tumor immunology

Question 1

CD8 T

Answer 1

they kill tumor cells

They recognize the tumors antigen presented by MHC 1. These effectors cells need prevention of AG by an APC, as tumors cells are not as effective as APC. Once the T cell are activated, the presence of costimulatory molecules are not required

CD4 T cell helps by producing cytokines for efficient formation of CD8

Question 2

NK cells

Answer 2

they kill tumors lacking MHC 1 and tumors covered with antibody via ADCC (antibody dependent cell cytoxicity)

The killing is perforin/granzyme mediated (individual who are perforin deficient have a higher incidence of cancer)

they release cytokines such as TNF alpha Interferon gamma and chemokine to stimulate T cell

maturation of APC trough TNF alpha and INF gamma

Lymphokine activated killer LAK that are IL2 activated NK cemm generated in vitro derived form tumor infiltrating lymphocyte from a cancer patients

Question 3

CD8 T cells Immune reaction against tumor

Answer 3

Tumors cells and antigens are ingested by the host APC

CROSS-PRIMING: induction of anti tumors T ell response. The cross priming has to be done via APC due to the lack of costimulatory molecule expression on the tumor cell.

APC activate CTL trough MHC 1 peptide complex with co stimulation

APC activate CD4 helper via MHC 2 peptide complex which lead to cytokine production which helps CTL differentiation activation and proliferation

CD8 differentiate in Tumor specific T cells

you are at the effector phase of anti tumor CTL response

–> 1 killing event every 6h per CTL for intratumoral killing

it does so by Bas/FasL binding (CD95L) which induced Caspase 8 activation then Cas 3

Question 4

Tumor killing by NK cells

Answer 4

Missing self mechanism or stress induced

missing self is characterized by the absence of MHC molecule at the surface

Stress induced self is due to the up regulation of stress induced ligand on the tumor self surfaces which promotes cell recognition and killing

all of these is trough a cytokines and cytotoxic mediators

Question 5

natural killer T cell

Answer 5

they are very important for immune surveillance and are Fas/FASL killing dependent

they are anti tumoral via

• direct tumor cell killing by NKT - recognize CD1d and directly kill
• indirect killing via activation of NK - or indirectly via activation of NK cell iNKT activated by APC, which hen promote NK activation that then tumor cell elimination
• inhibition of angiogenesis via inhibition of TAM (but need confirmation for this) - can limit tumor growth by suppressing the production of pro angiogenic factors by macrophage

TAM - Tumor associated macrophage

Question 6

i NKT

Answer 6

Invariant natural killer T (iNKT) cells, also known as type I or classical NKT cells, are a distinct population of T cells that express an invariant aβ T-cell receptor (TCR) and a number of cell surface molecules in common with natural killer (NK) cells.

Question 7

macrophage

Answer 7

M1

they get activated by interferon gamma; they release lysosomal enzymes ROS and nitrogen species.

they also production TNF alpha, which can lead to tumor regression by eliciting intratumoral thrombosis and enhancing of MHC 1 expression on tumor cells

Question 8

cytokines

Answer 8

TNF alpha and IFN gamma - enhance MHC1 expression on tumor cell

IFN gamma activates macrophage to kill tumor cell

all INF enhances cancer cell removal through activities of the immune cells

IL12 support strong TH1 and CTL response

Question 9

antibodies

Answer 9

are found in many cancer patient and were first considered not very effective

they can however used to complement system activation

they mediate ADCC and ADCP

they can block Ctl access to tumor

Question 10

B cells

Answer 10

they are thought to be essential for the formation of tertiary lymphoid structure that may promote local anti tumoral immune response

these TLS are typically found in chronic inflammation and require the recruitment of T follicular helper cell for establishment

intra tumoral B cells correlate with a good prognosis as well as TLS

Question 11

Tumor infiltrating B cell

Answer 11

1. B cells infiltrating various human cancers produce class-switched affinity-matured anti-tumour antibodies with protective effects
2. Human TIB cells produce cytokines enhancing type 1 cellular immunity
3. B cells concentrate low-dose antigens by membrane IgG-mediated antigen capture and induce CD4+ and CD8+ T cell priming via antigen presentation [and cross-presentation [84–, respectively.
4. Human B cells have been shown to secrete TRAIL, inducing in vitro tumour cell killing as well as to produce Granzyme B after BCR and IL-21 receptor stimulation but whether this activity results in anti-tumour effects or immune suppression is not known.
5. Human peripheral blood B cells promote the survival and proliferation of CTLs via CD70/CD27 interaction , but whether such mechanism is active also in tumour microenvironment is not known.
6. TIB cells acquire a regulatory phenotype and produce immunosuppressive cytokines and have been shown to suppress tumour immunity in mice
7. B cells produce CXCL13 and Lymphotoxin (LT), which induce the formation of tertiary lymphoid structures in mouse tumour models and under inflammatory conditions in humans Whether this also takes place in the human tumour microenvironment is not known.
8. TIB cells promote angiogenesis in a STAT3-dependent manner or promote lymphangiogenesis that facilitates tumour growth and dissemination, respectively, in mice. TIB-cell-derived LTα stimulates the recurrence of castration-resistant prostate tumours in mice. TIB-cell-derived BAFF might be involved in the promotion of human pancreatic cancer

Question 12

Tertiary lymphoid structure

Answer 12

Tertiary lymphoid structures (TLSs) are formations at sites with persistent inflammatory stimulation, including tumors. These ectopic lymphoid organs mainly consist of chemo-attracting B cells, T cells, and supporting dendritic cells (DCs).

require CXCL13

Question 13

immunologies editing

Answer 13

both protects against and promote tumors growth

three phases

emimiation - mutated cells recognized and eliminated by several cell types of the IS

equilibrium - elimination of mutated cells is not complete and some tumors arise these acquire characteristic allowing escape from the IS with survive-al benefits - selection pressure mechanism of the IS called immune editing

escape - most aggressive and least immunogenic cells thrive and spread. Some tumors cells have accumulated enough mutation to be invisible to the the IS

Question 14

Anti-tumoral microenvironment:

Answer 14

Type I IFN, TNF-a, Th1 (IL-12, IFNg)
M1 macrophages, NK cells, CTL, N1 neutrophils Tertiary lymphoid structures, HEV

Question 15

pro-tumoral microenvirnnement

Answer 15

Pro-tumoral microenvironment: IL-10, TGFbeta, IDO
M2 macrophages, MDSCs, Treg Chronic inflammation

Question 16

cancer related inflammation

Answer 16

• infiltration of leukocytes
• presence of soluble mediators (cytokines and growth factors)
• tissue remodelling
• angiogenesis
• increased cellular stress and genotoxic stress

which promotes tumors growth and progression

Question 17

macrophage and cancer

Answer 17

• Macrophages constitute the major inflammatory infiltrates of most solid tumors * Overexpression of CCL2 in murine fibrosarcoma => more macrophages
  => increased tumor growth
• Deletion of CSF-1 (cytokine mobilising/attracting macrophages to tumor) in mammary carcinoma => TAM depletion, delayed tumor angiogenesis and delayed progression, reduced pulmonary metastasis [less chemokine and protease (MMPs, cathepsins, plasminogen activator) release]

*Systemic depletion of macrophages by clodronate liposomes
 reduction in tumor growth and angiogenesis, lower number of cancer stem cells

• Factors produced by tumors cells and tumor infiltrating T(reg) cells and TAMs inducing M1 to M2 transition in tumors :
• TGFbeta
• IL-10
• M-CSF

Question 18

In many tumors TAMs are acting pro-tumorally

Answer 18

induce cell/DNA damage (ROI/RNI) during chronic inflammation
release growth factors
release angiogenic factors
suppressing TH1 responses => immune evasion
supporting TH2 cells and Tregs, inducing anergy in T cells => immune evasion promote invasion of surrounding tissue (MMP release)
promote metastasis (intravasation, dissemination, creating metastatic
niche/seeding, metastatic colonisation) through release of
proteases and chemokines
influencing metabolism => immune suppressive activity on T cells, adaptation to
hypoxic conditions

Question 19

Suggested experimental therapies based on TANs

Answer 19

• Total neutrophil depletion to prevent formation of TANs as such might be too dangerous, since it would create an immune suppressed state

*Blocking TAN mediators
oBlockade of VEGF and EGF, many clinical trials
oInhibition of MMP9 was ineffective in experimental models and clinical trials oBlockade of neutrophil elastase (NE), promising in mouse lung cancer model
Inhibitors of NE are being tested in other diseases

*Blocking TAN recruitment
oCXCR1 inhibitor (repertaxin) in clinical trial for ischemia/reperfusion and breast cancer (pilot clinical studies – Phase II)
oAnti-CXCR2 effective in spontaneous models of inflammation-driven intestinal and cutaneous cancer models

REMARKS
More research needed, because TANs are at least as complex than TAMS and less studies so far.

Question 20

Myeloid-derived suppressor cells (MDSCs)

Answer 20

*Arise from immature myeloid progenitors, through aberant differentiation which is promoted by factors in the (tumor) microenvironment. MDSC expansion : IL-6, IL-10, VEGF, PGE-2, GM-CSF, and TGF-b2 ;

*Human MDSCs comprise both
*G-MDSCs : granulocytic, expressing CD15,CD66b,CD33, CD14neg
*Mo-MDSCs : monocytic, expressing CD14, no/low HLA-DR, CD11bhigh, CD33high

*Frequency and type of MDSCs is dependent on tumor type
*Melanoma : Mo-MDSCs
*Renal cancer : G-MDSCs

*Present both intratumorally and in peripheral lymphoid organs, effector functions maybe different

*Functions
*Immune suppression (see next slide) *Facilitating metastasis
*Release of proteases
*Induction of stemness of cancer cells
*Induction of EMT (epithelial to mesenchymal transition)
*Enhancing angiogenesis

*Chemokines involved in recruitment of MDSCs *CCL2
*CXCL12
*CXCL1,2,5 (mice studies), probably CXCL6 and CXCL8 in humans

Question 21

Anti-tumor T cell responses are inhibited by :

Answer 21

*MDSCs (myeloid-derived suppressor cells)
*Treg, Breg, DCreg

*Metabolic changes
*low Arg concentration prevents T cell proliferation
*IDO (indoleamine-2,3-dioxygenase) breaks down L-Tryptophan, which selectively impairs the growth and survival of CTL and NK, and promotes Treg development
*Decreased cystine availability through MDSCs, diminishes the supply for T cells and limits the amount of cysteine available to T cells, cysteine is required for CTL activation and function

*TAMs are poor Ag-presenting cells
*Oxydative environment can cause nitration/nitrosylation of TCR/CD8 hampering their function
*TAMs/TANs/MDSCs produce a whole spectrum of pro tumoral molecules (see other slides)