Chronic inflammation plays an obscure role in cancer initiation, with broad references implicating immune exhaustion (IEX) or free radical mediated cell damage. Chronic inflammation is, however, paradoxically synonymous with the term “immune tolerance” which in other cases presents itself as a therapeutic limitation to the efficacy of tumor immune therapies particularly those involving microbial -associated molecular patterns (MAMPs) in regimens. As “tolerance” remains to this day a “phenomenon” there is a pressing need to fully understand every biological aspect of this apparent negative feedback response, because doing so will serve to guide development of targeted immune therapies. In this work, we employ a rudimentary model, which can be adopted in which it is possible to provoke negative feedback through sustained antigen stimulation in immunocompetent cells, as we monitor, define and characterize phenotype evolution using next generation whole transcriptome sequencing + validation studies. This model can be used to study /create in vitro the “M2” phenotype, which is itself involved in aggressive tumors with synergistic rapid expansion of myeloid-derived suppressor cells (MDSCs), dysfunctional CD8+ T cytotoxic (CTL)/ and dysfunctional natural killer (NK) cells. Briefly, the data in this work, shows negative feedback dominates at 7 to 11 days, after acute being associated with phase specific (time dependent) elevated checkpoints; e.g. PDL1+/MSN, HAVCR2/TIM-3+, SPP1+, C3ar1+, CD73+, IL1RN+, LILRbs+, glycoproteins, integrins etc. Here we report on phase specific patterns and bidirectional changes aligning with immune escape, much centered around loss of host defense against viral infection and malignancy. Negative feedback is associated with rampant induction of degradative proteases, SOCS/JAK/STAT/IL-10, the CCL2/7 axis tantamount to sustained loss of MHC1/2 antigen recognition systems, Type I interferon response, NOD signaling, antiviral/antibacterial defense, p62/SQSTM also aligning with a disturbed metabolic signature. The data in this work demonstrates that the colloquial terms “tolerance and IEX” are somewhat flawed terminology, because this negative feedback is a potent, intentional and formidable immune offense to eradicate the active arm of immune defense.
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The data show that “tolerance” aligns with six distinct chronological differential gene (DEG) expression patterns that circumscribe extensive immune suppression which dominate during chronic inflammation. These involve the following time dependent patterns: 1) transcripts overexpressed, e.g. checkpoint receptors; PDL1+/MSN, HAVCR2/TIM-3+, SPP1+, C3ar1+, CD73+, IL1RN+, LILRbs+, glycoproteins, etc.; 2) transcripts overexpressed only in chronic; e.g cytokine suppressor signaling (SOC3/Jak/Stat), cyto/chemokines (IL-10, CCL2, CCL7), proteases (cathepsins L, D, K, Adam 8, PIM2), and adhesives (TSPAN3, QSOX1, PDPN, ITGA5), (PLK2, ADGRE1, CALM1, PCNA, etc.); 3) transcripts downregulated in acute and chronic; e.g. a severe collective loss in MHC1/II antigen presentation capacity (CD74, H2-Q4, H2-Q6, etc.), NOD signaling, and interferon (IFN) type I signaling systems; 4) transcripts downregulated in chronic only, including OXPHOS/metabolic genes (Aldo A, C, Eno2, Gpi1, etc.), antiviral/antibacterial defense genes (Lyz1, Lyz2, Card19, Ninj1), and autophagy-related genes (p62/SQSTM1). In the category of Tolerance were: 5) transcripts induced sharply in acute, no longer responsive in chronic; IFN Type 1 antiviral response genes (OAS, BST2, ISG15, ISG20, IRF7, RSAD2/Viperin), TLR2, antibacterial defense genes (SAA3, SP140), and proinflammatory cytokines (CCL5, TNF, IL1a, and IL1b) along with the IL-1/TLR signaling axis. Last, 6) reverse tolerance, corresponded to restored baseline levels to maintain cell mitotic and thymosin homeostasis. In conclusion, these data suggest chronic inflammation precipitates negative feedback, aligning with the same checkpoint targets being sought after today in tumor immune therapies.