Osteoporosis is a common aging-related disease diagnosed primarily using bone mineral density (BMD). We assessed genetic determinants of BMD as estimated by heel quantitative ultrasound in 426,824 individuals, identifying 518 genome-wide significant loci (301 novel), explaining 20% of its variance. We identified 13 bone fracture loci, all associated with estimated BMD (eBMD), in ~1.2 million individuals. We then identified target genes enriched for genes known to influence bone density and strength (maximum odds ratio (OR) = 58, P = 1 × 10-75) from cell-specific features, including chromatin conformation and accessible chromatin sites. We next performed rapid-throughput skeletal phenotyping of 126 knockout mice with disruptions in predicted target genes and found an increased abnormal skeletal phenotype frequency compared to 526 unselected lines (P < 0.0001). In-depth analysis of one gene, DAAM2, showed a disproportionate decrease in bone strength relative to mineralization. This genetic atlas provides evidence linking associated SNPs to causal genes, offers new insight into osteoporosis pathophysiology, and highlights opportunities for drug development.

Key Points: Anti-sclerostin treatment increases bone mass and fracture resistance in MM Anti-sclerostin in combination with zoledronic acid is superior to zoledronic acid alone in increasing fracture resistance.

Osteocytes are master regulators of the skeleton. We mapped the transcriptome of osteocytes from different skeletal sites, across age and sexes in mice to reveal genes and molecular programs that control this complex cellular-network. We define an osteocyte transcriptome signature of 1239 genes that distinguishes osteocytes from other cells. 77% have no previously known role in the skeleton and are enriched for genes regulating neuronal network formation, suggesting this programme is important in osteocyte communication. We evaluated 19 skeletal parameters in 733 knockout mouse lines and reveal 26 osteocyte transcriptome signature genes that control bone structure and function. We showed osteocyte transcriptome signature genes are enriched for human orthologs that cause monogenic skeletal disorders (P = 2.4 × 10⁻²²) and are associated with the polygenic diseases osteoporosis (P = 1.8 × 10⁻¹³) and osteoarthritis (P = 1.6 × 10⁻⁷). Thus, we reveal the molecular landscape that regulates osteocyte network formation and function and establish the importance of osteocytes in human skeletal disease.

Osteoarthritis causes debilitating pain and disability, resulting in a considerable socioeconomic burden, yet no drugs are available that prevent disease onset or progression. Here, we develop, validate and use rapid-throughput imaging techniques to identify abnormal joint phenotypes in randomly selected mutant mice generated by the International Knockout Mouse Consortium. We identify 14 genes with functional involvement in osteoarthritis pathogenesis, including the homeobox genePitx1, and functionally characterize 6 candidate human osteoarthritis genes in mouse models. We demonstrate sensitivity of the methods by identifying age-related degenerative joint damage in wild-type mice. Finally, we phenotype previously generated mutant mice with an osteoarthritis-associated polymorphism in theDio2gene byCRISPR/Cas9genome editing and demonstrate a protective role in disease onset with public health implications. We hope this expanding resource of mutant mice will accelerate functional gene discovery in osteoarthritis and offer drug discovery opportunities for this common, incapacitating chronic disease.

The inflammatory microenvironment of solid tumors creates a protumorigenic milieu that resembles chronic inflammation akin to a subverted wound healing response. Here, we investigated the effect of converting the tumor microenvironment from a chronically inflamed state to one of acute microbial inflammation by injecting microbial bioparticles directly into tumors. Intratumoral microbial bioparticle injection led to rapid and dramatic changes in the tumor immune composition, the most striking of which was a substantial increase in the presence of activated neutrophils. In situ photoconversion and intravital microscopy indicated that tumor neutrophils transiently switched from sessile producers of VEGF to highly motile neutrophils that clustered to make neutrophil-rich domains in the tumor. The neutrophil clusters remodeled tumor tissue and repressed tumor growth. Single-cell transcriptional analysis of microbe-stimulated neutrophils showed a profound shift in gene expression towards heightened activation and antimicrobial effector function. Microbe-activated neutrophils also upregulated chemokines known to regulate neutrophil and CD8+ T-cell recruitment. Microbial therapy also boosted CD8+ T-cell function and enhanced the therapeutic benefit of checkpoint inhibitor therapy in tumor-bearing mice and provided protection in a model of tumor recurrence. These data indicate that one of the major effector mechanisms of microbial therapy is the conversion of tumor neutrophils from a wound healing to an acutely activated cytotoxic phenotype, highlighting a rationale for broader deployment of microbial therapy in the treatment of solid cancers. Significance: Intratumoral injection of microbial bioparticles stimulates neutrophil antitumor functions, suggesting pathways for optimizing efficacy of microbial therapies and paving the way for their broader utilization in the clinic.

In the version of this article initially published, in Fig. 5a, the data in the right column of ‘DAAM2 gRNA1’ were incorrectly plotted as circles indicating ‘untreated’ rather than as squares indicating ‘treated’. The error has been corrected in the HTML and PDF versions of the article.