Delayed severe cytokine storm and immune cell infiltration in SARS-CoV-2-infected aged Chinese rhesus macaques

As of June 2020, Coronavirus Disease 2019(COVID-19) has killed an estimated 440 000 people worldwide, 74% of whom were aged ≥65 years,making age the most significant risk factor for death caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) infection. To examine the effect of age on death, we established a SARSCoV-2 infection model in Chinese rhesus macaques(Macaca mulatta) of varied ages. Results indicated that infected young macaques manifested impaired respiratory function, active viral replication, severe lung damage, and infiltration of CD11b^+ and CD8^+ cells in lungs at one-week post infection(wpi), but also recovered rapidly at 2 wpi. In contrast, aged macaques demonstrated delayed immune responses with a more severe cytokine storm, increased infiltration of CD11b^+ cells, and persistent infiltration of CD8^+ cells in the lungs at 2 wpi. In addition,peripheral blood T cells from aged macaques showed greater inflammation and chemotaxis, but weaker antiviral functions than that in cells from young macaques. Thus, the delayed but more severe cytokine storm and higher immune cell infiltration may explain the poorer prognosis of older aged patients suffering SARS-CoV-2 infection.

Northern pig-tailed macaques(Macaca leonina)infected with SARS-CoV-2 show rapid viral clearance and persistent immune response

Coronavirus disease 2019(COVID-19),which is caused by severe acute respiratory syndrome coronavirus(SARS-CoV-2),has become an unprecedented global health emergency.At present,SARS-CoV-2-infected nonhuman primates are considered the gold standard animal model for COVID-19 research.Here,we showed that northern pig-tailed macaques(Macaca leonina,NPMs)supported SARS-CoV-2 replication.Furthermore,compared with rhesus macaques,NPMs showed rapid viral clearance in lung tissues,nose swabs,throat swabs,and rectal swabs,which may be due to higher expression of interferon(IFN)-αin lung tissue.However,the rapid viral clearance was not associated with good outcome.In the second week post infection,NPMs developed persistent or even more severe inflammation and body injury compared with rhesus macaques.These results suggest that viral clearance may have no relationship with COVID-19 progression and SARS-CoV-2-infected NPMs could be considered as a critically ill animal model in COVID-19 research.

Combinational benefit of antihistamines and remdesivir for reducing SARS-CoV-2 replication and alleviating inflammation-induced lung injury in mice

COVID-19 is an immune-mediated inflammatory disease caused by SARS-CoV-2 infection,the combination of anti-inflammatory and antiviral therapy is predicted to provide clinical benefits.We recently demonstrated that mast cells(MCs)are an essential mediator of SARS-CoV-2-initiated hyperinflammation.We also showed that spike protein-induced MC degranulation initiates alveolar epithelial inflammation for barrier disruption and suggested an off-label use of antihistamines as MC stabilizers to block degranulation and consequently suppress inflammation and prevent lung injury.In this study,we emphasized the essential role of MCs in SARS-CoV-2-induced lung lesions in vivo,and demonstrated the benefits of co-administration of antihistamines and antiviral drug remdesivir in SARS-CoV-2-infected mice.Specifically,SARSCoV-2 spike protein-induced MC degranulation resulted in alveolar-capillary injury,while pretreatment of pulmonary microvascular endothelial cells with antihistamines prevented adhesion junction disruption;predictably,the combination of antiviral drug remdesivir with the antihistamine loratadine,a histamine receptor 1(HR1)antagonist,dampened viral replication and inflammation,thereby greatly reducing lung injury.Our findings emphasize the crucial role of MCs in SARS-CoV-2-induced inflammation and lung injury and provide a feasible combination antiviral and anti-inflammatory therapy for COVID-19 treatment.

Captopril alleviates lung inflammation in SARS-CoV-2-infected hypertensive mice

Severe acute respiratory syndrome coronavirus 2(SARS-Co V-2)is the etiologic agent responsible for the global coronavirus disease 2019(COVID-19)pandemic.Numerous studies have demonstrated that cardiovascular disease may affect COVID-19 progression.In the present study,we investigated the effect of hypertension on viral replication and COVID-19 progression using a hypertensive mouse model infected with SARS-Co V-2.Results revealed that SARS-Co V-2 replication was delayed in hypertensive mouse lungs.In contrast,SARS-Co V-2 replication in hypertensive mice treated with the antihypertensive drug captopril demonstrated similar virus replication as SARS-Co V-2-infected normotensive mice.

Particulate matter exposure exacerbates susceptibility to SARS-CoV-2 infection in humanized ACE2 mice

The global outbreak of coronavirus disease 2019(COVID-19),which is caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),as of 8 May 2021,has surpassed 150700000 infections and 3279000 deaths worldwide.Evidence indicates that SARS-CoV-2 RNA can be detected on particulate matter(PM),and COVID-19 cases are correlated with levels of air pollutants.However,the mechanisms of PM involvement in the spread of SARS-CoV-2 remain poorly understood.Here,we found that PM exposure increased the expression level of angiotensin-converting enzyme 2(ACE2)and transmembrane serine protease 2(TMPRSS2)in several epithelial cells and increased the adsorption of the SARS-CoV-2 spike protein.Instillation of PM in a hACE2 mouse model significantly increased the expression of ACE2 and Tmprss2 and viral replication in the lungs.Furthermore,PM exacerbated the pulmonary lesions caused by SARS-CoV-2 infection in the hACE2 mice.In conclusion,our study demonstrated that PM is an epidemiological factor of COVID-19,emphasizing the necessity of wearing anti-PM masks to cope with this global pandemic.

Mast cell degranulation-triggered by SARS-CoV-2 induces tracheal-bronchial epithelial inflammation and injury

SARS-CoV-2 infection-induced hyper-inflammation is a key pathogenic factor of COVID-19.Our research,along with others',has demonstrated that mast cells(MCs)play a vital role in the initiation of hyper-inflammation caused by SARS-CoV-2.In previous study,we observed that SARS-CoV-2 infection induced the accumulation of MCs in the peri-bronchus and bronchioalveolar-duct junction in humanized mice.Additionally,we found that MC degranulation triggered by the spike protein resulted in inflammation in alveolar epithelial cells and capillary endothelial cells,leading to subsequent lung injury.The trachea and bronchus are the routes for SARS-CoV-2 transmission after virus inhalation,and inflammation in these regions could promote viral spread.MCs are widely distributed throughout the respiratory tract.Thus,in this study,we investigated the role of MCs and their degranulation in the development of inflammation in tracheal-bronchial epithelium.Histological analyses showed the accumulation and degranulation of MCs in the peri-trachea of humanized mice infected with SARS-CoV-2.MC degranulation caused lesions in trachea,and the formation of papillary hyperplasia was observed.Through transcriptome analysis in bronchial epithelial cells,we found that MC degranulation significantly altered multiple cellular signaling,particularly,leading to upregulated immune responses and inflammation.The administration of ebastine or loratadine effectively suppressed the induction of inflammatory factors in bronchial epithelial cells and alleviated tracheal injury in mice.Taken together,our findings confirm the essential role of MC degranulation in SARS-CoV-2-induced hyper-inflammation and the subsequent tissue lesions.Furthermore,our results support the use of ebastine or loratadine to inhibit SARS-CoV-2-triggered degranulation,thereby preventing tissue damage caused by hyper-inflammation.

Factors associated with needle sharing among people who inject drugs in Yunnan, China: a combined network and regression analysis

Background:Network analyses have been widely utilized to evaluate large datasets,but have not yet been used to explore factors associated with risk behaviours.In combination with traditional regression analysis,network analyses may provide useful information and highlight key factors for reducing needle sharing behaviours among people who inject drugs(PWID).Methods:Sociodemographic data,and information on injection behaviour and sexual practices were collected from a cross-sectional survey that was conducted with PWID in five prefectures of Yunnan province,China.A combination of logistic regression and correlation network analyses were used to explore key factors for reducing needle-sharing behaviours among PWID.Results:In a total of 1049 PWID,37.5%had a history of needle or syringe sharing.The logistic analysis showed that Zhaotong,Qujing,Dehong,or Lincang residents,diazepam use,longer injection duration,needle reuse,and infection with HIV,viral hepatitis,tuberculosis and/or malaria were independently associated with needle sharing.The correlation network analyses showed that,compared to PWID who had never shared needles,PWID who did share needles would achieve harm reduction goals faster and more permanently.HIV serostatus and marital status were found to be closely associated with other risk factors.By combining regression analyses with network analyses,it was shown that PWID who are HIV seropositive will be an ideal target group for harm reduction programs.Conclusion:Needle-sharing behaviours are common among PWID in Yunnan,and harm reduction programs may help PWID who are HIV seropositive reduce risk behaviours and prevent blood borne diseases.

High seroprevalence of toxoplasma gondii and HIV-1 co-infection among drug users in Yunnan province, southwest China

Dear Editor, Toxoplasma gondii was discovered more than 100 years ago and has a broad-spectrum of intermediate hosts in addi- tion to its definitive host, felids. Although it does not cause symptomatic illness in most adults, it can lead to mental retardation in congenitally infected children and serious diseases in immunocompromised patients （Hill et al., 2005）. The first report of T. gondii infection in China was pub- lished in Chinese in 1964; subsequently, many other cases have been carried out. Currently, most publications about the seroprevalence of T. gondii infection in Yunnan have examined infections in pets, domestic animals, and wild animals; however, few previously published studies have assessed human T. gondii infection in Yunnan province.

SARS-CoV-2-triggered mast cell rapid degranulation induces alveolar epithelial inflammation and lung injury

SARS-CoV-2 infection-induced hyper-inflammation links to the acute lung injury and COVID-19 severity.Identifying the primary mediators that initiate the uncontrolled hypercytokinemia is essential for treatments.Mast cells(MCs)are strategically located at the mucosa and beneficially or detrimentally regulate immune inflammations.In this study,we showed that SARS-CoV-2-triggered MC degranulation initiated alveolar epithelial inflammation and lung injury.SARS-CoV-2 challenge induced MC degranulation in ACE-2 humanized mice and rhesus macaques,and a rapid MC degranulation could be recapitulated with Spike-RBD binding to ACE2 in cells;MC degranulation altered various signaling pathways in alveolar epithelial cells,particularly,the induction of pro-inflammatory factors and consequential disruption of tight junctions.Importantly,the administration of clinical MC stabilizers for blocking degranulation dampened SARS-CoV-2-induced production of pro-inflammatory factors and prevented lung injury.These findings uncover a novel mechanism for SARS-CoV-2 initiating lung inflammation,and suggest an off-label use of MC stabilizer as immunomodulators for COVID-19 treatments.

Pro-inflammatory microenvironment and systemic accumulation of CXCR3+cell exacerbate lung pathology of old rhesus macaques infected with SARS-CoV-2

Understanding the pathological features of severe acute respiratory syn drome coronavirus 2(SARS-CoV-2)infect io n in an animal model is crucial for the treatment of coronavirus disease 2019(COVID-19).Here,we compared imnnunopathological changes in young and old rhesus macaques(RMs)before and after SARS-CoV-2 infection at the tissue level.Quantitative analysis of multiplex immunofluoresce nee staining images of formali n-fixed paraffi n-embedded(FFPE)sections showed that SARS-CoV-2 infectio n specifically induced elevated levels of apoptosis,autophagy,and nuclear factor kappa-B(NF-kB)activation of angiotensirv convert!ng enzyme 2(ACE2)+cells,and increased interferon a(IFN-a)-and interleukin 6(IL-6)-secreting cells and C-X-C motif chemokine receptor 3(CXCR3)+cells in lung tissue of old RMs.This pathological pattern,which may be related to the age-related pro-inflammatory microenvironment in both lungs and spleens,was significantly correlated with the systemic accumulation of CXCR3+cells in lungs,spleens,and peripheral blood.Furthermore,the ratio of CXCR3+to T-box protein expression in T cell(T-bet)+(CXCR3+/T-bet+ratio)in CD8+cells may be used as a predictor of severe COVID-19.These findings uncovered the impact of aging on the immunopathology of early SARS-CoV-2 infection and demonstrated the potential application of CXCR3+cells in predicting severe COVID-19.

Association of TRIMCyp and TRIM5α from assam macaques leads to a functional trade-off between HIV-1 and N-MLV inhibition

TRIM5α restricts retroviruses in a species-specific manner. Cyclophilin A was independently retrotransposed into the TRIM5 loci in different species, leading to the generation of antiviral TR1M5-cyclophilin A （TRIMCyp） proteins. Previously, we found that assam macaques express a TRIMCyp chimera （amTRIMCyp）, along with a TRIM5α allelic protein （amTRIM5α）. Herein, we investigated the antiviral activity of amTRIMCyp and amTRIM5α individually, as well as their interaction and joint effects. amTRIMCyp showed a divergent restriction pattern from amTRIM5αc Although both proteins potently restricted the replication of HIV-1, only amTRIM5αt inhibited N-MLV. Remarkably, cellular anti-HIV-1 activity increased when amTRIMCyp and amTRIM5αt were coexpressed, indicating a synergistic block of HIV-1 replication. Consistently, PMBCs from heterozygous amTRIM50t/TRIMCyp showed stronger resistance to HIV-1 infection than those from amTRIM5a/TRIM5α homozygotes. The anti-HIV-1 synergistic effect was dependent on the amTRIMCyp-amTRIM5α interaction. In contrast, amTRIMCyp completely abrogated the anti-N-MLV activity mediated by amTRIM5α, showing a dominant-negative effect, indicating that the generation of amTRIMCyp was involved in the trade-off between divergent restriction activities. Our results provide a new paradigm to study functional trade-offs mediated by allelic proteins, a theoretical basis for utilizing animal models with various TRIM5 alleles, as well as novel HIV-1 gene therapy strategies.