Abstract Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive lung disease characterized by scarring and tissue remodelling. Current treatments have limited efficacy and significant side effects. To address these limitations, we developed AD-214, an anti-CXCR4-Fc-fusion protein comprised of an anti-CXCR4 i-body (AD-114) tethered at its C terminus to constant domains 2 and 3 of the Fc region of a mutated human IgG1 lacking effector function. AD-214 binds with high affinity and specificity to CXCR4, modulates intracellular signaling and inhibits key fibrotic pathways. Using fibrosis models, we demonstrate that AD-214 treatment significantly reduces collagen deposition and lung remodelling and has a unique mode of action. In Phase 1 clinical trials intravenous (IV) infusion of AD-214 led to high and sustained CXCR4 receptor occupancy (RO); however, whether RO and efficacy are causally linked remained to be determined. Herein, we demonstrate that CXCR4 RO by AD-214 inhibits primary human leukocyte migration, a model fibrotic process, and that migration inhibition is achievable at concentrations of AD-214 present in the serum of healthy human volunteers administered AD-214. Taken together, these data provide proof of concept for AD-214 as a novel treatment strategy for IPF, and suggest that clinically feasible dosing regimens may be efficacious.

The maintenance of a strong IL21 production in memory CD4 T cells, especially in HIV-1-specific cells, represents a major correlate of natural immune protection against the virus. However, the molecular mechanisms underlying IL21 production during HIV-1 infection, which is only elevated among the naturally protected elite controllers (EC), are still unknown. We recently found out that lipophagy is a critical immune mediator that control an antiviral metabolic state following CD8A T cell receptor engagement, playing an important role in the natural control of HIV-1 infection. This led us to investigate whether the beneficial role of a strong macroautophagy/autophagy, could also be used to ensure effective IL21 production as well. Herein, we confirm that after both polyclonal and HIV-1-specific activation, memory CD4 T cells (Mem) from EC display enhanced activity of the autophagy-mediated proteolysis compared to ART. Our results indicate that the enhanced autophagy activity in EC was controlled by the energy-sensing PRKAA1 (protein kinase AMP-activated catalytic subunit alpha 1). We further confirmed the critical role of the autophagy-mediated proteolysis in the strong IL21 production in EC by using BECN1 gene silencing as well as protease, PRKAA1, and lysosomal inhibitors. Finally, we established that high autophagy-mediated proteolysis in EC fuels their cellular rates of mitochondrial respiration due to glutaminolysis. Our data confirm the critical role of autophagy in dictating the metabolic input, which is required not only to ensure protective cytotoxic CD8A T cell responses, but also to provide strong IL21 production among antiviral CD4 T cells.Abbreviations: AKG: alpha-ketoglutarate; ART: patients under antiretroviral therapy; ATG7: autophagy related 7; BaF: bafilomycin A1; BECN1: beclin 1; Chloro.: chloroquine; EC: elite controllers; EIF4EBP1: eukaryotic translation initiation factor 4E binding protein 1; FOXO3: forkhead box O3; GLS: glutaminase; GLUD1: glutamate dehydrogenase 1; HIVneg: HIV-1-uninfected control donors; IFNG/IFN-γ: interferon gamma; IL21: interleukin 21; MTOR: mechanistic target of rapamycin kinase; PBMC: peripheral blood mononuclear cells; PRKAA1: protein kinase AMP-activated catalytic subunit alpha 1; SQSTM1: sequestosome 1; TCA: tricarboxylic acid cycle; ULK1: unc-51 like autophagy activating kinase.

Pyruvate dehydrogenase (PDH) is the gatekeeper enzyme of the tricarboxylic acid (TCA) cycle. Here we show that the deglycase DJ-1 (encoded by PARK7, a key familial Parkinson's disease gene) is a pacemaker regulating PDH activity in CD4+ regulatory T cells (Treg cells). DJ-1 binds to PDHE1-β (PDHB), inhibiting phosphorylation of PDHE1-α (PDHA), thus promoting PDH activity and oxidative phosphorylation (OXPHOS). Park7 (Dj-1) deletion impairs Treg survival starting in young mice and reduces Treg homeostatic proliferation and cellularity only in aged mice. This leads to increased severity in aged mice during the remission of experimental autoimmune encephalomyelitis (EAE). Dj-1 deletion also compromises differentiation of inducible Treg cells especially in aged mice, and the impairment occurs via regulation of PDHB. These findings provide unforeseen insight into the complicated regulatory machinery of the PDH complex. As Treg homeostasis is dysregulated in many complex diseases, the DJ-1-PDHB axis represents a potential target to maintain or re-establish Treg homeostasis.
© 2022. The Author(s), under exclusive licence to Springer Nature Limited.

Pyruvate dehydrogenase (PDH) is the gatekeeper enzyme into the tricarboxylic acid (TCA) cycle. Here we show that PARK7/DJ-1, a key familial Parkinson’s disease (PD) gene, is a pacemaker controlling PDH activity in CD4 regulatory T cells (Tregs). DJ-1 bound to PDH-E1 beta (PDHB), inhibiting the phosphorylation of PDH-E1 alpha (PDHA), thus promoting PDH activity and oxidative phosphorylation (OXPHOS). Dj-1 depletion impaired Treg proliferation and cellularity maintenance in older mice, increasing the severity during the remission phase of experimental autoimmune encephalomyelitis (EAE). The compromised proliferation and differentiation of Tregs in Dj-1 knockout mice were caused via regulating PDH activity. These findings provide novel insight into the already complicated regulatory machinery of the PDH complex and demonstrate that the DJ-1-PDHB axis represents a potent target to maintain Treg homeostasis, which is dysregulated in many complex diseases.

T cell immunoglobulin and ITIM domain (TIGIT) is a recently identified T cell coinhibitory receptor. Studies have shown that TIGIT is expressed in colon adenocarcinoma, uterine corpus endometrioid carcinoma, breast carcinoma and kidney renal clear cell carcinoma. However, the role of the TIGIT/human poliovirus receptor (CD155) pathway in the pathogenesis of hepatocellular carcinoma (HCC) remains to be elucidated. In the present study, the expression of TIGIT and CD155 in HCC tissues and peripheral blood were determined, and correlations among TIGIT, CD155, TIGIT+ CD4+ T cells, TIGIT+ regulatory T (Treg) cells and α‑fetoprotein (AFP) were investigated in order to identify a potential target for diagnosing and treating HCC. Immunohistochemistry, reverse transcription‑quantitative PCR analysis and western blotting were used to examine the expression of TIGIT and CD155 in cancerous tissues and peripheral blood collected from patients with HCC. The frequency of TIGIT+ CD4+ T cells and TIGIT+ Treg cells and the concentration of inflammatory cytokines secreted by T cell subsets were analyzed by flow cytometry and a Merck Milliplex assay. Correlations between the frequency of TIGIT+ CD4+ T and TIGIT+ Treg cells and AFP were analyzed using Spearman's rank correlation test. With the degree of cancerous differentiation from high to low, the expression levels of TIGIT and CD155 were upregulated in the cancerous tissues from patients with HCC. TIGIT+ CD4+ T cell and TIGIT+ Treg cell frequencies were decreased in peripheral blood from postoperative patients with HCC. The increased expression of TIGIT was positively correlated with the level of AFP. These results indicate that co‑inhibitory receptor TIGIT may be involved in the pathogenesis of HCC and represent a novel target for the diagnosis and treatment of HCC.