RNA polymerase III (Pol III) is an essential 17-subunit complex responsible for the transcription of small housekeeping RNAs such as transfer RNAs and 5S ribosomal RNA. Biallelic variants in four genes (POLR3A, POLR3B, and POLR1C and POLR3K) encoding Pol III subunits have previously been found in individuals with (neuro-) developmental disorders. In this report, we describe three individuals with biallelic variants in POLR3GL, a gene encoding a Pol III subunit that has not been associated with disease before. Using whole exome sequencing in a monozygotic twin and an unrelated individual, we detected homozygous and compound heterozygous POLR3GL splice acceptor site variants. RNA sequencing confirmed the loss of full-length POLR3GL RNA transcripts in blood samples of the individuals. The phenotypes of the described individuals are mainly characterized by axial endosteal hyperostosis, oligodontia, short stature, and mild facial dysmorphisms. These features largely fit within the spectrum of phenotypes caused by previously described biallelic variants in POLR3A, POLR3B, POLR1C, and POLR3K. These findings further expand the spectrum of POLR3-related disorders and implicate that POLR3GL should be included in genetic testing if such disorders are suspected.

Lupus nephritis is a potentially fatal autoimmune disease for which the current treatment is ineffective and often toxic. To develop mechanistic hypotheses of disease, we analyzed kidney samples from patients with lupus nephritis and from healthy control subjects using single-cell RNA sequencing. Our analysis revealed 21 subsets of leukocytes active in disease, including multiple populations of myeloid cells, T cells, natural killer cells and B cells that demonstrated both pro-inflammatory responses and inflammation-resolving responses. We found evidence of local activation of B cells correlated with an age-associated B-cell signature and evidence of progressive stages of monocyte differentiation within the kidney. A clear interferon response was observed in most cells. Two chemokine receptors, CXCR4 and CX3CR1, were broadly expressed, implying a potentially central role in cell trafficking. Gene expression of immune cells in urine and kidney was highly correlated, which would suggest that urine might serve as a surrogate for kidney biopsies.

Cytokine responses from monocytes and macrophages exposed to bacteria are of particular importance in innate immunity. Focusing on the impact of the immunoregulatory cytokine interleukin (IL)-27 on control of innate immune system responses, we examined human immune responses to bacterial products and bacterial infection by E. coli and S. typhimurium. Since the effect of IL-27 treatment in human myeloid cells infected with bacteria is understudied, we treated human monocytes and macrophages with IL-27 and either LPS, flagellin, or bacteria, to investigate the effect on inflammatory signaling and cytokine responses. We determined that simultaneous stimulation with IL-27 and LPS derived from E. coli or S. typhimurium resulted in enhanced IL-12p40, TNF-$\alpha$, and IL-6 expression compared to that by LPS alone. To elucidate if IL-27 manipulated the cellular response to infection with bacteria, we infected IL-27 treated human macrophages with S. typhimurium. While IL-27 did not affect susceptibility to S. typhimurium infection or S. typhimurium-induced cell death, IL-27 significantly enhanced proinflammatory cytokine production in infected cells. Taken together, we highlight a role for IL-27 in modulating innate immune responses to bacterial infection.

Preventing the immune escape of tumor cells by blocking inhibitory checkpoints, such as the interaction between programmed death ligand-1 (PD-L1) and programmed death-1 (PD-1) receptor, is a powerful anticancer approach. However, many patients do not respond to checkpoint blockade. Tumor PD-L1 expression is a potential efficacy biomarker, but the complex mechanisms underlying its regulation are not completely understood. Here, we show that the eukaryotic translation initiation complex, eIF4F, which binds the 5' cap of mRNAs, regulates the surface expression of interferon-$\gamma$-induced PD-L1 on cancer cells by regulating translation of the mRNA encoding the signal transducer and activator of transcription 1 (STAT1) transcription factor. eIF4F complex formation correlates with response to immunotherapy in human melanoma. Pharmacological inhibition of eIF4A, the RNA helicase component of eIF4F, elicits powerful antitumor immune-mediated effects via PD-L1 downregulation. Thus, eIF4A inhibitors, in development as anticancer drugs, may also act as cancer immunotherapies.

Recently, deficiency in the cytosolic DNA sensor RNA Polymerase III was described in children with severe primary varicella-zoster virus (VZV) infection in the CNS and lungs. In the present study we examined adult patients with VZV CNS infection caused by viral reactivation. By whole exome sequencing we identified mutations in POL III genes in two of eight patients. These mutations were located in the coding regions of the subunits POLR3A and POLR3E. In functional assays, we found impaired expression of antiviral and inflammatory cytokines in response to the POL III agonist Poly(dA:dT) as well as increased viral replication in patient cells compared to controls. Altogether, this study provides significant extension on the current knowledge on susceptibility to VZV infection by demonstrating mutations in POL III genes associated with impaired immunological sensing of AT-rich DNA in adult patients with VZV CNS infection.