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The cGAS‐STING signaling pathway plays a pivotal role in sensing cytosolic DNA and initiating innate immune responses against various threats, with disruptions in this pathway being associated with numerous immune‐related disorders. Therefore, precise regulation of the cGAS‐STING signaling is crucial to ensure appropriate immune responses. Recent research, including ours, underscores the importance of protein condensation in driving the activation and maintenance of innate immune signaling within the cGAS‐STING pathway. Consequently, targeting condensation processes in this pathway presents a promising approach for modulating the cGAS‐STING signaling and potentially managing associated disorders. In this review, we provide an overview of recent studies elucidating the role and regulatory mechanism of protein condensation in the cGAS‐STING signaling pathway while emphasizing its pathological implications. Additionally, we explore the potential of understanding and manipulating condensation dynamics to develop novel strategies for mitigating cGAS‐STING‐related disorders in the future. [ABSTRACT FROM AUTHOR]

Aberrant activation of the cyclic guanosine monophosphate–adenosine monophosphate synthase–stimulator of interferon genes (cGAS-STING) pathway causes autoimmunity in humans and mice; however, the exact mechanism by which the cGAS-STING pathway initiates adaptive immunity and tissue pathology is still not fully understood. Here, we used a cGAS knockin (KI) mouse model that develops systemic autoimmunity. In the lungs of cGAS-KI mice, blood vessels were enclosed by organized lymphoid tissues that resemble tertiary lymphoid structures (TLSs). Cell-intrinsic cGAS induction promoted up-regulation of CCR5 in CD8+ T cells and led to CCL5 production in vascular endothelial cells. Peripheral CD8+ T cells were recruited to the lungs and produced CXCL13 and interferon-γ. The latter triggered endothelial cell death, potentiated CCL5 production, and was essential for TLS establishment. Blocking CCL5 or CCR5, or depleting CD8+ T cells, impaired TLS formation. cGAS-mediated TLS formation also enhanced humoral and antitumor responses. These data demonstrate that cGAS signaling drives a specialized lymphoid structure that underlies autoimmune tissue pathology. Editor's summary: Overactivation of the innate immune sensing cGAS-STING pathway can lead to inflammation and autoimmunity. To investigate how cGAS hyperactivation drives lung inflammation, Zhao et al. generated a cGAS conditional knockin mouse model. Hyperactivation of cGAS resulted in the formation of tertiary lymphoid structures (TLSs) in the lung, which enhanced antibody responses and antitumor immunity. CCL5-producing endothelial cells in the lung promoted CD8+ T cell recruitment to TLSs via CCR5 signaling, which was induced by T cell–intrinsic cGAS expression. Blocking CCR5/CCL5 impaired TLS formation, suggesting that CCR5/CCL5 could be targeted therapeutically to treat autoimmunity or to enhance antitumor immunity. —Hannah Isles [ABSTRACT FROM AUTHOR]

Background: Oncolytic viral therapy is a promising method for tumor treatment. Currently, several oncolytic viruses (OVs) have been used as tumor therapy at different phases of research and clinical trials. OVs not only directly lyse tumor cells due to viral replication but also initiate host antitumor immune responses. Previous studies have primarily focused on how OVs activate adaptive immune responses in immune cells. However, the role of innate immune responses in tumors induced by OVs remains unclear. Methods: To determine the innate immune responses induced by vesicular stomatitis virus (VSV), the mutant VSVΔM51 strain was used for the infection and quantitative polymerase chain reaction (qPCR) was employed to measure the transcriptional levels of antiviral genes. The knockdown efficiency of RIG‐I was examined by qPCR. Viral titers were measured by plaque assays. Tumor models were established by intradermally implanting RIG‐I‐knockdown and control LLC cells into the flank of wild type C57BL/6J mice. When the tumors reached approximately 50mm3, they were infected with VSVΔM51 via intratumoral injections to examine its therapeutic effect. Results: Infection with VSVΔM51 triggered remarkable innate immune responses in several tumor cell lines through the cytoplasmic RIG‐I sensing pathway. Moreover, we found that intratumoral injection of VSVΔM51 effectively reduced tumor growth in murine LCC lung cancer model. Importantly, VSVΔM51‐induced antitumor therapy was more effective in murine LLC tumor model established using Rig‐I‐knockdown cells compared with the tumor model established using control cells. Conclusion: RIG‐I‐mediated innate immune signaling in tumor cells plays a negative role in regulating antitumor therapy with VSVΔM51 virus. [ABSTRACT FROM AUTHOR]

Abstract Background The nuclear transcription factor NF-κB binds to the HIV-1 long terminal repeat (LTR) and is a key regulator of HIV-1 gene expression in cells latently infected with this virus. In this report, we have analyzed the ability of Kaposi's sarcoma associate herpes virus (KSHV, also known as Human Herpes virus 8)-encoded viral FLIP (Fas-associated death domain-like IL-1 beta-converting enzyme inhibitory protein) K13 to activate the HIV-1 LTR. Results We present evidence that vFLIP K13 activates HIV-1 LTR via the activation of the classical NF-κB pathway involving c-Rel, p65 and p50 subunits. K13-induced HIV-1 LTR transcriptional activation requires the cooperative interaction of all three components of the IKK complex and can be effectively blocked by inhibitors of the classical NF-κB pathway. K13 mutants that lacked the ability to activate the NF-κB pathway also failed to activate the HIV-1 LTR. K13 could effectively activate a HIV-1 LTR reporter construct lacking the Tat binding site but failed to activate a construct lacking the NF-κB binding sites. However, coexpression of HIV-1 Tat with K13 led to synergistic activation of HIV-1 LTR. Finally, K13 differentially activated HIV-1 LTRs derived from different strains of HIV-1, which correlated with their responsiveness to NF-κB pathway. Conclusions Our results suggest that concomitant infection with KSHV/HHV8 may stimulate HIV-1 LTR via vFLIP K13-induced classical NF-κB pathway which cooperates with HIV-1 Tat protein.

Abstract Background Human immunodeficiency virus (HIV) infection continues to increase at alarming rates in drug abusers, especially in women. Drugs of abuse can cause long-lasting damage to the brain and HIV infection frequently leads to a dementing illness.To determine how these drugs interact with HIV to cause CNS damage, we used an in vitro human neuronal culture characterized for the presence of dopaminergic receptors, transporters and estrogen receptors. We determined the combined effects of dopaminergic drugs, methamphetamine, or cocaine with neurotoxic HIV proteins, gp120 and Tat. Results Acute exposure to these substances resulted in synergistic neurotoxic responses as measured by changes in mitochondrial membrane potential and neuronal cell death. Neurotoxicity occurred in a sub-population of neurons. Importantly, the presence of 17beta-estradiol prevented these synergistic neurotoxicities and the neuroprotective effects were partly mediated by estrogen receptors. Conclusion Our observations suggest that methamphetamine and cocaine may affect the course of HIV dementia, and additionally suggest that estrogens modify the HIV-drug interactions.