McGonagle, D;Kearney, M;O'Regan, A;O'Donnell, J;Quartuccio, L;Watad, A;Bridgewood, C;
| DOI: 10.1016/S2665-9913(21)00322-2
In patients with moderate-to-severe COVID-19 pneumonia, an aberrant post-viral alveolitis with excessive inflammatory responses and immunothrombosis underpins use of immunomodulatory therapy (eg, corticosteroids and interleukin-6 receptor antagonism). By contrast, immunosuppression in individuals with mild COVID-19 who do not require oxygen therapy or in those with critical disease undergoing prolonged ventilation is of no proven benefit. Furthermore, a window of opportunity is thought to exist for timely immunosuppression in patients with moderate-to-severe COVID-19 pneumonia shortly after clinical presentation. In this Viewpoint, we explore the shortcomings of a universal immunosuppression approach in patients with moderate-to-severe COVID-19 due to disease heterogeneity related to ongoing SARS-CoV-2 replication, which can manifest as RNAaemia in some patients treated with immunotherapy. By contrast, immunomodulatory therapy has overall benefits in patients with rapid SARS-CoV-2 clearance, via blunting of multifaceted, excessive innate immune responses in the lungs, potentially uncontrolled T-cell responses, possible autoimmune responses, and immunothrombosis. We highlight this therapeutic dichotomy to better understand the immunopathology of moderate-to-severe COVID-19, particularly the role of RNAaemia, and to refine therapy choices.
Porniece Kumar, M;Cremer, AL;Klemm, P;Steuernagel, L;Sundaram, S;Jais, A;Hausen, AC;Tao, J;Secher, A;Pedersen, TÅ;Schwaninger, M;Wunderlich, FT;Lowell, BB;Backes, H;Brüning, JC;
PMID: 34931084 | DOI: 10.1038/s42255-021-00499-0
Insulin acts on neurons and glial cells to regulate systemic glucose metabolism and feeding. However, the mechanisms of insulin access in discrete brain regions are incompletely defined. Here we show that insulin receptors in tanycytes, but not in brain endothelial cells, are required to regulate insulin access to the hypothalamic arcuate nucleus. Mice lacking insulin receptors in tanycytes (IR∆Tan mice) exhibit systemic insulin resistance, while displaying normal food intake and energy expenditure. Tanycytic insulin receptors are also necessary for the orexigenic effects of ghrelin, but not for the anorexic effects of leptin. IR∆Tan mice exhibit increased agouti-related peptide (AgRP) neuronal activity, while displaying blunted AgRP neuronal adaptations to feeding-related stimuli. Lastly, a highly palatable food decreases tanycytic and arcuate nucleus insulin signalling to levels comparable to those seen in IR∆Tan mice. These changes are rooted in modifications of cellular stress responses and of mitochondrial protein quality control in tanycytes. Conclusively, we reveal a critical role of tanycyte insulin receptors in gating feeding-state-dependent regulation of AgRP neurons and systemic insulin sensitivity, and show that insulin resistance in tanycytes contributes to the pleiotropic manifestations of obesity-associated insulin resistance.
Chen X, Liu Z, Ma C, Ma L, Liu X.
PMID: - | DOI: 10.3389/fnbeh.2019.00110
Parvalbumin (PV) expressing GABAergic interneurons provide large source of GABA to spiny projection neurons (SPNs) in the striatum. However, the roles of PV+ interneurons in the regulation of SPNs in the ventral striatum and emotional states are largely unknown. Here, we investigated whether stimulation of ventral striatal (accumbal) PV+ interneurons would drive emotional valence in mice. We found that during conditioned place preference (CPP) training, activation of accumbal PV+ interneurons evoked place preference while suppressing them resulted in conditioned place aversion (CPA). Activation of PV+interneurons during place conditioning increased Fos expression in SPNs in the direct pathway (dSPNs) and impaired lithium chloride-induced CPA. Activation of dSPNs and SPNs in the indirect pathway (iSPNs) induced CPP and CPA, respectively; conversely, suppression of dSPNs or iSPNs induced CPA or CPP. In addition, activation or suppression of calretinin-expressing (CR) GABAergic interneurons did not induce place preference or aversion. These data suggest that PV+ interneurons can bidirectionally determine the emotional valence through their regulation of accumbal SPN activities and raise the possibility that manipulation of PV+ interneuron activity may have the potential to alter emotional valence and treat related mental disorders.
Neutrophil-epithelial interactions augment infectivity and pro-inflammatory responses to SARS-CoV-2 infection
bioRxiv : the preprint server for biology
Calvert, BA;Quiroz, EJ;Lorenzana, Z;Doan, N;Kim, S;Senger, CN;Wallace, WD;Salomon, MP;Henley, JE;Ryan, AL;
PMID: 34401877 | DOI: 10.1101/2021.08.09.455472
In response to viral infection, neutrophils release inflammatory mediators as part of the innate immune response, contributing to pathogen clearance through virus internalization and killing. Pre-existing co-morbidities, correlating to incidence of severe COVID-19, are associated with chronic airway neutrophilia and examination of COVID-19 lung tissue revealed a series of epithelial pathologies associated with infiltration and activation of neutrophils. To determine the impact of neutrophil-epithelial interactions on the infectivity and inflammatory response to SARS-CoV-2 infection, we developed a co-culture model of airway neutrophilia. We discovered that SARS-CoV-2 infection of the airway epithelium alone does not result in a notable release of pro-inflammatory cytokines, however in the presence of neutrophils, the inflammatory response is both polarized and significantly augmented, epithelial barrier integrity in impaired and viral load of the airway epithelium increased. This study reveals a key role for neutrophil-epithelial interactions in determining inflammation, infectivity, and outcomes in response to SARS-CoV-2 infection.We have developed a model to study neutrophil-epithelial interactions which better reflects the in vivo situation than monocultures Neutrophils significantly augment SARS-CoV-2 mediated, pro-inflammatory cytokine release from the epithelium indicating a key interactionSARS-CoV-2 infection leads to a polarized inflammatory response in differentiated airway epitheliumDisruption of the epithelial barrier via addition of neutrophils or cytokines leads to increased infectionStudy reveals a key role for neutrophil-epithelial interactions in determining outcome/infectivity.
The Journal of neuroscience : the official journal of the Society for Neuroscience
Feinberg, PA;Becker, SC;Chung, L;Ferrari, L;Stellwagen, D;Anaclet, C;Durán-Laforet, V;Faust, TE;Sumbria, RK;Schafer, DP;
PMID: 35790400 | DOI: 10.1523/JNEUROSCI.0601-22.2022
Interferon regulatory factor 8 (IRF8) is a transcription factor necessary for the maturation of microglia, as well as other peripheral immune cells. It also regulates the transition of microglia and other immune cells to a pro-inflammatory phenotype. Irf8 is also a known risk gene for multiple sclerosis and lupus and it has recently been shown to be downregulated in schizophrenia. While most studies have focused on IRF8-dependent regulation of immune cell function, little is known about how it impacts neural circuits. Here, we show by RNAseq from Irf8-/- male and female mouse brains that several genes involved in regulation of neural activity are dysregulated. We then show these molecular changes are reflected in heightened neural excitability and a profound increase in susceptibility to lethal seizures in male and female Irf8-/- mice. Finally, we identify that TNF-α is elevated specifically in microglia in the CNS and genetic or acute pharmacological blockade of TNF-α in the Irf8-/- central nervous system (CNS) rescued the seizure phenotype. These results provide important insights into the consequences of IRF8 signaling and TNF-α on neural circuits. Our data further suggest that neuronal function is impacted by loss of IRF8, a factor involved in neuropsychiatric and neurodegenerative diseases.SIGNIFICANCE STATEMENTHere, we identify a previously unknown and key role for Interferon regulator factor 8 (IRF8) in regulating neural excitability and seizures. We further determine these effects on neural circuits are through elevated TNF-α in the CNS. As IRF8 has most widely been studied in the context of regulating the development and inflammatory signaling in microglia and other immune cells, we have uncovered a novel function. Further, IRF8 is a risk gene for multiple sclerosis (MS) and lupus, IRF8 is dysregulated in schizophrenia, and elevated TNF-α has been identified in a multitude of neurological conditions. Thus, elucidating these IRF8 and TNF-α-dependent effects on brain circuit function have profound implications for understanding underlying, therapeutically-relevant mechanisms of disease.
J Neurosci. 2015 May 27;35(21):8232-44.
Li X, Rubio FJ, Zeric T, Bossert JM, Kambhampati S, Cates HM, Kennedy PJ, Liu QR, Cimbro R, Hope BT, Nestler EJ, Shaham Y.
PMID: 26016895 | DOI: 10.1038/jid.2015.200.
Cue-induced methamphetamine seeking progressively increases after withdrawal (incubation of methamphetamine craving), but the underlying mechanisms are largely unknown. We determined whether this incubation is associated with alterations in candidate genes in dorsal striatum (DS), a brain area implicated in cue- and context-induced drug relapse. We first measured mRNA expression of 24 candidate genes in whole DS extracts after short (2 d) or prolonged (1 month) withdrawal in rats following extended-access methamphetamine or saline (control condition) self-administration (9 h/d, 10 d). We found minimal changes. Next, using fluorescence-activated cell sorting, we compared gene expression in Fos-positive dorsal striatal neurons, which were activated during "incubated" cue-induced drug-seeking tests after prolonged withdrawal, with nonactivated Fos-negative neurons. We found significant increases in mRNA expression of immediate early genes (Arc, Egr1), Bdnf and its receptor (Trkb), glutamate receptor subunits (Gria1, Gria3, Grm1), and epigenetic enzymes (Hdac3, Hdac4, Hdac5, GLP, Dnmt3a, Kdm1a) in the Fos-positive neurons only. Using RNAscope to determine striatal subregion and cell-type specificity of the activated neurons, we measured colabeling of Fos with Drd1 and Drd2 in three DS subregions. Fos expression was neither subregion nor cell-type specific (52.5 and 39.2% of Fos expression colabeled with Drd1 and Drd2, respectively). Finally, we found that DS injections of SCH23390 (C17H18ClNO), a D1-family receptor antagonist known to block cue-induced Fos induction, decreased incubated cue-induced methamphetamine seeking after prolonged withdrawal. Results demonstrate a critical role of DS in incubation of methamphetamine craving and that this incubation is associated with selective gene-expression alterations in cue-activated D1- and D2-expressing DS neurons.
SARS-CoV-2 Infects Endothelial Cells In Vivo and In Vitro
Frontiers in cellular and infection microbiology
Liu, F;Han, K;Blair, R;Kenst, K;Qin, Z;Upcin, B;Wörsdörfer, P;Midkiff, CC;Mudd, J;Belyaeva, E;Milligan, NS;Rorison, TD;Wagner, N;Bodem, J;Dölken, L;Aktas, BH;Vander Heide, RS;Yin, XM;Kolls, JK;Roy, CJ;Rappaport, J;Ergün, S;Qin, X;
PMID: 34307198 | DOI: 10.3389/fcimb.2021.701278
SARS-CoV-2 infection can cause fatal inflammatory lung pathology, including thrombosis and increased pulmonary vascular permeability leading to edema and hemorrhage. In addition to the lung, cytokine storm-induced inflammatory cascade also affects other organs. SARS-CoV-2 infection-related vascular inflammation is characterized by endotheliopathy in the lung and other organs. Whether SARS-CoV-2 causes endotheliopathy by directly infecting endothelial cells is not known and is the focus of the present study. We observed 1) the co-localization of SARS-CoV-2 with the endothelial cell marker CD31 in the lungs of SARS-CoV-2-infected mice expressing hACE2 in the lung by intranasal delivery of adenovirus 5-hACE2 (Ad5-hACE2 mice) and non-human primates at both the protein and RNA levels, and 2) SARS-CoV-2 proteins in endothelial cells by immunogold labeling and electron microscopic analysis. We also detected the co-localization of SARS-CoV-2 with CD31 in autopsied lung tissue obtained from patients who died from severe COVID-19. Comparative analysis of RNA sequencing data of the lungs of infected Ad5-hACE2 and Ad5-empty (control) mice revealed upregulated KRAS signaling pathway, a well-known pathway for cellular activation and dysfunction. Further, we showed that SARS-CoV-2 directly infects mature mouse aortic endothelial cells (AoECs) that were activated by performing an aortic sprouting assay prior to exposure to SARS-CoV-2. This was demonstrated by co-localization of SARS-CoV-2 and CD34 by immunostaining and detection of viral particles in electron microscopic studies. Moreover, the activated AoECs became positive for ACE-2 but not quiescent AoECs. Together, our results indicate that in addition to pneumocytes, SARS-CoV-2 also directly infects mature vascular endothelial cells in vivo and ex vivo, which may contribute to cardiovascular complications in SARS-CoV-2 infection, including multipleorgan failure.
Laboratory investigation; a journal of technical methods and pathology
Granai, M;Warm, V;Vogelsberg, A;Milla, J;Greif, K;Vogel, U;Bakchoul, T;Rosenberger, P;Quintanilla-Martinez, L;Schürch, C;Klingel, K;Fend, F;Bösmüller, H;
PMID: 37224922 | DOI: 10.1016/j.labinv.2023.100179
In critically ill SARS-CoV-2 infected patients, early leukocyte recruitment to the respiratory system was found to be orchestrated by leukocyte trafficking molecules accompanied by massive secretion of pro-inflammatory cytokines and hypercoagulability. Our study aimed to explore the interplay between leukocyte activation and pulmonary endothelium in different disease stages of fatal COVID-19. Our study comprised 10 COVID-19 post-mortem lung specimens and 20 control lung samples (5 ARDS, 2 viral pneumonia, 3 bacterial pneumonia, and 10 normal) which were stained for antigens representing the different steps of leucocyte migration: E-selectin, P-selectin, PSGL-1, ICAM1, VCAM1, and CD11b. Image analysis software QuPath was used for quantification of positive leukocytes (PSGL-1 and CD11b) and endothelium (E-selectin, P-selectin, ICAM1, VCAM1). Expression of IL-6 and IL-1ß was quantified by qRT-PCR. Expression of P-selectin and PSGL-1 was strongly increased in the COVID-19 cohort compared to all control groups (ratio =17,23, p<0,0001; ratio=2,75, p<0,0001 respectively). Importantly, P-selectin was found in endothelial cells and associated with aggregates of activated platelets adherent to the endothelial surface in COVID-19 cases. In addition, PSGL-1 staining disclosed positive perivascular leucocyte cuffs, reflecting capillaritis. Moreover, CD11b showed a strongly increased positivity in COVID-19 compared to all controls (ratio=2,89; p=0,0002), indicating a proinflammatory immune microenvironment. Of note, CD11b exhibited distinct staining patterns at different stages of COVID-19 disease. Only in cases with very short disease course, high levels of IL-1ß and IL-6 mRNA were observed in lung tissue. The striking upregulation of PSGL-1 and P-selectin reflects the activation of this receptor-ligand pair in COVID-19, increasing the efficiency of initial leucocyte recruitment, thus promoting tissue damage and immunothrombosis. Our results show that endothelial activation and unbalanced leukocyte migration play a central role in COVID-19 involving the P-selectin-PSGL-1 axis.
Emerging microbes & infections
Li, C;Song, W;Chan, JF;Chen, Y;Liu, F;Ye, Z;Lam, AH;Cai, J;Lee, AC;Wong, BH;Chu, H;Lung, DC;Sridhar, S;Chen, H;Zhang, AJ;Yuen, KY;
PMID: 37122119 | DOI: 10.1080/22221751.2023.2207678
SummaryIntranasal infection of newly-weaned Syrian hamsters by SARS-CoV-2 Omicron variants can lead to brain inflammation and neuron degeneration with detectable low viral load and sparse expression of viral nucleoprotein.AbstractChildren infected by SARS-CoV-2 Omicron variant may develop neurological complications. To study the pathogenesis in the growing brain, we intranasally challenged newly-weaned or mature hamsters with SARS-CoV-2 Omicron BA.2, BA.5 or Delta variant. Omicron BA.2 and Delta infection produced a significantly lower viral load in the lung tissues of newly-weaned than mature hamsters despite comparable histopathological damages. Newly-weaned hamsters had higher brain viral load, significantly increased cerebrospinal fluid concentration of TNF-α and CXCL10 and inflammatory damages including mild meningitis and parenchymal vascular congestion, despite sparse expression of nucleocapsid antigen in brain cells. Furthermore, 63.6% (28/44) of all SARS-CoV-2 infected newly-weaned hamsters showed microgliosis in olfactory bulb, cerebral cortex and hippocampus. In infected mature hamsters, microgliosis were observed mainly in olfactory bulb and olfactory cortex of 35.3% (12/34) of their brains. Neuronal degeneration was found in 75% (33/44) of newly-weaned hamsters affecting multiple regions including olfactory bulb, olfactory cortex, midbrain cortex and hippocampus, while such changes were mainly observed in hippocampus of mature hamsters. Importantly, similar brain histopathology was observed in Omicron BA.5 infected newly-weaned hamsters. Our study suggested that SARS-CoV-2 may affect the brain at young age. This kind of brain involvement and histological changes are not virus variant or subvariant specific. Incidentally, moderate amount of eosinophilic infiltration was observed in the mucosa of nasal turbinate and trachea of newly-weaned hamsters infected by Omicron BA.2 and BA.5 but not Delta variant. This histological finding is consistent with the higher incidence of laryngotracheobronchitis in young children infected by the Omicron variant.
Kaewborisuth, C;Wanitchang, A;Koonpaew, S;Srisutthisamphan, K;Saenboonrueng, J;Im-Erbsin, R;Inthawong, M;Sunyakumthorn, P;Thaweerattanasinp, T;Tanwattana, N;Jantraphakorn, Y;Reed, MC;Lugo-Roman, LA;Hunsawong, T;Klungthong, C;Jones, AR;Fernandez, S;Teeravechyan, S;Lombardini, ED;Jongkaewwattana, A;
PMID: 35632541 | DOI: 10.3390/vaccines10050786
Virus-like particles (VLPs) are highly immunogenic and versatile subunit vaccines composed of multimeric viral proteins that mimic the whole virus but lack genetic material. Due to the lack of infectivity, VLPs are being developed as safe and effective vaccines against various infectious diseases. In this study, we generated a chimeric VLP-based COVID-19 vaccine stably produced by HEK293T cells. The chimeric VLPs contain the influenza virus A matrix (M1) proteins and the SARS-CoV-2 Wuhan strain spike (S) proteins with a deletion of the polybasic furin cleavage motif and a replacement of the transmembrane and cytoplasmic tail with that of the influenza virus hemagglutinin (HA). These resulting chimeric S-M1 VLPs, displaying S and M1, were observed to be enveloped particles that are heterogeneous in shape and size. The intramuscular vaccination of BALB/c mice in a prime-boost regimen elicited high titers of S-specific IgG and neutralizing antibodies. After immunization and a challenge with SARS-CoV-2 in K18-hACE2 mice, the S-M1 VLP vaccination resulted in a drastic reduction in viremia, as well as a decreased viral load in the lungs and improved survival rates compared to the control mice. Balanced Th1 and Th2 responses of activated S-specific T-cells were observed. Moderate degrees of inflammation and viral RNA in the lungs and brains were observed in the vaccinated group; however, brain lesion scores were less than in the PBS control. Overall, we demonstrate the immunogenicity of a chimeric VLP-based COVID-19 vaccine which confers strong protection against SARS-CoV-2 viremia in mice.
Annals of Diagnostic Pathology
Mezache, L;Nuovo, G;Suster, D;Tili, E;Awad, H;Radwański, P;Veeraraghavan, R;
| DOI: 10.1016/j.anndiagpath.2022.151983
Cardiac manifestations are common in severe COVID-19. This study compared the histologic, viral, and molecular findings in cardiac tissue in fatal COVID-19 (n = 11) and controls (n = 11). In situ hybridization (SARS-CoV2 RNA) and immunohistochemistry for viral proteins and the host response were quantified for the samples and compared with qRTPCR and Western blot data. Control hearts showed a high resident population of macrophages that had variable ACE2 expression. Cardiac ACE2 expression was 10× greater in the heart tissues of cases and controls with obesity or type II diabetes. Multifocal endothelial cell swelling and degeneration, perivascular edema plus microvascular thrombi were unique to the cases. SARS-CoV2 RNA and nucleocapsid protein were rarely detected in situ in any COVID-19 heart. However, in each case abundant SARS-CoV-2 spike protein was evident. Co-expression experiments showed that the spike protein localized mostly to the ACE2+ interstitial macrophages/pericytes that were activated as evidenced by increased IL6 and TNFα expression. Western blots confirmed the presence of the viral spike protein, but not the nucleocapsid protein, in the cardiac homogenates. The intercalated disc proteins connexin 43, the primary cardiac gap junction protein, and NaV1.5, the predominant cardiac sodium channel, each showed marked lateral migration in the myocytes in the cases, which would increase the risk of reentrant arrhythmias. It is concluded that the viral spike protein, endocytosed by macrophages/pericytes, can induce a myocarditis with the possibility of conduction dysfunction due to abnormal localization of key intercalated disc proteins.
Chiba, S;Kiso, M;Nakajima, N;Iida, S;Maemura, T;Kuroda, M;Sato, Y;Ito, M;Okuda, M;Yamada, S;Iwatsuki-Horimoto, K;Watanabe, T;Imai, M;Armbrust, T;Baric, RS;Halfmann, PJ;Suzuki, T;Kawaoka, Y;
PMID: 35100870 | DOI: 10.1128/mbio.03044-21
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide since December 2019, causing coronavirus disease 2019 (COVID-19). Although vaccines for this virus have been developed rapidly, repurposing drugs approved to treat other diseases remains an invaluable treatment strategy. Here, we evaluated the inhibitory effects of drugs on SARS-CoV-2 replication in a hamster infection model and in in vitro assays. Favipiravir significantly suppressed virus replication in hamster lungs. Remdesivir inhibited virus replication in vitro, but was not effective in the hamster model. However, GS-441524, a metabolite of remdesivir, effectively suppressed virus replication in hamsters. Co-administration of favipiravir and GS-441524 more efficiently reduced virus load in hamster lungs than did single administration of either drug for both the prophylactic and therapeutic regimens; prophylactic co-administration also efficiently inhibited lung inflammation in the infected animals. Furthermore, pretreatment of hamsters with favipiravir and GS-441524 effectively protected them from virus transmission via respiratory droplets upon exposure to infected hamsters. Repurposing and co-administration of antiviral drugs may help combat COVID-19. IMPORTANCE During a pandemic, repurposing drugs that are approved for other diseases is a quick and realistic treatment option. In this study, we found that co-administration of favipiravir and the remdesivir metabolite GS-441524 more effectively blocked SARS-CoV-2 replication in the lungs of Syrian hamsters than either favipiravir or GS-441524 alone as part of a prophylactic or therapeutic regimen. Prophylactic co-administration also reduced the severity of lung inflammation. Moreover, co-administration of these drugs to naive hamsters efficiently protected them from airborne transmission of the virus from infected animals. Since both drugs are nucleotide analogs that interfere with the RNA-dependent RNA polymerases of many RNA viruses, these findings may also help encourage co-administration of antivirals to combat future pandemics.