BLOC1S1 control of vacuolar organelle fidelity modulates T _H 2 cell immunity and allergy susceptibility

The levels of biogenesis of lysosome organelles complex 1 subunit 1 (BLOC1S1) control mitochondrial and endolysosome organelle homeostasis and function. Reduced fidelity of these vacuolar organelles is increasingly being recognized as important in instigating cell-autonomous immune cell activation. We reasoned that exploring the role of BLOC1S1 in CD4 ⁺ T cells, may further advance our understanding of regulatory events linked to mitochondrial and/or endolysosomal function in adaptive immunity. Transcript levels of the canonical transcription factors driving CD4 ⁺ T cell polarization in response to activation showed that, the T _H 2 regulator GATA3 and phosphorylated STAT6 were preferentially induced in BLOC1S1 depleted primary CD4 ⁺ T (TKO) cells. In parallel, in response to both T cell receptor activation and in response to T _H 2 polarization the levels of IL-4, IL-5 and IL-13 were markedly induced in the absence of BLOC1S1. At the organelle level, mitochondrial DNA leakage evoked cGAS-STING and NF-kB pathway activation with subsequent T _H 2 polarization. The induction of autophagy with rapamycin reduced cytosolic mtDNA and reverses these T _H 2 signatures. Furthermore, genetic knockdown of STING and STING and NF-κB inhibition ameliorated this immune regulatory cascade in TKO cells. Finally, at a functional level, TKO mice displayed increased susceptible to allergic conditions including atopic dermatitis and allergic asthma. In conclusion, BLOC1S1 depletion mediated disruption of mitochondrial integrity to initiate a predominant T _H 2 responsive phenotype via STING-NF-κB driven signaling of the canonical T _H 2 regulatory program.