Integrated Analysis of Single-Cell and Bulk RNA Sequencing Data Reveals Memory-like NK Cell Subset Associated with Mycobacterium tuberculosis Latency.

Natural killer (NK) cells are innate-like lymphocytes that belong to the family of type-1 innate lymphoid cells and rapidly respond to virus-infected and tumor cells. In this study, we have combined scRNA-seq data and bulk RNA-seq data to define the phenotypic and molecular characteristics of peripheral blood NK cells. While the role of NK cells in immune surveillance against virus infections and tumors has been well established, their contribution to protective responses to other intracellular microorganisms, such as Mycobacterium tuberculosis (Mtb), is still poorly understood. In this study, we have combined scRNA-seq data and bulk RNA-seq data to illuminate the molecular characteristics of circulating NK cells in patients with active tuberculosis (TB) disease and subjects with latent Mtb infection (LTBI) and compared these characteristics with those of healthy donors (HDs) and patients with non-TB other pulmonary infectious diseases (ODs). We show here that the NK cell cluster was significantly increased in LTBI subjects, as compared to patients with active TB or other non-TB pulmonary diseases and HD, and this was mostly attributable to the expansion of an NK cell population expressing KLRC2, CD52, CCL5 and HLA-DRB1, which most likely corresponds to memory-like NK2.1 cells. These data were validated by flow cytometry analysis in a small cohort of samples, showing that LTBI subjects have a significant expansion of NK cells characterized by the prevalence of memory-like CD52+ NKG2C+ NK cells. Altogether, our results provide some new information on the role of NK cells in protective immune responses to Mtb.

B-Cell Receptor Signaling Is Thought to Be a Bridge between Primary Sjogren Syndrome and Diffuse Large B-Cell Lymphoma.

Primary Sjogren syndrome (pSS) is the second most common autoimmune disorder worldwide, which, in the worst scenario, progresses to Non-Hodgkin Lymphoma (NHL). Despite extensive studies, there is still a lack of knowledge about developing pSS for NHL. This study focused on cells' signaling in pSS progression to the NHL type of diffuse large B-cell lymphoma (DLBCL). Using bulk RNA and single cell analysis, we found five novel pathologic-independent clusters in DLBCL based on cells' signaling. B-cell receptor (BCR) signaling was identified as the only enriched signal in DLBCL and pSS peripheral naive B-cells or salivary gland-infiltrated cells. The evaluation of the genes in association with BCR has revealed that targeting CD79A, CD79B, and LAMTOR4 as the shared genes can provide novel biomarkers for pSS progression into lymphoma.

Interleukin 9 neutralisation reduces collagen-induced arthritis severity in mouse models.

OBJECTIVES: Interleukin 9 (IL-9) is a mediator of tissue damage in several inflammatory diseases. In this study we aimed to evaluate the effects of in vivo IL-9 neutralisation in mice developing collagen induced arthritis (CIA). METHODS: DBA/1 were immunised with collagen in Freund's complete adjuvant (CFA) to induce arthritis. Anti-IL-9 mAb was injected in mice after the onset of arthritis (Group A) or on the same day as sensitisation and again on the day of the challenge (Group B). Histological analysis was performed in joints of mice and spleen cells were also analysed by flow cytometry. A geneset analysis was carried out on whole tarsal joint tissue transcriptomes. RESULTS: IL-9 was over-expressed in swollen joints of mice developing arthritis. Treatment with anti-IL-9 mAb after arthritis onset efficiently down-modulated the severity of joint inflammation. Similarly, anti-IL-9 mAb administered on the same day as sensitisation and on the day of challenge also delayed the onset of arthritis. Anti-IL-9 mAb injection after the onset of arthritis was associated with a decrease of CD4+ TNF-α+ cells and an increase of CD4+ FoxP3+ IL-10+ cells. Geneset analysis in CIA showed an up-regulation of GATA3 with no significant direct interactions between IL-9 and GATA3, which instead was mediated by IL-5 through STAT6. CONCLUSIONS: Our results suggest that IL-9 is involved in the immunopathogenesis of CIA. Further implications for the clinical translation of our findings are discussed.

The Abundance of Tumor-Infiltrating CD8+ Tissue Resident Memory T Lymphocytes Correlates with Patient Survival in Glioblastoma.

Glial tumors alone account for 40% of all CNS tumors and present a low survival rate. The tumor microenvironment is a critical regulator of tumor progression and therapeutic effectiveness in glioma. Growing evidence from numerous studies of human solid tumor-infiltrating CD8+ T cells indicates that tissue-resident memory T cells (TRM) represent a substantial subpopulation of tumor-infiltrating lymphocytes (TILs). Although it is reported that some types of cancer patients with high immune infiltration tend to have better outcomes than patients with low immune infiltration, it seems this does not happen in gliomas. This study aimed to characterize TRMs cells in the glioma tumor microenvironment to identify their potential predictive and prognostic role and the possible therapeutic applications. Fluorescence activated cell sorting (FACS) analysis and immunofluorescence staining highlighted a statistically significant increase in CD8+ TRM cells (CD103+ and CD69+ CD8+ T cells) in gliomas compared to control samples (meningioma). In-silico analysis of a dataset of n = 153 stage IV glioma patients confirmed our data. Moreover, the gene expression analysis showed an increase in the expression of TRM-related genes in tumor tissues compared to normal tissues. This analysis also highlighted the positive correlation between genes associated with CD8+ TRM and TILs, indicating that CD8+ TRMs cells are present among the infiltrating T cells. Finally, high expression of Integrin subunit alpha E (ITGAE), the gene coding for the integrin CD103, and high CD8+ TILs abundance were associated with more prolonged survival, whereas high ITGAE expression but low CD8+ TILs abundance were associated with lower survival.

Interleukin-6 Is a Promising Marker of COVID-19 in Children: A Case Series of 2 Brothers with Severe COVID-19 Pneumonia.

BACKGROUND To date, Coronavirus disease 2019 (COVID-19) remains a global health concern, with fatalities mostly in older age groups with underlying medical conditions, while children are less likely to manifest severe symptoms. CASE REPORT We describe the clinical cases of 2 brothers admitted to our Children's Hospital for persistent fever and cough during the COVID-19 pandemic. Case 1. A 1.5-year-old boy had fever, expiratory dyspnea, desaturation, oxygen saturation 94-96% with O2, and bilateral hissing and crackling rales. His interleukin-6 level in the acute phase of the disease was 100.41 and at the resolution it was 46.2 pg/ml. Treatment with amoxicillin plus clavulanic acid, methylprednisolone, and O2 allowed progressive improvement of clinical conditions and laboratory data. Case 2. A 3-month-old toddler was admitted to our hospital for fever, cough, and tachypnea, which started 2 days before hospitalization. He had fever, cough, conjunctivitis, mucous rhinorrhea, and 99% oxygen saturation on room air. Thorax auscultation showed whistles and buzzes. He had a positive molecular test result from a COVID-19 swab. Interleukin-6 levels during all the phases of the disease were <6.25 pg/ml. The chest X-ray was normal. Treatment with azithromycin and methylprednisolone was followed by progressive improvement of clinical conditions. CONCLUSIONS These cases support the strong correlation between interleukin-6 levels and severe clinical manifestations such as COVID-19 pneumonia, and this marker predicts a more severe clinical outcome in children. Testing serum levels of interleukin-6 in children with COVID-19 could be useful to better understand the outcome of lung damage.

Immunity and Nutrition: The Right Balance in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is an increasingly urgent medical problem that strongly impairs quality of life for patients. A global rise in incidence has been observed over the last few decades, with the highest incidence rates recorded in North America and Europe. Still, an increased incidence has been reported in the last ten years in newly industrialized countries in Asia, including China and India, both with more than one billion inhabitants. These data underline that IBD is an urgent global health problem. In addition, it is estimated that between 20% and 30% of IBD patients will develop colorectal cancer (CRC) within their lifetime and CRC mortality is approximately 50% amongst IBD patients. Although the exact etiology of IBD is still being defined, it is thought to be due to a complex interaction between many factors, including defects in the innate and adaptive immune system; microbial dysbiosis, i.e., abnormal levels of, or abnormal response to, the gastrointestinal microbiome; a genetic predisposition; and several environmental factors. At present, however, it is not fully understood which of these factors are the initiators of inflammation and which are compounders. The purpose of this review is to analyze the complex balance that exists between these elements to maintain intestinal homeostasis and prevent IBD or limit adverse effects on people's health.

A Rapid and Simple Multiparameter Assay to Quantify Spike-Specific CD4 and CD8 T Cells after SARS-CoV-2 Vaccination: A Preliminary Report.

mRNA and Adenovirus vaccines for COVID-19 are used to induce humoral and cell-mediated immunity, with the aim to generate both SARS-CoV-2 B and T memory cells. In present study, we described a simple assay to detect and quantify Spike-specific CD4+ and CD8+ T cell responses induced by vaccination in healthy donors and in subjects with B cell compart impairment, in which antibody response is absent due to primary immunodeficiencies or CD20 depleting therapy. We detect and quantified memory T cell immune responses against SARS-CoV-2 evocated by vaccination in both groups, irrespective to the humoral response. Furthermore, we identified TNF-α as the main cytokine produced by T memory cells, after antigen-specific stimulation in vitro, that could be considered, other than IFN-γ, an additional biomarker of induction of T memory cells upon vaccination. Further studies on the vaccine-induced T cell responses could be crucial, not only in healthy people but also in immunocompromised subjects, where antigen specific T cells responses play a protective role against SARS-CoV-2.

Tumor-Derived Small Extracellular Vesicles Induce Pro-Inflammatory Cytokine Expression and PD-L1 Regulation in M0 Macrophages via IL-6/STAT3 and TLR4 Signaling Pathways.

Tumor-associated macrophages play a key role in promoting tumor progression by exerting an immunosuppressive phenotype associated with the expression of programmed cell death ligand 1 (PD-L1). It is well known that tumor-derived small extracellular vesicles (SEVs) affect the tumor microenvironment, influencing TAM behavior. The present study aimed to examine the effect of SEVs derived from colon cancer and multiple myeloma cells on macrophage functions. Non-polarized macrophages (M0) differentiated from THP-1 cells were co-cultured with SEVs derived from a colorectal cancer (CRC) cell line, SW480, and a multiple myeloma (MM) cell line, MM1.S. The expression of PD-L1, interleukin-6 (IL-6), and other inflammatory cytokines as well as of the underlying molecular mechanisms were evaluated. Our results indicate that SEVs can significantly upregulate the expressions of PD-L1 and IL-6 at both the mRNA and protein levels and can activate the STAT3 signaling pathway. Furthermore, we identified the TLR4/NF-kB pathway as a convergent mechanism for SEV-mediated PD-L1 expression. Overall, these preliminary data suggest that SEVs contribute to the formation of an immunosuppressive microenvironment.

Role of hematopoietic cells in Mycobacterium tuberculosis infection.

Tuberculosis remains one of the most significant causes of mortality worldwide and the current situation shows a re-emergence of TB due to the emergence of new antibiotic-resistant strains and the widespread of disease caused by immunodeficiencies. For these reasons, a big effort is made to improve the therapeutic strategies against Mycobacterium tuberculosis and to perform new therapeutic and diagnostic strategies. This review analyzes the various hematopoietic populations, their role and the different changes they undergo during Mycobacterium tuberculosis infection or disease. We have examined the population of lymphocytes, monocytes, neutrophils, eosinophils and platelets, in orderto understand how each of them is modulated during the course of infection/disease. In this way it will be possible to highlight the correlations between these cell populations and the different stages of tubercular infection. In fact, Mycobacterium tuberculosis is able to influence both proliferation and differentiation of hematopoietic stem cells. Several studies have highlighted that Mycobacterium tuberculosis can also infect progenitor cells in the bone marrow during active disease driving towards an increase of myeloid differentiation. This review focuses how the different stages of tubercular infection could impact on the different hematopoietic populations, with the aim to correlate the changes of different populations as biomarkers useful to discriminate infection from disease and to evaluate the effectiveness of new therapies.

Innate Immune Response to Tick-Borne Pathogens: Cellular and Molecular Mechanisms Induced in the Hosts.

Many pathogens are transmitted by tick bites, including Anaplasma spp., Ehrlichia spp., Rickettsia spp., Babesia and Theileria sensu stricto species. These pathogens cause infectious diseases both in animals and humans. Different types of immune effector mechanisms could be induced in hosts by these microorganisms, triggered either directly by pathogen-derived antigens or indirectly by molecules released by host cells binding to these antigens. The components of innate immunity, such as natural killer cells, complement proteins, macrophages, dendritic cells and tumor necrosis factor alpha, cause a rapid and intense protection for the acute phase of infectious diseases. Moreover, the onset of a pro-inflammatory state occurs upon the activation of the inflammasome, a protein scaffold with a key-role in host defense mechanism, regulating the action of caspase-1 and the maturation of interleukin-1ß and IL-18 into bioactive molecules. During the infection caused by different microbial agents, very similar profiles of the human innate immune response are observed including secretion of IL-1α, IL-8, and IFN-α, and suppression of superoxide dismutase, IL-1Ra and IL-17A release. Innate immunity is activated immediately after the infection and inflammasome-mediated changes in the pro-inflammatory cytokines at systemic and intracellular levels can be detected as early as on days 2-5 after tick bite. The ongoing research field of "inflammasome biology" focuses on the interactions among molecules and cells of innate immune response that could be responsible for triggering a protective adaptive immunity. The knowledge of the innate immunity mechanisms, as well as the new targets of investigation arising by bioinformatics analysis, could lead to the development of new methods of emergency diagnosis and prevention of tick-borne infections.

Mycobacterium tuberculosis Drives Expansion of Low-Density Neutrophils Equipped With Regulatory Activities.

In human tuberculosis (TB) neutrophils represent the most commonly infected phagocyte but their role in protection and pathology is highly contradictory. Moreover, a subset of low-density neutrophils (LDNs) has been identified in TB, but their functions remain unclear. Here, we have analyzed total neutrophils and their low-density and normal-density (NDNs) subsets in patients with active TB disease, in terms of frequency, phenotype, functional features, and gene expression signature. Full-blood counts from Healthy Donors (H.D.), Latent TB infected, active TB, and cured TB patients were performed. Frequency, phenotype, burst activity, and suppressor T cell activity of the two different subsets were assessed by flow cytometry while NETosis and phagocytosis were evaluated by confocal microscopy. Expression analysis was performed by using the semi-quantitative RT-PCR array technology. Elevated numbers of total neutrophils and a high neutrophil/lymphocyte ratio distinguished patients with active TB from all the other groups. PBMCs of patients with active TB disease contained elevated percentages of LDNs compared with those of H.D., with an increased expression of CD66b, CD33, CD15, and CD16 compared to NDNs. Transcriptomic analysis of LDNs and NDNs purified from the peripheral blood of TB patients identified 12 genes differentially expressed: CCL5, CCR5, CD4, IL10, LYZ, and STAT4 were upregulated, while CXCL8, IFNAR1, NFKB1A, STAT1, TICAM1, and TNF were downregulated in LDNs, as compared to NDNs. Differently than NDNs, LDNs failed to phagocyte live Mycobacterium tuberculosis (M. tuberculosis) bacilli, to make oxidative burst and NETosis, but caused significant suppression of antigen-specific and polyclonal T cell proliferation which was partially mediated by IL-10. These insights add a little dowel of knowledge in understanding the pathogenesis of human TB.

Anti-16-kilodalton mycobacterial protein immunoglobulin m levels in healthy but purified protein derivative-reactive children decrease after chemoprophylaxis.

Serum responses against Mycobacterium tuberculosis HSP16 were determined for children with tuberculosis (TB) and for healthy purified protein derivative (PPD)-positive and PPD-negative children. Immunoglobulin G (IgG) and IgM responses were higher for TB patients than for other groups. After chemotherapy, IgM and IgG responses decreased for TB patients and PPD-positive subjects. Monitoring of anti-M. tuberculosis HSP16 responses could assist in the management of pediatric TB.