The immunostimulatory RNA RN7SL1 enables CAR-T cells to enhance autonomous and endogenous immune function.

Poor tumor infiltration, development of exhaustion, and antigen insufficiency are common mechanisms that limit chimeric antigen receptor (CAR)-T cell efficacy. Delivery of pattern recognition receptor agonists is one strategy to improve immune function; however, targeting these agonists to immune cells is challenging, and off-target signaling in cancer cells can be detrimental. Here, we engineer CAR-T cells to deliver RN7SL1, an endogenous RNA that activates RIG-I/MDA5 signaling. RN7SL1 promotes expansion and effector-memory differentiation of CAR-T cells. Moreover, RN7SL1 is deployed in extracellular vesicles and selectively transferred to immune cells. Unlike other RNA agonists, transferred RN7SL1 restricts myeloid-derived suppressor cell (MDSC) development, decreases TGFB in myeloid cells, and fosters dendritic cell (DC) subsets with costimulatory features. Consequently, endogenous effector-memory and tumor-specific T cells also expand, allowing rejection of solid tumors with CAR antigen loss. Supported by improved endogenous immunity, CAR-T cells can now co-deploy peptide antigens with RN7SL1 to enhance efficacy, even when heterogenous CAR antigen tumors lack adequate neoantigens.

Microbiota-Nourishing Immunity: A Guide to Understanding Our Microbial Self.

In ecological terms, the microbiome is defined as the microbiota and its environment, a definition that encompasses the human host. The size, species composition, and biogeography of microbial communities is shaped by host interactions, and, in turn, the microbiota influences many aspects of human health. Here we discuss the concept of microbiota-nourishing immunity, a host-microbe chimera composed of the microbiota and host factors that shape the microbial ecosystem, which functions in conferring colonization resistance against pathogens. We propose that dysbiosis is a biomarker of a weakening in microbiota-nourishing immunity and that homeostasis can be defined as a state of immune competence. Microbiota-nourishing immunity thus provides a conceptual framework to further examine the mechanisms that preserve a healthy microbiome and the drivers and consequences of dysbiosis.

Neurovascular Complications of Iatrogenic Fusarium solani Meningitis.

A multinational outbreak of nosocomial fusarium meningitis occurred among immunocompetent patients who had undergone surgery with epidural anesthesia in Mexico. The pathogen involved had a high predilection for the brain stem and vertebrobasilar arterial system and was associated with high mortality from vessel injury. Effective treatment options remain limited; in vitro susceptibility testing of the organism suggested that it is resistant to all currently approved antifungal medications in the United States. To highlight the severe complications associated with fusarium infection acquired in this manner, we report data, clinical courses, and outcomes from 13 patients in the outbreak who presented with symptoms after a median delay of 39 days.

Tumour DDR1 promotes collagen fibre alignment to instigate immune exclusion.

Immune exclusion predicts poor patient outcomes in multiple malignancies, including triple-negative breast cancer (TNBC)1. The extracellular matrix (ECM) contributes to immune exclusion2. However, strategies to reduce ECM abundance are largely ineffective or generate undesired outcomes3,4. Here we show that discoidin domain receptor 1 (DDR1), a collagen receptor with tyrosine kinase activity5, instigates immune exclusion by promoting collagen fibre alignment. Ablation of Ddr1 in tumours promotes the intratumoral penetration of T cells and obliterates tumour growth in mouse models of TNBC. Supporting this finding, in human TNBC the expression of DDR1 negatively correlates with the intratumoral abundance of anti-tumour T cells. The DDR1 extracellular domain (DDR1-ECD), but not its intracellular kinase domain, is required for immune exclusion. Membrane-untethered DDR1-ECD is sufficient to rescue the growth of Ddr1-knockout tumours in immunocompetent hosts. Mechanistically, the binding of DDR1-ECD to collagen enforces aligned collagen fibres and obstructs immune infiltration. ECD-neutralizing antibodies disrupt collagen fibre alignment, mitigate immune exclusion and inhibit tumour growth in immunocompetent hosts. Together, our findings identify a mechanism for immune exclusion and suggest an immunotherapeutic target for increasing immune accessibility through reconfiguration of the tumour ECM.

An Immunocompetent Mongolian Gerbil Model for Hepatitis E Virus Genotype 1 Infection.

BACKGROUND & AIMS: Hepatitis E virus (HEV), primarily genotype 1 (HEV-1), causes approximately 20.1 million infections, 44,000 deaths, and 3000 stillbirths annually. Current evidence indicates that HEV-1 is only transmitted in humans. Here, we evaluated whether Mongolian gerbils can serve as animal models for HEV-1 infection. METHODS: Mongolian gerbils were used for HEV-1 and hepatitis E virus genotype 3 infection experiments. HEV infection parameters, including detection of HEV RNA and HEV antigen, liver function assessment, and histopathology, were evaluated. RESULTS: We adapted a clinical isolate of HEV-1 for Mongolian gerbils by serial passaging in feces of aged male gerbils. The gerbil-adapted strain obtained at passage 3 induced a robust, acute HEV infection, characterized by stable fecal virus shedding, elevated liver enzymes, histopathologic changes in the liver, and seroconversion to anti-HEV. An infectious complementary DNA clone of the adapted virus was generated. HEV-1-infected pregnant gerbils showed a high rate of maternal mortality and vertical transmission. HEV RNA or antigens were detected in the liver, kidney, intestine, placenta, testis, and fetus liver. Liver and placental transcriptomic analyses indicated activation of host immunity. Tacrolimus prolonged HEV-1 infection, whereas ribavirin cleared infection. The protective efficacy of a licensed HEV vaccine was validated using this model. CONCLUSIONS: HEV-1 efficiently infected Mongolian gerbils. This HEV-1 infection model will be valuable for investigating hepatitis E immunopathogenesis and evaluating vaccines and antivirals against HEV.

Understanding immunosenescence to improve responses to vaccines.

In the older adult, the benefits of vaccination to prevent infectious disease are limited, mainly because of the adaptive immune system's inability to generate protective immunity. The age-dependent decrease in immunological competence, often referred to as 'immunosenescence', results from the progressive deterioration of innate and adaptive immune responses. Most insights into mechanisms of immunological aging have been derived from studies of mouse models. In this Review, we explore how well such models are applicable to understanding the aging process throughout the 80-100 years of human life and discuss recent advances in identifying and characterizing the mechanisms that underlie age-associated defective adaptive immunity in humans.

Environmental and genetic activation of a brain-adipocyte BDNF/leptin axis causes cancer remission and inhibition.

Cancer is influenced by its microenvironment, yet broader, environmental effects also play a role but remain poorly defined. We report here that mice living in an enriched housing environment show reduced tumor growth and increased remission. We found this effect in melanoma and colon cancer models, and that it was not caused by physical activity alone. Serum from animals held in an enriched environment (EE) inhibited cancer proliferation in vitro and was markedly lower in leptin. Hypothalamic brain-derived neurotrophic factor (BDNF) was selectively upregulated by EE, and its genetic overexpression reduced tumor burden, whereas BDNF knockdown blocked the effect of EE. Mechanistically, we show that hypothalamic BDNF downregulated leptin production in adipocytes via sympathoneural beta-adrenergic signaling. These results suggest that genetic or environmental activation of this BDNF/leptin axis may have therapeutic significance for cancer.

Perturbations of the T-cell receptor repertoire in response to SARS-CoV-2 in immunocompetent and immunocompromised individuals.

BACKGROUND: Functional T-cell responses are essential for virus clearance and long-term protection after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, whereas certain clinical factors, such as older age and immunocompromise, are associated with worse outcome. OBJECTIVE: We sought to study the breadth and magnitude of T-cell responses in patients with coronavirus disease 2019 (COVID-19) and in individuals with inborn errors of immunity (IEIs) who had received COVID-19 mRNA vaccine. METHODS: Using high-throughput sequencing and bioinformatics tools to characterize the T-cell receptor ß repertoire signatures in 540 individuals after SARS-CoV-2 infection, 31 IEI recipients of COVID-19 mRNA vaccine, and healthy controls, we quantified HLA class I- and class II-restricted SARS-CoV-2-specific responses and also identified several HLA allele-clonotype motif associations in patients with COVID-19, including a subcohort of anti-type 1 interferon (IFN-1)-positive patients. RESULTS: Our analysis revealed that elderly patients with COVID-19 with critical disease manifested lower SARS-CoV-2 T-cell clonotype diversity as well as T-cell responses with reduced magnitude, whereas the SARS-CoV-2-specific clonotypes targeted a broad range of HLA class I- and class II-restricted epitopes across the viral proteome. The presence of anti-IFN-I antibodies was associated with certain HLA alleles. Finally, COVID-19 mRNA immunization induced an increase in the breadth of SARS-CoV-2-specific clonotypes in patients with IEIs, including those who had failed to seroconvert. CONCLUSIONS: Elderly individuals have impaired capacity to develop broad and sustained T-cell responses after SARS-CoV-2 infection. Genetic factors may play a role in the production of anti-IFN-1 antibodies. COVID-19 mRNA vaccines are effective in inducing T-cell responses in patients with IEIs.

Encephalitozoon cuniculi Microsporidia in Cerebrospinal Fluid from Immunocompetent Patients, Czech Republic.

We retrospectively analyzed of 211 frozen cerebrospinal fluid samples from immunocompetent persons in the Czech Republic and detected 6 Encephalitozoon cuniculi-positive samples. Microsporidiosis is generally underestimated and patients are not usually tested for microsporidia, but latent infection in immunodeficient and immunocompetent patients can cause serious complications if not detected and treated.

Burkholderia semiarida as Cause of Recurrent Pulmonary Infection in Immunocompetent Patient, China.

Burkholderia semiarida was previously identified solely as a plant pathogen within the Burkholderia cepacia complex. We present a case in China involving recurrent pneumonia attributed to B. semiarida infection. Of note, the infection manifested in an immunocompetent patient with no associated primary diseases and endured for >3 years.

Non-HIV Immunocompetent Patient with COVID-19 and Severe Pneumocystis jirovecii Pneumonia Co-Infection.

Pneumocystis jirovecii pneumonia is an opportunistic infection that affects HIV-infected and immunocompromised persons and rarely affects immunocompetent patients. However, after the advent of the COVID-19 pandemic, some COVID-19 patients without immunocompromise or HIV were infected with P. jirovecii. Clinical manifestations were atypical, easily misdiagnosed, and rapidly progressive, and the prognosis was poor.

Evaluating patient immunocompetence through antibody response to pneumococcal polysaccharide vaccine using a newly developed 23 serotype multiplexed assay.

Assessing T-cell independent antibody response to polysaccharide vaccines is crucial for diagnosing humoral immune deficiencies. However, immunocompetence criteria based on S. pneumoniae vaccination remain unclear. We evaluated IgG antibody vaccine response in healthy individuals to establish interpretive criteria. Pre- and 4-week post-vaccination sera were collected from 79 adults. Antibody concentrations to PNEUMOVAX 23 serotypes were measured using a multiplexed platform. Immunocompetence was determined by fold increase in post-vaccination response, percentage of serotypes achieving 4- or 2-fold antibody ratio, and post-vaccination concentration ≥ 1.3 µg/mL. Immunogenicity varied widely across the 23 serotypes (26.6% to 94.9% for ≥4-fold increase, 51.9% to 98.7% for ≥2-fold increase). Immunocompetence based on historic criteria of ≥4-fold increase in antibody ratio to ≥70% of serotypes was low (72.2%), but increased to 98.7% with criteria of at least a 2-fold increase and/or post-vaccination concentration ≥ 1.3 µg/mL. Current criteria for assessing immunocompetence may be overly stringent and require updating.

Sulfuric acid-induced skin neoplasms in immunocompetent mice.

This study investigates the carcinogenic potential of chronic dermal exposure (16 weeks) to sulfuric acid (SA) in immunocompetent mice. Clinical assessments, histopathological analyses, immunohistochemical analyses and biochemical assays were conducted to evaluate skin irritation, oxidative stress biomarkers and the potential carcinogenic effect of SA. Results indicated that prolonged exposure to SA leads to various alterations in skin structure, notably inflammation, preneoplastic and neoplastic proliferation in hair follicles, as well as hyperkeratosis and acanthosis, resulting in an increased epidermal thickness of 98.50 ± 21.6 µm. Immunohistochemistry analysis further corroborates these observations, showcasing elevated nuclear expression of p53 and Ki-67, with a significant mitotic index of (57.5% ± 2.5%). Moreover, biochemical analyses demonstrate that SA induces lipid peroxidation in the skin, evidenced by a high level of Malondialdehyde and a consequential reduction in catalase activity. These findings suggest that prolonged exposure to SA can induce skin neoplasms, highlighting the need for stringent safety measures in environments where SA is frequently used. This study underscores the potential occupational health risks associated with SA exposure.

Disseminated Blastomycosis in an Immunocompetent Patient.

Blastomycoses dermatitidis is a dimorphic fungus that can cause disseminated blastomycosis with varying clinical manifestations and multiorgan involvement. While blastomycosis commonly causes pulmonary disease, extrapulmonary spread can result in skin, bone, and central nervous system involvement. Cutaneous blastomycosis can present as pustular lesions that evolve into ulcerative or verrucous plaques. We present a case of disseminated blastomycosis in an immunocompetent patient with both pulmonary and cutaneous features. The patient developed hypoxic respiratory failure and was subsequently diagnosed with disseminated blastomycosis after undergoing bronchoscopy with bronchial washing. He was found to have ulcerative nasal lesions as part of his disseminated disease. He was successfully treated with amphotericin B and ultimately discharged from the hospital.

Establishment of orthotopic osteosarcoma animal models in immunocompetent rats through muti-rounds of in-vivo selection.

Immunodeficient murine models are usually used as the preclinical models of osteosarcoma. Such models do not effectively simulate the process of tumorigenesis and metastasis. Establishing a suitable animal model for understanding the mechanism of osteosarcoma and the clinical translation is indispensable. The UMR-106 cell suspension was injected into the marrow cavity of Balb/C nude mice. Tumor masses were harvested from nude mice and sectioned. The tumor fragments were transplanted into the marrow cavities of SD rats immunosuppressed with cyclosporine A. Through muti-rounds selection in SD rats, we constructed orthotopic osteosarcoma animal models using rats with intact immune systems. The primary tumor cells were cultured in-vitro to obtain the immune-tolerant cell line. VX2 tumor fragments were transplanted into the distal femur and parosteal radius of New Zealand white rabbit to construct orthotopic osteosarcoma animal models in rabbits. The rate of tumor formation in SD rats (P1 generation) was 30%. After four rounds of selection and six rounds of acclimatization in SD rats with intact immune systems, we obtained immune-tolerant cell lines and established the orthotopic osteosarcoma model of the distal femur in SD rats. Micro-CT images confirmed tumor-driven osteolysis and the bone destruction process. Moreover, the orthotopic model was also established in New Zealand white rabbits by implanting VX2 tumor fragments into rabbit radii and femurs. We constructed orthotopic osteosarcoma animal models in rats with intact immune systems through muti-rounds in-vivo selection and the rabbit osteosarcoma model.

Longitudinally extensive posterolateral myelitis revealing invasive CNS aspergillosis in an immunocompetent patient.

BACKGROUND: Fungal infections of the central nervous system usually affect immunocompromised patients. Primary Aspergillus myelitis has never been described. REPORT: A 45-year-old immunocompetent male with subacute paraplegia was treated for inflammatory myelitis before clinical deterioration requiring mechanical ventilation. Purulent meningitis preceded the formation of a paraspinal nodule biopsied by neurosurgery. Histopathological analysis revealed the presence of fungal hyphae, and polymerase chain reaction was positive for Aspergillus fumigatus. No cause of immunodeficiency was identified in this patient. DISCUSSION: Primary Aspergillus myelitis may be confused with inflammatory myelitis and should be considered even in the absence of apparent immunosuppression.

Prevalence and progression of pneumonia in immunocompetent adults with varicella.

Pneumonia is the most common complication of varicella infections. Although previous studies have tended to focus mainly on immunocompromised patients, varicella pneumonia can also occur in healthy adults. Therefore, in this study, we aimed to assess the progression of varicella pneumonia in immunocompetent hosts. This retrospective study involved immunocompetent adult outpatients with varicella who attended the adult Fever Emergency facility of Peking University Third Hospital from April 1, 2020, to October 31, 2022. Varicella pneumonia was defined as a classic chickenpox-type rash in patients with infiltrates on chest computed tomography. The study included 186 patients, 57 of whom had a contact history of chickenpox exposure. Antiviral pneumonia therapy was administered to 175 patients by treating physicians. Computed tomography identified pneumonia in 132 patients, although no deaths from respiratory failure occurred. Seventy of the discharged patients were subsequently contacted, all of whom reported being well. Follow-up information, including computed tomography findings, was available for 37 patients with pneumonia, among whom 24 reported complete resolution whereas the remaining 13 developed persistent calcifications. Notably, we established that the true incidence of varicella pneumonia is higher than that previously reported, although the prognosis for immunocompetent hosts is generally good.

No evidence for an up-regulation of female immune function in response to elevated risk of sexual conflict.

Sexual conflict is widespread among sexually reproducing organisms. Phenotypic plasticity in female resistance traits has the potential to moderate the harm imposed by males during mating, yet female plasticity has rarely been explored. In this experiment, we investigated whether female seed beetles invest more in immunocompetence, measured as phenoloxidase (PO) capacity, when exposed to cues signalling a greater risk of sexual conflict. Risk perception was manipulated by housing focal individuals alone or with a companion as developing larvae, followed by exposure to a mating-free male- or female-biased social environment when adults. We predicted that females exposed to cues of increased sexual conflict would have increased PO capacity. However, PO capacity did not differ between either larval or adult social treatments. Our results suggest that females may not perceive a risk to their fitness on the basis of increased male presence or are unable to adjust this aspect of their phenotype in response to that risk.

Measuring immunocompetence in the natural population and captive individuals of noble pen shell Pinna nobilis affected by Pinna nobilis Picornavirus (PnPV).

Mass Mortality Events (MMEs) affecting the noble pen shell Pinna nobilis have been reported since 2016. In this work, we used an in vitro flow cytometric assay to evaluate phagocytosis, coupled with cytology and Electron Microscopy (TEM), to define animal immunocompetence following infection by P. nobilis Picornavirus (PnPV). The study was performed on 27 animals in July 2021 and May 2022 on two natural population from the Ebro Delta (Catalonia, Spain) and animals maintained in captivity at facilities in Valencia and Murcia Aquarium. Hemolymph was collected in the field and in captivity as a non-destructive sampling method. Based on dimension and internal complexity, flow cytometry identified three haemocyte types, distinguished in granulocytes, hyalinocytes and a third type, biggest in size and with high internal complexity and granularity. Those cells corresponded at ultrastructure to hemocytes with advanced phases of PnPV infection and related to cytopathic effect of the replicating virus displaying numerous Double Membrane Vesicles (DMVs) and cells corpse fusion. The results showed that pen shell in captivity had significantly lower Total Hemocyte Count (THC) compared with natural population of Alfacs Bay (mean number of 7-9 x 104 vs 2-5 x 105 cells/mL, respectively). FACS (Fluorescence-activated cell sorting) based phagocytosis analysis demonstrate that animals in captivity at IMEDMAR-UCV and Murcia Aquarium, had scarce or absent ability to phagocyte the two stimuli (Staphylococcus aureus and Zymosan A) (10,2 % ± 1,7 of positives) if compared with the natural population in Alfacs Bay (28,5 % ± 5,6 of positive). Ultrastructure images showed that PnPV itself can lead to an alteration of the hemocyte cytoskeleton, impairing the capabilities to perform an active phagocytosis and an efficient phagolysosome fusion.

Unusual Cutibacterium acnes splenic abscess with bacteremia in an immunocompetent man: phylotyping and clonal complex analysis.

BACKGROUND: Cutibacterium acnes is an anaerobic bacterium mostly implicated in cutaneous and body-implant infections. Splenic abscess is a rare entity and C. acnes abscesses have only exceptionally been reported. We describe a spontaneous splenic C. acnes abscess in an immunocompetent man with no predisposing factors or identified portal of entry. His isolates were subjected to single-locus sequence typing (SLST) to explore their genetic relatedness and better understand this rare infection. CASE PRESENTATION: A splenic abscess was diagnosed on a computed-tomography scan in a 74-year-old man with chronic abdominal pain. No risk factor was identified. Abscess-drained pus and post-drainage blood cultures grew C. acnes. SLST of abscess and blood isolates showed that they belonged to the same C. acnes SLST type C1 found in normal skin and rarely in inflammatory skin disease. Specific virulence factors could not be identified. CONCLUSION: C. acnes abscesses are extremely rare and can develop in immunocompetent patients without an identifiable portal of entry. Molecular typing of clinical isolates can help confirm infection (versus contamination) and enables genetic background comparisons. Further research is needed to understand C. acnes tropism and virulence.