Tadokoro, K. | bioRxiv Science

bioRxiv2025

Characterization of bronchovascular-bundle mesenchymal stromal cells regulating antibody-secreting cell niche in rejecting lung allografts

A transplanted lung offers a permissive milieu for local adaptive immune cell responses. Here, we characterize a transcriptionally and anatomically distinct adult lung-resident mesenchymal stromal population (MSC) that supports a pro-survival niche for antibody-secreting cells in rejecting lung allografts through a novel IL-6 trans-signaling/CXCL12 axis. By using a mouse orthotopic lung transplant model and Blimp1EYFP recipients, we identify spatial localization of antibody-secreting cells (ASCs) and terminally differentiated plasma cells (PCs) along the bronchovascular bundles (BVBs). A previously described Foxf1+Gli1+Itga8- subset of collagen- expressing MSCs, which forms a 3-dimensional network along the bronchovascular bundles (BVB-MSCs), was found to be the major source of the PC survival factors CXCL12 and IL-6. Cxcl12iCre/ERT2Rosa26tdTomatomice utilized as donors, validated the expansion of this population in a rejecting graft and their intimate association with ASCs. CXCL12 expression was increased in murine allografts and in Foxf1+ mesenchymal cells (MCs) isolated from human CLAD patients. IL-6 trans-signaling/STAT3 signaling axis was shown to upregulate CXCL12 secretion in human MCs, and Olamkicept-mediated neutralization of IL-6 trans-signaling in murine RAS attenuates CXCL12 expression, intra-graft ASC population, and fibrogenesis. Our findings represent the first delineation of specialized CXCL12-expressing mesenchymal stromal cells in adult lungs and the contribution of IL-6 trans-signaling driven CXCL12 expression to sustaining intra-graft ASC niches and allograft fibrogenesis. One Sentence SummaryWe characterize CXCL12-expressing mesenchymal cells and their role in a pro-survival niche for antibody-secreting cells in rejecting lung allografts.

pathology↗

bioRxiv2021

Stronger density-dependent growth of Japanese sardine with lower food availability: Comparison of growth and zooplankton biomass between a historical and current stock-increase period in the western North Pacific

Density dependence is a fundamental concept for fish population dynamics. Although density-dependent growth and maturity among older juveniles and adults is important for regulating fish population size and for fisheries management, the mechanism of density dependence for marine fishes remains unclear. Here, we examined changes in Japanese sardine growth with increasing abundance beginning in the 2010s and how the current pattern of density-dependent growth differs from that of a previous stock-increase period from the 1970s to early 1980s. During the current period of increasing abundance, mean standard length has already dropped to the lowest level yet observed and growth has declined more sharply with increased abundance than in the 1970s and 1980s. Mesozooplankton biomass in July in the summer feeding grounds was also lower during the current period. Therefore, our results suggest that summer food availability in the western North Pacific controls the strength of density-dependent growth. A lower carrying capacity for Japanese sardine could account for the stronger density dependence of growth observed in the 2010s; this indicates that future Japanese sardine abundance might not increase as much as in the 1980s unless food availability improves.

ecology↗