Boltje, T. J. | Search bioRxiv

bioRxiv2026

Local glycan engineering induces systemic antitumor immune reactions via antigen cross-presentation

Immune checkpoint inhibitors (ICI) have revolutionized cancer therapy, yet response rates remain suboptimal across many solid tumors, and resistance mechanisms, particularly those involving glycans, are not fully understood. Recent studies have identified sialic acid-containing glycans and their interactions with Siglec receptors on tumor-associated macrophages as an important contributor to immune suppression within the tumor microenvironment (TME). Targeting this sialic acid-Siglec axis by glycan engineering with sialidases and other glycosidases has shown therapeutic potential in preclinical models. However, safe and effective delivery of sialidases to tumors remains a challenge. Here, we present a novel approach using adeno-associated virus (AAV)-mediated therapy to deliver sialidases (AAVSia) and other glycosidases, including fucosidase, directly to the TME. Intratumoral administration of AAVSia in mouse models resulted in significant tumor growth reduction, enhanced survival, and robust systemic antitumor immunity through improved cross-presentation and dendritic cell activation. Furthermore, combining local sialidase expression with fucosidase treatment and classical PD-1 blockade allowed a synergistic effect, amplifying antitumor response. Our findings highlight the therapeutic promise of glycoengineering the TME using local delivery systems and support the development of combination strategies to overcome glycan-mediated resistance in cancer immunotherapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=129 SRC="FIGDIR/small/720097v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@dc9d72org.highwire.dtl.DTLVardef@1e4e455org.highwire.dtl.DTLVardef@4a8f93org.highwire.dtl.DTLVardef@11813a3_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2026

A new stress-response pathway in Mycobacterium tuberculosis

Metabolic adaptations are key in the virulence of the pathogen Mycobacterium tuberculosis (Mtb). However, our current understanding of these adaptations is limited to common pathways in central carbon metabolism. Here we apply an untargeted bottom-up approach to discover unknown stress-responsive metabolites and their biosynthetic enzyme. We show that upon exposure to hypoxia, nitric oxide and activated macrophages, Mtb rapidly produces high levels of an unknown metabolite that we identify as 6-{gamma}-amino-butyric acid-trehalose (GABA-trehalose). Formation of millimolar GABA-trehalose levels under these stresses is driven by a rapid rise in GABA, which is also excreted. We demonstrate that GABA-trehalose is produced from GABA and trehalose by the uncharacterized ATP-grasp enzyme Rv1722, involving a carboxylate-hydroxyl ligation that is non-canonical for ATP-grasp enzymes. Phylogenetic analyses demonstrate that the gene rv1722 is present in most slow-growing mycobacteria but absent in most rapid-growing mycobacteria. While the role of GABA-trehalose in Mtb metabolism remains unclear, we postulate that the increased NADH/NAD+ ratio under hypoxia and nitric oxide exposure promotes GABA formation and inhibits its breakdown, leading to GABA accumulation and excretion. Rv1722-driven coupling of GABA and trehalose constitutes an alternative to excretion that conserves carbon and nitrogen. Taken together, our bottom-up approach reveals a new stress-response pathway in Mtb that rapidly produces large quantities of GABA-trehalose. These findings extend our knowledge of the metabolic adaptations that a major human pathogen utilizes in response to immune system-imposed stresses.

biochemistry↗