IL-32诱导的巨噬细胞极化及细胞因子级联反应在多发性骨髓瘤耐药中的作用及机制研究

Drug resistance is one of the greatest challenges in the treatment of multiple myeloma(MM). In recent years, our group and many researchers have demonstrated that macrophages (MΦs) in bone marrow microenvironment play an important role in the process of MM drug resistance. Macrophage has been classified into distinct types, which identified as M1 (or "classically activated") and M2 (or "alternatively activated"), respectively with the function of anti-tumor and pro-tumor. It is well documented that MΦs in the bone marrow microenvironment of MM are mainly the M2 type, but the regulation of MΦs polarization, and the influence of different polarization states involved in MM drug resistance remain unclear. We have found that the inflammatory factor IL-32 could increase the expression of M2 characteristic surface markers, promote MΦs secrete multiple cytokines, and enhance the capacity of MΦs protecting the myeloma cells from chemotherapy drug-induced apoptosis. These results indicated that IL- 32 may play a crucial role in the process of drug resistance through altering the polarization of MΦs. This application is aimed to explore the role and mechanism of IL-32 induced macrophage polarization and cytokine cascade involved in the drug resistance of multiple myeloma, and to find effective strategies to block or antagonize the effect of IL-32. It is highly significant for a better understanding of the mechanisms underlying the development of drug resistance and improving the treatment of MM.

化疗耐药是多发性骨髓瘤（MM）治疗中的主要问题。近年来，本课题组及越来越多的研究者发现骨髓微环境中的巨噬细胞（MΦs）在诱导MM耐药的过程中发挥重要作用。MΦs主要有M1和M2两种极化类型，分别具有抗肿瘤和促肿瘤的作用。目前认为MM骨髓微环境中的MΦs以M2型为主，但MΦs的这种极化状态是如何被调控，不同极化状态的MΦs是否对MM耐药产生影响尚不清楚。我们在前期研究中发现炎性因子IL-32能够上调M2型特征性表面分子的表达，促进MΦs分泌多种细胞因子，增加MΦs对MM细胞的保护作用，提示IL-32可能在调控MΦs极化进而诱导MM耐药的过程中具有重要作用。本项目拟在前期工作基础上进一步研究IL-32诱导的MΦs极化及细胞因子级联反应在MM耐药中的作用，深入探讨其具体机制，并寻找有效的策略来阻断或拮抗IL-32的这种作用，旨在阐明MM耐药的机理，以期为克服MM耐药提供新的靶点和实验基础。

骨髓微环境中含量丰富的巨噬细胞（MΦs）在诱导多发性骨髓瘤（MM）耐药的过程中发挥重要作用。我们发现MM患者外周血血清以及骨髓上清中IL-32含量较健康供者明显增加，qRT-PCR和 Western blot证实骨髓中的IL-32主要来源于MM细胞。rhIL-32可以刺激MΦs上调M2型表面分子CD206、Dectin-1（CD369）的表达和IL-10的分泌，并下调M1型表面分子CD86的表达。此外，rIL-32能够激活MΦs内STAT3和NF-ΚB通路，两个通路的抑制剂能够阻断上述IL-32诱导MΦs极化的现象。MΦs能够减少BTZ诱导的MM细胞的凋亡，而rhIL-32可明显增加MΦs对MM细胞的保护作用，具有浓度依赖性。MM细胞株与MΦs共培养后BTZ诱导的凋亡蛋白PARP 和caspase3受到明显抑制，rhIL-32刺激后的MΦs具有更明显的抑制作用。总的来说，IL-32通过激活STAT3和NF-ΚB通路诱导MΦs向M2型极化，从而调控MΦs诱导MM耐药。