Biology subjects

Nkongolo, S.

Publications and source records attributed to Nkongolo, S..

5 recordsLinked to original sources

bioRxiv2026

Serum IgM crosslinks hepatitis B subviral particles into supramolecular immune complexes

Hepatitis B virus (HBV)-infected cells release hepatitis B surface antigen (HBsAg)-rich subviral particles (SVPs) in large excess over infectious virions. SVPs bind antibodies against HBsAg (anti-HBs), including neutralizing antibodies, but the physical products of antibody capture in human blood are uncharacterized. Here we used cryo-electron tomography (cryo-ET) to image HBsAg-enriched serum from a patient with severe acute Hepatitis B and observed three-dimensional assemblies of intact IgM-SVP immune complexes. These associations persisted at a lower particle density and were validated by a spatial-randomization null model. Subtomogram averaging and single-particle cryo-electron microscopy (cryo-EM) identified three serum IgM Fc-core assemblies, IgM-J-CD5L, IgM-J and IgM-J-SC, with cryo-EM maps reaching 2.8 angstrom resolution. Mapping these Fc core assemblies into tomograms revealed full-length IgM engaging individual SVPs through several Fab arms and bridging neighboring particles into immune complex networks containing multiple IgM molecules and SVPs. Thus, serum IgM uses multivalent Fab interactions to crosslink HBsAg-rich SVPs into supramolecular immune complexes. This observation extends the SVP decoy model from passive antibody sequestration to higher-order particle organization.

molecular biology↗

bioRxiv2026

Hepatitis B virus proteome analysis identifies apolipoprotein C1 facilitating particle production and virus entry

Background & AimsAntiviral therapies targeting hepatitis B virus (HBV) suppress viral replication, but rarely achieve functional cure. Understanding HBV-host cell interaction is crucial for developing novel therapeutic approaches. Here, we report host cell proteins associated with HBV virions and filamentous subviral particles (fSVPs) and characterize one of them, apolipoprotein C1 (ApoC1), mechanistically. MethodsHighly purified HBV virions and fSVPs were obtained by sequential use of several biophysical methods. Particles were analyzed by mass spectrometry and associated proteins were evaluated phenotypically using an HBV infection model. The top hit, ApoC1 was characterized in detail. ResultsAssociated with virions and fSVPs, we identified in addition to known chaperones such as HSP90AB1 and HSC70, several apolipoprotein-related factors. RNAi-based phenotypic validation identified strongest effects for ApoC1, likely due to two complementary effects. First, ApoC1 depletion reduced intracellular cholesterol level impairing HBV infection and SVP production, which was compensated by exogenous cholesterol substitution. Second, ApoC1 that is mainly enriched in high-density lipoprotein (HDL), associates with HBV virions and fSVPs and increases HBV infectivity. The same was found for hepatitis D virus (HDV), a satellite virus utilizing HBV envelopes. Supplementation of exogenous HDL enhanced infection most likely via scavenger receptor class B type 1 (SR-B1), the natural HDL receptor. Consistently, inhibition of SR-B1 suppressed HBV and HDV infection. ConclusionsWe established a method for obtaining highly purified HBV virions and fSVPs and identified the HDL component ApoC1 to associate with both particle types. ApoC1 promotes HBV and HDV infection most likely via SR-B1 facilitating viral entry.

molecular biology↗

bioRxiv2024

Virus-associated Inflammation Imprints an Inflammatory Profile on Long-lived Monocyte-derived Macrophages in the Human Liver

Chronic liver injury triggers the activation and recruitment of immune cells, causing antigen-independent tissue damage and liver disease progression. Tissue inflammation can reshape macrophage composition through monocyte replacement. Replacement of tissue macrophages with monocytes differentiating in an inflammatory environment can potentially imprint a phenotype that switches the liver from an immunotolerant organ to one predisposed to tissue damage. We longitudinally sampled the liver of chronic hepatitis B (CHB) patients with active liver inflammation starting antiviral therapy. Antiviral therapy suppressed viral replication and liver inflammation, which coincided with decreased myeloid activation markers. Single-cell RNA sequencing mapped peripheral inflammatory markers to a monocyte-derived macrophage population, distinct from Kupffer cells, with an inflammatory transcriptional profile. The inflammatory macrophages (iMacs) differentiated from blood monocytes and established a long-lived population. The iMacs retained their core transcriptional signature, consistent with trained immunity, resulting in a population of macrophages primed for inflammation potentially driving progressive liver disease.

immunology↗

bioRxiv2023

Liver-specific Inflammatory Signatures Predict Clinically Significant Liver Damage.

Background and AimsInflammation drives progression of chronic liver disease. However, the triggers of inflammation remain undefined during chronic hepatitis B (CHB) because hepatic flares are spontaneous and difficult to capture. We used nucleoside analogue (NA) withdrawal to investigate early inflammatory events because liver damage after stopping therapy occurs in a predictable time frame. 11 CHB patients underwent 192 weeks of NA therapy before a protocol defined stop. Liver fine-needle aspirates (FNAs) were collected at baseline and 4-weeks post-withdrawal and analyzed using flow cytometry and single-cell RNA sequencing (scRNA-seq). Intrahepatic mononuclear cells (IHMCs) from uninfected livers were used to validate transcriptomic findings. At 4 weeks post NA-withdrawal, HBV DNA rebounded but alanine aminotransferase (ALT) levels remained normal, 7/11 patients developed ALT elevations (>2xULN) at later timepoints. There were no changes in cell frequencies between baseline and viral rebound. ScRNA-seq revealed upregulation of IFN stimulated genes (ISGs) and pro-inflammatory cytokine MIF upon viral rebound. In vitro experiments confirmed the type I IFN-dependent ISG profile whereas MIF was induced primarily by IL-12. MIF exposure further amplified inflammatory cytokine production by myeloid cells. Our data show that innate immune activation is detectable in the liver before clinically-significant liver damage is detectable in the serum.

immunology↗

bioRxiv2021

Clinical implementation of single-cell RNA sequencing using liver fine needle aspirate tissue sampling and centralized processing captures compartment specific immuno-diversity

Blood samples are frequently collected in human studies of the immune system but poorly represent tissue-resident immunity. Understanding the immunopathogenesis of tissue-restricted diseases, such as chronic hepatitis B, necessitates direct investigation of local immune responses. We developed a workflow that enables frequent, minimally invasive collection of liver fine-needle aspirates in multi-site international studies and centralized single-cell RNA sequencing data generation using the Seq-Well S3 picowell-based technology. All immunological cell types were captured, including liver macrophages, and showed distinct compartmentalization and transcriptional profiles, providing a systematic assessment of the capabilities and limitations of peripheral blood samples when investigating tissue-restricted diseases. The ability to electively sample the liver of chronic viral hepatitis patients and generate high-resolution data will enable multi-site clinical studies to power fundamental and therapeutic discovery.

immunology↗