CpG oligodeoxynucleotide as immune adjuvant enhances photodynamic therapy response in murine metastatic breast cancer - PubMed (original) (raw)
CpG oligodeoxynucleotide as immune adjuvant enhances photodynamic therapy response in murine metastatic breast cancer
Yumin Xia et al. J Biophotonics. 2014 Nov.
Abstract
Breast cancer is the most common cause of cancer death in women. The side effects and complications following current breast cancer therapy can be devastating. Moreover, the prognosis in late stages of the diseases is usually poor. Photodynamic therapy (PDT) is a promising cancer treatment modality that is capable of both local tumor destruction and immune stimulation. However, treatment with PDT alone is often non-curative due to tumor-induced immune cell dysfunction and immune suppression. This phenomenon has motivated a new approach by combining immunostimulants with PDT to enhance anti-tumor immunity. In the present study, we investigated PDT mediated by verteporfin and 690 nm light delivered 15 min later, in combination with an immunomodulation approach using CpG oligodeoxynucleotide for the treatment of 4T1 metastatic breast cancer in a BALB/c immunocompetent mouse model. In vitro, CpG primed immature dendritic cells (DC) via toll like receptor 9 to phagocytose PDT killed tumor cells leading to DC maturation and activation. Peritumoral injection of CpG after PDT in mice gave improved local tumor control and a survival advantage compared to either treatment alone (p < 0.05). CpG may be a valuable dendritic cell targeted immunoadjuvant to combine with PDT.
Keywords: CpG oligodeoxynucleotide; breast cancer; dendritic cells; photodynamic therapy.
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Figures
Photomicrographs showing immunohistochemical expression of CD3 in thin sections.
Figure 1
Percentages of immature dendritic cells (iDC) (gated for CD11c) that express maturation markers (A) CD86, (B) CD80 and (C) MHC class II after indicated treatments. Bone marrow cells were isolated from 7 weeks old BALB/c mice and DCs were prepared as described in material and methods section. Next, DCs were incubated with supernatants from PDT treated 4T1 cells and CpG-ODN and examined for of DC maturation phenotypes by flow cytometric analysis. P value. *P < 0.05, **P < 0.01, ***P < 0.001.
Figure 2
Detection of metastasis with 4T1 tumor. Female BALB/c mice, weighing 20–25 g were depilated on one mammary fat pad. 1 × 106 4T1 cells suspended in 100 μL PBS were injected in one mammary fat pad. Animals were euthanized at day 20 to examine the metastases in the distant organs. Tissues were harvested and processed for histological examination with HE staining in (A) liver (B) lung (C) spleen (D) abdominal muscle (E) skin. Scale bar 100 μM. (N = 3).
Figure 3
(A) Tumor growth curves and (B) Tumor volume of mice with 4T1 tumors after receiving either; no treatment, BPD-PDT alone, CpG alone in 3 injections, or CpG combined with BPD-PDT either before or after: Female BALB/c mice, weighing 20–25 g were depilated on one mammary fat pad. 1 × 106 4T1 cells suspended in 100 μL PBS were injected in one mammary fat pad. Two orthogonal tumor dimensions (a and b) were measured with Vernier calipers and the volume calculated according to the formula = 4/3π [(a + b)/2]3. P value *P < 0.05, **P < 0.01, ***P < 0.001 (N = 5).
Figure 4
Kaplan-Meier curves of mouse survival: Female BALB/c mice, weighing 20–25 g were depilated on one mammary fat pad. 1 × 106 4T1 cells suspended in 100 μL PBS were injected in one mammary fat pad and animals were followed for Survival time. Control 40 ± 2.20 days; CpG alone: 36 ± 1.89 days; PDT alone: 41 ± 2.16 days; PDT + CpG: 46 ± 1.99 days; CpG + PDT: 43 ± 1.50 days (P for both orders of combination vs. PDT alone <0.01; and P for both orders of combination vs. CpG alone <0.001) (N = 5).
Figure 5
Photomicrographs showing immunohistochemical expression of CD3 in thin sections from (A) normal mouse (B) untreated tumor (C) CpG alone treatment (D) PDT alone treatment (E) PDT + CpG treatment (F) CpG + PDT treatment. Female BALB/c mice, weighing 20–25 g were depilated on one mammary fat pad. 1 × 106 4T1 cells þsuspended in 100 μL PBS were injected in one mammary fat pad. Paraffin section from tumor site were stained using anti-CD3 antibody. DAPI was used to stain the nuclei. Significantly higher numbers of CD3 expressing cells were seen in treatment groups which received combination (both CpG and PDT) therapy. Scale bar 100 μM.
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