Aristolochic acid (AA) is the causative nephrotoxic alkaloid in aristolochic acid nephropathy, which results in a tubulointerstitial fibrosis. AA causes direct proximal tubule damage. There is also an influx of macrophages, although their role in the pathogenesis is poorly understood. Here we demonstrate that AA directly stimulates migration, inflammation, and reactive oxygen species (ROS) production in macrophages ex vivo. Cells lacking interferon regulatory factor 4 (IRF4), a known regulator of macrophage migration and phenotype, had a reduced migratory response, though effects on ROS production and inflammation were preserved or increased relative to wild-type cells. Macrophage-specific IRF4 knockout mice were protected from both acute and chronic kidney effects of AA administration based on functional and histological analysis. Renal macrophages from kidneys of AA-treated macrophage-specific IRF4 knockout mice demonstrated increased apoptosis and ROS production compared with wildtype controls, indicating that AA directly polarizes macrophages to a promigratory and proinflammatory phenotype. However, knockout mice had reduced renal macrophage abundance following AA administration. While macrophages lacking IRF4 can adopt a proinflammatory phenotype upon AA exposure, their inability to migrate to the kidney and increased rates of apoptosis upon infiltration provide protection from AA in vivo. These results provide evidence of direct AA effects on macrophages in AAN and add to the growing body of evidence that supports a key role of IRF4 in modulating macrophage function in kidney injury.
Kensuke Sasaki, Andrew S. Terker, Jiaqi Tang, Shirong Cao, Juan Pablo Arroyo, Aolei Niu, Suwan Wang, Xiaofeng Fan, Yahua Zhang, Stephanie R. Bennett, Ming-zhi Zhang, Raymond C. Harris
Mammalian skeletal muscle contains heterogenous myofibers with different contractile and metabolic properties that sustain muscle mass and endurance capacity. The transcriptional regulators that govern these myofiber gene programs have been elucidated. However, the hormonal cues that direct the specification of myofiber types and muscle endurance remain largely unknown. Here we uncover the secreted factor Tsukushi (TSK) as an extracellular signal that is required for maintaining muscle mass, strength, and endurance capacity, and contributes to muscle regeneration. Mice lacking TSK exhibited reduced grip strength and impaired exercise capacity. Muscle transcriptomic analysis revealed that TSK deficiency results in a remarkably selective impairment in the expression of myofibrillar genes characteristic of slow-twitch muscle fibers that is associated with abnormal neuromuscular junction formation. AAV-mediated overexpression of TSK failed to rescue these myofiber defects in adult mice, suggesting that the effects of TSK on myofibers are likely restricted to certain developmental stages. Finally, mice lacking TSK exhibited diminished muscle regeneration following cardiotoxin-induced muscle injury. These findings support a crucial role of TSK as a hormonal cue in the regulation of contractile gene expression, endurance capacity, and muscle regeneration.
Qiuyu Wang, Xiaoxue Qiu, Tongyu Liu, Cheehoon Ahn, Jeffrey F. Horowitz, Jiandie D. Lin
Recent research on altering threat memory has focused on a reconsolidation window. During reconsolidation, threat memories are retrieved and become labile. Reconsolidation of distinct threat memories is synapse-dependent whereas the underlying regulatory mechanism of the specificity of reconsolidation is poorly understood. We designed a unique behavioral paradigm in which a distinct threat memory can be retrieved through the associated conditioned stimulus. In addition, we proposed a regulatory mechanism by which the activation of acid-sensing ion channels (ASICs), strengthens the distinct memory trace associated with the memory reconsolidation to determine its specificity. The activation of ASICs by carbon dioxide (CO2) inhalation when paired with memory retrieval, triggers the reactivation of the distinct memory trace, resulting in greater memory lability. ASICs potentiate the memory trace by altering the amygdala-dependent synaptic transmission and plasticity at selectively targeted synapses. Our results suggest that inhaling CO2 during the retrieval event increases the lability of a threat memory through a synapse-specific reconsolidation process.
Erin E. Koffman, Charles M. Kruse, Kritika Singh, Farzaneh Sadat Naghavi, Melissa A. Curtis, Jennifer Egbo, Mark Houdi, Boren Lin, Hui Lu, Jacek Debiec, Jianyang Du
BACKGROUND. Most subjects with prior COVID-19 disease manifest long–term, protective immune responses against re-infection. Accordingly, we tested the hypothesis that humoral immune and reactogenicity responses to a SARS-CoV-2 mRNA vaccine differ in subjects with and without prior COVID-19. METHODS. Health care workers (n=61) with (n=30) and without (n=31) prior COVID-19 disease received two, 30 µg doses of Pfizer BNT162b2 vaccine 3 weeks apart. Serum IgG antibody against the Spike receptor-binding domain (RBD); serum neutralizing activity; and vaccine reactogenicity were assessed longitudinally every 2 weeks for 56 days after the 1st injection. RESULTS. The COVID group manifested more rapid increases in Spike IgG antibody and serum neutralizing activity post 1st vaccine dose but showed little or no increase after the 2nd dose compared to the infection-naïve group. In fact, Spike IgG was maximum after the 1st dose in 36% of the COVID group versus 0% of the infection-naïve group. Peak IgG antibody was lower but appeared to fall more slowly in the COVID-19 versus the infection-naïve group. Finally, adverse systemic reactions e.g., fever, headache and malaise, were more frequent and lasted longer after both the 1st and 2nd injection in the COVID group than in the infection-naïve group. CONCLUSION. Subjects with prior COVID-19 demonstrate a robust, accelerated humoral immune response to the 1st dose but attenuated response to the 2nd dose of BNT162b2 vaccine compared to controls. The COVID-19 group also experiences greater reactogenicity. Humoral responses and reactogenicity to BNT162b2 differ qualitatively and quantitatively in subjects with prior COVID-19 compared to infection-naive subjects. FUNDING. This work was supported by Institutional Funds.
Steven G. Kelsen, Alan S. Braverman, Mark O. Aksoy, Jacob A. Hayman, Puja S. Patel, Charu Rajput, Huaqing Zhao, Susan G. Fisher, Michael R. Ruggieri Sr., Nina T. Gentile
Adiponectin receptor 1 (ADIPOR1) is a lipid and glucose metabolism regulator that possesses intrinsic ceramidase activity. Mutations of the ADIPOR1 gene have been associated with non-syndromic and syndromic retinitis pigmentosa. Here we show that the absence of AdipoR1 in mice leads to progressive photoreceptor degeneration, significant reduction of electroretinogram amplitudes, decreased retinoid content in the retina, and reduced cone opsin expression. Single-cell RNA-Seq results indicated that ADIPOR1 encodes the most abundantly expressed ceramidase in mice and one of the two most highly expressed ceramidases in the human retina, next to acid ceramidase ASAH1. We discovered an accumulation of ceramides in the AdipoR1-/- retina, likely due to insufficient ceramidase activity for healthy retina function, resulting in photoreceptor death. Combined treatment with desipramine and L-cycloserine (DC) lowered ceramide levels and exerted a protective effect on photoreceptors in AdipoR1-/- mice. Moreover, we observed improvement in cone-mediated retinal function in the DC-treated animals. Lastly, we found that prolonged DC-treatment corrected the electrical responses of the primary visual cortex to visual stimuli, approaching near-normal levels for some parameters. These results highlight the importance of ADIPOR1 ceramidase in the retina, and show that pharmacological inhibition of ceramide generation can provide a therapeutic strategy for ADIPOR1-related retinopathy.
Dominik Lewandowski, Andrzej T. Foik, Roman Smidak, Elliot H. Choi, Jianye Zhang, Thanh Hoang, Aleksander Tworak, Susie Suh, Henri Leinonen, Zhiqian Dong, Antonio F.M. Pinto, Emily Tom, Jennings C. Luu, Joan Y. Lee, Xiuli Ma, Erhard Bieberich, Seth Blackshaw, Alan Saghatelian, David C. Lyon, Dorota Skowronska-Krawczyk, Marcin Tabaka, Krzysztof Palczewski
Monocyte-derived macrophages are key players in tissue homeostasis and diseases regulated by a variety of signaling molecules. Recent literature has highlighted the ability for biogenic amines to regulate macrophage functions, but the mechanisms governing biogenic amine signaling in and around immune cells remains nebulous. In the central nervous system (CNS), biogenic amine transporters are regarded as the master regulators of neurotransmitter signaling. While we and others have shown that macrophages express these transporters, relatively little is known of their function in these cells. To address these knowledge gaps, we investigated the function of norepinephrine (NET) and dopamine (DAT) transporters on human monocyte-derived macrophages. We found that both NET and DAT are present and can uptake substrate from the extracellular space at baseline. Not only was DAT expressed in cultured monocyte-derived macrophages (MDMs), but it was also detected in a subset of intestinal macrophages in situ. Surprisingly, we discovered a NET-independent, DAT-mediated immuno-modulatory mechanism in response to lipopolysaccharide (LPS). LPS induced reverse transport of dopamine through DAT, engaging an autocrine/paracrine signaling loop that regulated the macrophage response. Removing this signaling loop enhanced the pro-inflammatory response to LPS. Collectively, our data introduce a potential role for DAT in the regulation of innate immunity.
Phillip M. Mackie, Adithya Gopinath, Dominic M. Montas, Alyssa Nielsen, Aidan Smith, Rachel A. Nolan, Kaitlyn Runner, Stephanie M. Matt, John McNamee, Joshua E. Riklan, Kengo Adachi, Andria Doty, Adolfo Ramirez-Zamora, Long Yan, Peter J. Gaskill, Wolfgang J. Streit, Michael S. Okun, Habibeh Khoshbouei
Sustained proliferative signaling and resisting cell death are hallmarks of cancer. Zinc finger protein 277 (ZNF277; murine Zfp277), a transcription factor regulating cellular senescence, is overexpressed in colon cancer but its actions in intestinal homeostasis and neoplasia are unclear. Using human and murine intestine, human colon cancer cells, and ApcMin/+ mice with dysregulated β-catenin signaling and exuberant intestinal neoplasia, we explored the actions of ZNF/Zfp277 and defined the underlying mechanisms. In normal human and murine intestine, ZNF/Zfp277 was expressed uniquely in early stem cell progenitors, undifferentiated transit-amplifying cells (TACs). Zfp277 was overexpressed in the ApcMin/+ mouse colon, implicating ZNF/Zfp277 as a transcriptional target of β-catenin signaling. We confirmed this by showing β-catenin knockdown reduced ZNF277 expression and, using chromatin immunoprecipitation, identified two β-catenin binding sites in the ZNF277 promoter. Zfp277 deficiency attenuated intestinal epithelial cell proliferation and tumor formation, and strikingly prolonged ApcMin/+ mouse survival. RNA-Seq and PCR analyses revealed Zfp277 modulates expression of genes in key cancer pathways including β-catenin signaling, the HOXD family that regulates development, and p21WAF1, a cell cycle inhibitor and tumor suppressor. In both human colon cancer cells and the murine colon, ZNF/Zfp277 deficiency induced p21WAF1 expression and promoted senescence. Our findings identify ZNF/Zfp277 as both a TAC marker and colon cancer oncogene that regulates cellular proliferation and senescence, in part by repressing p21WAF1 expression.
Guofeng Xie, Zhongsheng Peng, Jinqing Liang, Shannon M. Larabee, Cinthia B. Drachenberg, Harris Yfantis, Jean-Pierre Raufman
Myocardial infarction causes pathological changes in the autonomic nervous system, which exacerbate heart failure and predispose to fatal ventricular arrhythmias and sudden death. These changes are characterized by sympathetic activation and parasympathetic dysfunction (reduced vagal tone). Reasons for the central vagal withdrawal and, specifically, whether myocardial infarction causes changes in cardiac vagal afferent neurotransmission that then affect efferent tone, remain unknown. The objective of this study was to evaluate whether myocardial infarction causes changes in vagal neuronal afferent signaling. Using in-vivo neural recordings from the inferior vagal (nodose) ganglia and immunohistochemical analyses, structural and functional alterations in vagal sensory neurons were characterized in a chronic porcine infarct model and compared with normal animals. Myocardial infarction caused an increase in the number of nociceptive neurons, but a paradoxical decrease in functional nociceptive signaling. No changes in mechanosensitive neurons were observed. Notably, nociceptive neurons demonstrated an increase in GABAergic expression. Given that nociceptive signaling through the vagal ganglia increases efferent vagal tone, the results of this study suggest that a decrease in functional nociception, possibly due to an increase in expression of inhibitory neurotransmitters, may contribute to vagal withdrawal after myocardial infarction.
Siamak Salavatian, Jonathan D. Hoang, Naoko Yamaguchi, Zulfiqar A. Lokhandwala, Mohammed Amer Swid, J. Andrew Armour, Jeffrey L. Ardell, Marmar Vaseghi
Mitophagy and mitochondrial integrated stress response (ISR) are two primary protective mechanisms to maintain functional mitochondria. Whether these two processes are coordinately regulated remains unclear. Here we show that mitochondrial fission 1 protein (Fis1), which is required for completion of mitophagy, serves as a signaling hub linking mitophagy and ISR. In mouse hepatocytes, high fat diet (HFD) feeding induces unresolved oxidative stress, defective mitophagy and enhanced type I interferon (IFN-I) response implicated in promoting metabolic inflammation. Adenoviral-mediated acute hepatic Fis1 over-expression is sufficient to reduce oxidative damage and improve glucose homeostasis in HFD fed mice. RNA-seq analysis reveals that Fis1 triggers a retrograde mitochondria-to-nucleus communication upregulating ISR genes encoding anti-oxidant defense, redox homeostasis and proteostasis pathways. Fis1-mediated ISR also suppresses expression of IFN-I stimulated genes through Atf5, which inhibits the transactivation activity of Irf3 known to control IFN-I production. Metabolite analysis demonstrates that Fis1 activation leads to accumulation of fumarate, a TCA cycle intermediate capable of increasing Atf5 activity. Consequently, hepatic Atf5 over-expression or monomethyl fumarate (MMF) treatment improves glucose homeostasis in HFD fed mice. Collectively, these results support the potential use of small molecules targeting the Fis1-Atf5 axis, such as MMF, to treat metabolic diseases.
Yae-Huei Liou, Jean Personnaz, David Jacobi, Nelson H. Knudsen, Mayer M. Chalom, Kyle A. Starost, Israel C. Nnah, Chih-Hao Lee
Type 1 diabetes is an autoimmune disease characterized by insulin-producing beta-cell destruction. While islet transplantation restores euglycemia and improves patient outcomes, an ideal transplant site remains elusive. Brown adipose tissue (BAT) is a highly vascularized and anti-inflammatory microenvironment. As these tissue features can promote islet graft survival, we hypothesize that islets transplanted into BAT will maintain islet graft and BAT function, while delaying immune-mediated rejection. We performed syngeneic and allogeneic islet transplants into BAT or under the kidney capsule of streptozotocin (STZ)-induced diabetic NOD.Rag and NOD mice to investigate islet graft function, BAT function, metabolism, and immune-mediated rejection. Islet grafts within BAT restored euglycemia similarly to kidney capsule controls. Islets transplanted in BAT maintained expression of islet hormones, transcription factors, and were vascularized. Compared to kidney capsule and euglycemic mock surgery controls, no differences in glucose or insulin tolerance, thermogenic regulation, or energy expenditure were observed with islet grafts in BAT. Immune profiling of BAT revealed enriched anti-inflammatory macrophages and T cells. Compared to kidney capsule, islets transplanted in BAT demonstrated significant delays in autoimmune and allograft rejection, possibly due to increased anti-inflammatory immune populations. Our data support BAT as an alternative islet transplantation site that may improve graft survival.
Jessica D. Kepple, Jessie M. Barra, Martin E. Young, Chad S. Hunter, Hubert M. Tse
No posts were found with this tag.