Hypoxia is a major characteristic of the solid tumor microenvironment. To understand how chimeric antigen receptor-T cells (CAR-T cells) function in hypoxic conditions, we characterized CD19-specific and BCMA-specific human CAR-T cells generated in atmospheric (18% oxygen) and hypoxic (1% oxygen) culture for expansion, differentiation status, and CD4:CD8 ratio. CAR-T cells expanded to a much lower extent in 1% oxygen than in 18% oxygen. Hypoxic CAR-T cells also had a less differentiated phenotype and a higher CD4:CD8 ratio than atmospheric CAR-T cells. CAR-T cells were then added to antigen-positive and antigen-negative tumor cell lines at the same or lower oxygen level and characterized for cytotoxicity, cytokine and granzyme B secretion, and PD-1 upregulation. Atmospheric and hypoxic CAR-T cells exhibited comparable cytolytic activity and PD-1 upregulation; however, cytokine production and granzyme B release were greatly decreased in 1% oxygen, even when the CAR-T cells were generated in atmospheric culture. Together, these data show that at solid tumor oxygen levels, CAR-T cells are impaired in expansion, differentiation and cytokine production. These effects may contribute to the inability of CAR-T cells to eradicate solid tumors seen in many patients.

Inflammation in atopic dermatitis is mediated in part by the chemokine CCL1 and its receptor, CCR8. Recombinant Molluscum contagiosum viral protein (rMC148p), a cc-chemokine homolog, inhibits CCL1-induced chemotaxis of cells expressing CCR8. rMC148p was prepared using the baculovirus/Sf9 insect cell expression system. The recombinant MC148 fusion protein (rMC148fp), rMC148-TAT-6xHis, was similarly prepared by adding base sequences onto the PCR primers to fuse TAT and 6xHis to rMC148p at the carboxyl terminus. rMC148fp retains the capacity of rMC148p to inhibit CCL1-induced chemotaxis. Furthermore, unlike rMC148p, topically applied rMC148fp penetrates stratum corneum of human neonatal foreskins and concentrates along the basal and lower spinous cell layers of the epidermis. rMC148fp may be a safe and effective agent in the treatment of atopic dermatitis and other CCR8-mediated disorders.