Indiana University-Purdue University Indianapolis (IUPUI) / We have previously demonstrated that disabling the transcription factor Nuclear Matrix Protein 4 (NMP4) improved parathyroid hormone (PTH)-induced trabecular bone gain in ovariectomized (OVX) and healthy mice. Here we evaluated whether loss of Nmp4 enhanced bone restoration in OVX mice under concurrent PTH combination therapies and anti-catabolic mono-therapies. Wild type (WT) and Nmp4-/- mice were OVX at 12wks of age followed by therapy regimens, administered from 16wks-24wks, and included individually or combined PTH, alendronate (ALN), zoledronate (ZOL), and raloxifene (RAL). Generally the PTH+RAL and PTH+ZOL therapies were more effective in restoring bone than the PTH mono-therapy. Loss of Nmp4 further improved the restoration of femoral trabecular bone under these treatments. RAL and ZOL mono-therapies moderately increased bone volume but unexpectedly the Nmp4-/- mice showed an enhanced RAL-induced increase in femoral trabecular bone. Immunohistochemical and flow cytometry analyses of the bone marrow and serum profiling for markers of bone formation and resorption indicated that the heightened osteoanabolism of the Nmp4-/- mice under these diverse osteoporosis treatments was partially attributed to an expansion of the osteoprogenitor pool. To address whether the enhanced bone formation observed in Nmp4-/- mice produced structurally sound tissue, mechanical testing was conducted on the femurs of healthy mice treated with intermittent PTH, RAL mono-therapy, or PTH+RAL. Nmp4-/- femurs showed modestly improved mechanical and material properties. At the cellular level, loss of Nmp4 accelerated mineralization in differentiating mesenchymal stem/progenitor cells (MSPCs). Transcriptomic and biochemical analyses indicated that loss of Nmp4 elevated ribosome biogenesis and expanded the capacity of the endoplasmic reticulum for processing protein. Preliminary data showed that disabling Nmp4 increased both aerobic glycolysis and oxidative phosphorylation in osteoprogenitors, which is an emerging hallmark of anabolic osteogenic cells. Transcriptomic analysis also suggested NMP4 targeted pathways driving bone formation. These included but not limited to BMP, IGF1, TGFβ and Wnt signaling pathways. Finally, transcriptomic profiling revealed that Nmp4-/- MSPCs showed a significant perturbation in numerous immunomodulatory pathways, particularly in the interleukin system. The heightened osteoanabolism of the Nmp4-/- skeleton enhances the effectiveness of diverse osteoporosis treatments, providing a promising target pathway for identifying barriers to pharmacologically-induced bone formation.

Indiana University-Purdue University Indianapolis (IUPUI) / Airway inflammation is the most common and important component of respiratory diseases, such as influenza and asthma. Severe influenza A virus infection typically triggers detrimental lung inflammation with massive immune cell infiltration and hyper-production of cytokines and chemokines. We identified a novel function for nuclear matrix protein 4 (NMP4), a zinc-finger-containing transcription factor known for its function in bone formation and spermatogenesis, in regulating antiviral immune responses and immunopathology. Nmp4-deficient mice are protected from influenza induced immunopathology and body weight loss. While having no effects on viral clearance or CD8/CD4 T cell or humoral immune responses, Nmp4 deficiency in either lung structural cells or hematopoietic cells significantly reduces the recruitment of neutrophils and monocytes to the lungs. Furthermore, NMP4 binds to the promoters and/or conserved non-coding sequences of the chemokine genes Ccl2 and Cxcl1 and upregulates their expression in mouse lung epithelial cells and macrophages. These chemokines attract monocytes and neutrophils to the airway, resulting in exaggerated airway inflammation and collateral lung damage. Another transcription factor forkhead box P3 (FOXP3) is critical for the development of regulatory T cells (Tregs) that function to control immune responses. Unlike human FOXP3 gene that encodes two major isoforms, a full length (FOXP3-FL) isoform and a short isoform lacking the exon 2 region (FOXP3-ΔE2), mouse Foxp3 gene only encodes Foxp3-FL isoform. We generate Foxp3-ΔE2 mice to study its function and find that Tregs expressing the Foxp3-ΔE2 isoform have intrinsic defects, thus allowing intensified adaptive immune responses without changes in innate immunity against influenza infection. In a model of chronic asthma, mice expressing only the Foxp3-ΔE2 isoform have significantly increased allergic airway inflammation and elevated production of allergen-specific IgE compared with mice expression the Foxp3-FL isoform. Mechanistically, Tregs expressing the Foxp3-ΔE2 isoform are less stable and prone to trans-differentiation into effector Th9-like cells, which are closely associated with the pathogenesis of asthma. These data suggest that the two Foxp3 isoforms have different functions in regulating airway immune responses. Overall, we have defined the important roles of both transcription factors NMP4 and FOXP3 in regulating airway inflammation. / 2022-08-17

We have shown that nuclear matrix protein 4 (Nmp4) attenuates the response to intermittent parathyroid hormone (PTH) in healthy and ovariectomized (OVX) female mice using a global knockout of the Nmp4 gene. Additionally, these mice have increased bone marrow osteoprogenitors and CD8+ T-cells which support osteoblast differentiation. The animals were not protected from bone loss following OVX, but retained the hypersensitivity seen in the intact mice. Mesenchymal stem/progenitor cells (osteoprogenitors) demonstrated increased growth rate in culture and showed more robust differentiation into mineralizing bone cells. Chromosome precipitation followed by next generation sequencing and bioinformatics analysis characterized Nmp4 as a negative regulator of synthetic processes and suggested the IGF1/Akt and BMP2/Smad biochemical pathways which are likely targets for Nmp4 regulation. We have experimentally verified these pathways in immortalized bone marrow mesenchymal cells from wild type and Nmp4-KO mice. Disabling Nmp4 in estrogen replete or depleted mice confers an enhanced bone formation from intermittent parathyroid hormone.