The Arms Race Between KRAB-Zinc Finger Proteins and Endogenous Retroelements and Its Impact on Mammals.

Nearly half of the human genome consists of endogenous retroelements (EREs) and their genetic remnants, a small fraction of which carry the potential to propagate in the host genome, posing a threat to genome integrity and cell/organismal survival. The largest family of transcription factors in tetrapods, the Krüppel-associated box domain zinc finger proteins (KRAB-ZFPs), binds to specific EREs and represses their transcription. Since their first appearance over 400 million years ago, KRAB-ZFPs have undergone dramatic expansion and diversification in mammals, correlating with the invasions of new EREs. In this article we review our current understanding of the structure, function, and evolution of KRAB-ZFPs and discuss growing evidence that the arms race between KRAB-ZFPs and the EREs they target is a major driving force for the evolution of new traits in mammals, often accompanied by domestication of EREs themselves.

Mechanisms governing activity-dependent synaptic pruning in the developing mammalian CNS.

Almost 60 years have passed since the initial discovery by Hubel and Wiesel that changes in neuronal activity can elicit developmental rewiring of the central nervous system (CNS). Over this period, we have gained a more comprehensive picture of how both spontaneous neural activity and sensory experience-induced changes in neuronal activity guide CNS circuit development. Here we review activity-dependent synaptic pruning in the mammalian CNS, which we define as the removal of a subset of synapses, while others are maintained, in response to changes in neural activity in the developing nervous system. We discuss the mounting evidence that immune and cell-death molecules are important mechanistic links by which changes in neural activity guide the pruning of specific synapses, emphasizing the role of glial cells in this process. Finally, we discuss how these developmental pruning programmes may go awry in neurodevelopmental disorders of the human CNS, focusing on autism spectrum disorder and schizophrenia. Together, our aim is to give an overview of how the field of activity-dependent pruning research has evolved, led to exciting new questions and guided the identification of new, therapeutically relevant mechanisms that result in aberrant circuit development in neurodevelopmental disorders.

Hobit confers tissue-dependent programs to type 1 innate lymphoid cells.

Identification of type 1 innate lymphoid cells (ILC1s) has been problematic. The transcription factor Hobit encoded by Zfp683 has been proposed as a major driver of ILC1 programs. Using Zfp683 reporter mice, we showed that correlation of Hobit expression with ILC1s is tissue- and context-dependent. In liver and intestinal mucosa, Zfp683 expression correlated well with ILC1s; in salivary glands, Zfp683 was coexpressed with the natural killer (NK) master transcription factors Eomes and TCF1 in a unique cell population, which we call ILC1-like NK cells; during viral infection, Zfp683 was induced in conventional NK cells of spleen and liver. The impact of Zfp683 deletion on ILC1s and NK cells was also multifaceted, including a marked decrease in granzyme- and interferon-gamma (IFNγ)-producing ILC1s in the liver, slightly fewer ILC1s and more Eomes+ TCF1+ ILC1-like NK cells in salivary glands, and only reduced production of granzyme B by ILC1 in the intestinal mucosa. NK cell-mediated control of viral infection was unaffected. We conclude that Hobit has two major impacts on ILC1s: It sustains liver ILC1 numbers, while promoting ILC1 functional maturation in other tissues by controlling TCF1, Eomes, and granzyme expression.

Hypertension: Do Inflammation and Immunity Hold the Key to Solving this Epidemic?

Elevated cardiovascular risk including stroke, heart failure, and heart attack is present even after normalization of blood pressure in patients with hypertension. Underlying immune cell activation is a likely culprit. Although immune cells are important for protection against invading pathogens, their chronic overactivation may lead to tissue damage and high blood pressure. Triggers that may initiate immune activation include viral infections, autoimmunity, and lifestyle factors such as excess dietary salt. These conditions activate the immune system either directly or through their impact on the gut microbiome, which ultimately produces chronic inflammation and hypertension. T cells are central to the immune responses contributing to hypertension. They are activated in part by binding specific antigens that are presented in major histocompatibility complex molecules on professional antigen-presenting cells, and they generate repertoires of rearranged T-cell receptors. Activated T cells infiltrate tissues and produce cytokines including interleukin 17A, which promote renal and vascular dysfunction and end-organ damage leading to hypertension. In this comprehensive review, we highlight environmental, genetic, and microbial associated mechanisms contributing to both innate and adaptive immune cell activation leading to hypertension. Targeting the underlying chronic immune cell activation in hypertension has the potential to mitigate the excess cardiovascular risk associated with this common and deadly disease.

Adverse Mechanical Ventilation and Pneumococcal Pneumonia Induce Immune and Mitochondrial Dysfunctions Mitigated by Mesenchymal Stem Cells in Rabbits.

BACKGROUND: Mechanical ventilation for pneumonia may contribute to lung injury due to factors that include mitochondrial dysfunction, and mesenchymal stem cells may attenuate injury. This study hypothesized that mechanical ventilation induces immune and mitochondrial dysfunction, with or without pneumococcal pneumonia, that could be mitigated by mesenchymal stem cells alone or combined with antibiotics. METHODS: Male rabbits underwent protective mechanical ventilation (8 ml/kg tidal volume, 5 cm H2O end-expiratory pressure) or adverse mechanical ventilation (20 ml/kg tidal-volume, zero end-expiratory pressure) or were allowed to breathe spontaneously. The same settings were then repeated during pneumococcal pneumonia. Finally, infected animals during adverse mechanical ventilation received human umbilical cord-derived mesenchymal stem cells (3 × 106/kg, intravenous) and/or ceftaroline (20 mg/kg, intramuscular) or sodium chloride, 4 h after pneumococcal challenge. Twenty-four-hour survival (primary outcome), lung injury, bacterial burden, immune and mitochondrial dysfunction, and lung transcriptomes (secondary outcomes) were assessed. RESULTS: High-pressure adverse mechanical ventilation reduced the survival of infected animals (0%; 0 of 7) compared with spontaneous breathing (100%; 7 of 7) and protective mechanical ventilation (86%; 6 of 7; both P < 0.001), with higher lung pathology scores (median [interquartile ranges], 5.5 [4.5 to 7.0] vs. 12.6 [12.0 to 14.0]; P = 0.046), interleukin-8 lung concentrations (106 [54 to 316] vs. 804 [753 to 868] pg/g of lung; P = 0.012), and alveolar mitochondrial DNA release (0.33 [0.28 to 0.36] vs. 0.98 [0.76 to 1.21] ng/µl; P < 0.001) compared with infected spontaneously breathing animals. Survival (0%; 0 of 7; control group) was improved by mesenchymal stem cells (57%; 4 of 7; P = 0.001) or ceftaroline alone (57%; 4 of 7; P < 0.001) and improved even more with a combination treatment (86%; 6 of 7; P < 0.001). Mesenchymal stem cells reduced lung pathology score (8.5 [7.0 to 10.5] vs. 12.6 [12.0 to 14.0]; P = 0.043) and alveolar mitochondrial DNA release (0.39 (0.34 to 0.65) vs. 0.98 (0.76 to 1.21) ng/µl; P = 0.025). Mesenchymal stem cells combined with ceftaroline reduced interleukin-8 lung concentrations (665 [595 to 795] vs. 804 [753 to 868] pg/g of lung; P = 0.007) compared to ceftaroline alone. CONCLUSIONS: In this preclinical study, mesenchymal stem cells improved the outcome of rabbits with pneumonia and high-pressure mechanical ventilation by correcting immune and mitochondrial dysfunction and when combined with the antibiotic ceftaroline was synergistic in mitigating lung inflammation.

Cellular Immunity in COVID-19 Convalescents with PCR-Confirmed Infection but with Undetectable SARS-CoV-2-Specific IgG.

We investigated immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a group of convalescent, potential blood donors in Germany who had PCR-confirmed SARS-CoV-2 infection. Sixty days after onset of symptoms, 13/78 (17%) study participants had borderline or negative results to an ELISA detecting IgG against the S1 protein of SARS-CoV-2. We analyzed participants with PCR-confirmed infection who had strong antibody responses (ratio >3) as positive controls and participants without symptoms of SARS-CoV-2 infection and without household contact with infected patients as negative controls. Using interferon-γ ELISpot, we observed that 78% of PCR-positive volunteers with undetectable antibodies showed T cell immunity against SARS-CoV-2. We observed a similar frequency (80%) of T-cell immunity in convalescent donors with strong antibody responses but did not detect immunity in negative controls. We concluded that, in convalescent patients with undetectable SARS-CoV-2 IgG, immunity may be mediated through T cells.

Distinct cellular immune profiles in the airways and blood of critically ill patients with COVID-19.

BACKGROUND: Knowledge of the pathophysiology of COVID-19 is almost exclusively derived from studies that examined the immune response in blood. We here aimed to analyse the pulmonary immune response during severe COVID-19 and to compare this with blood responses. METHODS: This was an observational study in patients with COVID-19 admitted to the intensive care unit (ICU). Mononuclear cells were purified from bronchoalveolar lavage fluid (BALF) and blood, and analysed by spectral flow cytometry; inflammatory mediators were measured in BALF and plasma. FINDINGS: Paired blood and BALF samples were obtained from 17 patients, four of whom died in the ICU. Macrophages and T cells were the most abundant cells in BALF, with a high percentage of T cells expressing the ƴδ T cell receptor. In the lungs, both CD4 and CD8 T cells were predominantly effector memory cells (87·3% and 83·8%, respectively), and these cells expressed higher levels of the exhaustion marker programmad death-1 than in peripheral blood. Prolonged ICU stay (>14 days) was associated with a reduced proportion of activated T cells in peripheral blood and even more so in BALF. T cell activation in blood, but not in BALF, was higher in fatal COVID-19 cases. Increased levels of inflammatory mediators were more pronounced in BALF than in plasma. INTERPRETATION: The bronchoalveolar immune response in COVID-19 has a unique local profile that strongly differs from the immune profile in peripheral blood. Fully elucidating COVID-19 pathophysiology will require investigation of the pulmonary immune response.

Acute IL-1RA treatment suppresses the peripheral and central inflammatory response to spinal cord injury.

BACKGROUND: The acute phase response (APR) to CNS insults contributes to the overall magnitude and nature of the systemic inflammatory response. Aspects of this response are thought to drive secondary inflammatory pathology at the lesion site, and suppression of the APR can therefore afford some neuroprotection. In this study, we examined the APR in a mouse model of traumatic spinal cord injury (SCI), along with its relationship to neutrophil recruitment during the immediate aftermath of the insult. We specifically investigated the effect of IL-1 receptor antagonist (IL-1RA) administration on the APR and leukocyte recruitment to the injured spinal cord. METHODS: Adult female C57BL/6 mice underwent either a 70kD contusive SCI, or sham surgery, and tissue was collected at 2, 6, 12, and 24 hours post-operation. For IL-1RA experiments, SCI mice received two intraperitoneal injections of human IL-1RA (100mg/kg), or saline as control, immediately following, and 5 hours after impact, and animals were sacrificed 6 hours later. Blood, spleen, liver and spinal cord were collected to study markers of central and peripheral inflammation by flow cytometry, immunohistochemistry and qPCR. Results were analysed by two-way ANOVA or student's t-test, as appropriate. RESULTS: SCI induced a robust APR, hallmarked by elevated hepatic expression of pro-inflammatory marker genes and a significantly increased neutrophil presence in the blood, liver and spleen of these animals, as early as 2 hours after injury. This peripheral response preceded significant neutrophil infiltration of the spinal cord, which peaked 24 hours post-SCI. Although expression of IL-1RA was also induced in the liver following SCI, its response was delayed compared to IL-1ß. Exogenous administration of IL-1RA during this putative therapeutic window was able to suppress the hepatic APR, as evidenced by a reduction in CXCL1 and SAA-2 expression as well as a significant decrease in neutrophil infiltration in both the liver and the injured spinal cord itself. CONCLUSIONS: Our data indicate that peripheral administration of IL-1RA can attenuate the APR which in turn reduces immune cell infiltration at the spinal cord lesion site. We propose IL-1RA treatment as a viable therapeutic strategy to minimise the harmful effects of SCI-induced inflammation.

Anacardic 6-pentadecyl salicylic acid induces apoptosis in breast cancer tumor cells, immunostimulation in the host and decreases blood toxic effects of taxol in an animal model.

Many antineoplastic agents induce myelosuppression and leukopenia as secondary effects in patients. The development of anticancer agents that simultaneously provoke antitumor immune response represents an important therapeutic advance. The administration of 6-pentadecyl salicylic acid (6SA) contributes to the antitumor immunity using 4T1 breast cancer cells in Balb/c female mice, with Taxol as a positive control and in cotreatment with 6SA (6SA + Taxol; CoT). Our results show that 6SA reduces tumor volume and size by inducing caspase-8-mediated apoptosis without reducing tumor infiltrated lymphocytes. Also, 6SA reduced lung metastasis and increased the proportion of immune cells in blood, lymph nodes and bone marrow; more evidently, in the proportion of tumor-infiltrated natural killer (NK) cells and cytotoxic T lymphocytes. Taxol reduces helper and cytotoxic lymphocytes causing systemic immunosuppression and myelosuppression in bone marrow, whereas 6SA does not decrease any immune cell subpopulations in circulating blood and lymph nodes. More importantly, the CoT decreased the Taxol-induced cytotoxicity in circulating T cells and bone marrow. Treatment with 6SA increases the secretion of IL-2, IL-12, GM-CSF, TNF-α and IFN-γ and significantly reduces IL-10 and IL-17 secretion, suggesting that the reduction of regulatory T cells and tumor-associated macrophages contribute to the host control of tumor development. Finally, 6SA has an effective antineoplastic activity against breast cancer cells in an immunocompetent animal, reduces the myelosuppression and leukopenia that Taxol produces, improves the antitumoral immunological microenvironment and increases the overall survival of the animals improving the quality of life of patients with cancer.

Biology of peripheral ulcerative keratitis.

Peripheral ulcerative keratitis (PUK) is a progressive peripheral thinning of the corneal stroma caused by proinflammatory mediators' release from corneal limbal vasculitis. The clinical presentation is an epithelial defect with a crescent-shaped stromal inflammation. Its exact pathophysiologic mechanisms of PUK remain partially understood, but the overall understanding of the fundamental processes that mediate and effect corneal immunity has continued to expand over the past 25 years. The unique anatomical and physiological characteristics of the periphery in relation to collagen bundles and peripheral corneal vascular arch contribute to the occurrence of this type of ulcer in this region, in addition to the concentration of complement and immunoglobulins. There is a relevant participation of the adjacent conjunctiva. Both cell-mediated immunity and humoral immunity are implicated in the pathogenesis of PUK, and the postulated mechanisms are autoimmune reactions to corneal antigens, deposition of circulating immune complexes and hypersensitivity reactions to foreign antigens. These immunocomplexes are deposited in limbic vessels resulting in the activation of the classical pathway of the complement system and, consequently, in the chemotaxis of inflammatory cells and in the release of several pro-inflammatory cytokines, which allow the production and release of matrix metalloproteinases. The release of inflammatory cytokines by infiltrating cells may induce keratocyte activation, which could then generate more release of a variety of cytokines, such as the neutrophil calgranulin C, thus facilitating an autoimmune response to the protein and precipitating an antibody- and cell-mediated hyperimmune reaction in the peripheral cornea.

Neutralizing and binding activities against SARS-CoV-1/2, MERS-CoV, and human coronaviruses 229E and OC43 by normal human intravenous immunoglobulin derived from healthy donors in Japan.

BACKGROUND: There are several types of coronaviruses that infect humans and cause disease. The latest is severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is an emerging global threat with no current effective treatment. Normal intravenous immunoglobulin (N-IVIG) has been administered to coronavirus disease 2019 (COVID-19) patients to control severe inflammation and the cellular immune response. However, the neutralizing activity of N-IVIG against SARS-CoV-2 has not yet been fully evaluated. The aim of this study was to determine whether N-IVIG manufactured before the start of the COVID-19 pandemic contained IgG antibodies against the circulating human coronaviruses (HCoVs) that cross-react with the highly pathogenic coronaviruses SARS-CoV-1, Middle East respiratory syndrome coronavirus (MERS-CoV), and SARS-CoV-2. No cases of SARS-CoV-1 or MERS-CoV have been reported in Japan. STUDY DESIGN AND METHODS: The neutralizing and binding activities of N-IVIG against SARS-CoV-1, MERS-CoV, SARS-CoV-2, HCoV 229E, and HCoV OC43 were evaluated. Nine N-IVIG lots manufactured between 2000 and 2018, derived from donors in Japan, were tested. Binding activity was evaluated by indirect immunofluorescence assay. RESULTS: None of the N-IVIG lots tested displayed neutralizing or binding activity against SARS-CoV-1, MERS-CoV, or SARS-CoV-2. However, they displayed substantial neutralizing and binding activity against HCoV OC43 and weak neutralizing and substantial binding activity against HCoV 229E. CONCLUSION: N-IVIG derived from healthy donors in Japan before the start of the COVID-19 pandemic had no direct effect against SARS-CoV-2. Further studies are warranted to determine the effects of N-IVIG manufactured after the start of the COVID-19 pandemic against SARS-CoV-2.

Unique properties of TCR-activated p38 are necessary for NFAT-dependent T-cell activation.

Nuclear factor of activated T cells (NFAT) transcription factors are required for induction of T-cell cytokine production and effector function. Although it is known that activation via the T-cell antigen receptor (TCR) results in 2 critical steps, calcineurin-mediated NFAT1 dephosphorylation and NFAT2 up-regulation, the molecular mechanisms underlying each are poorly understood. Here we find that T cell p38, which is activated by an alternative pathway independent of the mitogen-activated protein (MAP) kinase cascade and with different substrate specificities, directly controls these events. First, alternatively (but not classically) activated p38 was required to induce the expression of the AP-1 component c-Fos, which was necessary for NFAT2 expression and cytokine production. Second, alternatively (but not classically) activated p38 phosphorylated NFAT1 on a heretofore unidentified site, S79, and in its absence NFAT1 was unable to interact with calcineurin or migrate to the nucleus. These results demonstrate that the acquisition of unique specificities by TCR-activated p38 orchestrates NFAT-dependent T-cell functions.

Identifying Hub Genes, Key Pathways and Immune Cell Infiltration Characteristics in Pediatric and Adult Ulcerative Colitis by Integrated Bioinformatic Analysis.

BACKGROUND AND AIMS: In the present study, we investigated the differentially expressed genes (DEGs), pathways and immune cell infiltration characteristics of pediatric and adult ulcerative colitis (UC). METHODS: We conducted DEG analysis using the microarray dataset GSE87473 containing 19 pediatric and 87 adult UC samples downloaded from the Gene Expression Omnibus. Gene ontology and pathway enrichment analyses were conducted using Metascape. We constructed the protein-protein interaction (PPI) network and the drug-target interaction network of DEGs and identified hub modules and genes using Cytoscape and analyzed immune cell infiltration in pediatric and adult UC using CIBERSORT. RESULTS: In total, 1700 DEGs were screened from the dataset. These genes were enriched mainly in inter-cellular items relating to cell junctions, cell adhesion, actin cytoskeleton and transmembrane receptor signaling pathways and intra-cellular items relating to the splicing, metabolism and localization of RNA. CDC42, POLR2A, RAC1, PIK3R1, MAPK1 and SRC were identified as hub DEGs. Immune cell infiltration analysis revealed higher proportions of naive B cells, resting memory T helper cells, regulatory T cells, monocytes, M0 macrophages and activated mast cells in pediatric UC, along with lower proportions of memory B cells, follicular helper T cells, γδ T cells, M2 macrophages, and activated dendritic cells. CONCLUSIONS: Our study suggested that hub genes CDC42, POLR2A, RAC1, PIK3R1, MAPK1 and SRC and immune cells including B cells, T cells, monocytes, macrophages and mast cells play vital roles in the pathological differences between pediatric and adult UC and may serve as potential biomarkers in the diagnosis and treatment of UC.

Revealing the link between macrophage in microenvironment of osteosarcoma and poor prognosis by utilizing the Integrated analysis.

OBJECTIVES: Osteosarcoma (OS) is the most common type of primary malignant bone tumor, The effect of tumor microenvironment components on OS oncogenesis remains unknown. METHODS: To investigate the function of immune cells in osteosarcoma, we provided a text-based GMT (Gene Matrix Transposed) file in which each line defines one of lm22 with their markers. We used STRING to draw DEG's PPI network and selected hub genes and modules. Then, survival analysis was conducted to hub genes. We identified 10,390 common genes, and identified 218 DEGs based on the combined t-value and Z scores. RESULTS: The KEGG and GSEA enrichment analysis showed that macrophages are significantly activated in osteosarcoma. PPI network analysis revealed that hub gene CD163 molecule. We found that the expression of CD163 was negatively associated with the OS of osteosarcoma patients. These results suggest that macrophages are a risk factor in patients with osteosarcoma. CONCLUSIONS: This study has systematically validated results of the studies carried out previously and filled up the gap in the field of OS on large-scaled meta-analysis. In addition, for the hub gene (CD163) and the macrophage cell capable of being used as a novel biomarker in promoting early diagnosis and development of therapeutic approaches.

CB2 receptor-selective agonists as candidates for targeting infection, inflammation, and immunity in SARS-CoV-2 infections.

The COVID-19 pandemic caused by SARS-CoV-2 is a deadly disease afflicting millions. The pandemic continues affecting population due to nonavailability of drugs and vaccines. The pathogenesis and complications of infection mainly involve hyperimmune-inflammatory responses. Thus, therapeutic strategies rely on repurposing of drugs aimed at reducing infectivity and inflammation and modulate immunity favourably. Among, numerous therapeutic targets, the endocannabinoid system, particularly activation of cannabinoid type-2 receptors (CB2R) emerged as an important one to suppress the hyperimmune-inflammatory responses. Recently, potent antiinflammatory, antiviral and immunomodulatory properties of CB2R selective ligands of endogenous, plant, and synthetic origin were showed mediating CB2R selective functional agonism. CB2R activation appears to regulate numerous signaling pathways to control immune-inflammatory mediators including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. Many CB2R ligands also exhibit off-target effects mediating activation of PPARs, opioids, and TRPV, suggestive of adjuvant use with existing drugs that may maximize efficacy synergistically and minimize therapeutic doses to limit adverse/ side effects. We hypothesize that CB2R agonists, due to immunomodulatory, antiinflammatory, and antiviral properties may show activity against COVID-19. Based on the organoprotective potential, relative safety, lack of psychotropic effects, and druggable properties, CB2R selective ligands might make available promising candidates for further investigation.

Infiltration of Immune Competent Cells into Primary Tumors and Their Surrounding Connective Tissues in Xenograft and Syngeneic Mouse Models.

To fight cancer more efficiently with cell-based immunotherapy, more information about the cells of the immune system and their interaction with cancer cells in vivo is needed. Therefore paraffin wax embedded primary breast cancers from the syngeneic mouse WAP-T model and from xenografted tumors of breast, colon, melanoma, ovarian, neuroblastoma, pancreatic, prostate, and small cell lung cancer were investigated for the infiltration of immunocompetent cells by immunohistochemistry using antibodies against leukocyte markers. The following markers were used: CD45 as a pan-leukocyte marker, BSA-I as a dendritic cell marker, CD11b as an NK cell marker, and CD68 as a marker for macrophages. The labeled immune cells were attributed to the following locations: adjacent adipose tissue, tumor capsule, intra-tumoral septae, and cancer cells directly. In xenograft tumors, the highest score of CD45 and CD11b positive, NK, and dendritic cells were found in the adjacent adipose tissue, followed by lesser infiltration directly located at the cancer cells themselves. The detected numbers of CD45 positive cells differed between the tumor entities: few infiltrating cells in breast cancer, small cell lung cancer, neuroblastoma, a moderate infiltration in colon cancer, melanoma and ovarian cancer, strongest infiltration in prostate and pancreatic cancer. In the syngeneic tumors, the highest score of CD45 and CD11b positive, NK and dendritic cells were observed in the tumor capsule, followed by a lesser infiltration of the cancer tissue. Our findings argue for paying more attention to investigate how immune-competent cells can reach the tumor cells directly.

Cell Immunity in Implant-Associated Infections Caused by Biofilm-Forming Microorganisms.

High biofilm-forming capacity of Staphylococcus spp. strains isolated from biomaterial of patients with infectious complications after primary knee replacement developed within 6-12 months after surgery was experimentally demonstrated. Differential leukocyte counts and some indicators of cell immunity in these patients were compared with those in patients without purulent complications and healthy volunteers. In patients with implant-associated infection, the relative numbers of T cells (both T-helpers and T-suppressors) B cells were significantly (p<0.05) reduced, while the number of NK cells was significantly increased in comparison with the corresponding parameters in other groups. The revealed changes attest to cell immunity failure in biofilm infection.

Whipworm Infection Promotes Bacterial Invasion, Intestinal Microbiota Imbalance, and Cellular Immunomodulation.

Infections with Trichuris trichiura are among the most common causes of intestinal parasitism in children worldwide, and the diagnosis is based on microscopic egg identification in the chronic phase of the infection. During parasitism, the adult worm of the trichurid nematode maintains its anterior region inserted in the intestinal mucosa, which causes serious damage and which may open access for gut microorganisms through the intestinal tissue. The immune-regulatory processes taking place during the evolution of the chronic infection are still not completely understood. By use of the Swiss Webster outbred mouse model, mice were infected with 200 eggs, and tolerance to the establishment of a chronic Trichuris muris infection was induced by the administration of a short pulse of dexamethasone during nematode early larval development. The infected mice presented weight loss, anemia, an imbalance of the microbiota, and intense immunological cell infiltration in the large intestine. It was found that mice have a mixed Th1/Th2/Th17 response, with differences being found among the different anatomical locations. After 45 days of infection, the parasitism induced changes in the microbiota composition and bacterial invasion of the large intestine epithelium. In addition, we describe that the excretory-secretory products from the nematode have anti-inflammatory effects on mouse macrophages cultured in vitro, suggesting that T. muris may modulate the immune response at the site of insertion of the worm inside mouse tissue. The data presented in this study suggest that the host immune state at 45 days postinfection with T. muris during the chronic phase of infection is the result of factors derived from the worm as well as alterations to the microbiota and bacterial invasion. Taken together, these results provide new information about the parasite-host-microbiota relationship and open new treatment possibilities.

Single-Cell Sequencing of Mouse Heart Immune Infiltrate in Pressure Overload-Driven Heart Failure Reveals Extent of Immune Activation.

BACKGROUND: Inflammation is a key component of cardiac disease, with macrophages and T lymphocytes mediating essential roles in the progression to heart failure. Nonetheless, little insight exists on other immune subsets involved in the cardiotoxic response. METHODS: Here, we used single-cell RNA sequencing to map the cardiac immune composition in the standard murine nonischemic, pressure-overload heart failure model. By focusing our analysis on CD45+ cells, we obtained a higher resolution identification of the immune cell subsets in the heart, at early and late stages of disease and in controls. We then integrated our findings using multiparameter flow cytometry, immunohistochemistry, and tissue clarification immunofluorescence in mouse and human. RESULTS: We found that most major immune cell subpopulations, including macrophages, B cells, T cells and regulatory T cells, dendritic cells, Natural Killer cells, neutrophils, and mast cells are present in both healthy and diseased hearts. Most cell subsets are found within the myocardium, whereas mast cells are found also in the epicardium. Upon induction of pressure overload, immune activation occurs across the entire range of immune cell types. Activation led to upregulation of key subset-specific molecules, such as oncostatin M in proinflammatory macrophages and PD-1 in regulatory T cells, that may help explain clinical findings such as the refractivity of patients with heart failure to anti-tumor necrosis factor therapy and cardiac toxicity during anti-PD-1 cancer immunotherapy, respectively. CONCLUSIONS: Despite the absence of infectious agents or an autoimmune trigger, induction of disease leads to immune activation that involves far more cell types than previously thought, including neutrophils, B cells, Natural Killer cells, and mast cells. This opens up the field of cardioimmunology to further investigation by using toolkits that have already been developed to study the aforementioned immune subsets. The subset-specific molecules that mediate their activation may thus become useful targets for the diagnostics or therapy of heart failure.

Sustained Increases in Immune Transcripts and Immune Cell Trafficking During the Recovery of Experimental Brain Ischemia.

BACKGROUND AND PURPOSE: Stroke is a major cause of chronic neurological disability. There is considerable interest in understanding how acute transcriptome changes evolve into subacute and chronic patterns that facilitate or limit spontaneous recovery. Here we mapped longitudinal changes in gene expression at multiple time points after stroke in mice out to 6 months. METHODS: Adult C57BL/6 mice were subjected to transient middle cerebral artery occlusion. Longitudinal transcriptome levels were measured at 10 time points after stroke from acute to recovery phases of ischemic stroke. Localization and the number of mononuclear phagocytes were determined in the postischemic brain. Whole-mount brain imaging was performed in asplenic mice receiving GFP+ (green fluorescent protein)-tagged splenocytes. RESULTS: Sustained stroke-induced mRNA abundance changes were observed in both hemispheres with 2989 ipsilateral and 822 contralateral genes significantly perturbed. In the hemisphere ipsilateral to the infarct, genes associated with immune functions were strongly affected, including temporally overlapping innate and adaptive immunity and macrophage M1 and M2 phenotype-related genes. The strong immune gene activation was accompanied by the sustained infiltration of peripheral immune cells at acute, subacute, and recovery stages of stroke. The infiltrated immune cells were found in the infarcted area but also in remote regions at 2 months after stroke. CONCLUSIONS: The study identifies that immune components are the predominant molecular signatures and they may propagate or continuously respond to brain injury in the subacute to chronic phase after central nervous system injury. The study suggests a potential immune-based strategy to modify injury progression and tissue remodeling in ischemic stroke, even months after the initiating event.