Summary The last century has witnessed the emergence of several previously unknown viruses as life-threatening human pathogens. Several examples include HIV, Ebola, Lujo, and, most recently, the ...Middle East respiratory syndrome (MERS) and Ebola. In this study, we describe a method for the swift generation of a human-derived monoclonal antibody, known as LCA60, as a treatment for MERS infections. LCA60 antibody was generated using the Cellclone Technology from the immortalized B cells of a human donor recovering from MERS. Only four months were required from the initial screening of B cells to the development of a stable CHO cell line suitable for the production of clinical grade antibody, thereby delineating a rapid pathway for the development of antiviral therapies against emerging viruses. Currently, the LCA60 antibody is being considered for clinical development, which includes prophylaxis in individuals at risk and a treatment for severe MERS-CoV infections.
Triggering receptor expressed in myeloid (TREM) cells 2, a receptor expressed by myeloid cells, osteoclasts and microglia, is known to play a protective role in bones and brain. Mutations of the ...receptor (or of its coupling protein, DAP12) sustain in fact a genetic disease affecting the two organs, the polycystic lipomembraneous osteodysplasia with sclerosing leukoencephalopathy (PLOSL or Nasu-Hakola disease). So far, specific agonist(s) of TREM2 have not been identified and its (their) transduction mechanisms are largely unknown. Heat shock protein 60 (Hsp60) is a mitochondrial chaperone that can also be harboured at the cell surface. By using constructs including the extracellular domain of TREM2 and the Fc domain of IgGs we have identified Hsp60 as the only TREM2-binding protein exposed at the surface of neuroblastoma N2A cells and astrocytes, and lacking in U373 astrocytoma. Treatment with Hsp60 was found to stimulate the best known TREM2-dependent process, phagocytosis, however, only in the microglial N9 cells rich in the receptor. Upon TREM2 down-regulation, the Hsp60-induced stimulation of N9 phagocytosis was greatly attenuated. Hsp60 is also released by many cell types, segregated within exosomes or shedding vesicles which might then undergo dissolution. However, the affinity of its binding (Kd = 3.8 μM) might be too low for the soluble chaperone released from the vesicles to the extracellular space to induce a significant activation of TREM2. It might in contrast be appropriate for the binding of TREM2 to Hsp60 exposed at the surface of cells closely interacting with microglia. The ensuing stimulation of phagocytosis could play protective effects on the brain.
Background and Aims Triggering receptor expressed on myeloid cells (TREM)–2 is a surface receptor detected on macrophages, dendritic cells, and microglia that binds repeated anionic motifs on yeast ...and Gram-positive and Gram-negative bacteria. Little is known about TREM-2 expression and function in the intestine or its role in inflammatory bowel disease (IBD). We investigated the expression of TREM-2 in the intestinal lamina propria and its role in the development of colonic inflammation. Methods We measured levels of TREM-2 in lamina propria mononuclear cells from surgical specimens collected from patients with IBD or cancer (controls). We analyzed the development of colitis in TREM-2 knockout and wild-type mice. Colon samples were isolated from mice and analyzed for cytokine expression, phagocytosis of bacteria, proliferation in colonic crypts, lamina propria mononuclear cell function, and T-cell activation by ovalbumin. Results TREM-2 was virtually absent from colon samples of control patients, but levels were significantly higher in within the inflamed mucosa of patients with IBD; it was mainly expressed by CD11c+ cells. Levels of TREM-2 increased as acute or chronic colitis was induced in mice. TREM-2 knockout mice developed less severe colitis than wild-type mice; the knockout mice lost less body weight, had a lower disease activity index, and had smaller mucosal lesions in endoscopic analysis. Colon dendritic cells from TREM-2 knockout mice produced lower levels of inflammatory cytokines and had reduced levels of bacterial killing and T-cell activation than cells from wild-type mice. Conclusions TREM-2 contributes to mucosal inflammation during development of colitis in mice. Levels of TREM-2 are increased within the inflamed mucosa of patients with IBD, indicating its potential as a therapeutic target.
Interleukin‐12 (IL‐12) is a key cytokine for the development of T helper type 1 (Th1) responses; however, naïve CD4+ T cells do not express IL‐12Rβ2, and are therefore unresponsive to IL‐12. We have ...examined the mechanisms that control Th1‐specific expression of the human IL‐12Rβ2 gene at early time points after T‐cell stimulation. We have identified a Th1‐specific enhancer element that binds signal transducer and activator of transcription 4 (STAT4) in vivo in developing Th1 but not Th2 cells. T‐cell receptor (TCR) signaling induced histone hyperacetylation and recruitment of BRG1, the ATPase subunit of the SWI/SNF‐like BAF chromatin remodeling complex, to the IL‐12Rβ2 regulatory regions and was associated with low‐level gene transcription at the IL‐12Rβ2 locus. However, high‐level IL‐12Rβ2 expression required TCR triggering in the presence of IL‐12. Our results indicate a synergistic role of TCR‐induced chromatin remodeling and cytokine‐induced STAT4 activation to direct IL‐12Rβ2 expression during Th1 cell development.
The triggering receptor expressed on myeloid cell type 1 (TREM-1) is a cell surface molecule that has been identified on both human and murine polymorphonuclear neutrophils and mature monocytes. The ...activation of TREM-1 in the presence of microbial components amplifies the inflammatory response and may be responsible for the hyperresponsiveness observed during the initial stage of sepsis. To investigate the effect of the modulation of the TREM-1 pathway during experimental murine sepsis, we used analogue synthetic peptides derived from the extracellular moiety of TREM-1. The TREM-1 ligand was expressed on both peritoneal and peripheral neutrophils during experimental peritonitis in mice. The TREM-1 peptides inhibited the recognition by TREM-1 of its ligand and protected endotoxinic mice from death. In septic rats, the TREM-1 peptides improved the hemodynamic status, attenuated the development of lactic acidosis, modulated the production of such proinflammatory cytokines as tumor necrosis factor alpha and interleukin-1{szligbeta}, and improved survival. The protective effect of these peptides on arterial pressure could partly be explained by a decreased production of nitric oxide. These data suggest that in vivo modulation of TREM-1 might be a suitable therapeutic tool for the treatment of sepsis.
Little information is available about the nature of the immune response in children after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or vaccination. The aim of this study ...is to define the seroprevalence and the features of the antibody response in children of Southern Switzerland during the different waves of Coronavirus Disease 2019 (COVID-19) pandemic. By analyzing 756 sera collected from children aged 0 to 16 years admitted to the Institute of Pediatrics of Southern Switzerland during the prepandemic period (before March 2020) and the first four pandemic waves (between March 2020 and June 2022), we investigated binding titers, cross-reactivity, and neutralizing properties of the serum antibodies against SARS-CoV-2 variants. Seroprevalence varied from 6% during the first wave to 14% and 17% during the second and third waves, respectively, peaking at 39% during the fourth wave. The 96 seropositive cases were mostly asymptomatic (42.7%) or showed mild (20.8%) to moderate (32.3%) symptoms. Moderate symptoms and close contact with COVID-19-positive individuals were associated with a higher infection risk (
P
< 0.001). The antibody response was mainly driven by IgG directed to the receptor-binding domain (RBD) of Wuhan-1 SARS-CoV-2 Spike (S). Children infected in the first three waves produced antibodies with up to 11-fold and 5.5-fold reduction in binding and neutralizing titers, respectively, against different SARS-CoV-2 variants, including Beta, Delta, and Omicron BA.1, BA.2, and BA.5. Such reductions were less pronounced in children infected during the fourth wave, who showed the highest frequency and titers of neutralizing antibodies against the same variants. Compared to infection, vaccination with a Wuhan-1-based messenger RNA (mRNA) vaccine induced higher and heterogenous levels of antibodies cross-reacting to the different SARS-CoV-2 variants analyzed.
Conclusions
: Despite the high burden of COVID-19 in Southern Switzerland, we observed an initial low seroprevalence of SARS-CoV-2 in children, which increased in the later waves. The antibody response was poor in the first three waves and improved in the fourth wave, when children produced higher levels of neutralizing antibodies after vaccination or infection with Delta and/or Omicron variants.
What is Known:
• Children were marginally affected by the initial SARS-CoV-2 variants.
• The number of infected and hospitalized children increased after the appearance of the Omicron variants.
What is New:
• Seroprevalence of SARS-CoV-2 in children of Southern Switzerland increased overtime.
• Children produced higher levels of neutralizing antibodies after vaccination or infection with Delta and/or Omicron variants in the fourth wave compared to children infected in the first three waves.
Chronic hepatitis B is a global public health problem, and coinfection with hepatitis delta virus (HDV) worsens disease outcome. Here, we describe a hepatitis B virus (HBV) surface antigen ...(HBsAg)-targeting monoclonal antibody (mAb) with the potential to treat chronic hepatitis B and chronic hepatitis D.
HBsAg-specific mAbs were isolated from memory B cells of HBV vaccinated individuals. In vitro neutralization was determined against HBV and HDV enveloped with HBsAg representing eight HBV genotypes. Human liver-chimeric mice were treated twice weekly with a candidate mAb starting 3 weeks post HBV inoculation (spreading phase) or during stable HBV or HBV/HDV coinfection (chronic phase).
From a panel of human anti-HBs mAbs, VIR-3434 was selected and engineered for pre-clinical development. VIR-3434 targets a conserved, conformational epitope within the antigenic loop of HBsAg and neutralized HBV and HDV infection with higher potency than hepatitis B immunoglobulins in vitro. Neutralization was pan-genotypic against strains representative of HBV genotypes A-H. In the spreading phase of HBV infection in human liver-chimeric mice, a parental mAb of VIR-3434 (HBC34) prevented HBV dissemination and the increase in intrahepatic HBV RNA and covalently closed circular DNA. In the chronic phase of HBV infection or co-infection with HDV, HBC34 treatment decreased circulating HBsAg by >1 log and HDV RNA by >2 logs.
The potently neutralizing anti-HBs mAb VIR-3434 reduces circulating HBsAg and HBV/HDV viremia in human liver-chimeric mice. VIR-3434 is currently in clinical development for treatment of patients with chronic hepatitis B or D.
Chronic infection with hepatitis B virus and co-infection with hepatitis D virus place approximately 290 million individuals worldwide at risk of severe liver disease and cancer. Available treatments result in low rates of functional cure or require lifelong therapy that does not eliminate the risk of liver disease. We isolated and characterized a potent human antibody that neutralizes hepatitis B and D viruses and reduces infection in a mouse model. This antibody could provide a new treatment for patients with chronic hepatitis B and D.
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•Identification of a human mAb VIR-3434 that potently neutralizes HBV and HDV.•VIR-3434 targets a conserved, conformational epitope of the HBsAg antigenic loop.•VIR-3434 treatment blocks intrahepatic HBV spread in human liver-chimeric mice.•VIR-3434 treatment reduces circulating HBsAg and HDV RNA in co-infected mice.•Data have enabled clinical development of VIR-3434 against chronic hepatitis B/D.
IRF-1-deficient mice show a striking defect in the development of T helper 1 (Th1) cells. In the present report, we investigate
the expression of IRF-1 during differentiation of human T helper cells. ...No significant differences of IRF-1 mRNA expression
were found in established Th1 and Th2 cells; however, interleukin 12 (IL-12) induced a strong up-regulation of IRF-1 transcripts
in Th1 but not in Th2 cells. We demonstrate that IL-12-induced up-regulation of IRF-1 is mediated by signal transducer and
activator of transcription-4, which binds to the interferon (IFN)-γ-activated sequence present in the promoter of the IRF-1
gene. Strong IL-12-dependent activation of a reporter gene construct containing the IRF-1 IFN-γ-activated sequence element
provides further evidence for the key role of signal transducer and activator of transcription-4 in the IL-12-induced up-regulation
of IRF-1 transcripts in T cells. IRF-1 expression was strongly induced after stimulation of naive CD4 + T cells via the T cell receptor, irrespective of the cytokines present at priming, indicating that this transcription factor
does not play a major role in initiating a Th1-specific transcriptional cascade in differentiating helper T cells. However,
our finding that IRF-1 is a target gene of IL-12 suggests that some of the IL-12-induced effector functions of Th1 cells may
be mediated by IRF-1.
Triggering receptor expressed on myeloid cells 2 (TREM-2) is a membrane-bound receptor expressed by microglia and macrophages. Engagement of TREM-2 on these cells has been reported to reduce ...inflammatory responses and, in microglial cells, to promote phagocytosis. TREM-2 function is critical within the CNS, as its genetic deficiency in humans causes neurodegeneration with myelin and axonal loss. Blockade of TREM-2 worsened the mouse model for multiple sclerosis. In the present study, a soluble form of TREM-2 protein has been identified by immunoprecipitation and by ELISA. Soluble TREM-2 protein (sTREM-2) was detected in human CSF, and was compared among subjects with relapsing-remitting multiple sclerosis (RR-MS; n = 52), primary progressive multiple sclerosis (PP-MS; n = 21), other inflammatory neurologic diseases (OIND; n = 19), and non-inflammatory neurologic diseases (NIND; n = 41). Compared to NIND subjects, CSF sTREM-2 levels were significantly higher in RR-MS (P = 0.004 by ANOVA) and PP-MS (P < 0.001) subjects, as well as in OIND (P < 0.001) subjects. In contrast, levels of sTREM-2 in blood did not differ among the groups. Furthermore, TREM-2 was detected on a subset of CSF monocytes by flow cytometry, and was also highly expressed on myelin-laden macrophages in eight active demyelinating lesions from four autopsied multiple sclerosis subjects. The elevated levels of sTREM-2 in CSF of multiple sclerosis patients may inhibit the anti-inflammatory function of the membrane-bound receptor suggesting sTREM-2 to be a possible target for future therapies.
Interleukin-12 (IL-12), a heterodimeric cytokine produced by activated monocytes and dendritic cells, plays a crucial role in regulating interferon (IFN)-gamma production and in the generation of ...IFN-gamma-producing T helper 1 (Th1) cells. Here we show that the IL-12 receptor (IL-12R) beta 2 subunit, a recently cloned binding and signal transducing component of the IL-12R, is expressed on human Th1 but not Th2 clones and is induced during differentiation of human naive cells along the Th1 but not the Th2 pathway. IL-12 and type I but not type II interferons induce expression of the IL-12R beta 2 chain during in vitro T cell differentiation after antigen receptor triggering. The selective expression and regulation of the IL-12R beta 2 subunit may help to understand the basis of Th1/Th2 differentiation and may provide therapeutic options for altering the Th1/Th2 balance in several immuno-pathological conditions such as autoimmune diseases and allergies.
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