expression of VCAM and ICAM in the PP organizers is dependent on LT signal, indicating that DP^high organizer by itself represents an activated state (16). In addition to these adhesion molecules, expression of homeostatic chemokines such as CXCL13, CCL19, and CCL21 is induced in the organizer by LT and they are expressed in both of tissues (24, 25). Thus, it is likely that additional signals are responsible for further activating the organizer cells of MLN. Because the NF-B pathway is implicated in the induction of some of these molecules, it is plausible that MLN contains stimulants that induce NF-B pathway. What are then responsible stimuli in MLN is totally obscure at present, but this difference may not be due to the presence of Ag stimulation because all of our comparisons were performed at embryonic stage. Of note is that most of these differences between PP and MLN vanished during neonatal development. Hence, it is likely that such an activated state is a result of extrinsic signal.

However, there is also a group of genes whose preferential expression in MLN is maintained after birth. Interestingly, some of those genes have been implicated in mesenchymal cell differentiation to skeletal cells. One group consists of Spp1 (osteopontin) and Egr2, which are known to be involved in osteogenesis, and both of which are derived from mesenchymal cells (26, 37). Another group consists of Lhx8, Meox2, and Prrx1, whose preferential expression in MLN was confirmed by quantitative PCR. Although each gene has a unique role in embryogenesis, it is interesting that cleft palate was found as the common phenotype of the null mutant mice of all three molecules. It is well established that mesenchymal condensation is a requisite process to complete the formation of palate. Thus, it is plausible that a similar mechanism is also operating in MLN. Because some mice survive to term in all of these mutations, it would be interesting to examine these mice whether there is any defect in the LN development. Taken together, all of these results suggest that DP^high organizer cells in MLN are under additional stimuli other than LT signal.

At this moment, the mechanism that renders DP^high organizer additionally activated in MLN but not in PP is unknown. The first LN anlagen are thought to be generated in the area between vascular and lymphatic systems when the lymphatic vessels bud from the vein (38, 39). In contrast, our observation suggests that PP anlagen are generated irrespective of lymphatic systems, because the lymphatic system in mouse intestine develops independently of PP formation (data not shown). Thus, it could be possible that this unique architecture that comprises venous and lymphatic vessels may be responsible for the activation of the organizers in MLN. Nonetheless, this study clearly showed that DP^high organizers in MLN and PP are different. Further study will provide an insight into the mechanism determining the differences in the organogenesis processes of LN and PP.

	Acknowledgment

 
We thank Dr. Toshio Kitamura of Tokyo University for providing anti-VCAM-1 M/K-2 clone.

	Disclosures

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 
The authors have no financial conflict of interest.

	Footnotes

 
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

¹ This work was supported by Grants-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology (to A.T. and S.N.).

² Address correspondence and reprint requests to Dr. Shin-ichi Nishikawa, Laboratory for Stem Cell Biology, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan. E-mail address: nishikawa{at}cdb.riken.jp

³ Abbreviations used in this paper: PLT, peripheral lymphoid tissue; LN, lymph node; MLN, mesenteric LN; PP, Peyer’s patch; DP, double positive; RANK, receptor activator for NF-B; RANKL, RANK ligand; LT, lymphotoxin; E17.5, embryonic day 17.5; P4, postnatal day 4.

⁴ The online version of this article contains supplemental material.

Received for publication October 12, 2006. Accepted for publication May 9, 2007.

	References

Top Abstract Introduction Materials and Methods Results Discussion Disclosures References

 

1. Du Pasquier, L.. 2005. Meeting the demand for innate and adaptive immunities during evolution. Scand. J. Immunol. 62: (Suppl. 1):39-48. [Medline]
2. Suniara, R. K., E. J. Jenkinson, J. J. Owen. 2000. An essential role for thymic mesenchyme in early T cell development. J. Exp. Med. 191: 1051-1056. [Abstract/Free Full Text]
3. Anderson, G., E. J. Jenkinson. 2001. Lymphostromal interactions in thymic development and function. Nat. Rev. Immunol. 1: 31-40. [Medline]
4. Nishikawa, S. I., H. Hashi, K. Honda, S. Fraser, H. Yoshida. 2000. Inflammation, a prototype for organogenesis of the lymphopoietic/hematopoietic system. Curr. Opin. Immunol. 12: 342-345. [Medline]
5. Pixley, F. J., E. R. Stanley. 2004. CSF-1 regulation of the wandering macrophage: complexity in action. Trends Cell Biol. 14: 628-638. [Medline]
6. Yoshida, H., A. Naito, J. Inoue, M. Satoh, S. M. Santee-Cooper, C. F. Ware, A. Togawa, S. Nishikawa, S. Nishikawa. 2002. Different cytokines induce surface lymphotoxin- on IL-7 receptor- cells that differentially engender lymph nodes and Peyer’s patches. Immunity 17: 823-833. [Medline]
7. Yoshida, H., H. Kawamoto, S. M. Santee, H. Hashi, K. Honda, S. Nishikawa, C. F. Ware, Y. Katsura, S. I. Nishikawa. 2001. Expression of ₄₇ integrin defines a distinct pathway of lymphoid progenitors committed to T cells, fetal intestinal lymphotoxin producer, NK, and dendritic cells. J. Immunol. 167: 2511-2521. [Abstract/Free Full Text]
8. Adachi, S., H. Yoshida, K. Honda, K. Maki, K. Saijo, K. Ikuta, T. Saito, S. I. Nishikawa. 1998. Essential role of IL-7 receptor in the formation of Peyer’s patch anlage. Int. Immunol. 10: 1-6. [Abstract/Free Full Text]
9. Cupedo, T., M. F. Vondenhoff, E. J. Heeregrave, A. E. De Weerd, W. Jansen, D. G. Jackson, G. Kraal, R. E. Mebius. 2004. Presumptive lymph node organizers are differentially represented in developing mesenteric and peripheral nodes. J. Immunol. 173: 2968-2975. [Abstract/Free Full Text]
10. Dougall, W. C., M. Glaccum, K. Charrier, K. Rohrbach, K. Brasel, T. De Smedt, E. Daro, J. Smith, M. E. Tometsko, C. R. Maliszewski, et al 1999. RANK is essential for osteoclast and lymph node development. Genes Dev. 13: 2412-2424. [Abstract/Free Full Text]
11. Kim, N., P. R. Odgren, D. K. Kim, S. C. Marks, Jr, Y. Choi. 2000. Diverse roles of the tumor necrosis factor family member TRANCE in skeletal physiology revealed by TRANCE deficiency and partial rescue by a lymphocyte-expressed TRANCE transgene. Proc. Natl. Acad. Sci. USA 97: 10905-10910. [Abstract/Free Full Text]
12. Kong, Y. Y., H. Yoshida, I. Sarosi, H. L. Tan, E. Timms, C. Capparelli, S. Morony, A. J. Oliveira-dos-Santos, G. Van, A. Itie, et al 1999. OPGL is a key regulator of osteoclastogenesis, lymphocyte development and lymph-node organogenesis. Nature 397: 315-323. [Medline]
13. Mebius, R. E.. 2003. Organogenesis of lymphoid tissues. Nat. Rev. Immunol. 3: 292-303. [Medline]
14. Adachi, S., H. Yoshida, H. Kataoka, S. Nishikawa. 1997. Three distinctive steps in Peyer’s patch formation of murine embryo. Int. Immunol. 9: 507-514. [Abstract/Free Full Text]
15. Hashi, H., H. Yoshida, K. Honda, S. Fraser, H. Kubo, M. Awane, A. Takabayashi, H. Nakano, Y. Yamaoka, S. Nishikawa. 2001. Compartmentalization of Peyer’s patch anlagen before lymphocyte entry. J. Immunol. 166: 3702-3709. [Abstract/Free Full Text]
16. Honda, K., H. Nakano, H. Yoshida, S. Nishikawa, P. Rennert, K. Ikuta, M. Tamechika, K. Yamaguchi, T. Fukumoto, T. Chiba, S. I. Nishikawa. 2001. Molecular basis for hematopoietic/mesenchymal interaction during initiation of Peyer’s patch organogenesis. J. Exp. Med. 193: 621-630. [Abstract/Free Full Text]
17. Dejardin, E., N. M. Droin, M. Delhase, E. Haas, Y. Cao, C. Makris, Z. W. Li, M. Karin, C. F. Ware, D. R. Green. 2002. The lymphotoxin- receptor induces different patterns of gene expression via two NF-B pathways. Immunity 17: 525-535. [Medline]
18. Matsumoto, M., K. Iwamasa, P. D. Rennert, T. Yamada, R. Suzuki, A. Matsushima, M. Okabe, S. Fujita, M. Yokoyama. 1999. Involvement of distinct cellular compartments in the abnormal lymphoid organogenesis in lymphotoxin--deficient mice and alymphoplasia (aly) mice defined by the chimeric analysis. J. Immunol. 163: 1584-1591. [Abstract/Free Full Text]
19. Ngo, V. N., H. Korner, M. D. Gunn, K. N. Schmidt, D. S. Riminton, M. D. Cooper, J. L. Browning, J. D. Sedgwick, J. G. Cyster. 1999. Lymphotoxin / and tumor necrosis factor are required for stromal cell expression of homing chemokines in B and T cell areas of the spleen. J. Exp. Med. 189: 403-412. [Abstract/Free Full Text]
20. Iba, K., M. E. Durkin, L. Johnsen, E. Hunziker, K. Damgaard-Pedersen, H. Zhang, E. Engvall, R. Albrechtsen, U. M. Wewer. 2001. Mice with a targeted deletion of the tetranectin gene exhibit a spinal deformity. Mol. Cell Biol. 21: 7817-7825. [Abstract/Free Full Text]
21. Natarajan, D., E. Andermarcher, P. N. Schofield, C. A. Boulter. 2000. Mouse Nov gene is expressed in hypaxial musculature and cranial structures derived from neural crest cells and placodes. Dev. Dyn. 219: 417-425. [Medline]
22. Tsutsumi, C., M. Okuno, L. Tannous, R. Piantedosi, M. Allan, D. S. Goodman, W. S. Blaner. 1992. Retinoids and retinoid-binding protein expression in rat adipocytes. J. Biol. Chem. 267: 1805-1810. [Abstract/Free Full Text]
23. Van Lint, P., C. Libert. 2006. Matrix metalloproteinase-8: cleavage can be decisive. Cytokine Growth Factor Rev. 17: 217-223. [Medline]
24. Muller, G., U. E. Hopken, M. Lipp. 2003. The impact of CCR7 and CXCR5 on lymphoid organ development and systemic immunity. Immunol. Rev. 195: 117-135. [Medline]
25. Okada, T., V. N. Ngo, E. H. Ekland, R. Forster, M. Lipp, D. R. Littman, J. G. Cyster. 2002. Chemokine requirements for B cell entry to lymph nodes and Peyer’s patches. J. Exp. Med. 196: 65-75. [Abstract/Free Full Text]
26. Grose, R., B. S. Harris, L. Cooper, P. Topilko, P. Martin. 2002. Immediate early genes krox-24 and krox-20 are rapidly up-regulated after wounding in the embryonic and adult mouse. Dev. Dyn. 223: 371-378. [Medline]
27. Maeda, M., K. Ohashi, A. Ohashi-Kobayashi. 2005. Further extension of mammalian GATA-6. Dev. Growth Differ. 47: 591-600. [Medline]
28. Jin, J. Z., J. Ding. 2006. Analysis of Meox-2 mutant mice reveals a novel postfusion-based cleft palate. Dev. Dyn. 235: 539-546. [Medline]
29. Mankoo, B. S., N. S. Collins, P. Ashby, E. Grigorieva, L. H. Pevny, A. Candia, C. V. Wright, P. W. Rigby, V. Pachnis. 1999. Meox2 is a component of the genetic hierarchy controlling limb muscle development. Nature 400: 69-73. [Medline]
30. ten Berge, D., A. Brouwer, J. Korving, M. J. Reijnen, E. J. van Raaij, F. Verbeek, W. Gaffield, F. Meijlink. 2001. Prx1 and Prx2 are upstream regulators of sonic hedgehog and control cell proliferation during mandibular arch morphogenesis. Development 128: 2929-2938. [Abstract/Free Full Text]
31. Zhao, Y., Y. J. Guo, A. C. Tomac, N. R. Taylor, A. Grinberg, E. J. Lee, S. Huang, H. Westphal. 1999. Isolated cleft palate in mice with a targeted mutation of the LIM homeobox gene lhx8. Proc. Natl. Acad. Sci. USA 96: 15002-15006. [Abstract/Free Full Text]
32. Aguila, H. L., D. W. Rowe. 2005. Skeletal development, bone remodeling, and hematopoiesis. Immunol. Rev. 208: 7-18. [Medline]
33. Olsen, B. R., A. M. Reginato, W. Wang. 2000. Bone development. Annu. Rev. Cell Dev. Biol. 16: 191-220. [Medline]
34. Baggiolini, M., B. Dewald, B. Moser. 1997. Human chemokines: an update. Annu. Rev. Immunol. 15: 675-705. [Medline]
35. Kim, K. S., K. Rajarathnam, I. Clark-Lewis, B. D. Sykes. 1996. Structural characterization of a monomeric chemokine: monocyte chemoattractant protein-3. FEBS Lett. 395: 277-282. [Medline]
36. Janatpour, M. J., S. Hudak, M. Sathe, J. D. Sedgwick, L. M. McEvoy. 2001. Tumor necrosis factor-dependent segmental control of MIG expression by high endothelial venules in inflamed lymph nodes regulates monocyte recruitment. J. Exp. Med. 194: 1375-1384. [Abstract/Free Full Text]
37. Yoshitake, H., S. R. Rittling, D. T. Denhardt, M. Noda. 1999. Osteopontin-deficient mice are resistant to ovariectomy-induced bone resorption. Proc. Natl. Acad. Sci. USA 96: 8156-8160. [Abstract/Free Full Text]
38. Karkkainen, M. J., P. Haiko, K. Sainio, J. Partanen, J. Taipale, T. V. Petrova, M. Jeltsch, D. G. Jackson, M. Talikka, H. Rauvala, et al 2004. Vascular endothelial growth factor C is required for sprouting of the first lymphatic vessels from embryonic veins. Nat. Immunol. 5: 74-80. [Medline]
39. Wigle, J. T., G. Oliver. 1999. Prox1 function is required for the development of the murine lymphatic system. Cell 98: 769-778. [Medline]

This article has been cited by other articles:

				N. H. Ruddle and E. M. Akirav Secondary Lymphoid Organs: Responding to Genetic and Environmental Cues in Ontogeny and the Immune Response J. Immunol., August 15, 2009; 183(4): 2205 - 2212. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Data Supplement Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Okuda, M. Articles by Nishikawa, S.-i. Search for Related Content PubMed PubMed Citation Articles by Okuda, M. Articles by Nishikawa, S.-i.