Intestinal Interleukin-17 Receptor Signaling Mediates Reciprocal Control of the Gut Microbiota and Autoimmune Inflammation.

Interleukin-17 (IL-17) and IL-17 receptor (IL-17R) signaling are essential for regulating mucosal host defense against many invading pathogens. Commensal bacteria, especially segmented filamentous bacteria (SFB), are a crucial factor that drives T helper 17 (Th17) cell development in the gastrointestinal tract. In this study, we demonstrate that Th17 cells controlled SFB burden. Disruption of IL-17R signaling in the enteric epithelium resulted in SFB dysbiosis due to reduced expression of α-defensins, Pigr, and Nox1. When subjected to experimental autoimmune encephalomyelitis, IL-17R-signaling-deficient mice demonstrated earlier disease onset and worsened severity that was associated with increased intestinal Csf2 expression and elevated systemic GM-CSF cytokine concentrations. Conditional deletion of IL-17R in the enteric epithelium demonstrated that there was a reciprocal relationship between the gut microbiota and enteric IL-17R signaling that controlled dysbiosis, constrained Th17 cell development, and regulated the susceptibility to autoimmune inflammation.

Global patterns of antigen receptor repertoire disruption across adaptive immune compartments in COVID-19.

Whereas pathogen-specific T and B cells are a primary focus of interest during infectious disease, we have used COVID-19 to ask whether their emergence comes at a cost of broader B cell and T cell repertoire disruption. We applied a genomic DNA-based approach to concurrently study the immunoglobulin-heavy (IGH) and T cell receptor (TCR) ß and δ chain loci of 95 individuals. Our approach detected anticipated repertoire focusing for the IGH repertoire, including expansions of clusters of related sequences temporally aligned with SARS-CoV-2-specific seroconversion, and enrichment of some shared SARS-CoV-2-associated sequences. No significant age-related or disease severity-related deficiencies were noted for the IGH repertoire. By contrast, whereas focusing occurred at the TCRß and TCRδ loci, including some TCRß sequence-sharing, disruptive repertoire narrowing was almost entirely limited to many patients aged older than 50 y. By temporarily reducing T cell diversity and by risking expansions of nonbeneficial T cells, these traits may constitute an age-related risk factor for COVID-19, including a vulnerability to new variants for which T cells may provide key protection.

ß2 Integrins differentially regulate γδ T cell subset thymic development and peripheral maintenance.

The γδ T cells reside predominantly at barrier sites and play essential roles in immune protection against infection and cancer. Despite recent advances in the development of γδ T cell immunotherapy, our understanding of the basic biology of these cells, including how their numbers are regulated in vivo, remains poor. This is particularly true for tissue-resident γδ T cells. We have identified the ß2 family of integrins as regulators of γδ T cells. ß2-integrin-deficient mice displayed a striking increase in numbers of IL-17-producing Vγ6Vδ1+ γδ T cells in the lungs, uterus, and circulation. Thymic development of this population was normal. However, single-cell RNA sequencing revealed the enrichment of genes associated with T cell survival and proliferation specifically in ß2-integrin-deficient IL-17+ cells compared to their wild-type counterparts. Indeed, ß2-integrin-deficient Vγ6+ cells from the lungs showed reduced apoptosis ex vivo, suggesting that increased survival contributes to the accumulation of these cells in ß2-integrin-deficient tissues. Furthermore, our data revealed an unexpected role for ß2 integrins in promoting the thymic development of the IFNγ-producing CD27+ Vγ4+ γδ T cell subset. Together, our data reveal that ß2 integrins are important regulators of γδ T cell homeostasis, inhibiting the survival of IL-17-producing Vγ6Vδ1+ cells and promoting the thymic development of the IFNγ-producing Vγ4+ subset. Our study introduces unprecedented mechanisms of control for γδ T cell subsets.

An IL-17F.S65L Knock-In Mouse Reveals Similarities and Differences in IL-17F Function in Oral Candidiasis: A New Tool to Understand IL-17F.

Oropharyngeal candidiasis (OPC) is an opportunistic infection of the oral mucosa caused by the commensal fungus Candida albicans IL-17R signaling is essential to prevent OPC in mice and humans, but the individual roles of its ligands, IL-17A, IL-17F, and IL-17AF, are less clear. A homozygous IL-17F deficiency in mice does not cause OPC susceptibility, whereas mice lacking IL-17A are moderately susceptible. In humans, a rare heterozygous mutation in IL-17F (IL-17F.S65L) was identified that causes chronic mucocutaneous candidiasis, suggesting the existence of essential antifungal pathways mediated by IL-17F and/or IL-17AF. To investigate the role of IL-17F and IL-17AF in more detail, we exploited this "experiment of nature" by creating a mouse line bearing the homologous mutation in IL-17F (Ser65Leu) by CRISPR/Cas9. Unlike Il17f-/- mice that are resistant to OPC, Il17fS65L/S65L mice showed increased oral fungal burdens similar to Il17a -/- mice. In contrast to humans, however, disease was only evident in homozygous, not heterozygous, mutant mice. The mutation was linked to modestly impaired CXC chemokine expression and neutrophil recruitment to the infected tongue but not to alterations in oral antimicrobial peptide expression. These findings suggest mechanisms by which the enigmatic cytokine IL-17F contributes to host defense against fungi. Moreover, because these mice do not phenocopy Il17f-/- mice, they may provide a valuable tool to interrogate IL-17F and IL-17AF function in vivo in other settings.

Trypanosoma cruzi-Derived Molecules Induce Anti-Tumour Protection by Favouring Both Innate and Adaptive Immune Responses.

Lung cancer remains the leading cause of cancer mortality worldwide. Thus, the development of strategies against this type of cancer is of high value. Parasite infections can correlate with lower cancer incidence in humans and their use as vaccines has been recently explored in preclinical models. In this study, we investigated whether immunisations with a Trypanosoma cruzi lysate from epimastigotes protect from lung tumour growth in mice. We also explore the role of parasite glycans in the induction of the protective immune response. A pre-clinical murine cancer model using the lung tumour cell line LL/2 was used to evaluate the anti-tumour potential, both in preventive and therapeutic settings, of a T. cruzi epimastigote-derived protein lysate. Immunisation with the parasite lysate prevents tumour growth and induces both humoral and cellular anti-tumour immune responses to LL-2 cancer cells. The induced immunity and tumour protection were associated with the activation of natural killer (NK) cells, the production of interferon-γ (IFN-γ) and tumour cell cytotoxicity. We also show that mannose residues in the T. cruzi lysate induce Toll-like receptor (TLR) signalling. The evaluated T. cruzi lysate possesses anti-tumour properties likely by activating innate and adaptive immunity in a process where carbohydrates seem to be essential.

Safety and immunogenicity of one versus two doses of the COVID-19 vaccine BNT162b2 for patients with cancer: interim analysis of a prospective observational study.

BACKGROUND: The efficacy and safety profiles of vaccines against SARS-CoV-2 in patients with cancer is unknown. We aimed to assess the safety and immunogenicity of the BNT162b2 (Pfizer-BioNTech) vaccine in patients with cancer. METHODS: For this prospective observational study, we recruited patients with cancer and healthy controls (mostly health-care workers) from three London hospitals between Dec 8, 2020, and Feb 18, 2021. Participants who were vaccinated between Dec 8 and Dec 29, 2020, received two 30 µg doses of BNT162b2 administered intramuscularly 21 days apart; patients vaccinated after this date received only one 30 µg dose with a planned follow-up boost at 12 weeks. Blood samples were taken before vaccination and at 3 weeks and 5 weeks after the first vaccination. Where possible, serial nasopharyngeal real-time RT-PCR (rRT-PCR) swab tests were done every 10 days or in cases of symptomatic COVID-19. The coprimary endpoints were seroconversion to SARS-CoV-2 spike (S) protein in patients with cancer following the first vaccination with the BNT162b2 vaccine and the effect of vaccine boosting after 21 days on seroconversion. All participants with available data were included in the safety and immunogenicity analyses. Ongoing follow-up is underway for further blood sampling after the delayed (12-week) vaccine boost. This study is registered with the NHS Health Research Authority and Health and Care Research Wales (REC ID 20/HRA/2031). FINDINGS: 151 patients with cancer (95 patients with solid cancer and 56 patients with haematological cancer) and 54 healthy controls were enrolled. For this interim data analysis of the safety and immunogenicity of vaccinated patients with cancer, samples and data obtained up to March 19, 2021, were analysed. After exclusion of 17 patients who had been exposed to SARS-CoV-2 (detected by either antibody seroconversion or a positive rRT-PCR COVID-19 swab test) from the immunogenicity analysis, the proportion of positive anti-S IgG titres at approximately 21 days following a single vaccine inoculum across the three cohorts were 32 (94%; 95% CI 81-98) of 34 healthy controls; 21 (38%; 26-51) of 56 patients with solid cancer, and eight (18%; 10-32) of 44 patients with haematological cancer. 16 healthy controls, 25 patients with solid cancer, and six patients with haematological cancer received a second dose on day 21. Of the patients with available blood samples 2 weeks following a 21-day vaccine boost, and excluding 17 participants with evidence of previous natural SARS-CoV-2 exposure, 18 (95%; 95% CI 75-99) of 19 patients with solid cancer, 12 (100%; 76-100) of 12 healthy controls, and three (60%; 23-88) of five patients with haematological cancers were seropositive, compared with ten (30%; 17-47) of 33, 18 (86%; 65-95) of 21, and four (11%; 4-25) of 36, respectively, who did not receive a boost. The vaccine was well tolerated; no toxicities were reported in 75 (54%) of 140 patients with cancer following the first dose of BNT162b2, and in 22 (71%) of 31 patients with cancer following the second dose. Similarly, no toxicities were reported in 15 (38%) of 40 healthy controls after the first dose and in five (31%) of 16 after the second dose. Injection-site pain within 7 days following the first dose was the most commonly reported local reaction (23 [35%] of 65 patients with cancer; 12 [48%] of 25 healthy controls). No vaccine-related deaths were reported. INTERPRETATION: In patients with cancer, one dose of the BNT162b2 vaccine yields poor efficacy. Immunogenicity increased significantly in patients with solid cancer within 2 weeks of a vaccine boost at day 21 after the first dose. These data support prioritisation of patients with cancer for an early (day 21) second dose of the BNT162b2 vaccine. FUNDING: King's College London, Cancer Research UK, Wellcome Trust, Rosetrees Trust, and Francis Crick Institute.

Immune responses in the human female reproductive tract.

Mucosal surfaces are key interfaces between the host and its environment, but also constitute ports of entry for numerous pathogens. The gut and lung mucosae act as points of nutrient and gas exchange, respectively, but the physiological purpose of the female reproductive tract (FRT) is to allow implantation and development of the fetus. Our understanding of immune responses in the FRT has traditionally lagged behind our grasp of the situation at other mucosal sites, but recently reproductive immunologists have begun to make rapid progress in this challenging area. Here, we review current knowledge of immune responses in the human FRT and their heterogeneity within and between compartments. In the commensal-rich vagina, the immune system must allow the growth of beneficial microbes, whereas the key challenge in the uterus is allowing the growth of the semi-allogeneic fetus. In both compartments, these objectives must be balanced with the need to eliminate pathogens. Our developing understanding of immune responses in the FRT will help us develop interventions to prevent the spread of sexually transmitted diseases and to improve outcomes of pregnancy for mothers and babies.

MCPIP1/Regnase-1 Restricts IL-17A- and IL-17C-Dependent Skin Inflammation.

The IL-17 family cytokines IL-17A and IL-17C drive the pathogenesis of psoriatic skin inflammation, and anti-IL-17A Abs were recently approved to treat human psoriasis. Little is known about mechanisms that restrain IL-17 cytokine-mediated signaling, particularly IL-17C. In this article, we show that the endoribonuclease MCP-1-induced protein 1 (MCPIP1; also known as regnase-1) is markedly upregulated in human psoriatic skin lesions. Similarly, MCPIP1 was overexpressed in the imiquimod (IMQ)-driven mouse model of cutaneous inflammation. Mice with an MCPIP1 deficiency (Zc3h12a+/-) displayed no baseline skin inflammation, but they showed exacerbated pathology following IMQ treatment. Pathology in Zc3h12a+/- mice was associated with elevated expression of IL-17A- and IL-17C-dependent genes, as well as with increased accumulation of neutrophils in skin. However, IL-17A and IL-17C expression was unaltered, suggesting that the increased inflammation in Zc3h12a+/- mice was due to enhanced downstream IL-17R signaling. Radiation chimeras demonstrated that MCPIP1 in nonhematopoietic cells is responsible for controlling skin pathology. Moreover, Zc3h12a+/-Il17ra-/- mice given IMQ showed almost no disease. To identify which IL-17RA ligand was essential, Zc3h12a+/-Il17a-/- and Zc3h12a+/-Il17c-/- mice were given IMQ; these mice had reduced but not fully abrogated pathology, indicating that MCPIP1 inhibits IL-17A and IL-17C signaling. Confirming this hypothesis, Zc3h12a-/- keratinocytes showed increased responsiveness to IL-17A and IL-17C stimulation. Thus, MCPIP1 is a potent negative regulator of psoriatic skin inflammation through IL-17A and IL-17C. Moreover, to our knowledge, MCPIP1 is the first described negative regulator of IL-17C signaling.

Aspergillus fumigatus Preexposure Worsens Pathology and Improves Control of Mycobacterium abscessus Pulmonary Infection in Mice.

Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. Mutations in this chloride channel lead to mucus accumulation, subsequent recurrent pulmonary infections, and inflammation, which, in turn, cause chronic lung disease and respiratory failure. Recently, rates of nontuberculous mycobacterial (NTM) infections in CF patients have been increasing. Of particular relevance is infection with Mycobacterium abscessus, which causes a serious, life-threatening disease and constitutes one of the most antibiotic-resistant NTM species. Interestingly, an increased prevalence of NTM infections is associated with worsening lung function in CF patients who are also coinfected with Aspergillus fumigatus We established a new mouse model to investigate the relationship between A. fumigatus and M. abscessus pulmonary infections. In this model, animals exposed to A. fumigatus and coinfected with M. abscessus exhibited increased lung inflammation and decreased mycobacterial burden compared with those of mice infected with M. abscessus alone. This increased control of M. abscessus infection in coinfected mice was mucus independent but dependent on both transcription factors T-box 21 (Tbx21) and retinoic acid receptor (RAR)-related orphan receptor gamma t (RORγ-t), master regulators of type 1 and type 17 immune responses, respectively. These results implicate a role for both type 1 and type 17 responses in M. abscessus control in A. fumigatus-coinfected lungs. Our results demonstrate that A. fumigatus, an organism found commonly in CF patients with NTM infection, can worsen pulmonary inflammation and impact M. abscessus control in a mouse model.

Chemokines in tuberculosis: the good, the bad and the ugly.

Mycobacterium tuberculosis (Mtb) infects about one-third of the world's population, with a majority of infected individuals exhibiting latent asymptomatic infection, while 5-10% of infected individuals progress to active pulmonary disease. Research in the past two decades has elucidated critical host immune mechanisms that mediate Mtb control. Among these, chemokines have been associated with numerous key processes that lead to Mtb containment, from recruitment of myeloid cells into the lung to activation of adaptive immunity, formation of protective granulomas and vaccine recall responses. However, imbalances in several key chemokine mediators can alter the delicate balance of cytokines and cellular responses that promote mycobacterial containment, instead precipitating terminal tissue destruction and spread of Mtb infection. In this review, we will describe recent insights in the involvement of chemokines in host responses to Mtb infection and Mtb containment (the good), chemokines contributing to inflammation during TB (the bad), and the role of chemokines in driving cavitation and lung pathology (the ugly).

Unexpected role for IL-17 in protective immunity against hypervirulent Mycobacterium tuberculosis HN878 infection.

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), infects one third of the world's population. Among these infections, clinical isolates belonging to the W-Beijing appear to be emerging, representing about 50% of Mtb isolates in East Asia, and about 13% of all Mtb isolates worldwide. In animal models, infection with W-Beijing strain, Mtb HN878, is considered "hypervirulent" as it results in increased mortality and causes exacerbated immunopathology in infected animals. We had previously shown the Interleukin (IL) -17 pathway is dispensable for primary immunity against infection with the lab adapted Mtb H37Rv strain. However, it is not known whether IL-17 has any role to play in protective immunity against infection with clinical Mtb isolates. We report here that lab adapted Mtb strains, such as H37Rv, or less virulent Mtb clinical isolates, such as Mtb CDC1551, do not require IL-17 for protective immunity against infection while infection with Mtb HN878 requires IL-17 for early protective immunity. Unexpectedly, Mtb HN878 induces robust production of IL-1ß through a TLR-2-dependent mechanism, which supports potent IL-17 responses. We also show that the role for IL-17 in mediating protective immunity against Mtb HN878 is through IL-17 Receptor signaling in non-hematopoietic cells, mediating the induction of the chemokine, CXCL-13, which is required for localization of T cells within lung lymphoid follicles. Correct T cell localization within lymphoid follicles in the lung is required for maximal macrophage activation and Mtb control. Since IL-17 has a critical role in vaccine-induced immunity against TB, our results have far reaching implications for the design of vaccines and therapies to prevent and treat emerging Mtb strains. In addition, our data changes the existing paradigm that IL-17 is dispensable for primary immunity against Mtb infection, and instead suggests a differential role for IL-17 in early protective immunity against emerging Mtb strains.

Mycobacterium tuberculosis impairs dendritic cell functions through the serine hydrolase Hip1.

Mycobacterium tuberculosis is a highly successful human pathogen that primarily resides in host phagocytes, such as macrophages and dendritic cells (DCs), and interferes with their functions. Although multiple strategies used by M. tuberculosis to modulate macrophage responses have been discovered, interactions between M. tuberculosis and DCs are less well understood. DCs are the primary APCs of the immune system and play a central role in linking innate and adaptive immune responses to microbial pathogens. In this study, we show that M. tuberculosis impairs DC cytokine secretion, maturation, and Ag presentation through the cell envelope-associated serine hydrolase, Hip1. Compared to wild-type, a hip1 mutant strain of M. tuberculosis induced enhanced levels of the key Th1-inducing cytokine IL-12, as well as other proinflammatory cytokines (IL-23, IL-6, TNF-α, IL-1ß, and IL-18) in DCs via MyD88- and TLR2/9-dependent pathways, indicating that Hip1 restricts optimal DC inflammatory responses. Infection with the hip1 mutant also induced higher levels of MHC class II and costimulatory molecules CD40 and CD86, indicating that M. tuberculosis impairs DC maturation through Hip1. Further, we show that M. tuberculosis promotes suboptimal Ag presentation, as DCs infected with the hip1 mutant showed increased capacity to present Ag to OT-II- and early secreted antigenic target 6-specific transgenic CD4 T cells and enhanced Th1 and Th17 polarization. Overall, these data show that M. tuberculosis impairs DC functions and modulates the nature of Ag-specific T cell responses, with important implications for vaccination strategies.

IL-10 restrains IL-17 to limit lung pathology characteristics following pulmonary infection with Francisella tularensis live vaccine strain.

IL-10 production during intracellular bacterial infections is generally thought to be detrimental because of its role in suppressing protective T-helper cell 1 (Th1) responses. Francisella tularensis is a facultative intracellular bacterium that activates both Th1 and Th17 protective immune responses. Herein, we report that IL-10-deficient mice (Il10(-/-)), despite having increased Th1 and Th17 responses, exhibit increased mortality after pulmonary infection with F. tularensis live vaccine strain. We demonstrate that the increased mortality observed in Il10(-/-)-infected mice is due to exacerbated IL-17 production that causes increased neutrophil recruitment and associated lung pathology. Thus, although IL-17 is required for protective immunity against pulmonary infection with F. tularensis live vaccine strain, its production is tightly regulated by IL-10 to generate efficient induction of protective immunity without mediating pathology. These data suggest a critical role for IL-10 in maintaining the delicate balance between host immunity and pathology during pulmonary infection with F. tularensis live vaccine strain.

S100A8/A9 proteins mediate neutrophilic inflammation and lung pathology during tuberculosis.

RATIONALE: A hallmark of pulmonary tuberculosis (TB) is the formation of granulomas. However, the immune factors that drive the formation of a protective granuloma during latent TB, and the factors that drive the formation of inflammatory granulomas during active TB, are not well defined. OBJECTIVES: The objective of this study was to identify the underlying immune mechanisms involved in formation of inflammatory granulomas seen during active TB. METHODS: The immune mediators involved in inflammatory granuloma formation during TB were assessed using human samples and experimental models of Mycobacterium tuberculosis infection, using molecular and immunologic techniques. MEASUREMENTS AND MAIN RESULTS: We demonstrate that in human patients with active TB and in nonhuman primate models of M. tuberculosis infection, neutrophils producing S100 proteins are dominant within the inflammatory lung granulomas seen during active TB. Using the mouse model of TB, we demonstrate that the exacerbated lung inflammation seen as a result of neutrophilic accumulation is dependent on S100A8/A9 proteins. S100A8/A9 proteins promote neutrophil accumulation by inducing production of proinflammatory chemokines and cytokines, and influencing leukocyte trafficking. Importantly, serum levels of S100A8/A9 proteins along with neutrophil-associated chemokines, such as keratinocyte chemoattractant, can be used as potential surrogate biomarkers to assess lung inflammation and disease severity in human TB. CONCLUSIONS: Our results thus show a major pathologic role for S100A8/A9 proteins in mediating neutrophil accumulation and inflammation associated with TB. Thus, targeting specific molecules, such as S100A8/A9 proteins, has the potential to decrease lung tissue damage without impacting protective immunity against TB.

Antitumor activity of human hydatid cyst fluid in a murine model of colon cancer.

This study evaluates the antitumor immune response induced by human hydatic cyst fluid (HCF) in an animal model of colon carcinoma. We found that anti-HCF antibodies were able to identify cell surface and intracellular antigens in CT26 colon cancer cells. In prophylactic tumor challenge experiments, HCF vaccination was found to be protective against tumor formation for 40% of the mice (P = 0.01). In the therapeutic setting, HCF vaccination induced tumor regression in 40% of vaccinated mice (P = 0.05). This vaccination generated memory immune responses that protected surviving mice from tumor rechallenge, implicating the development of an adaptive immune response in this process. We performed a proteomic analysis of CT26 antigens recognized by anti-HCF antibodies to analyze the immune cross-reactivity between E. granulosus (HCF) and CT26 colon cancer cells. We identified two proteins: mortalin and creatine kinase M-type. Interestingly, CT26 mortalin displays 60% homology with E. granulosus hsp70. In conclusion, our data demonstrate the capacity of HCF vaccination to induce antitumor immunity which protects from tumor growth in an animal model. This new antitumor strategy could open new horizons in the development of highly immunogenic anticancer vaccines.

Acute Immune Signatures and Their Legacies in Severe Acute Respiratory Syndrome Coronavirus-2 Infected Cancer Patients.

Given the immune system's importance for cancer surveillance and treatment, we have investigated how it may be affected by SARS-CoV-2 infection of cancer patients. Across some heterogeneity in tumor type, stage, and treatment, virus-exposed solid cancer patients display a dominant impact of SARS-CoV-2, apparent from the resemblance of their immune signatures to those for COVID-19+ non-cancer patients. This is not the case for hematological malignancies, with virus-exposed patients collectively displaying heterogeneous humoral responses, an exhausted T cell phenotype and a high prevalence of prolonged virus shedding. Furthermore, while recovered solid cancer patients' immunophenotypes resemble those of non-virus-exposed cancer patients, recovered hematological cancer patients display distinct, lingering immunological legacies. Thus, while solid cancer patients, including those with advanced disease, seem no more at risk of SARS-CoV-2-associated immune dysregulation than the general population, hematological cancer patients show complex immunological consequences of SARS-CoV-2 exposure that might usefully inform their care.

Butyrophilin-like proteins display combinatorial diversity in selecting and maintaining signature intraepithelial γδ T cell compartments.

Butyrophilin-like (Btnl) genes are emerging as major epithelial determinants of tissue-associated γδ T cell compartments. Thus, the development of signature, murine TCRγδ+ intraepithelial lymphocytes (IEL) in gut and skin depends on Btnl family members, Btnl1 and Skint1, respectively. In seeking mechanisms underlying these profound effects, we now show that normal gut and skin γδ IEL development additionally requires Btnl6 and Skint2, respectively, and furthermore that different Btnl heteromers can seemingly shape different intestinal γδ+ IEL repertoires. This formal genetic evidence for the importance of Btnl heteromers also applied to the steady-state, since sustained Btnl expression is required to maintain the signature TCR.Vγ7+ IEL phenotype, including specific responsiveness to Btnl proteins. In sum, Btnl proteins are required to select and to maintain the phenotypes of tissue-protective γδ IEL compartments, with combinatorially diverse heteromers having differential impacts on different IEL subsets.

A dynamic COVID-19 immune signature includes associations with poor prognosis.

Improved understanding and management of COVID-19, a potentially life-threatening disease, could greatly reduce the threat posed by its etiologic agent, SARS-CoV-2. Toward this end, we have identified a core peripheral blood immune signature across 63 hospital-treated patients with COVID-19 who were otherwise highly heterogeneous. The signature includes discrete changes in B and myelomonocytic cell composition, profoundly altered T cell phenotypes, selective cytokine/chemokine upregulation and SARS-CoV-2-specific antibodies. Some signature traits identify links with other settings of immunoprotection and immunopathology; others, including basophil and plasmacytoid dendritic cell depletion, correlate strongly with disease severity; while a third set of traits, including a triad of IP-10, interleukin-10 and interleukin-6, anticipate subsequent clinical progression. Hence, contingent upon independent validation in other COVID-19 cohorts, individual traits within this signature may collectively and individually guide treatment options; offer insights into COVID-19 pathogenesis; and aid early, risk-based patient stratification that is particularly beneficial in phasic diseases such as COVID-19.

Author Correction: A dynamic COVID-19 immune signature includes associations with poor prognosis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: A dynamic COVID-19 immune signature includes associations with poor prognosis.

A Correction to this paper has been published: https://doi.org/10.1038/s41591-020-01186-5.