In my search for answers, I have been focusing in on how the tumor escapes detection by the immune system. We need to know what is going on in vivo during the different stages of melanoma.
The tumor mass is undoubtedly a multifaceted show, where different cell types, including neoplastic cells, fibroblasts, endothelial, and immune-competent cells, interact with one another continuously. Macrophages represent up to 50% of the tumor mass, and they certainly operate as fundamental actors. Macrophages constitute an extremely heterogeneous population; they originate from blood monocytes, which differentiate into distinct macrophage types, schematically identified as M1 (or classically activated) and M2 (or alternatively activated).
It is now generally accepted that TAMs have an M2 phenotype and show mostly pro-tumoral functions, promoting tumor cell survival, proliferation, and dissemination. High levels of TAM are often, although not always, correlated with a bad prognosis, and recent studies have also highlighted a link between their abundance and the process of metastasis.
In a recent research paper “Immunotype and Immunohistologic Characteristics of Tumor Infiltrating Immune Cells are Associated with Clinical Outcome in Metastatic Melanoma”1 et al Slingluff 2012, it breaks down the Immunohistologic Characteristics into three distinct immunotypes:
A) No infiltration of immune cells in the tumor’s microenvironment.
B) Infiltrating Immune cells only in close proximity to the tumor’s vascular system
C) Diffuse immune cell infiltrates throughout a metastatic tumor and its microenvironment.
Immunohistologic Characteristics of Tumor Infiltrating Immune Cells
Overall, the most predominant immune cells were T cells (53%), followed by the B cell lineage cells (33%), and then by macrophages (13%), with NK and mature dendritic cells only hardly present.
With the setting of the tumor’s microenvironment evaluated, we will focus the low survival immunotype A patients.
How can we improve the overall survival and the immune response to Melanoma? We need to push the differentiation of the macrophages towards the M1 phenotype.
Macrophages are important tumor-infiltrating cells and play pivotal roles in tumor growth and metastasis. Macrophages participate in immune responses to tumors in a polarized manner: classic M1 macrophages produce interleukin (IL) 12 to promote tumoricidal responses, whereas M2 macrophages and M2-Like produce IL10 and help tumor progression. The mechanisms governing macrophage polarization are unclear but in 1990 it was discovered treatment of M2 macrophages with GM-CSF or IFN-gamma led to production of M1 phenotypic markers upon LPS stimulation. It also has been seen that if you block the IL-10 receptor with an antibody along with LPS (TLR4 agonist) stimulation or CpG (TLR9 agonist) stimulation you shift the Macrophage plasticity towards the M1 phenotype.
So what causes the high Macrophage (M2) to migrate towards the Tumor and its microenvironment? Does the tumor somehow recruit these (TAMs) Tumor Associated Macrophages? What are the characteristics of the M2 phenotype?
Hallmarks of M2 macrophages are IL-10high IL-12low IL-1rahigh IL-1 decoyRhigh production, CCL17 and CCL22 secretion, high expression of mannose, scavenger and galactose-type receptors, poor antigen-presenting capability and wound-healing promotion.
CCL17 and CCL22 chemokines within tumor microenvironment are related to infiltration of regulatory T cells in Macrophage 2 in melanoma. Early Detection of Tumor Cells by Innate Immune Cells leads to Treg Recruitment through CCL22 Production by Tumor Cells and Tumor Assocated Marophages (TAMs). It has been suggested that at early times during tumorigenesis, the detection of tumor cells by innate effectors (monocytes and NK cells) imposes a selection for CCL22 secretion that recruits Treg to evade this early antitumor immune response. The activated T-cells upregulate the CTLA-4 and PD-1. PD-1 ligation induces IL-10 production by monocytes, which together with PD-1 inhibits CD4+ T cell responses/activation. This is way for the immune system to use a checkpoint so that immune response does not lead to an autoimmune response. These receptors keeps the immune system in check.
Now in another paper I found this:
If you look at the above micrographs, you will see that the two patients that had relapsed (10710 and 10737) had IL-1b and IL-6 and TNF alpha missing. The macrophages were not activated!!!! The "Danger Signal" known as inflammation was missing! The non-responders most likely had their macrophages polarized to a M2-like phenotype by the Tregs and or IL-10.
So if the Macrophages are M2-like in the Tumor’s microenviroment, then if we control the Tregs, the upregulation of the of CTLA-4, PD-1 on the T-cells including the Tregs, and control the IL-10 production through anti-IL-10 antibody on the macrophages, we can shift the M2-like Macrophages into the M1 thus producing IL-12 shifting the differentiation of the Niave CD4+ T-cell the TH1 phenotype to activate the T-cells.
This all can be done with Yervor, Anti-PD-1 and Anti-IL-10 receptor antibody. You can get the tomor to shed antigentic protein by either whole radiation, Chemotherapy (TMZ- + Patrin-2) or Heat Shock.
CpG oligonucleotides induced NF-_B activation through the triggering of TLR9 signaling in TAM (Fig. 2), and the co-use of an IL-10 receptor Ab reduced IL-10 signaling in TAM, thereby reducing their M2 polarization.
Plasticity of Macrophage Function during Tumor Progression: Regulation by Distinct Molecular Mechanisms
Source: http://www.jimmunol.org/content/180/4/2011.full.pdf
HMGB1 from the dying tumors (irradiation, Chemotherapy, Heat Shock) will act as the Danger signal and bind to the TLR4 and activating the Macrophage (M1) and secrete IL-12 which acts upon the naïve CD4 T helper cells to differentiate to the Th1 phenotype.
petoh et al. has revealed an interesting role of TLR signalling in cancer therapy. They studied the immune-stimulatory properties of dying tumour cells after chemotherapy or radiation therapy. Using TLR4 and MyD88-deficient DCs, they show that TLR4 signaling is required for crosspresentation of antigens from apoptotic tumour cells on MHC class I to generate antitumour cytotoxic T cell (CTL) responses. Apetoh et al.also identified a “danger signal” from dying tumour cells, the nuclear protein highmobility group box 1 protein (HMGB1, see Figure) that triggers this protective immune response through activation of TLR4. According to their work, the interaction of high mobility group box 1 protein (HMGB1) released from dying tumour cells with Toll-like receptor 4 (TLR4) on dendritic cells is required for the crosspresentation of tumour antigens and the promotion of tumour specific cytotoxic T-cell responses.
So to sum it up, If you take Yervoy + Anti-PD1 + Anti-IL-10 along with radiation/Chemo could we get the right T-cell activation and Immune Response?
My guess you will activate the TLR4 pathway and induce the RIGHT IMMUNE RESPONSE.
So can we Get the Oncologists on board to propose and setup a clinical trial?
Time will only tell.
Remember the this blog. It will lead to a CURE!!!
“It is not the strongest of the species that survives, nor the most intelligent, but the one most responsive to change.”
~Charles Darwin~
Take Care,
Jimmy B
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