Harit, K. | bioRxiv Science

bioRxiv2026

Deletion of OTUD7B in astrocytes protects against cerebral malaria by inhibiting microvesicle-induced TRAF3/TRAF6-mediated neuroinflammation

Cerebral malaria is a severe neurological complication of Plasmodium falciparum infection. Damage of the blood-brain barrier (BBB) and endothelial dysfunction are established drivers of the disease pathology, however, whether astrocytes, a major constituent of the BBB, influence the disease outcome remains unclear. Using the murine model of experimental cerebral malaria (ECM), we show that astrocytes decisively regulate the outcome of ECM and the deubiquitinating enzyme OTUD7B in astrocytes fosters the disease. Mice lacking astrocytic OTUD7B showed reduced brain pathology and were protected from ECM compared with wildtype littermate controls. Transcriptomic profiling of ex vivo-isolated astrocytes revealed reduced proinflammatory chemokines and cytokines in the absence of OTUD7B. Plasmodium infection-associated microvesicles triggered a pro-inflammatory response in astrocytes, which was dependent on OTUD7B. Mechanistically, OTUD7B cleaved K48-linked ubiquitin chains from TRAF3 and TRAF6 upon stimulation with microvesicles or activation of TLR3/TLR9 by plasmodial nucleic acids. The OTUD7B-dependent TRAF3 and TRAF6 stabilization led to sustained NF-{kappa}B and p38 MAP kinase signaling and CXCL10 expression. Therapeutic silencing of CNS Otud7b or Cxcl10 expression after disease onset protected mice from ECM, identifying the cerebral OTUD7B-Cxcl10 axis as an attractive therapeutic target.

immunology↗

bioRxiv2024

The deubiquitinating enzyme CYLD impairs NF-κB- and STAT1-dependent macrophage intrinsic immunity to Staphylococcus aureus

In atopic dermatitis (AD), lesional skin is frequently colonized by Staphylococcus (S.) aureus, contributing to the severity and clinical symptoms of the disease. The inflammatory milieu in the skin is characterized by a type 2 inflammatory signature, including M2 macrophages, which cannot eradicate S. aureus. Since S. aureus is effectively controlled in macrophages activated by pattern recognition receptor (PRR)-induced NF-{kappa}B and interferon (IFN)-{gamma}-induced STAT1 stimulation, we hypothesized that pre-treatment with LPS as a PRR/TLR4-activating agent and IFN-{gamma} would induce effective control of S. aureus in monocyte-derived macrophages (MDMs) of AD patients. Our data show that the deubiquitinating enzyme CYLD is strongly expressed in skin macrophages and MDMs from AD patients compared to healthy controls and impairs the anti-staphylococcal activity of PRR-activated and IFN-treated MDMs. Functionally, CYLD impaired M1 macrophage polarization, as evidenced by reduced expression of CD80, TNF, and IL-6 upon LPS- and IFN-{gamma} treatment in CYLD-deficient as compared to wild-type (WT) MDM/THP1 macrophages. Mechanistically, CYLD inhibited IFN-{gamma}-induced STAT1 phosphorylation and activation by binding to STAT1 and inducing its K63 deubiquitination. CYLD also interacted with TRAF6 and NEMO/IKK{gamma} in the MYD88 signaling pathway and with RIPK2 in the NOD2 pathway, leading to impaired activation of NF-{kappa}B. Inhibition of both STAT1 by siRNA and NF-{kappa}B by IKK inhibitor treatment, respectively, independently abolished the control of S. aureus in both CYLD-deficient and WT THP1 macrophages, which harbored identical high numbers of the pathogen. The in vivo inhibitory function of CYLD on the control of S. aureus was also observed upon infection of Cyld-deficient and WT mice. Collectively, these data illustrate that the increased expression of CYLD in macrophages of AD patients is a factor contributing to the ineffective control of S. aureus, diminishes M1 macrophage polarization, and that CYLD deletion unleashes the break on effective STAT1 and NF-{kappa}B-dependent control of S. aureus.

immunology↗