Educating Perfect Natural Killers

Mining Tissue Match for Immune Co-culture

Mutant p53 knockdown in KPC (pancreatic ductal adenocarcinoma) cells of immune deficient mice had no effect on primary tumor growth, by contrast the reduced tumor growth in the immune-proficient syngeneic host was due to altered immune cell recruitment.

In vivo, the increased production of pro-inflammatory cytokines coupled with increased Natural Killer (NK) cell ligand expression permits the recruitment of immune cells and clearance of abnormal cells. Elimination of senescent tumors by NK cells may occur as a result of the cooperation of signals associated with p53 expression or senescence, which regulate NK cell recruitment, and other signals that induce NKG2D ligand expression on tumor cells.

Coculture of wild-type (wt) p53-induced human tumor cells with primary human NK cells enhanced NKG2D-dependent degranulation and IFN-γ production by NK cells. Taken together findings define the involvement of p53 in the regulation of specific NKG2D ligands that enhance NK cell–mediated target recognition.

Inhibitory KIR-educated NK cells showed significantly increased expression of the glucose transporter Glut1 in comparison to NKG2A-educated or uneducated NK cells, with and without exposure to target cells. Educated NK cells displayed significantly higher rates of cellular glycolysis than uneducated NK cells indicating they may reside in different metabolic states prior to activation. The ability to metabolize glucose may represent a mechanism for the superior functionality of educated NK cells expressing KIR receptors. 

Cancer cells acquire immunoediting abilities by which they evade surveillance and escape eradication. Murine p53 missense mutation G242A (human G245A) suppresses activation of host NK cells, enabling breast cancer cells to avoid immune assault. Serial injection of EMT6 breast cancer cells that carry wild-type (wt) Trp53 promoted NK activity, while SVTneg2 cells carrying Trp53 G242A+/+ mutation decreased NK cell numbers and increased CD8+ T lymphocyte numbers in spleen. Upon co-culture with isolated NK cells, EMT6 cells activated NK cells and proliferation, increasing interferon-gamma (IFN-γ) production; however, SVTneg2 cells suppressed NK cell activation. p53 can modulate expression by cancer cells of Mult-1 and H60a activating and inhibitory ligands for NKG2D receptors of NK cells, respectively, to enhance immune surveillance against cancer. p53 is requisite for NK cell-based immune recognition and elimination of cancerous cells, and p53 missense mutant in cancer cells impairs NK cell responses.

NK cells are the oldest member of the innate lymphoid cell family (ILC) and the only representative of cytotoxic ILCs. These tissue-resident innate immune cells have a similar functional diversity to T cells including lineage-specifying transcription factors that drive certain effector programs. ILCs are present in almost every tissue, but strongly enriched at barrier surfaces, where they regulate immunity to infection, chronic inflammation, and tissue maintenance. ILCs orchestrate tissue homeostasis through their ability to sustain bidirectional interactions with epithelial cells, neurons, stromal cells, adipocytes, and many other tissue-resident cells. ILCs provide an integrated view on how immune responses in tissues are synchronized with functional relevance far beyond the classical view of the role of the immune system in discrimination between self/non-self and host defense.

Codondex has evidenced p53 genetic variations, in multiple samples of same biopsy tissue from pancreatic tumors and oral squamous cell carcinoma's that may distinguish host tumor tissue gradients. The effect of highly-specific tissue-selected cell co-culture to educate ILC/NK cells may enhance the prospect for tissue penetration by these expanded, activated cytotoxic cells to improve overall survival.  

An Integrated P53 Puzzle - Glycolysis in Cancer, Diabetes and Immunity!

Oxygen poor, hypoxic tissue promotes a cellular shift in mitochondrial metabolism from OXPHOS to less energy efficient glycolysis. Each shift induces environmental, epigenetic and genetic factors that alter a cells response to insult, attack and disease. Endothelial tip cells at micro-vessel ends are predominantly glycolytic. However, deletion of PFKFB3, the critical regulator of glycolysis reduced the sprouting of micro-vessel tips and elevated PFKFB3 levels improved tip cell sprouting, direction and cell behavior.

In response to DNA damage p53 promotes nucleotide biosynthesis by repressing the expression of PFKFB3. This increases the flux of glucose, through the pentose phosphate pathway (PPP) to increase nucleotide production, which results in more efficient repair of DNA damage and cell survival.

In Panc1 pancreatic cells, pro-apoptotic TGFβ1 enhanced PFKFB3 expression and stimulated glycolysis. Extracellular lactate induces endothelial mesenchymal transition (EMT) by remodeling the extracellular matrix and releasing activated TGFβ1.  TGFβ is a potent immunosuppressive cytokine that can impede development and function of natural killer (NK) and other immune cells. Furthermore, high extracellular lactate levels can contribute to immune evasion, thereby promoting tumor growth and metastasis. In tumor microenvironments glycolysis also leads to accumulated lactate, which stabilizes hypoxia inducible factor 1α (HIF-1) and upregulates the expression of anti-apoptotic, VEGF (in axis with NRP-1 dependency) resulting in angiogenesis and stimulation of cell migration. 

Hypoxia induces the loss of differentiation markers of several tumor types while increasing expression of embryonic markers such as transcription factors NANOG, OCT4, SOX2, and the Notch ligand. This reprogramming, toward a cancer stem phenotype is associated with increased tumorigenesis. In non-small cell lung carcinoma cells hypoxia increased NANOG expression that contributed to hypoxia-induced tumor cell resistance against cytotoxic lymphocyte (CTL)-mediated lysis.

Under stress the outer mitochondrial membrane incorporates Pink1, which binds and phosphorylates p53 at serine 392 and aids phagophore formation to enhance mitophagy. This reduces transport of p53-s392 to the nucleus where it would otherwise disrupt transcription of Nanog. p53 regulates Pink1 and Parkin, which regulate mitochondrial antigen presentation of both MHC classes. 

The development of type 1 diabetes involves a complex interaction between pancreatic β-cells and cells of the innate and adaptive immune systems. Analyses of the interactions between NK cells, NKT cells, dendritic cell populations and T cells have highlighted how these can influence the onset of autoimmunity. NK cells were observed in the pancreas, in NoD mice before T cell infiltration and are critically required in the pancreas for accelerated diabetes.

The islet in type 2 diabetes (T2D) is characterized by IAPP amyloid deposits, a protein co-expressed with insulin by β-cells. Human IAPP (hIAPP) misfolded protein stress activates HIF-1/PFKFB3 signaling, which increases glycolysis, mitochondrial fragmentation and perinuclear clustering, considered protective against increased cytosolic Ca2+, characteristic of amylin toxic oligomer stress. β-cells in adult humans are minimally replicative and fail to execute the second pro-regenerative phase of the HIF-1/PFKFB3 injury pathway. β-cells remain trapped in the pro-survival first phase of the HIF-1 injury repair response with a metabolism and mitochondrial network adapted to slow the rate of cell attrition at the expense of β-cell function. The senescent-like state may support the reduced NK cell activity and presence of more pro-inflammatory M1 macrophages in T2D

p53 deficient tumors can be metabolically reprogrammed and regressed by deleting isoforms of p63 or p73 to upregulate IAPP and amylin, which through the calcitonin receptor (CalcR) and receptor-activity-modifying-protein 3 (RAMP3) inhibit glycolysis, induce ROS and apoptosis. In epidermal keratinocytes p63 promotes glycolytic metabolism  by binding PFKFB3 consensus sites required for mRNA and protein expression.

Senescent cells typically upregulate anti-apoptotic pathways, and are preferentially susceptible to inhibition of these pro-survival mechanisms. This has been dubbed the ‘Achilles heel’ of senescent cells and may relate to the low mitochondrial membrane potential found in many senescent cells that ease the release of apoptosis-stimulating factors from mitochondria to promote survival. Similar weaknesses may be present through glycolysis in cancer, diabetes, other diseases and immune response.