Streptococcuspyogenes infects human endometrium by limiting the innate immune response

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Abstract

Group A Streptococcus (GAS), a Gram-positive human-specific pathogen yields 517,000 deaths annually worldwide, including 163,000 due to invasive infections and among them puerperal fever. Before efficient prophylactic measures were introduced, the mortality rate for mothers during childbirth was about 10%; puerperal fever still accounts for over 75,000 maternal deaths annually. Yet little is known regarding the factors and mechanisms of GAS invasion and establishment in postpartum infection. We characterized the early steps of infection in an ex vivo infection model of the human decidua, the puerperal fever portal of entry. Coordinate analysis of GAS behavior and the immune response led us to demonstrate that (i) GAS growth was stimulated by tissue products; (ii) GAS invaded tissue and killed ~50% of host cells within two hours; these processes required SpeB protease and Streptolysin O activities, respectively; (iii) GAS impaired the tissue immune response. Immune impairment occurred both at the RNA level, with only partial induction of the innate immune response, and protein level, in an SLO- and SpeB-dependent manner. Our study indicates that efficient GAS invasion of decidua and the restricted host immune response favored its propensity to develop rapid invasive infections in a gynecological-obstetrical context.

Authors

Antonin Weckel, Thomas Guilbert, Clara Lambert, Céline Plainvert, Francois Goffinet, Claire Poyart, Céline Méhats, Agnès Fouet

PD-1 blockade improves Kupffer cell bacterial clearance in acute liver injury

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Abstract

Acute liver failure (ALF) patients display systemic innate immune suppression and increased susceptibility to infections. PD-1 expression by macrophages has been associated with immune suppression during sepsis and cancer. We therefore examined the role of PD-1/PD-L1 pathway in regulating Kupffer cell inflammatory and antimicrobial responses in acetaminophen (APAP) induced acute liver injury. Using intravital imaging and flow cytometry we found impaired Kupffer cell bacterial clearance and systemic bacterial dissemination in mice with liver injury. Increased PD-1 and PD-L1 expression was detected in Kupffer cells and lymphocyte subsets, respectively, during resolution of injury. Gene expression profiling of PD-1+ Kupffer cells revealed an immune-suppressive profile and reduced pathogen responses. Compared to wild-type, PD-1 deficient or anti-PD-1 treated mice with liver injury showed improved Kupffer cell bacterial clearance, reduced tissue bacterial load and protection from sepsis. Blood sample analyses of ALF patients revealed enhanced PD-1 and PD-L1 expression of monocytes and lymphocytes, respectively, and that plasma soluble PD-L1 levels predict patient outcome and sepsis. PD-1 in vitro blockade restored monocyte functionality. Our study describes a role for PD-1/PD-L1 axis in suppressing Kupffer cell and monocyte antimicrobial responses after liver injury and suggests anti-PD-1 immunotherapy as a strategy to reduce infection susceptibility in ALF.

Authors

Evangelos Triantafyllou, Cathrin L. C. Gudd, Marie-Anne Mawhin, Hannah C. Husbyn, Francesca M. Trovato, Matthew K. Siggins, Thomas O'Connor, Hiromi Kudo, Sujit K. Mukherjee, Julia A. Wendon, Christine Bernsmeier, Robert D. Goldin, Marina Botto, Wafa Khamri, Mark J.W. McPhail, Lucia A. Possamai, Kevin J. Woollard, Charalambos G. Antoniades, Mark R. Thursz

Clinical, laboratory, and temporal predictors of neutralizing antibodies to SARS-CoV-2 among COVID-19 convalescent plasma donor candidates

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Abstract

Background: SARS-CoV-2-specific antibodies may protect from reinfection and disease, providing rationale for administration of plasma containing SARS-CoV-2 neutralizing antibodies (nAb) as a treatment for COVID-19. Clinical factors and laboratory assays to streamline plasma donor selection, and the durability of nAb responses, are incompletely understood. Methods: Potential convalescent plasma donors with virologically-documented SARS-CoV-2 infection were tested for serum IgG to SARS-CoV-2 spike protein S1 domain, nucleoprotein (NP), and for nAb. Results: Amongst 250 consecutive persons, including 27 (11%) requiring hospitalization, studied a median of 67 days since symptom onset, 97% were seropositive on one or more assays. Sixty percent of donors had nAb titers ≥1:80. Correlates of higher nAb titer included older age (adjusted odds ratio [AOR] 1.03/year of age, 95% CI 1.00-1.06), male sex (AOR 2.08, 95% CI 1.13-3.82), fever during acute illness (AOR 2.73, 95% CI 1.25-5.97), and disease severity represented by hospitalization (AOR 6.59, 95% CI 1.32-32.96). Receiver operating characteristic (ROC) analyses of anti-S1 and anti-NP antibody results yielded cutoffs that corresponded well with nAb titers, with the anti-S1 assay being slightly more predictive. NAb titers declined in 37 of 41 paired specimens collected a median of 98 days (range, 77-120) apart (P<0.001). Seven individuals (2.8%) were persistently seronegative and lacked T cell responses. Conclusions: Nab titers correlated with COVID-19 severity, age, and sex. Standard commercially available SARS-CoV-2 IgG results can serve as useful surrogates for nAb testing. Functional nAb levels were found to decline and a small proportion of persons recovered from COVID-19 lack adaptive immune responses.

Authors

Jim Boonyaratanakornkit, Chihiro Morishima, Stacy Selke, Danniel Zamora, Sarah A. McGuffin, Adrienne E. Shapiro, Victoria L. Campbell, Christopher L. McClurkan, Lichen Jing, Robin Gross, Janie Liang, Elena Postnikova, Steven Mazur, Vladimir V. Lukin, Anu Chaudhary, Marie K. Das, Susan L. Fink, Andrew Bryan, Alexander L. Greninger, Keith R. Jerome, Michael R. Holbrook, Terry B. Gernsheimer, Mark H. Wener, Anna Wald, David M. Koelle

BCG vaccination in healthcare providers and the protection against COVID-19

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Abstract

A number of COVID-19 vaccine candidates have shown promising results, but substantial uncertainty remains regarding their effectiveness and global roll-out. Boosting innate immunity with Bacillus Calmette Guerin (BCG) or other live attenuated vaccines may also play a role in the fight against the COVID-19 pandemic. BCG has long been known for its non-specific beneficial effects, most likely explained by epigenetic and metabolic reprogramming of innate immune cells, termed trained immunity. In this issue of the JCI, Rivas et al. add to these arguments by showing that BCG-vaccinated healthcare providers from a Los Angeles healthcare organization had less COVID-19 diagnosis and serology, compared to unvaccinated individuals. Prospective clinical trials are thus warranted to explore BCG effects in COVID-19. We posit that beyond COVID-19, vaccines that elicit trained immunity, such as the BCG, may mitigate the impact of emerging pathogens in future pandemics.

Authors

Mihai G. Netea, Jos W.M. van der Meer, Reinout van Crevel

Neutrophil-to-hepatocyte communication via LDLR-dependent miR-223-enriched extracellular vesicle transfer ameliorates nonalcoholic steatohepatitis

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Abstract

Neutrophil infiltration around lipotoxic hepatocytes is a hallmark of nonalcoholic steatohepatitis (NASH); however, how these two types of cells communicate remain obscure. We have previously demonstrated that neutrophil-specific microRNA-223 (miR-223) is elevated in hepatocytes to limit NASH progression in obese mice. Here we demonstrated that this elevation of miR-223 in hepatocytes was due to preferential uptake of miR-223-enriched extracellular vesicles (EVs) derived from neutrophils as well other types of cells albeit to a lesser extent. This selective uptake was dependent on the expression of low-density lipoprotein receptor (LDLR) on hepatocytes and apolipoprotein E (APOE) on neutrophil-derived EVs, which was enhanced by free fatty acids. Once internalized by hepatocytes, the EV-derived miR-223 acted to inhibit hepatic inflammatory and fibrogenic gene expression. In the absence of this LDLR-APOE dependent uptake of miR-223-enriched EVs, the progression of steatosis to NASH was accelerated. In contrast, augmentation of this transfer by treatment with an inhibitor of proprotein convertase subtilisin/kexin type 9, a drug used to lower blood cholesterol by upregulating LDLR, ameliorated NASH in mice. This specific role of LDLR and APOE in the selective control of miR-223-enriched EV transfer from neutrophils to hepatocytes may serve as a potential therapeutic target for NASH.

Authors

Yong He, Robim M. Rodrigues, Xiaolin Wang, Wonhyo Seo, Jing Ma, Seonghwan Hwang, Yaojie Fu, Eszter Trojnar, Csaba Matyas, Suxian Zhao, Ruixue Ren, Dechun Feng, Pal Pacher, George Kunos, Bin Gao

Propranolol inhibits cavernous vascular malformations by β1 adrenergic receptor antagonism in animal models

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Abstract

Propranolol, a pleiotropic β-adrenergic blocker, was anecdotally reported to reduce cerebral cavernous malformations (CCM) in humans. However, propranolol has neither been rigorously evaluated in animal models nor was its mechanism of action in CCM defined. We report that propranolol or its S(-) enantiomer dramatically reduced embryonic venous cavernomas in ccm2 mosaic zebrafish, whereas R-(+)-propranolol, lacking β-antagonism, had no effect. Silencing of β1, but not β2, adrenergic receptor mimicked the beneficial effects of propranolol in a zebrafish CCM model as did a β1-selective antagonist, metoprolol. Thus, propranolol ameliorates cavernous malformations by β1 adrenergic antagonism in zebrafish. Oral propranolol significantly reduced lesion burden in two chronic murine models of the exceptionally aggressive Pdcd10/Ccm3 form of CCM. Propranolol or other β1-selective antagonists may be beneficial in CCM disease.

Authors

Wenqing Li, Robert Shenkar, Matthew R. Detter, Thomas Moore, Christian R. Benavides, Rhonda Lightle, Romuald Girard, Nicholas Hobson, Ying Cao, Yan Li, Erin Griffin, Carol Gallione, Joseph M. Zabramski, Mark H. Ginsberg, Douglas A. Marchuk, Issam A. Awad

Antigen-driven clonal selection shapes the persistence of HIV-1 infected CD4⁺ T cells in vivo

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Abstract

Clonal expansion of infected CD4+ T cells is a major mechanism of HIV-1 persistence and a barrier to cure. Potential causes are homeostatic proliferation, effects of HIV-1 integration, and interaction with antigens. Here we show that it is possible to link antigen responsiveness, full proviral sequence, integration site, and T cell receptor β-chain (TCRβ) sequence to examine the role of recurrent antigenic exposure in maintaining the HIV-1 reservoir. We isolated Cytomegalovirus (CMV)- and Gag-responding CD4+ T cells from 10 treated individuals. Proviral populations in CMV-responding cells were dominated by large clones, including clones harboring replication-competent proviruses. TCRβ repertoires showed high clonality driven by converging adaptive responses. Although some proviruses were in genes linked to HIV-1 persistence (BACH2, STAT5B, MKL1), proliferation of infected cells under antigenic stimulation occurred regardless of the site of integration. Paired TCRβ-integration site analysis showed that infection could occur early or late in the course of a clone’s response to antigen and could generate infected cell populations too large to be explained solely by homeostatic proliferation. Together these findings implicate antigen-driven clonal selection as a major factor in HIV-1 persistence, a finding that will be a difficult challenge to eradication efforts.

Authors

Francesco R. Simonetti, Hao Zhang, Garshasb P. Soroosh, Jiayi Duan, Kyle Rhodehouse, Alison L. Hill, Subul A. Beg, Kevin McCormick, Hayley E. Raymond, Christopher L. Nobles, John K. Everett, Kyungyoon J. Kwon, Jennifer A. White, Jun Lai, Joseph B. Margolick, Rebecca Hoh, Steven G. Deeks, Frederic D. Bushman, Janet D. Siliciano, Robert F. Siliciano

The integrated stress response mediates necrosis in murine Mycobacterium tuberculosis granulomas

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Abstract

The mechanism by which only some individuals infected with M. tuberculosis (Mtb) develop necrotic granulomas with progressive disease while others form controlled granulomas that contain the infection remains poorly defined. Mice carrying the sst1-suscepible (sst1S) genotype develop necrotic inflammatory lung lesions, similar to human TB granulomas, which are linked to macrophage dysfunction while their congenic counterparts (B6) mice do not. In this study we report that (i) sst1S macrophages developed aberrant, biphasic responses to TNF characterized by super-induction of stress and type I interferon pathways after prolonged TNF stimulation; (ii) the late-stage TNF response was driven via a JNK - IFNβ - PKR circuit; and (iii) induced the integrated stress response (ISR) via PKR-mediated eIF2α phosphorylation and the subsequent hyper-induction of ATF3 and ISR-target genes Chac1, Trib3, Ddit4. The administration of ISRIB, a small molecule inhibitor of the ISR, blocked the development of necrosis in lung granulomas of Mtb-infected sst1S mice and concomitantly reduced the bacterial burden. Hence induction of the ISR and the locked-in state of escalating stress driven by type I IFN pathway in sst1S macrophages plays a causal role in the development of necrosis in TB granulomas. Interruption of the aberrant stress response with inhibitors such as ISRIB may offer novel host-directed therapy strategies.

Authors

Bidisha Bhattacharya, Shiqi Xiao, Sujoy Chatterjee, Michael E. Urbanowski, Alvaro A. Ordonez, Elizabeth A. Ihms, Garima Agrahari, Shichun Lun, Robert Berland, Alexander Pichugin, Yuanwei Gao, John H. Connor, Alexander R. Ivanov, Bo-Shiun Yan, Lester Kobzik, Bang-Bon Koo, Sanjay K. Jain, William R. Bishai, Igor Kramnik

Bone marrow niche ATP levels determine leukemia-initiating cell activity via P2X7 in leukemic models

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Abstract

How particular bone marrow niche factors contribute to the leukemogenic activities of leukemia-initiating cells (LICs) remain largely unknown. Here, we showed that ATP levels were markedly increased in the bone marrow niches of mice with acute myeloid leukemia (AML), and LICs preferred to localizing to the endosteal niche with relatively high ATP levels, as indicated by a sensitive ATP indicator. ATP could efficiently induce the influx of ions into LICs in an MLL-AF9-induced murine AML model via the ligand-gated ion channel P2X7. P2x7 deletion led to notably impaired homing and self-renewal capacities of LICs and contributed to an ~5-fold decrease in the number of functional LICs but had no effect on normal hematopoiesis. ATP-P2X7 signaling enhanced the calcium flux-mediated phosphorylation of CREB, which further transactivated the Phgdh expression to maintain serine metabolism and LIC fates. P2X7-knockdown resulted in a markedly extended survival of recipients transplanted with either human AML cell lines or primary leukemia cells. Blockade of ATP-P2X7 signaling could efficiently inhibit leukemogenesis. Here, we provide a unique perspective for understanding how ATP-P2X7 signaling sustains the LIC activities, which may benefit the development of specific strategies for targeting LICs or other types of cancer stem cells

Authors

Xiaoxiao He, Jiangbo Wang, Xiaona Yang, Xiuze Zhang, Dan Huang, Xie Li, Yejun Zou, Chiqi Chen, Zhuo Yu, Li Xie, Yaping Zhang, Ligen Liu, Shangang Li, Yuzheng Zhao, Hongfang Shao, Ye Yu, Junke Zheng

Macrophage-mediated vascular permeability via VLA4/VCAM1 pathway dictates ascites development in ovarian cancer

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Abstract

The development of ascites correlates with advanced-stage disease and poor prognosis in ovarian cancer. Vascular permeability is the key pathophysiological change involved in ascites development. Previously, we provided the first evidence that perivascular M2-like macrophages protect the vascular barrier through direct contact with endothelial cells (ECs). Here, we investigated the molecular mechanism and its clinical significance in the ovarian cancer setting. We found that upon direct coculture with the endothelium, M2 macrophages tuned down their VLA4 and reduced the levels of VCAM1 in ECs. On the other hand, ectopically overexpressing VLA4 in macrophages or VCAM1 in ECs induced hyperpermeability. Mechanistically, downregulation of VLA4 or VCAM1 led to reduced levels of RAC1 and reactive oxygen species (ROS), which resulted in decreased phosphorylation of PYK2 (p-PYK2) and VE-cadherin (p-VE-cad), hence enhancing cell adhesion. Furthermore, targeting the VLA4/VCAM1 axis augmented vascular integrity and abrogated ascites formation in vivo. Lastly, VLA4 expression on the macrophages isolated from ascites dictated permeability ex vivo. Importantly, VLA4 antibody acted synergistically with bevacizumab to further enhance the vascular barrier. Taken together, we reveal here that M2 macrophages regulate the vascular barrier though the VCAM1/RAC1/ROS/p-PYK2/p-VE-cad cascade, which provides specific therapeutic targets for the treatment of malignant ascites.

Authors

Shibo Zhang, Bingfan Xie, Lijie Wang, Hua Yang, Haopei Zhang, Yuming Chen, Feng Wang, Changqing Liu, Huanhuan He