Pulmonary fibrosis is a disease in which excessive extracellular matrix (ECM) accumulation occurs in the lungs, which induces thickening of the alveolar walls, ultimately leading to the destruction of alveolar structures and respiratory failure. Idiopathic pulmonary fibrosis, the cause of which is unknown, has a poor prognosis with a median survival of 2–4 years after diagnosis. There is currently no known curative treatment. The mechanism underlying pulmonary fibrosis is thought to be initiated by the dysfunction of type II alveolar epithelial cells, which leads to ECM overproduction through the activation of fibroblasts. In addition, it has been suggested that a variety of cells contribute to fibrotic processes. In particular, clinical and basic research findings examining the roles of macrophages suggest that they may be pivotal regulators of pulmonary fibrosis. In this review, we discuss the characteristics, functions and origins of subsets of macrophages involved in pulmonary fibrosis, including resident alveolar, interstitial and monocyte-derived macrophages.

Single-cell RNA-sequencing (scRNA-seq) is valuable for analyzing cellular heterogeneity. Cell composition accuracy is critical for analyzing cell–cell interaction networks from scRNA-seq data. However, droplet- and plate-based scRNA-seq techniques have cell sampling bias that could affect the cell composition of scRNA-seq datasets. Here we developed terminator-assisted solid-phase cDNA amplification and sequencing (TAS-Seq) for scRNA-seq based on a terminator, terminal transferase, and nanowell/bead-based scRNA-seq platform. TAS-Seq showed high tolerance to variations in the terminal transferase reaction, which complicate the handling of existing terminal transferase-based scRNA-seq methods. In murine and human lung samples, TAS-Seq yielded scRNA-seq data that were highly correlated with flow-cytometric data, showing higher gene-detection sensitivity and more robust detection of important cell–cell interactions and expression of growth factors/interleukins in cell subsets than 10X Chromium v2 and Smart-seq2. Expanding TAS-Seq application will improve understanding and atlas construction of lung biology at the single-cell level.

BackgroundThe expansion of intratumoral stem-like CD8+ T (Tstem) cells provides a potential approach to improving the therapeutic efficacy of immune checkpoint blockade (ICB). Thus, here we demonstrate a strategy to facilitate Tstem cell expansion by combining an alarmin high-mobility group nucleosome binding domain 1 (HMGN1) peptide with programmed death-ligand 1 (PD-L1) blockade.MethodsThe antitumor effects of HMGN1, anti-PD-L1 antibody, and their combined treatment were monitored in the B16F10, LLC, Colon26, or the EO771 tumor-bearing mice. The comprehensive immunologic analyses, such as high-dimensional flow cytometry, transcriptome analysis, and single-cell RNA sequencing, were used to investigate the cellular and molecular mechanisms of antitumor immune responses after treatments.ResultsThe HMGN1 peptide synergizes with PD-L1 blockade in augmenting the number of mature DCs enriched in immunoregulatory molecules (mregDCs) in tumors, and enhancing their MHC class I antigen-presenting program, which is correlated with the expansion of intratumoral Tstem cells, specifically promoting the Tstem cells but restricting terminally exhausted CD8+ T (Tex) cells, owing to the regulatory molecules expressed on mregDCs.ConclusionOur results indicate that HMGN1 peptide serves as an immunoadjuvant to promote effective anti-PD-L1 immunotherapy and implicate that mregDCs play a role beyond facilitating Tstem cell expansion.

A series of 1,2-dihydro-5-imidazo[1,2-a]pyridinyl-2(1H)-pyridonones was synthesized and evaluated for positive inotropic activity, 1,2-Dihydro-5-imidazo[1,2-a]pyridin-6-yl-6-methyl-2- oxo-3-pyridinecarbonitrile (11a) hydrochloride monohydrate (E-1020) was found to be a potent and selective inhibitor of phosphodiesterase III and a long-acting, potent, orally active positive inotropic agent. Additional imidazo[1,2-a]pyridin-2-yl (3a), -3-yl (16), -7-yl (20) and -8-yl (24a) compounds were also prepared. Altering the pyridine substitution from the 2-position to the 6-position produced a 2-fold increase in the i.v. cardiotonic potency (ED50) from 52 to 23 micrograms/kg, while substitution at the 3-, 7- or 8-position reduced potency. In the 2-positional isomers, introduction of halogen groups enhanced the activity and 3-chloro-1,2-dihydro-5-(6-fluoroimidazo[1,2-a] pyridin-2-yl)-6-methyl-2(1H)-pyridinone (3u) was the most potent (i.v. ED50 11 micrograms/kg) in this series. E-1020 is presently under development for the treatment of congestive heart failure.

The expansion of intratumoral stem-like/progenitor exhausted CD8+ T (Tstem/Tpex) cells provides a potential approach to improve the therapeutic efficacy of immune checkpoint blockade (ICB). Thus, here we demonstrate a strategy to facilitate Tstem/Tpex cell expansion by combining an alarmin high-mobility group nucleosome binding domain 1 (HMGN1) peptide with programmed death-ligand 1 (PD-L1) blockade. The antitumor effects of HMGN1, anti–PD-L1, and their combined treatment were monitored in the B16F10, LLC, Colon26, or EO771 tumor–bearing mice. The comprehensive immunologic analyses, such as high-dimensional flow cytometry, transcriptome analysis, and single-cell RNA-sequencing (scRNA-seq), were used to investigate the cellular and molecular mechanisms of antitumor immune responses after treatments. We identified the immunostimulatory domain (EPKRR SARLS AKPPA KVEAK PKK) on HMGN1 and synthesized this domain as a therapeutic peptide (minP1). Combined treatment with minP1 and PD-L1 blockade induced durable tumor regression in tumor-bearing mice. minP1 increased the number of intratumoral mature DCs enriched in immunoregulatory molecules (mregDC) and enhanced their MHC class I antigen–presenting program. minP1 also synergized with PD-L1 blockade in augmenting intratumoral Tstem/Tpex cell number. Analysis of our scRNA-seq dataset by CellPhonDB suggested potential interactions between mregDCs and Tstem/Tpex cells in tumors. Our results indicate that HMGN1 peptide (minP1) serves as an immunoadjuvant to promote effective anti–PD-L1 immunotherapy with increased Tstem/Tpex cells in tumors.