Biology subjects

Hoffman, H. M.

Publications and source records attributed to Hoffman, H. M..

5 recordsLinked to original sources

bioRxiv2021

Single-Cell Transcriptomic Analysis of Livers During NLRP3 Inflammasome Activation Reveals a Novel Immune Niche

The NOD-like receptor protein 3 (NLRP3) inflammasome is a central contributor to human acute and chronic liver disease, yet the molecular and cellular mechanisms by which its activation precipitates injury remain incompletely understood. Here, we present single cell transcriptomic profiling of livers from a global transgenic Tamoxifen-inducible constitutively-activated Nlrp3A350V mutant mouse, and we investigate the changes in parenchymal and non-parenchymal liver cell gene expression that accompany inflammation and fibrosis. Our results demonstrate that NLRP3 activation causes chronic extramedullary myelopoiesis marked by an increase in proliferating myeloid progenitors that differentiate into neutrophils, monocytes, and monocyte-derived macrophages, results that were corroborated by flow cytometry and histological staining. We observed prominent neutrophil infiltrates with increased Ly6gHI and Ly6gINT cells exhibiting transcriptomic signatures of granulopoiesis typically found in the bone marrow. This was accompanied by a marked increase in Ly6cHI monocytes differentiating into Cd11bHITim4HIClec4fHI macrophages that express proinflammatory transcriptional programs similar to macrophages of non-alcoholic steatohepatitis (NASH) models. NLRP3 activation also downregulated metabolic pathways in hepatocytes and shifted hepatic stellate cells towards an activated pro-fibrotic state based on expression of collagen and extracellular matrix (ECM) regulatory genes. These results, which highlight abundant neutrophils and extramedullary granulopoiesis define an inflamed and fibrotic hepatic single cell microenvironment, precipitated solely by NLRP3 activation. Clinically, our data support the notion that neutrophils and NLRP3 should be explored as therapeutic targets in NASH-like inflammation.

immunology↗

bioRxiv2021

The Human Milk Oligosaccharide 3-Sialyllactose Promotes Inflammation Resolution and Reduces Atherosclerosis Development in Mice.

Macrophages contribute to the induction and resolution of inflammation and play a central role in the chronic low-grade inflammation in cardiovascular diseases caused by atherosclerosis. Human milk oligosaccharides (HMOs) are complex unconjugated glycans unique to human milk that benefit infant health and act as innate immune modulators. Here, we identify the HMO 3sialyllactose (3SL) as a natural inhibitor of TLR4-induced low-grade inflammation in macrophages and endothelium. Transcriptome analysis in macrophages revealed that 3SL attenuates a selected set of inflammatory gene expression and promotes activity of LXR and SREBP. These acute anti-inflammatory effects of 3SL were associated with reduced histone H3K27 acetylation at a subset of LPS-inducible enhancers distinguished by preferential enrichment for CTCF, IRF2, BCL6, and other transcription factor recognition motifs. In a murine atherosclerosis model, both subcutaneous and oral administration of 3SL significantly reduced atherosclerosis development and the associated inflammation. This study provides evidence that 3SL attenuates inflammation by a transcriptional mechanism to reduce atherosclerosis development in the context of cardiovascular disease.

immunology↗

bioRxiv2021

The role of IL-1 in adipose browning and muscle wasting in CKD-associated cachexia

Cytokines such as IL-6, TNF- and IL-1{beta} trigger inflammatory cascades which may play a role in the pathogenesis of chronic kidney disease (CKD)-associated cachexia. CKD was induced by 5/6 nephrectomy in mice. We studied energy homeostasis in Il1{beta}-/-/CKD, Il6-/-/CKD and Tnf-/-/CKD mice and compared with wild type (WT)/CKD controls. Parameters of cachexia phenotype were completely normalized in Il1{beta}-/-/CKD mice but were only partially rescued in Il6-/-/CKD and Tnf-/-/CKD mice. We tested the effects of anakinra, an IL-1 receptor antagonist, on CKD-associated cachexia. WT/CKD mice were treated with anakinra (2.5 mg.kg.day, IP) or saline for 6 weeks and compared with WT/sham controls. Anakinra normalized food intake and weight gain, fat and lean mass content, metabolic rate and muscle function, and also attenuated molecular perturbations of energy homeostasis in adipose tissue and muscle in WT/CKD mice. Anakinra attenuated browning of white adipose tissue in WT/CKD mice. Moreover, anakinra normalized gastrocnemius weight and fiber size as well as attenuated muscle fat infiltration in WT/CKD mice. This was accompanied by correcting the increased muscle wasting signaling pathways while promoting the decreased myogenesis process in gastrocnemius of WT/CKD mice. We performed qPCR analysis for the top 20 differentially expressed muscle genes previously identified via RNAseq analysis in WT/CKD mice versus controls. Importantly, 17 differentially expressed muscle genes were attenuated in anakinra treated WT/CKD mice. In conclusion, IL-1 receptor antagonism may represent a novel targeted treatment for adipose tissue browning and muscle wasting in CKD.

physiology↗

bioRxiv2021

Targeting interleukin-1 for reversing fat browning and muscle wasting in infantile nephropathic cystinosis

BackgroundCtns-/- mice, a mouse model of infantile nephropathic cystinosis, exhibit hypermetabolism with adipose tissue browning and profound muscle wasting. Inflammatory cytokines such as IL-1 trigger inflammatory cascades and play an important role in the pathogenesis of cachexia. Anakinra is an FDA-approved IL-1 receptor antagonist that blocks IL-1 signaling and may provide targeted novel therapy. MethodsCtns-/- mice were bred to Il6 -/- and Il1{beta} -/- mice. Ctns-/- mice and wild type control were treated with anakinra (2.5 mg.kg.day, IP) or saline as vehicle for 6 weeks. We quantitated total fat mass and studied expression of molecules regulating adipose tissue browning. We measured gastrocnemius weight, total lean mass content, muscle function (grip strength and rotarod activity), muscle fiber size, muscle fatty infiltration and expression of molecules regulating muscle metabolism. We also evaluated the effects of anakinra on the muscle transcriptome. ResultsIl-1{beta} deficiency or treatment with anakinra normalized food intake and weight gain, fat and lean mass content, metabolic rate and muscle function in Ctns-/- mice. Anakinra also diminished molecular perturbations of energy homeostasis in adipose tissue and muscle, specifically, aberrant expression of beige adipose cell biomarkers (UCP-1, CD137, Tmem26 and Tbx1) and molecules implicated in adipocyte tissue browning (Cox2/Pgf2, Tlr2, Myd88 and Traf6) in inguinal white adipose tissue in Ctns-/- mice. Moreover, anakinra normalized gastrocnemius weight and fiber size as well as attenuated muscle fat infiltration in Ctns-/- mice. This was accompanied by correction of the increased muscle wasting signaling pathways (increased protein content of ERK1/2, JNK, p38 MAPK and NF-{kappa}B p65 and gene expression of Atrogin-1 and Myostatin) and the decreased myogenesis process (decreased gene expression of MyoD and Myogenin) in gastrocnemius of Ctns-/- mice. Finally, anakinra normalized or attenuated 12 of those top 20 differentially expressed muscle genes in Ctns-/- mice. ConclusionsAnakinra attenuates adipose tissue browning and muscle wasting in Ctns-/- mice. IL-1 receptor blockade may represent a novel targeted treatment for cachexia in patients with infantile nephropathic cystinosis.

physiology↗

bioRxiv2020

Inhibition of the NLRP3 inflammasome prevents ovarian aging

Inflammation is a hallmark of many processes during aging and reproductive physiology, negatively affecting female fertility. The goal of this study was to evaluate the role of the NLRP3 inflammasome in ovarian aging and female fertility. Age-dependent increased expression of NLRP3 in the ovary was observed in female WT mice during reproductive aging. High expression of NLRP3, caspase 1 and IL-1{beta} was also observed in granulosa cells from patients with primary ovarian insufficiency. Ablation of the NLRP3 inflammasome improved the survival and pregnancy rates in mice, increased hormonal levels of AMH, a biochemical marker of ovarian reserve, and autophagy rates in ovarian tissue. Deficiency of the NLRP3 inflammasome also reduced serum FSH and estradiol levels. Consistent with these results, pharmacological inhibition of NLRP3 using a direct NLRP3 inhibitor, MCC950, improved fertility in female mice to levels comparable to those of Nlrp3-/- mice. These results suggest that the NLRP3 inflammasome is implicated in the age-dependent loss of female fertility and position this inflammasome as a potential new therapeutic target for the treatment of infertility.

immunology↗