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Could a B-1 cell derived phagocyte "be one" of the peritoneal macrophages during LPS-driven inflammation?

Popi AF, Osugui L, Perez KR, Longo-Maugéri IM, Mariano M - PLoS ONE (2012)

Bottom Line: A number of recent studies that describe the phagocytic and microbicidal activity of B-1 cells in vitro and in vivo support this hypothesis.Based on these data, we confirmed that B-1 cell differentiation into phagocytes also occurs in vivo.In conclusion, the results strongly suggest that B-1 cell derived phagocytes are a component of the LPS-elicited peritoneal macrophage population.

View Article: PubMed Central - PubMed

Affiliation: Discipline of Immunology, Department of Microbiology, Immunology and Parasitology, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brazil. afpopi@unifesp.br

ABSTRACT
The inflammatory response is driven by signals that recruit and elicit immune cells to areas of tissue damage or infection. The concept of a mononuclear phagocyte system postulates that monocytes circulating in the bloodstream are recruited to inflamed tissues where they give rise to macrophages. A recent publication demonstrated that the large increase in the macrophages observed during infection was the result of the multiplication of these cells rather than the recruitment of blood monocytes. We demonstrated previously that B-1 cells undergo differentiation to acquire a mononuclear phagocyte phenotype in vitro (B-1CDP), and we propose that B-1 cells could be an alternative origin for peritoneal macrophages. A number of recent studies that describe the phagocytic and microbicidal activity of B-1 cells in vitro and in vivo support this hypothesis. Based on these findings, we further investigated the differentiation of B-1 cells into phagocytes in vivo in response to LPS-induced inflammation. Therefore, we investigated the role of B-1 cells in the composition of the peritoneal macrophage population after LPS stimulation using osteopetrotic mice, BALB/Xid mice and the depletion of monocytes/macrophages by clodronate treatment. We show that peritoneal macrophages appear in op/op((-/-)) mice after LPS stimulation and exhibit the same Ig gene rearrangement (VH11) that is often found in B-1 cells. These results strongly suggest that op/op((-/-)) peritoneal "macrophages" are B-1CDP. Similarly, the LPS-induced increase in the macrophage population was observed even following monocyte/macrophage depletion by clodronate. After monocyte/macrophage depletion by clodronate, LPS-elicited macrophages were observed in BALB/Xid mice only following the transfer of B-1 cells. Based on these data, we confirmed that B-1 cell differentiation into phagocytes also occurs in vivo. In conclusion, the results strongly suggest that B-1 cell derived phagocytes are a component of the LPS-elicited peritoneal macrophage population.

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Clodronate treatment did not impede the proliferation of resident peritoneal “macrophages” from BALB/c mice treated with LPS.A) Peritoneal cells were collected from untreated and clodronate-treated mice 3 days after the last clodronate injection. Non-B cells were selected based on the total peritoneal CD19− cells, and the CD11b+F4/80+ cells were considered macrophages. This CD11b+F4/80+ cell population was not observed after clodronate treatment. B) Absolute number of peritoneal macrophages (CD19−CD11b+F4/80+) from non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. C) Percentage of CFSE+ cells present in the peritoneal macrophage population (CD19−CD11b+F4/80+) in BALB/c mice subjected to different treatments: control (without clodronate+saline injection); clodronate (clodronate+saline); LPS (without clodronate+LPS injection) and LPS+clodronate (clodronate+LPS). The same group legend was used in figure 4D and 4E. D) Absolute number of CFSE+ macrophages (CFSE+CD19−CD11b+F4/80+) showing high CFSE fluorescence (non-proliferating cells; CFSE+macrophages) and the decay in CFSE fluorescence (proliferating macrophages). E) Percentage of proliferating macrophages (CFSEdim) detected in different treated BALB/c mice. F) Absolute number of peritoneal B-1 cells (CD23−CD19+CD11b+) in non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. **p<0.01 and ***p<0.001 when the indicated groups are compared. The results are representative of two or three independent experiments using 5 mice per group per experiment.
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pone-0034570-g004: Clodronate treatment did not impede the proliferation of resident peritoneal “macrophages” from BALB/c mice treated with LPS.A) Peritoneal cells were collected from untreated and clodronate-treated mice 3 days after the last clodronate injection. Non-B cells were selected based on the total peritoneal CD19− cells, and the CD11b+F4/80+ cells were considered macrophages. This CD11b+F4/80+ cell population was not observed after clodronate treatment. B) Absolute number of peritoneal macrophages (CD19−CD11b+F4/80+) from non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. C) Percentage of CFSE+ cells present in the peritoneal macrophage population (CD19−CD11b+F4/80+) in BALB/c mice subjected to different treatments: control (without clodronate+saline injection); clodronate (clodronate+saline); LPS (without clodronate+LPS injection) and LPS+clodronate (clodronate+LPS). The same group legend was used in figure 4D and 4E. D) Absolute number of CFSE+ macrophages (CFSE+CD19−CD11b+F4/80+) showing high CFSE fluorescence (non-proliferating cells; CFSE+macrophages) and the decay in CFSE fluorescence (proliferating macrophages). E) Percentage of proliferating macrophages (CFSEdim) detected in different treated BALB/c mice. F) Absolute number of peritoneal B-1 cells (CD23−CD19+CD11b+) in non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. **p<0.01 and ***p<0.001 when the indicated groups are compared. The results are representative of two or three independent experiments using 5 mice per group per experiment.

Mentions: To determine the role of monocytes in macrophage accumulation, we injected clodronate-loaded liposomes intraperitoneally (i.p.). Clodronate treatment depletes monocytes and blocks tissue infiltration by macrophages in a variety of inflammatory settings [21], [22], [23]. First, we confirmed that the clodronate treatment protocol adopted in this study resulted in an effective and sustained depletion of peritoneal macrophages. As expected, clodronate-treated mice remained depleted of peritoneal macrophages for at least 5 days after the last clodronate-liposomes injection (Figure 4A). Considering this depletion, 24 hours after the last clodronate-liposomes injection, BALB/c mice were injected with LPS. To discriminate resident peritoneal cells from newly migrating cells, CFSE was injected into the peritoneal cavity prior to LPS injection. Thus, the resident cells were now CFSE+ cells. After 3 days, the peritoneal macrophage population was analyzed. First, peritoneal B cells were excluded based on their CD19 expression. Subsequently, macrophages were identified by their expression of CD11b and F4/80. As expected, this cell population increased after LPS stimulation in the non-clodronate treated mice (control group). Interestingly, the LPS stimulus induced an increase in the macrophage population, even though monocyte/macrophage depletion was induced by clodronate (Figure 4B). These data corroborate the increase in the macrophage population after LPS stimulation in op/op(−/−) mice.


Could a B-1 cell derived phagocyte "be one" of the peritoneal macrophages during LPS-driven inflammation?

Popi AF, Osugui L, Perez KR, Longo-Maugéri IM, Mariano M - PLoS ONE (2012)

Clodronate treatment did not impede the proliferation of resident peritoneal “macrophages” from BALB/c mice treated with LPS.A) Peritoneal cells were collected from untreated and clodronate-treated mice 3 days after the last clodronate injection. Non-B cells were selected based on the total peritoneal CD19− cells, and the CD11b+F4/80+ cells were considered macrophages. This CD11b+F4/80+ cell population was not observed after clodronate treatment. B) Absolute number of peritoneal macrophages (CD19−CD11b+F4/80+) from non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. C) Percentage of CFSE+ cells present in the peritoneal macrophage population (CD19−CD11b+F4/80+) in BALB/c mice subjected to different treatments: control (without clodronate+saline injection); clodronate (clodronate+saline); LPS (without clodronate+LPS injection) and LPS+clodronate (clodronate+LPS). The same group legend was used in figure 4D and 4E. D) Absolute number of CFSE+ macrophages (CFSE+CD19−CD11b+F4/80+) showing high CFSE fluorescence (non-proliferating cells; CFSE+macrophages) and the decay in CFSE fluorescence (proliferating macrophages). E) Percentage of proliferating macrophages (CFSEdim) detected in different treated BALB/c mice. F) Absolute number of peritoneal B-1 cells (CD23−CD19+CD11b+) in non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. **p<0.01 and ***p<0.001 when the indicated groups are compared. The results are representative of two or three independent experiments using 5 mice per group per experiment.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3316698&req=5

pone-0034570-g004: Clodronate treatment did not impede the proliferation of resident peritoneal “macrophages” from BALB/c mice treated with LPS.A) Peritoneal cells were collected from untreated and clodronate-treated mice 3 days after the last clodronate injection. Non-B cells were selected based on the total peritoneal CD19− cells, and the CD11b+F4/80+ cells were considered macrophages. This CD11b+F4/80+ cell population was not observed after clodronate treatment. B) Absolute number of peritoneal macrophages (CD19−CD11b+F4/80+) from non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. C) Percentage of CFSE+ cells present in the peritoneal macrophage population (CD19−CD11b+F4/80+) in BALB/c mice subjected to different treatments: control (without clodronate+saline injection); clodronate (clodronate+saline); LPS (without clodronate+LPS injection) and LPS+clodronate (clodronate+LPS). The same group legend was used in figure 4D and 4E. D) Absolute number of CFSE+ macrophages (CFSE+CD19−CD11b+F4/80+) showing high CFSE fluorescence (non-proliferating cells; CFSE+macrophages) and the decay in CFSE fluorescence (proliferating macrophages). E) Percentage of proliferating macrophages (CFSEdim) detected in different treated BALB/c mice. F) Absolute number of peritoneal B-1 cells (CD23−CD19+CD11b+) in non-clodronate treated (control group □) or clodronate-treated (▪) BALB/c mice after LPS or saline (−) injection. **p<0.01 and ***p<0.001 when the indicated groups are compared. The results are representative of two or three independent experiments using 5 mice per group per experiment.
Mentions: To determine the role of monocytes in macrophage accumulation, we injected clodronate-loaded liposomes intraperitoneally (i.p.). Clodronate treatment depletes monocytes and blocks tissue infiltration by macrophages in a variety of inflammatory settings [21], [22], [23]. First, we confirmed that the clodronate treatment protocol adopted in this study resulted in an effective and sustained depletion of peritoneal macrophages. As expected, clodronate-treated mice remained depleted of peritoneal macrophages for at least 5 days after the last clodronate-liposomes injection (Figure 4A). Considering this depletion, 24 hours after the last clodronate-liposomes injection, BALB/c mice were injected with LPS. To discriminate resident peritoneal cells from newly migrating cells, CFSE was injected into the peritoneal cavity prior to LPS injection. Thus, the resident cells were now CFSE+ cells. After 3 days, the peritoneal macrophage population was analyzed. First, peritoneal B cells were excluded based on their CD19 expression. Subsequently, macrophages were identified by their expression of CD11b and F4/80. As expected, this cell population increased after LPS stimulation in the non-clodronate treated mice (control group). Interestingly, the LPS stimulus induced an increase in the macrophage population, even though monocyte/macrophage depletion was induced by clodronate (Figure 4B). These data corroborate the increase in the macrophage population after LPS stimulation in op/op(−/−) mice.

Bottom Line: A number of recent studies that describe the phagocytic and microbicidal activity of B-1 cells in vitro and in vivo support this hypothesis.Based on these data, we confirmed that B-1 cell differentiation into phagocytes also occurs in vivo.In conclusion, the results strongly suggest that B-1 cell derived phagocytes are a component of the LPS-elicited peritoneal macrophage population.

View Article: PubMed Central - PubMed

Affiliation: Discipline of Immunology, Department of Microbiology, Immunology and Parasitology, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brazil. afpopi@unifesp.br

ABSTRACT
The inflammatory response is driven by signals that recruit and elicit immune cells to areas of tissue damage or infection. The concept of a mononuclear phagocyte system postulates that monocytes circulating in the bloodstream are recruited to inflamed tissues where they give rise to macrophages. A recent publication demonstrated that the large increase in the macrophages observed during infection was the result of the multiplication of these cells rather than the recruitment of blood monocytes. We demonstrated previously that B-1 cells undergo differentiation to acquire a mononuclear phagocyte phenotype in vitro (B-1CDP), and we propose that B-1 cells could be an alternative origin for peritoneal macrophages. A number of recent studies that describe the phagocytic and microbicidal activity of B-1 cells in vitro and in vivo support this hypothesis. Based on these findings, we further investigated the differentiation of B-1 cells into phagocytes in vivo in response to LPS-induced inflammation. Therefore, we investigated the role of B-1 cells in the composition of the peritoneal macrophage population after LPS stimulation using osteopetrotic mice, BALB/Xid mice and the depletion of monocytes/macrophages by clodronate treatment. We show that peritoneal macrophages appear in op/op((-/-)) mice after LPS stimulation and exhibit the same Ig gene rearrangement (VH11) that is often found in B-1 cells. These results strongly suggest that op/op((-/-)) peritoneal "macrophages" are B-1CDP. Similarly, the LPS-induced increase in the macrophage population was observed even following monocyte/macrophage depletion by clodronate. After monocyte/macrophage depletion by clodronate, LPS-elicited macrophages were observed in BALB/Xid mice only following the transfer of B-1 cells. Based on these data, we confirmed that B-1 cell differentiation into phagocytes also occurs in vivo. In conclusion, the results strongly suggest that B-1 cell derived phagocytes are a component of the LPS-elicited peritoneal macrophage population.

Show MeSH
Related in: MedlinePlus