Potential of gene editing and gut microbiome in immune regulation for the treatment of intractable diseases

Abstract

Immune regulation is central to the pathogenesis and treatment of challenging diseases such as cancer and Alzheimer's disease (AD). Harnessing gene editing technologies and modulating the gut microbiota present innovative strategies to influence immune responses for therapeutic benefit. In the realm of cancer immunotherapy, overcoming resistance to immune checkpoint inhibitors remains a significant hurdle. We performed an in vivo genome-wide CRISPR loss-of-function screen to identify tumor-intrinsic factors affecting responsiveness to anti- PD1 therapy. Tyrosylprotein sulfotransferase-2 (TPST2) emerged as a key suppressor of interferon-γ (IFNγ) signaling. TPST2 modifies the IFNγ receptor 1 through sulfation at a specific tyrosine residue, which attenuates downstream signaling and reduces antigen presentation. Silencing TPST2 in cancer cells enhanced the efficacy of anti-PD1 antibodies in mouse models by increasing tumor-infiltrating lymphocytes. Patient data analyses revealed that elevated TPST2 expression correlates with poor prognosis and altered immune landscapes across various cancers, highlighting TPST2 as a potential target to improve immunotherapeutic outcomes. In addressing AD, we investigated the role of the gut microbiome and its metabolites in amyloid pathology using the 5xFAD mouse model. A multi-omics approach showed that levels of soluble amyloid-beta (Aβ) are associated with inflammatory responses and identified related metabolites. Notably, increased concentrations of tryptophan and indole-3-lactic acid (ILA) were linked to decreased Aβ accumulation. Administration of these metabolites prevented both amyloid deposition and cognitive decline in mice. Mechanistic studies revealed that ILA activates microglia and astrocytes through the aryl hydrocarbon receptor (AhR) signaling pathway, facilitating amyloid clearance. Clinical analyses supported these findings, showing a higher abundance of Lactobacillus reuteri and greater expression of AhR pathway genes in individuals without AD, suggesting a protective effect. These studies collectively highlight the potential of gene editing and gut microbiota modulation in regulating immune responses to treat intractable diseases. Targeting TPST2 may enhance the effectiveness of cancer immunotherapies, while gut-derived metabolites like ILA offer promising avenues for preventing or mitigating AD progression through immune activation mechanisms.