Data from: CARD8 inflammasome activation during HIV-1 cell-to-cell transmission

Our previous work demonstrated that CARD8 detects HIV-1 infection by
sensing the enzymatic activity of the HIV protease, resulting in
CARD8-dependent inflammasome activation (Kulsuptrakul et al., 2023). CARD8
harbors a motif in its N-terminus that functions as a HIV protease
substrate mimic, permitting innate immune recognition of HIV-1 protease
activity, which when cleaved by HIV protease triggers CARD8 inflammasome
activation. Here, we sought to understand CARD8 responses in the context
of HIV-1 cell-to-cell transmission via a viral synapse. We observed that
cell-to-cell transmission of HIV-1 between infected T cells and primary
human monocyte-derived macrophages induces CARD8 inflammasome activation
in a manner that is dependent on viral protease activity and largely
independent of the NLRP3 inflammasome. Additionally, to further evaluate
the viral determinants of CARD8 sensing, we tested a panel of HIV protease
inhibitor resistant clones to establish how variation in HIV protease
affects CARD8 activation. We identified mutant HIV-1 proteases that
differentially cleave and activate CARD8 compared to wildtype HIV-1, thus
indicating that natural variation in HIV protease affects not only the
cleavage of the viral Gag-Pol polyprotein but also likely impacts innate
sensing and inflammation.

我们的前期研究表明，半胱天冬酶募集结构域8（CARD8）可通过感知HIV蛋白酶（HIV protease）的酶活性来检测人类免疫缺陷病毒1型（HIV-1）感染，进而触发依赖于CARD8的炎性小体（inflammasome）激活（Kulsuptrakul等人，2023）。CARD8的N端含有一段基序，该基序可作为HIV蛋白酶的底物模拟物，从而实现对HIV蛋白酶活性的天然免疫识别；当该基序被HIV蛋白酶切割后，即可触发CARD8炎性小体的激活。
本研究旨在探究在病毒突触介导的HIV-1细胞间传播过程中，CARD8的应答情况。我们观察到，受感染的T细胞与原代人单核细胞衍生巨噬细胞之间通过HIV-1的细胞间传播，可诱导CARD8炎性小体激活，且该激活过程依赖于病毒蛋白酶活性，在很大程度上不依赖于核苷酸结合寡聚化结构域样受体蛋白3（NLRP3）炎性小体。
此外，为进一步评估CARD8识别的病毒决定因素，我们测试了一组对HIV蛋白酶抑制剂（HIV protease inhibitor）具有耐药性的病毒克隆株，以明确HIV蛋白酶的序列变异如何影响CARD8的激活。
我们发现，与野生型HIV-1相比，突变型HIV-1蛋白酶可差异性地切割并激活CARD8，这表明HIV蛋白酶的自然变异不仅会影响病毒Gag-Pol多聚蛋白（Gag-Pol polyprotein）的切割过程，还可能对天然免疫识别与炎症反应产生影响。