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Expression of neuroimmune semaphorins 4A and 4D and their receptors in the lung is enhanced by allergen and vascular endothelial growth factor.

Smith EP, Shanks K, Lipsky MM, DeTolla LJ, Keegan AD, Chapoval SP - BMC Immunol. (2011)

Bottom Line: Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins".We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes.CD72 was found on lung immune, inflammatory, and epithelial cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.

ABSTRACT

Background: Semaphorins were originally identified as molecules regulating a functional activity of axons in the nervous system. Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins". It is known that Sema4A and Sema4D bind Tim-2 and CD72 expressed on leukocytes and PlexinD1 and B1 present on non-immune cells. These neuroimmune semaphorins and their receptors have been shown to play critical roles in many physiological and pathological processes including neuronal development, immune response regulation, cancer, autoimmune, cardiovascular, renal, and infectious diseases. However, the expression and regulation of Sema4A, Sema4D, and their receptors in normal and allergic lungs is undefined.

Results: Allergen treatment and lung-specific vascular endothelial growth factor (VEGF) expression induced asthma-like pathologies in the murine lungs. These experimental models of allergic airway inflammation were used for the expression analysis of immune semaphorins and their receptors employing immunohistochemistry and flow cytometry techniques. We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes. Surprisingly, under inflammation various cell types including macrophages, lymphocytes, and granulocytes in the lung expressed Tim-2, a previously defined marker for Th2 cells. CD72 was found on lung immune, inflammatory, and epithelial cells. Bronchial epithelial cells were positive for both plexins, whereas some endothelial cells selectively expressed Plexin D1. Plexin B1 expression was also detected on lung DC. Both allergen and VEGF upregulated the expression of neuroimmune semaphorins and their receptors in the lung tissue. However, the lung tissue Sema4A-Tim2 expression was rather weak, whereas Sema4D-CD72 ligand-receptor pair was vastly upregulated by allergen. Soluble Sema4D protein was present in the lung lysates and a whole Sema4A protein plus its dimer were readily detected in the bronchoalveolar (BAL) fluids under inflammation.

Conclusions: This study clearly shows that neuroimmune semaphorins Sema4A and Sema4D and their receptors might serve as potential markers for the allergic airway inflammatory diseases. Our current findings pave the way for further investigations of the role of immune semaphorins in inflammation and their use as potential therapeutic targets for the inflammatory lung conditions.

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Regulation of lung CD72 expression by allergen and VEGF. Sema4D receptor CD72 expression in mouse lung tissue and cells was analyzed by immunohistochemistry and flow cytometry (A-B). (A) Formalin-fixed paraffin-embedded lung tissue sections obtained from either control or OVA-treated WT mice were deparaffinized and immunohistochemistry was performed using appropriate Abs as described in Materials and Methods. Frozen lung tissue sections were used for VEGF tg mice. CD72 is the most abundantly expressed molecule in the lungs of PBS-treated mice. Its expression is further upregulated with OVA treatment. Note that subsets of inflammatory granulocytes and lymphocytes express CD72 (red arrow). In VEGF tg lungs CD72 expression was mainly targeted to inflammatory macrophages (red arrow). Red arrowhead points to the lung epithelial cell CD72 expression. (B) CD72 is expressed on lung MHCII+ cells including DC and is upregulated by OVA. Both CD4+ and CD8+ T cells in the lung express CD72 at low level which is further upregulated by allergen on CD4+ T cells.
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Figure 5: Regulation of lung CD72 expression by allergen and VEGF. Sema4D receptor CD72 expression in mouse lung tissue and cells was analyzed by immunohistochemistry and flow cytometry (A-B). (A) Formalin-fixed paraffin-embedded lung tissue sections obtained from either control or OVA-treated WT mice were deparaffinized and immunohistochemistry was performed using appropriate Abs as described in Materials and Methods. Frozen lung tissue sections were used for VEGF tg mice. CD72 is the most abundantly expressed molecule in the lungs of PBS-treated mice. Its expression is further upregulated with OVA treatment. Note that subsets of inflammatory granulocytes and lymphocytes express CD72 (red arrow). In VEGF tg lungs CD72 expression was mainly targeted to inflammatory macrophages (red arrow). Red arrowhead points to the lung epithelial cell CD72 expression. (B) CD72 is expressed on lung MHCII+ cells including DC and is upregulated by OVA. Both CD4+ and CD8+ T cells in the lung express CD72 at low level which is further upregulated by allergen on CD4+ T cells.

Mentions: IHC demonstrated an abundant CD72 expression in control murine lungs which was greatly pronounced with inflammation (Figure 5 A). Lung accessory-like cells (red arrow on the tissue picture obtained from a PBS-treated mouse) and alveolar type II-like cells (middle photomicrograph) were CD72-positive. In addition, we found CD72 to be expressed on bronchial epithelial cells in large bronchi but rarely in smaller bronchi. Alveolar macrophages were also CD72-positive. Under OVA-induced inflammatory conditions, some additional cells such as subsets of lymphocytes, granulocytes, and inflammatory macrophages were also found to express CD72 (Figure 5 A). A pattern of CD72 expression in WT control mice being on DOX water was similar to that observed in PBS-treated WT mice although the staining appears weaker (Figure 5 A). In VEGF tg mice the expression of CD72 was noted mainly on lung inflammatory macrophages and epithelial cells in large bronchi (Figure 5 A). Flow cytometry assessment of MHCII+ cells, DC and T cells showed the level of CD72 cell expression and its upregulation by allergen (Figure 5 B). As it has been reported previously, in the lymphoid tissue CD72 is expressed on B cells, DC, and a small fraction of activated T cells [1,2]. Indeed, in the murine lungs MHCII+ cells express Sema4D receptor CD72 (Figure 5 B). In accord with our IHC data, CD72 was also found to be expressed on lung DC and it was positively regulated by allergen. Interestingly, only a fraction of lung T cells express CD72 which further increases for CD4 + but not for CD8+ T cells after allergen treatment. Therefore, CD72 can potentially be a useful marker for a specific cell subset's activation status.


Expression of neuroimmune semaphorins 4A and 4D and their receptors in the lung is enhanced by allergen and vascular endothelial growth factor.

Smith EP, Shanks K, Lipsky MM, DeTolla LJ, Keegan AD, Chapoval SP - BMC Immunol. (2011)

Regulation of lung CD72 expression by allergen and VEGF. Sema4D receptor CD72 expression in mouse lung tissue and cells was analyzed by immunohistochemistry and flow cytometry (A-B). (A) Formalin-fixed paraffin-embedded lung tissue sections obtained from either control or OVA-treated WT mice were deparaffinized and immunohistochemistry was performed using appropriate Abs as described in Materials and Methods. Frozen lung tissue sections were used for VEGF tg mice. CD72 is the most abundantly expressed molecule in the lungs of PBS-treated mice. Its expression is further upregulated with OVA treatment. Note that subsets of inflammatory granulocytes and lymphocytes express CD72 (red arrow). In VEGF tg lungs CD72 expression was mainly targeted to inflammatory macrophages (red arrow). Red arrowhead points to the lung epithelial cell CD72 expression. (B) CD72 is expressed on lung MHCII+ cells including DC and is upregulated by OVA. Both CD4+ and CD8+ T cells in the lung express CD72 at low level which is further upregulated by allergen on CD4+ T cells.
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Related In: Results  -  Collection

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Figure 5: Regulation of lung CD72 expression by allergen and VEGF. Sema4D receptor CD72 expression in mouse lung tissue and cells was analyzed by immunohistochemistry and flow cytometry (A-B). (A) Formalin-fixed paraffin-embedded lung tissue sections obtained from either control or OVA-treated WT mice were deparaffinized and immunohistochemistry was performed using appropriate Abs as described in Materials and Methods. Frozen lung tissue sections were used for VEGF tg mice. CD72 is the most abundantly expressed molecule in the lungs of PBS-treated mice. Its expression is further upregulated with OVA treatment. Note that subsets of inflammatory granulocytes and lymphocytes express CD72 (red arrow). In VEGF tg lungs CD72 expression was mainly targeted to inflammatory macrophages (red arrow). Red arrowhead points to the lung epithelial cell CD72 expression. (B) CD72 is expressed on lung MHCII+ cells including DC and is upregulated by OVA. Both CD4+ and CD8+ T cells in the lung express CD72 at low level which is further upregulated by allergen on CD4+ T cells.
Mentions: IHC demonstrated an abundant CD72 expression in control murine lungs which was greatly pronounced with inflammation (Figure 5 A). Lung accessory-like cells (red arrow on the tissue picture obtained from a PBS-treated mouse) and alveolar type II-like cells (middle photomicrograph) were CD72-positive. In addition, we found CD72 to be expressed on bronchial epithelial cells in large bronchi but rarely in smaller bronchi. Alveolar macrophages were also CD72-positive. Under OVA-induced inflammatory conditions, some additional cells such as subsets of lymphocytes, granulocytes, and inflammatory macrophages were also found to express CD72 (Figure 5 A). A pattern of CD72 expression in WT control mice being on DOX water was similar to that observed in PBS-treated WT mice although the staining appears weaker (Figure 5 A). In VEGF tg mice the expression of CD72 was noted mainly on lung inflammatory macrophages and epithelial cells in large bronchi (Figure 5 A). Flow cytometry assessment of MHCII+ cells, DC and T cells showed the level of CD72 cell expression and its upregulation by allergen (Figure 5 B). As it has been reported previously, in the lymphoid tissue CD72 is expressed on B cells, DC, and a small fraction of activated T cells [1,2]. Indeed, in the murine lungs MHCII+ cells express Sema4D receptor CD72 (Figure 5 B). In accord with our IHC data, CD72 was also found to be expressed on lung DC and it was positively regulated by allergen. Interestingly, only a fraction of lung T cells express CD72 which further increases for CD4 + but not for CD8+ T cells after allergen treatment. Therefore, CD72 can potentially be a useful marker for a specific cell subset's activation status.

Bottom Line: Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins".We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes.CD72 was found on lung immune, inflammatory, and epithelial cells.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Vascular and Inflammatory Diseases, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA.

ABSTRACT

Background: Semaphorins were originally identified as molecules regulating a functional activity of axons in the nervous system. Sema4A and Sema4D were the first semaphorins found to be expressed on immune cells and were termed "immune semaphorins". It is known that Sema4A and Sema4D bind Tim-2 and CD72 expressed on leukocytes and PlexinD1 and B1 present on non-immune cells. These neuroimmune semaphorins and their receptors have been shown to play critical roles in many physiological and pathological processes including neuronal development, immune response regulation, cancer, autoimmune, cardiovascular, renal, and infectious diseases. However, the expression and regulation of Sema4A, Sema4D, and their receptors in normal and allergic lungs is undefined.

Results: Allergen treatment and lung-specific vascular endothelial growth factor (VEGF) expression induced asthma-like pathologies in the murine lungs. These experimental models of allergic airway inflammation were used for the expression analysis of immune semaphorins and their receptors employing immunohistochemistry and flow cytometry techniques. We found that besides accessory-like cells, Sema4A was also detected on bronchial epithelial and smooth muscle cells, whereas Sema4D expression was high on immune cells such as T and B lymphocytes. Surprisingly, under inflammation various cell types including macrophages, lymphocytes, and granulocytes in the lung expressed Tim-2, a previously defined marker for Th2 cells. CD72 was found on lung immune, inflammatory, and epithelial cells. Bronchial epithelial cells were positive for both plexins, whereas some endothelial cells selectively expressed Plexin D1. Plexin B1 expression was also detected on lung DC. Both allergen and VEGF upregulated the expression of neuroimmune semaphorins and their receptors in the lung tissue. However, the lung tissue Sema4A-Tim2 expression was rather weak, whereas Sema4D-CD72 ligand-receptor pair was vastly upregulated by allergen. Soluble Sema4D protein was present in the lung lysates and a whole Sema4A protein plus its dimer were readily detected in the bronchoalveolar (BAL) fluids under inflammation.

Conclusions: This study clearly shows that neuroimmune semaphorins Sema4A and Sema4D and their receptors might serve as potential markers for the allergic airway inflammatory diseases. Our current findings pave the way for further investigations of the role of immune semaphorins in inflammation and their use as potential therapeutic targets for the inflammatory lung conditions.

Show MeSH
Related in: MedlinePlus