Biology subjects

Aldridge, D. L.

Publications and source records attributed to Aldridge, D. L..

5 recordsLinked to original sources

bioRxiv2025

Pharmacological reduction of neutrophil infiltration reduces Clostridioides difficile infection severity

Clostridioides difficile is the leading cause of nosocomial infections and an urgent public health threat. This bacterial pathogen is challenging to treat due to antibiotic resistance and high recurrence rates, highlighting the need for additional therapeutic strategies. The host inflammatory response is a major driver of C. difficile-associated disease and associated with worse clinical outcomes. Currently, few strategies targeting the inflammatory response have been leveraged to treat CDI. Here, we show that administration of the prostaglandin E1 (PGE1) analog misoprostol markedly reduces CDI severity by modulating host immune responses. During CDI, misoprostol decreases circulating neutrophils and limits infiltration into the colon, reducing epithelial damage, intestinal pathology, and infection severity. Additionally, misoprostol reduces serum granulocyte colony-stimulating factor (G-CSF), an important cytokine in neutrophil mobilization, controlling neutrophil levels during CDI. Together, these findings highlight neutrophil infiltration as a key driver of C. difficile-associated disease and identify innate immune modulation as a potential host-directed therapeutic strategy.

immunology↗

bioRxiv2025

The type I IFN-IL-27 axis promotes mRNA vaccine-induced CD8+ T cell responses

The ability of lipid nanoparticle (LNP)-delivered mRNA vaccines to induce type I IFNs is critical to promote CD8+ T cell responses. The studies presented here indicate that immunization with nucleoside modified mRNA-LNP vaccines drives myeloid cell expression of the cytokine IL-27, which acts on antigen-specific CD8+ T cells to sustain T cell expansion. In vitro and in vivo studies revealed that type I IFN signaling is necessary for mRNA-LNP-induced IL-27 production, that immunization failed in IL-27 KO mice, and that immunization of IFNAR1-deficient mice with mRNA-LNP particles that also encode IL-27 mRNA restored antigen-specific CD8+ T cell responses. In addition, IL-27 mRNA-LNPs served as an adjuvant that improved cytolytic CD8+ T cell responses and the therapeutic efficacy of mRNA-LNPs to drive anti-pathogen and anti-tumor immunity. These studies highlight the central role of IL-27 in mRNA-LNP induced CD8+ T cell responses and the ability of this cytokine to augment the functionality of the CD8+ T cell response for prophylactic or therapeutic immunization.

immunology↗

bioRxiv2025

IL-27 limits HSPC differentiation during infection and protects from stem cell exhaustion

Many inflammatory stimuli can induce progenitor cells in the bone marrow to produce increased numbers of myeloid cells as part of the process of emergency myelopoiesis. These events are associated with trained immunity and have long-term impacts on hematopoietic stem and progenitor cell (HSPC) development but can also compromise their function. While many cytokines support emergency myelopoiesis, less is known about the mechanisms that temper these events. When mice that lack the cytokine IL-27 were infected with Toxoplasma gondii, there was enhanced generation of monocyte progenitors and increased numbers of inflammatory monocytes. In the bone marrow of infected mice there was increased production of IL-27 that localized with HSPCs and a survey of cytokine receptor expression highlighted that HSPCs were uniquely poised to respond to IL-27. Furthermore, the use of in vitro differentiation assays and mixed bone marrow chimeras revealed that HSPCs from IL-27 deficient mice are pre-disposed towards the monocyte lineage. Additional studies highlighted that after infection loss of the IL-27R resulted in reduced HSPC fitness that manifested as reduced proliferative responses and a decreased ability to reconstitute the hematopoietic system. Thus, the ability of IL-27 to act on HSPC provides a regulatory brake on differentiation to limit monocyte induction and preserve HSPC stemness.

immunology↗

bioRxiv2024

The latent stage of Toxoplasma gondii is targeted by the immune response and host protective

Latency is a microbial strategy for persistence. For Toxoplasma gondii the ability of the bradyzoite stage to form long-lived cysts is critical for transmission, while their presence in neurons is considered important for immune evasion. Development of a mathematical model highlighted that immune pressure on bradyzoites should contribute to dynamics of cyst formation and reactivation. Experimental data demonstrated that a cyst-derived antigen was recognized by CD8+ T cells and that IFN-{gamma} signaling in neurons contributes to cyst control. In addition, modeling and the use of a parasite strain unable to form bradyzoites revealed that this stage was not required for long-term persistence, but the absence of cyst formation resulted in increased tachyzoite replication in the CNS with associated tissue damage and mortality. Thus, the latent form of T. gondii is under immune pressure, mitigates infection-induced damage, and promotes survival of host and parasite.

microbiology↗

bioRxiv2020

Harmine enhances the activity of the HIV-1 latency-reversing agents ingenol A and SAHA

Infection of HIV-1 remains incurable because long-lived, latently-infected cells persist during prolonged antiretroviral therapy. Attempts to pharmacologically reactivate and purge the latent reservoir with latency reactivating agents (LRAs) such as protein kinase C (PKC) agonists (e.g. ingenol A) or histone deacetylase (HDAC) inhibitors (e.g. SAHA) have shown promising but incomplete efficacy. Using the J-Lat T cell model of HIV latency, we found that the plant-derived compound harmine enhanced the efficacy of existing PKC agonist LRAs in reactivating latently-infected cells. Treatment with harmine increased not only the number of reactivated cells but also increased HIV transcription and protein expression on a per-cell basis. Importantly, we observed an additive effect when harmine was used in combination with ingenol A and the HDAC inhibitor SAHA. An investigation into the mechanism revealed that harmine, when used with LRAs, increased the availability of transcription factors needed for viral reactivation such as NF{kappa}B, MAPK p38, and ERK1/2. We also found that harmine treatment resulted in reduced expression of HEXIM1, a negative regulator of transcriptional elongation. Despite harmines reported inhibitory effects on DYRK1A and consequent enhancement of NFAT signaling, the HIV reactivating effects of harmine occurred independent of DYRK1A and NFAT. Harmine increases the efficacy of LRAs by increasing the availability of HIV-1 transcription factors and decreasing expression of HEXIM1. Combination therapies with harmine and LRAs could benefit patients by achieving deeper reactivation of the latent pool of HIV provirus.

microbiology↗