Immunogenicity of COVID-19 adsorbed inactivated vaccine (CoronaVac) and additional doses of mRNA BNT162b2 vaccine in immunocompromised adults compared with immunocompetent persons.

Inactivated COVID-19 vaccines data in immunocompromised individuals are scarce. This trial assessed the immunogenicity of two CoronaVac doses and additional BNT162b2 mRNA vaccine doses in immunocompromised (IC) and immunocompetent (H) individuals. Adults with solid organ transplant (SOT), hematopoietic stem cell transplant, cancer, inborn immunity errors or rheumatic diseases were included in the IC group. Immunocompetent adults were used as control group for comparison. Participants received two CoronaVac doses within a 28-day interval. IC received two additional BNT162b2 doses and H received a third BNT162b2 dose (booster). Blood samples were collected at baseline, 28 days after each dose, pre-booster and at the trial end. We used three serological tests to detect antibodies to SARS-CoV-2 nucleocapsid (N), trimeric spike (S), and receptor binding domain (RBD). Outcomes included seroconversion rates (SCR), geometric mean titers (GMT) and GMT ratio (GMTR). A total of 241 IC and 100 H adults participated in the study. After two CoronaVac doses, IC had lower SCR than H: anti-N, 33.3% vs 79%; anti-S, 33.8% vs 86%, and anti-RBD, 48.5% vs 85%, respectively. IC also showed lower GMT than H: anti-N, 2.3 vs 15.1; anti-S, 58.8 vs 213.2 BAU/mL; and anti-RBD, 22.4 vs 168.0 U/mL, respectively. After the 3rd and 4th BNT162b2 doses, IC had significant anti-S and anti-RBD seroconversion, but still lower than H after the 3rd dose. After boosting, GMT increased in IC, but remained lower than in the H group. CoronaVac two-dose schedule immunogenicity was lower in IC than in H. BNT162b2 heterologous booster enhanced immune response in both groups.

Nocardiosis diseminada a punto de partida de infeccion de piel y partes blandas. Serie de casos de un centro de tercer nivel / Disseminated nocardiosis at the starting point of skin and soft parts infection. Series of cases from a third level center

Nocardia es una bacteria grampositiva con amplia distribución en el medio ambiente. Puede producir variadas de infecciones. Si bien, las vías respiratorias son la principal puerta de entrada de Nocardia sp. ­y como consecuencia de lo mismo 50% de los pacientes posee compromiso pulmonar- las infecciones por Nocardia van desde infecciones de piel y partes blandas hasta abscesos cerebrales. La piel puede ser el órgano de afectación primaria y el primer signo clínico de infección o formar parte de una infección diseminada. La nocardiosis diseminada, es una grave enfermedad que involucra a dos sitios no contiguos de infección o el rescate del agente causal en hemocultivos. Afecta a pacientes debilitados con condiciones o con cierto grado de inmunodepresión; particularmente de inmunidad celular; como trasplantados de órganos sólido o hematopoyeticos, uso de corticoides, neoplasias, VIH, alcoholismo ­aunque se describen infecciones en pacientes inmunocompetentes­. El diagnóstico es dificultoso y la sospecha clínica es fundamental para el inicio de la terapéutica. Se describen dos casos de infecciones de piel y partes blandas ocasionadas por Nocardia; de evolución subaguda-cronica;. Una de ellas localizada: micetoma de pie, la segunda, una celulitis abdominal recurrente complicada con compromiso sistémico; en ambas estuvo presente la demora en el diagnóstico.

Nocardia is a gram-positive bacteria with wide distribution in the environment. It can cause a wide range of infections. Although the respiratory tract is the main entry point for Nocardia sp. ­ and as a consequence of the same, 50% of patients have lung involvement ­ nocardia infections range from skin and soft tissue infections to brain abscesses. The skin can be the primary organ of involvement and the first clinical sign of infection or be part of a disseminated infection, secondary to a primary pulmonary form. Disseminated nocardiosis is a serious disease that involves two non-contiguous sites of infection or the recovery of the causative agent in blood cultures. It commonly affects patients with weakened conditions or a certain degree of immunosuppression; particularly cellular immunity, such as solid or hematopoietic organ transplants, use of corticosteroids, neoplasms, HIV, alcoholism - although infections are described in immunocompetent patients. The diagnosis is difficult and clinical suspicion is essential for the initiation of therapy. Two cases of skin and soft tissue infections caused by Nocardia were described of subacute-chronic evolution. One of them localized: mycetoma of the foot, the second, a recurrent abdominal cellulites complicated with systemic involvement; Delay in diagnosis was present in both

When It Comes to SARS-CoV-2 Clearance, People Who Are Immunocompromised Are Not All Alike.

This Medical News story discusses a recent study that found people who are immunocompromised clear SARS-CoV-2 at varying rates.

Prevalence of persistent SARS-CoV-2 in a large community surveillance study.

Persistent SARS-CoV-2 infections may act as viral reservoirs that could seed future outbreaks1-5, give rise to highly divergent lineages6-8 and contribute to cases with post-acute COVID-19 sequelae (long COVID)9,10. However, the population prevalence of persistent infections, their viral load kinetics and evolutionary dynamics over the course of infections remain largely unknown. Here, using viral sequence data collected as part of a national infection survey, we identified 381 individuals with SARS-CoV-2 RNA at high titre persisting for at least 30 days, of which 54 had viral RNA persisting at least 60 days. We refer to these as 'persistent infections' as available evidence suggests that they represent ongoing viral replication, although the persistence of non-replicating RNA cannot be ruled out in all. Individuals with persistent infection had more than 50% higher odds of self-reporting long COVID than individuals with non-persistent infection. We estimate that 0.1-0.5% of infections may become persistent with typically rebounding high viral loads and last for at least 60 days. In some individuals, we identified many viral amino acid substitutions, indicating periods of strong positive selection, whereas others had no consensus change in the sequences for prolonged periods, consistent with weak selection. Substitutions included mutations that are lineage defining for SARS-CoV-2 variants, at target sites for monoclonal antibodies and/or are commonly found in immunocompromised people11-14. This work has profound implications for understanding and characterizing SARS-CoV-2 infection, epidemiology and evolution.

Human Metapneumovirus (hMPV) Infection and MPV467 Treatment in Immunocompromised Cotton Rats Sigmodon hispidus.

Human metapneumovirus (hMPV) is an important cause of respiratory disease in immunocompromised individuals, yet hMPV infection has not been modeled before in immunocompromised animals. In this work, cotton rats S. hispidus immunosuppressed by cyclophosphamide were infected with hMPV, and viral replication and pulmonary inflammation in these animals were compared to those in normal hMPV-infected S. hispidus. The efficacy of prophylactic and therapeutic administration of the anti-hMPV antibody MPV467 was also evaluated. Immunosuppressed animals had higher pulmonary and nasal titers of hMPV on day 5 post-infection compared to normal animals, and large amounts of hMPV were still present in the respiratory tract of immunosuppressed animals on days 7 and 9 post-infection, indicating prolonged viral replication. Immunosuppression was accompanied by reduced pulmonary histopathology in hMPV-infected cotton rats compared to normal animals; however, a delayed increase in pathology and pulmonary chemokine expression was seen in immunosuppressed cotton rats. Prophylactic and therapeutic MPV467 treatments protected both upper and lower respiratory tracts against hMPV infection. The lung pathology and pulmonary expression of IP-10 and MIP-1α mRNA were reduced by therapeutic MPV467 administration. These results indicate that immunosuppressed cotton rats represent a useful model for studying hMPV pathogenesis and for evaluating therapeutics that could alleviate hMPV-induced disease in immunocompromised subjects.

Response to anti-SARS-CoV-2 mRNA vaccines in multiple myeloma and chronic lymphocytic leukemia patients.

Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) patients have increased morbidity and mortality rates of COVID-19 due to immunosuppression associated with the disease and ongoing therapy. The same immune impairment accompanying CLL and MM also affects suboptimal vaccine response. The study assessed the effectiveness of the humoral and T cell-mediated immunity following mRNA COVID-19 vaccination (using either BNT162b2 or mRNA-1273) in short-term (2-5 weeks after second dose) and long-term follow-up (12 weeks after vaccination). Between March and August 2021, blood samples were obtained from 62 CLL and 60 MM patients from eight different hematology departments in Poland. Total anti-RBD antibodies were detected in 37% MM patients before vaccination, increased to 91% and 94% in short- and long-term follow-up, respectively. In CLL, serological responses were detectable in 21% of patients before vaccination and increased to 45% in the short-term and 71% in long-term observation. We detected a tendency to higher frequencies of specific CD8+ T cells against SARS-CoV-2 after vaccination compared to samples before vaccination in MM patients and no changes in frequencies of specific T cells in CLL patients. Our study provides novel insights into mRNA vaccination efficacy in immunocompromised MM and CLL patients, and our findings highlight that specific CD8+ T cells against SARS-CoV-2 might be induced by vaccination but do not correlate positively with serological responses.

Emergence of Delta and Omicron variants carrying resistance-associated mutations in immunocompromised patients undergoing sotrovimab treatment with long-term viral excretion.

OBJECTIVES: To monitor the early emergence of genetic mutations related to reduced susceptibility to monoclonal anti-body (mAb)-based treatment in immunocompromised patients with long-term viral excretion using whole-genome sequencing at a tertiary university hospital in Barcelona, Spain. METHODS: Serial severe acute respiratory syndrome coronavirus 2-positive samples (mid-December 2021-mid-March 2022) from eight immunosuppressed, fully vaccinated patients (for solid-organ transplantation or haematologic malignancies) with long-term viral excretion despite undergoing mAb therapy (sotrovimab) for coronavirus disease 2019 were selected. Whole-genome sequencing was performed following the ARTIC, version 4.1, protocol on the MiSeq platform. Mutations in the coding sequence of the spike protein with a frequency of ≥5% were studied. RESULTS: A total of 37 samples from the studied cases were analysed. All the cases, except one, were confirmed to have the Omicron variant BA.1; one had Delta (AY.100). Thirty-four different mutations were detected within the receptor-binding domain of the spike protein in 62.5% of patients, eight of which were not lineage related and located in the sotrovimab target epitope (P337L, E340D, E340R, E340K, E340V, E340Q, R346T and K356T). Except for P337L, all changes showed a significant increase in frequency or fixation after the administration of sotrovimab. Some of them have been associated with either reduced susceptibility to mAb therapy, such as those at position 340, or the acquisition of a new glycosylation site (346 and 356 positions). CONCLUSIONS: This study highlights the importance of monitoring for early in vivo selection of mutations associated with reduced susceptibility to mAb therapy, especially in immunocompromised patients receiving anti-viral drugs, whose immune response is not able to control viral replication, resulting in long-term viral shedding, and those receiving selective evolution pressure. Virologic surveillance of genetically resistant viruses to available anti-viral therapies is considered a priority for both patients and the community.

Infecciones fúngicas invasivas en niños hospitalizados en un centro de referencia de Uruguay / Invasive fungal infections in children hospitalized at a pediatric reference hospital in Uruguay / Infecções fúngicas invasivas em crianças internadas em um centro hospitalar de referência no Uruguai

Introducción: las infecciones fúngicas invasivas (IFI) son un problema de salud en creciente aumento. Objetivo: describir las características epidemiológicas, microbiológicas y clínicas de los menores de 15 años con IFI hospitalizados en el Hospital Pediátrico, Centro Hospitalario Pereira Rossell entre 2010- 2019. Metodología: estudio retrospectivo, mediante revisión de historias clínicas. Variables: edad, sexo, comorbilidades, factores de riesgo, clínica, patógenos, tratamiento y evolución. Resultados: se registraron 26 casos de IFI en 23 niños. La mediana de edad fue 8 años, de sexo femenino 17, con comorbilidades 17: infección por VIH 5, enfermedad hematooncológica 4. Todos presentaban factores de riesgo para IFI. Las manifestaciones clínicas de sospecha fueron: fiebre en 19, síntomas neurológicos 11, respiratorios 9, gastrointestinales 6, urinarios 2, sepsis/shock en 3. Los agentes identificados fueron: Candida spp en 14, Cryptococcus neoformans complex 8 y Aspergillus fumigatus complex 4. Tratamiento: se indicó fluconazol en 15, asociado a anfotericina B 11. Todas las infecciones por candida fueron sensibles a los azoles. Fallecieron 7 niños, la mediana de edad fue 1 año. En 4 se identificó Candida spp, Aspergillus fumigatus complex 2 y Cryptococcus neoformans complex 1. Conclusiones: las IFI son poco frecuentes, afectan en su mayoría a niños inmunocomprometidos asociando elevada mortalidad. El diagnóstico requiere alto índice de sospecha. Candida spp y Cryptococcus spp fueron los agentes más involucrados. El inicio precoz del tratamiento acorde a la susceptibilidad disponible se asocia a menor mortalidad.

Summary: Introduction: invasive fungal infections (IFI) are an increasing health problem. Objective: describe the epidemiological, microbiological and clinical characteristics of children under 15 years of age with IFI hospitalized at the Pereira Rossell Hospital Center between 2010-2019. Methodology: retrospective study, review of medical records. Variables: age, sex, comorbidities, risk factors, symptoms, pathogens, treatment and evolution. Results: 26 cases of IFI were recorded involving 23 children. Median age 8 years, female 17, comorbidities 17, HIV infection 5, hematological-oncological disease 4. All with risk factors. Suspicion symptoms: fever 19, neurological symptoms 11, respiratory 9, gastrointestinal 6, urinary 2, sepsis / shock 3. Identified agents: Candida spp 14, Cryptococcus neoformans complex 8 and Aspergillus fumigatus complex 4. Treatment: fluconazole 15, associated with amphotericin B 11. All candida infections were sensitive to azoles. 7 died, median age 1 year. In 4, Candida spp was isolated, Aspergillus fumigatus complex in 2 and Cryptococcus neoformans complex in 1. Conclusions: IFI are rare, mostly affecting immunocompromised children, associated with high mortality. The diagnosis requires a high index of suspicion. Candida spp and Cryptococcus spp were the most involved agents. Early treatment according to available susceptibility is associated with lower mortality.

Introdução: as infecções fúngicas invasivas (IFI) são um problema de saúde crescente. Objetivo: descrever as características epidemiológicas, microbiológicas e clínicas de crianças menores de 15 anos com IFI internadas no Centro Hospitalar Pereira Rossell entre 2010 e 2019. Metodologia: estudo retrospectivo, revisão de prontuários. Variáveis: idade, sexo, comorbidades, fatores de risco, sintomas, patógenos, tratamento e evolução. Resultados: foram registrados 26 casos de IFI em 23 crianças. Idade mediana 8 anos, sexo feminino 17, comorbidades 17, infecção por HIV 5, doença hemato-oncológica 4. Todos com fatores de risco. Suspeita clínica: febre 19, sintomas neurológicos 11, respiratórios 9, gastrointestinais 6, urinários 2, sepse/choque 3. Agentes identificados: Candida spp 14, Cryptococcus neoformans complexo 8 e Aspergillus fumigatus complexo 4. Tratamento: fluconazol 15, associado à anfotericina B 11. Todas as infecções por cândida foram sensíveis aos azóis. 7 morreram, idade média de 1 ano. Em 4 das crianças Cândida spp foi isolada, Aspergillus fumigatus complexo em 2 e Cryptococcus neoformans complexo em 1. Conclusões: IFIs são raras, afetando principalmente crianças imunocomprometidas, associadas a alta mortalidade. O diagnóstico requer alto índice de suspeita. Cândida spp e Cryptococcus spp são os agentes mais envolvidos. O tratamento precoce de acordo com a suscetibilidade disponível está associado a menor mortalidade.

Tuberculosis pulmonar con baciloscopía positiva en pacientes inmunocomprometidos. Hospital de Clínicas, 2018-2019 / Smear-positive pulmonary tuberculosis in immunocompromised patients. Hospital de Clínicas, 2018-2019

Introducción: La tuberculosis representa la novena causa de muerte en todo el mundo. La infección latente puede reactivarse por situaciones que comprometan la inmunidad del huésped. La tuberculosis pulmonar es la manifestación más frecuente en pacientes inmunodeprimidos. La baciloscopia es la herramienta primaria en el diagnóstico de la tuberculosis pulmonar activa. Objetivos: Determinar la frecuencia de tuberculosis pulmonar con baciloscopia positiva en pacientes inmunocomprometidos que acuden al Servicio de Neumología del Hospital de Clínicas durante el periodo 2018 a 2019. Materiales y métodos: Diseño observacional, descriptivo, transversal, retrospectivo, muestreo no probabilístico de casos consecutivos. Se realizó la revisión de fichas clínicas de pacientes internados en la Cátedra de Neumología del Hospital de Clínicas (2018-2019), registrados en la estadística del servicio. Para el procesamiento y análisis de datos fue utilizada una planilla electrónica precodificada de Microsoft Excel. Resultados: Del total de historias clínicas de pacientes dentro de la población estudiada (n=34), en el 68% de los casos el diagnóstico se estableció mediante baciloscopia, el 65% de ellos con hallazgo tres cruces (+++). Conclusión: La frecuencia de baciloscopia positiva en inmunocomprometidos determinada fue elevada. Aunque se está disminuyendo su uso, es importante seguir practicando este estudio a todos los inmunocomprometidos con síntomas respiratorios debido a su bajo costo y practicidad.

Introduction: Tuberculosis represents the ninth leading cause of death worldwide. Latent infection can be reactivated by situations that compromise host immunity. Pulmonary tuberculosis is the most frequent manifestation in immunocompromised patients. Smear microscopy is the primary tool in the diagnosis of active pulmonary tuberculosis. Objectives: To determine the frequency of smear-positive pulmonary tuberculosis in immunocompromised patients attending the Pneumology Service of the Hospital de Clínicas during the period 2018 to 2019. Materials and methods: Observational, descriptive, cross-sectional, retrospective, non-probabilistic sampling of consecutive cases. A review of clinical records of patients admitted to the Department of Pneumology of the Hospital de Clínicas (2018-2019), registered in the statistics department of the service, was performed. A pre-coded Microsoft Excel spreadsheet was used for data processing and analysis. Results: Of the total patient medical records within the studied population (n=34), in 68% of the cases the diagnosis was established by smear microscopy, 65% of them with finding three crosses (+++). Conclusion: The frequency of positive smear microscopy in immunocompromised patients was high. Although its use is decreasing, it is important to continue performing this study in all immunocompromised patients with respiratory symptoms due to its low cost and practicality.

NK cell frequencies, function and correlates to vaccine outcome in BNT162b2 mRNA anti-SARS-CoV-2 vaccinated healthy and immunocompromised individuals.

Adaptive immune responses have been studied extensively in the course of mRNA vaccination against COVID-19. Considerably fewer studies have assessed the effects on innate immune cells. Here, we characterized NK cells in healthy individuals and immunocompromised patients in the course of an anti-SARS-CoV-2 BNT162b2 mRNA prospective, open-label clinical vaccine trial. See trial registration description in notes. Results revealed preserved NK cell numbers, frequencies, subsets, phenotypes, and function as assessed through consecutive peripheral blood samplings at 0, 10, 21, and 35 days following vaccination. A positive correlation was observed between the frequency of NKG2C+ NK cells at baseline (Day 0) and anti-SARS-CoV-2 Ab titers following BNT162b2 mRNA vaccination at Day 35. The present results provide basic insights in regards to NK cells in the context of mRNA vaccination, and have relevance for future mRNA-based vaccinations against COVID-19, other viral infections, and cancer.Trial registration: The current study is based on clinical material from the COVAXID open-label, non-randomized prospective clinical trial registered at EudraCT and clinicaltrials.gov (no. 2021-000175-37). Description: https://clinicaltrials.gov/ct2/show/NCT04780659?term=2021-000175-37&draw=2&rank=1 .

mRNA COVID-19 vaccine booster fosters B- and T-cell responses in immunocompromised patients.

SARS-CoV-2 vaccination has proven effective in inducing an immune response in healthy individuals and is progressively us allowing to overcome the pandemic. Recent evidence has shown that response to vaccination in some vulnerable patients may be diminished, and it has been proposed a booster dose. We tested the kinetic of development of serum antibodies to the SARS-CoV-2 Spike protein, their neutralizing capacity, the CD4 and CD8 IFN-γ T-cell response in 328 subjects, including 131 immunocompromised individuals (cancer, rheumatologic, and hemodialysis patients), 160 health-care workers (HCW) and 37 subjects older than 75 yr, after vaccination with two or three doses of mRNA vaccines. We stratified the patients according to the type of treatment. We found that immunocompromised patients, depending on the type of treatment, poorly respond to SARS-CoV-2 mRNA vaccines. However, an additional booster dose of vaccine induced a good immune response in almost all of the patients except those receiving anti-CD20 antibody. Similarly to HCW, previously infected and vaccinated immunocompromised individuals demonstrate a stronger SARS-CoV-2-specific immune response than those who are vaccinated without prior infection.

SARS-CoV-2 prolonged infection during advanced HIV disease evolves extensive immune escape.

Characterizing SARS-CoV-2 evolution in specific geographies may help predict properties of the variants that come from these regions. We mapped neutralization of a SARS-CoV-2 strain that evolved over 6 months from ancestral virus in a person with advanced HIV disease in South Africa; this person was infected prior to emergence of the Beta and Delta variants. We longitudinally tracked the evolved virus and tested it against self-plasma and convalescent plasma from ancestral, Beta, and Delta infections. Early virus was similar to ancestral, but it evolved a multitude of mutations found in Omicron and other variants. It showed substantial but incomplete Pfizer BNT162b2 escape, weak neutralization by self-plasma, and despite pre-dating Delta, it also showed extensive escape of Delta infection-elicited neutralization. This example is consistent with the notion that SARS-CoV-2 evolving in individual immune-compromised hosts, including those with advanced HIV disease, may gain immune escape of vaccines and enhanced escape of Delta immunity, and this has implications for vaccine breakthrough and reinfections.

IL-33 Coordinates Innate Defense to Systemic Candida albicans Infection by Regulating IL-23 and IL-10 in an Opposite Way.

Invasive candidiasis has high mortality rates in immunocompromised patients, causing serious health problems. In mouse models, innate immunity protects the host by rapidly mobilizing a variety of resistance and tolerance mechanisms to systemic Candida albicans infection. We have previously demonstrated that exogenous IL-33 regulates multiple steps of innate immunity involving resistance and tolerance processes. In this study, we systematically analyzed the in vivo functions of endogenous IL-33 using Il33 -/- mice and in vitro immune cell culture. Tubular epithelial cells mainly secreted IL-33 in response to systemic C. albicans infection. Il33 -/- mice showed increased mortality and morbidity, which were due to impaired fungal clearance. IL-33 initiated an innate defense mechanism by costimulating dendritic cells to produce IL-23 after systemic C. albicans infection, which in turn promoted the phagocytosis of neutrophils through secretion of GM-CSF by NK cells. The susceptibility of Il33 -/- mice was also associated with increased levels of IL-10, and neutralization of IL-10 resulted in enhanced fungal clearance in Il33 -/- mice. However, depletion of IL-10 overrode the effect of IL-33 on fungal clearance. In Il10 -/- mouse kidneys, MHC class II+F4/80+ macrophages were massively differentiated after C. albicans infection, and these cells were superior to MHC class II-F4/80+ macrophages that were preferentially differentiated in wild-type mouse kidneys in killing of extracellular hyphal C. albicans Taken together, our results identify IL-33 as critical early regulator controlling a serial downstream signaling events of innate defense to C. albicans infection.

Subversion of infiltrating prostate macrophages to a mixed immunosuppressive tumor-associated macrophage phenotype.

Tumor-associated macrophages (TAMs) support tumor progression within the tumor microenvironment (TME). Many questions remain as to the origin, development, and function of TAMs within the prostate TME. Evaluation of TAMs in prostate cancer (PCa) patients identified the immunosuppressive TAM marker CD163 in adjacent normal epithelium as an independent predictor of metastases or PCa death. Flow cytometry analyses identified prostate TAMs as frequently expressing both proinflammatory M1 (CCR7+) and immunosuppressive M2 (CD163+) markers. In vitro, we demonstrate PCa cells similarly subvert human M1 macrophages toward a mixed M1/M2 macrophage phenotype favoring tumor growth. Further the cytokine milieu-induced transition between immunosuppressive M2 to proinflammatory M1 (M2→M1) macrophages is abrogated by the presence of PCa cells. RNA sequencing suggests alterations in chemokine expression in prostate TAMs due to the presence of PCa cells. Together, our results suggest that prostate TAMs originate from inflammatory infiltrating macrophages, which are then reprogrammed mainly by PCa cells, but also the cytokine milieu. A better understanding of this subversion of macrophages within the prostate may lead to novel treatment strategies.

COVID-19 prophylaxis in immunosuppressed patients: Beyond vaccination.

Ivan Gentile and Nicola Schiano Moriello discuss the potential of monoclonal antibody prophylaxis against COVID-19 infection in immunocompromised patients.

Intratumoral stem-like CCR4+ regulatory T cells orchestrate the immunosuppressive microenvironment in HCC associated with hepatitis B.

BACKGROUND & AIMS: Regulatory T cell (Treg) depletion increases antitumor immunity. However, severe autoimmunity can occur following systemic loss of Tregs, which could be avoided by selectively depleting intratumoral Tregs. Herein, we aimed to investigate the role of tumor-infiltrating CCR4+ Tregs in hepatocellular carcinoma (HCC) and to provide a potential target strategy for immunotherapy. METHODS: CCR4+ Tregs were analyzed by flow cytometry in murine models and clinical samples. The function of tumor-infiltrating and induced CCR4+ Tregs was interrogated by genetic and epigenetic approaches. To block CCR4+ Treg chemotaxis, we developed an N-terminus recombinant protein of CCR4 (N-CCR4-Fc) as a neutralizing pseudo-receptor that effectively bound to its ligand CCL22. The efficacy of CCR4 antagonism as an immunotherapeutic agent was evaluated by tumor weights, growth kinetics and survival curves. RESULTS: CCR4+ Tregs were the predominant type of Tregs recruited to hepatitis B-associated HCC (HBV+ HCC), correlating with sorafenib resistance and HBV load titers. Compared with CCR4- Tregs, CCR4+ Tregs exhibited increased IL-10 and IL-35 expression, and enhanced functionality in suppressing CD8+ T cells. CCR4+ Tregs also displayed PD-1+TCF1+ stem-like properties. ATAC-seq data revealed substantial chromatin remodeling between tumor-infiltrating Tregs (TIL-Tregs) and induced Tregs, suggesting that long-term chromatin reprogramming accounted for the acquisition of enhanced immunosuppressive stem-like specificity by CCR4+ TIL-Tregs. Treatment with a CCR4 antagonist or N-CCR4-Fc blocked intratumoral Treg accumulation, overcame sorafenib resistance, and sensitized tumors to PD-1 checkpoint blockade. CONCLUSIONS: Intratumoral stem-like CCR4+ Tregs orchestrated immunosuppressive resource cells in the tumor microenvironment. CCR4 could be targeted to enhance antitumor immunity by specifically blocking infiltration of Tregs into the tumor microenvironment and inhibiting maintenance of the TIL-Treg pool. LAY SUMMARY: Targeting regulatory T cells is a promising approach in cancer immunotherapy; however, severe autoimmunity can occur following systemic regulatory T cell loss. This could be avoided by selectively depleting intratumoral regulatory T cells. Herein, targeting intratumoral stem-like CCR4+ regulatory T cells helped to overcome sorafenib resistance and sensitize tumors to immune checkpoint blockade in mouse models of liver cancer. This approach could have wide clinical applicability.