Table 2.
CCL2's effects on monocytes.
| Effect on monocytes | Source of CCL2 or CCL2/CCR2 blocking/KO | Cells/model | Methods and results | References |
|---|---|---|---|---|
| MATURATION/DIFFERENTIATION/CYTOKINE PRODUCTION | ||||
| Influences cytokine production | CCL2 purified from U-105 MG CM | h monocytes in serum-free conditions plated on 2% agarose | Proinflammatory cytokines IL-6↑, IL-1↑, TNF (=) (MH60 cell proliferation assay, D10 cell proliferation assay, L929 cytopathic assay) | (82) |
| rCCL2 | h CD11b+ cells treated with rCCL2 in serum-free medium | Proinflammatory cytokine IL-6↑ (cytokine and inflammation arrays) | (10) | |
| rCCL2, pertussis toxin |
h monocytes preincubated with medium +/– rCCL2, then stimulated with SAC and IFNγ | Preincubation with rCCL2: cytokine IL12p70↓ (ELISA) IL-12p35↓, IL-12 p40↓ (RT-PCR), with pertussis toxin pretreatment: IL12p70 (=) (ELISA) |
(83) | |
| rCCL2 | TPA-preactivated THP-1 cells stimulated in serum-free conditions with +/– rCCL2. | Proinflammatory cytokine TNFα↑ (ELISA) | (84) | |
| Intrinsic CCL2 of monocytes, anti-CCL2 Ab | h monocytes (GG or AA genotype in −2518) + M. tuberculosis H37Rv sonicate +/– anti-CCL2 Ab | GG vs. AA genotype: CCL2↑, IL-12p40↓, GG genotype + anti-CCL2 Ab: IL12-p40↑ (ELISA) | (85) | |
| Enhances maturation into M2 macrophages | rCCL2 | h CD11b+ after isolation and rCCL2 stimulation in serum-free conditions | M2 macrophage marker in CD14+ cells: CD206↑(FC) | (10) |
| INTEGRIN EXPRESSION AND ACTIVATION, ARREST | ||||
| Induces integrin expression | CCL2 purified from U-105 MG CM | h monocytes stimulated with CCL2 | Integrin expression: CD11a (=), CD11b↑, CD11c↑, CD18↑ (FC), Selectin LAM-1 (=) (FC) |
(82) |
| rCCL2 | h monocytes stimulated with rCCL2 | Integrin expression: CD11a (=), CD11b↑, CD11c↑, CD18↑, VLA-4α (=) (FC), general monocyte markers unaffected: CD14 (=), CD15 (=) (FC), adhesion↑ (adhesion assay) |
(86) | |
| Increases firm adhesion and arrest | wt and CCL2 KO mice upon inflammation, rCCL2 |
Labeled WEHI78/24 cells injected through femoral artery catheter and PLNs HEV analyzed | Inflamed PLN HEVs: arresting cells↑, CCL2 KO mice: arresting cells↓ CCL2 KO mice + rCCL2: arresting cells ↑ (intravital microscopy) | (87) |
| rCCL2 | Flow chamber assay with HUVEC monolayer (transduced with E-selectin adenovirus) and h monocytes | Adhesion↑ (videomicroscopy, quantification per HPF) | (88) | |
| Inflamed endothelial cells, anti-CCL2 Ab, CCL2 antisense oligomer, CCL2 antagonist, anti-CCR2 Ab, integrin-blocking Abs | Flow chamber assay with TNF- activated HPAEC monolayer and h monocytes | Upon blocking CCL2 or CCR2: adhesion↓, upon blocking integrins: adhesion↓ (videomicroscopy, quantification per HPF) | (89) | |
| Induction of arachidonic acid release | rCCL2, anti-CCL2 antiserum, pertussis toxin, phospholipase A2 inhibitors (p-bromophenacyl bromide, manoalide) | Prelabeled h monocytes and THP-1 cells stimulated with rCCL2 +/– pre-treatment with pertussis toxin or antiserum, migration assay toward rCCL2 in presence of phospholipase A2 inhibitors | [3H]Arachidonic acid release: with rCCL2↑, with anti-CCL2↓, with pertussis toxin↓ (liquid scintillation spectrometry), Migration toward rCCL2: in presence of phospholipase A2 inhibitors ↓ (modified Boyden Chamber migration assay) | (90) |
| ENHANCEMENT OF SURVIVAL | ||||
| Enhances survival | rCCL2 | h CD11b+ cells treated with rCCL2 under serum deprivation | Antiapoptotic proteins↑ (cFLIPL↑, Bcl-2↑, Bcl-XL↑), caspase cleavage↓ (caspase 8, −3, −6, −7 cleavage↓), Lamin A cleavage↓ (WB), survival↑ (WST-1 cell viability assay), apoptotic cells ↓ (FC) | (10) |
| ENHANCEMENT OF HOST DEFENSE, CELLULAR CLEANUP | ||||
| Hyperactivates autophagy | rCCL2 | h CD11b+ cells treated with rCCL2 under serum deprivation | Microtubule-associated protein cleavage: LC3 cleavage↑ (WB) | (10) |
| Induces respiratory burst | rCCL2 | h monocytes exposed to rCCL2 | NADPH oxidase activity↑ (H2O2 formation) | (91) |
| Purified CCL2 from TNF-stimulated fibrosarcoma cell line 8387 | h monocytes exposed to purified CCL2 |
N-acetyl beta-d-glucosamininase release↑ (release assay), superoxide anion release ↑ (release assay) |
(92) | |
| Tumor cell killing/growth inhibition | Purified CCL2 from supernatant of THP-1 cells stimulated with LPS, silica, and hydroxyurea | h monocytes exposed to purified CCL2 and added tumor cell suspension | Growth of tumor cell lines HT29, A375, HTB, MCF7, HTB 88 ↓ ([3H] thymidine incorporation assay) | (37) |
| CCL2-expressing CHO cells (CCL2 transfected) in vivo | m tumor model by injection of CCL2 expressing/non-expressing CHO cells or coinjection of CCL2 expressing and non-expressing CHO cells and HeLa cells | CCL2 expressing cells: tumor formation↓ coinjection of CCL2 expressing and non-expressing cells: tumor formation ↓(histology) | (93) | |
| Glioblastoma lines HBT20 and HBT28 (CCL2 transfected) | CCL2-expressing HBT20 and HBT28 cell lines cocultured with h monocytes activated with LPS | Tumor cell lines + activated monocytes: cytostasis↑ ([3H]thymidine deoxyribose uptake cytostasis assay) | (94) | |
Ab, antibody; CHO, Chinese hamster ovary cell; CM, conditioned medium; FC, flow cytometry; h, human; KO, knockout; HEV, high endothelial venule; HPF, high-power field,; PLN, peripheral lymph node; RT-PCR, reverse transcription PCR; rCCL2, recombinant CCL2; SAC, Staphylococcus aureus Cowan strain 1; SN, supernatant; TPA = PMA, tetradecanoylphorbol-acetate; WB, Western blot; ↑, upregulation; ↓, downregulation; (=), level stays the same.