TIMP‐2 Deficiency Alters Host Immune Response in Murine Lung Tumor Microenvironment
Authors: Jensen Sandra Mae , Kumar Sarvesh , Chowdhury Ananda , Wei Beiyang , Stetler‐Stevenson William George 
Published: November 2023

The cellular complexity of the tumor microenvironment (TME) is increasingly recognized as contributing to the initiation, progression, and metastasis of human lung cancer. Although many studies suggest a strong association between inflammation and lung cancer progression, immune cells within the TME may function as tumor‐promoting or tumor‐killing subclasses, making interpretation of findings difficult. Tumor‐promoting inflammatory cells (macrophages, neutrophils, mast cells and T and B lymphocytes) function to support tumor development by supplying bioactive molecules to the TME that sustain cell proliferation, extracellular matrix remodeling and angiogenesis. In addition, the recruitment of actively immunosuppressive myeloid‐derived suppressor cells (MDSCs) are now thought to be doubly beneficial for tumor development by promoting both angiogenesis and a means for tumors to evade immune destruction. The tissue inhibitor of metalloproteinase 2 (TIMP‐2) is widely expressed in the stromal compartment of normal tissues and functions as an endogenous inhibitor of tumor growth and angiogenesis, in vivo. In a recent meta‐analysis it was demonstrated that high TIMP‐2 expression is associated with a favorable prognosis in non‐small cell lung cancer. Preliminary studies suggest that TIMP‐2 may also modulate the immune response within the TME of lung tumor xenografts. In order to expand these findings, the current study was undertaken to examine the host immune response to LL/2 tumor formation in an orthotopic lung cancer model using a recently derived congenic TIMP‐2 deficient (T2D) mouse strain. A total of 1×106 LL/2‐Luc cells in 50ul PBS were administered via intra‐tracheal instillation to 6 to 8 week old male wildtype (WT) and T2D mice. H&E evaluation of whole lung tissue sections 4 weeks post tumor cell inoculation revealed a significant increase in the number of tumor nodules in lungs of T2D mice compared to controls (p = 0.003). In addition, tumors from T2D mice contained significantly larger regions of small basophilic (immune) cells at the tumor core (p = 0.007). Immunohistochemical staining using antibodies to monocyte (F4/80), lymphoid (CD3, CD4, CD8) and myeloid (CD11b) cell lineages was used to characterize immune cell subpopulations in the tumor core as well as at the LL/2 tumor stoma interface. Our findings demonstrate increased F4/80 and CD11b immunoreactivity at the tumor stromal interface of T2D tumors compared to WT controls, characteristic of tumor infiltrating macrophages and MDSCs, while the total T lymphocyte marker CD3 was associated with distinct immune cell foci at the tumor core. We conclude that TIMP‐2 may play an important role in regulating the host immune response to lung tumor formation in vivo, and should be further considered in designing novel therapeutic approaches for lung cancer.Support or Funding InformationThis work was funded by the NCI Center for Cancer Research Intramural Research Program Grant # ZIA SC009179‐24.