Biology subjects

Zamboni, D. S.

Publications and source records attributed to Zamboni, D. S..

7 recordsLinked to original sources

bioRxiv2026

NLRP3 inflammasome signaling orchestrates hepatic granuloma organization and protective immunity

Granulomas are organized immune structures that contribute to host defense against persistent pathogens, yet the mechanisms that coordinate their assembly and protective function remain incompletely understood. Here, using experimental visceral leishmaniasis caused by Leishmania infantum and samples from patients with active disease, we identify the NLRP3 inflammasome as a regulator of protective hepatic granulomatous immunity. Inflammasome-associated mediators were elevated in patients and correlated with systemic inflammation. In mice, L. infantum induced NLRP3 inflammasome activation within hepatic granulomas, while single-cell and spatial transcriptomic analyses revealed enrichment of inflammasome-associated transcription in hepatic macrophages and granuloma-associated regions. NLRP3 deficiency did not prevent granuloma initiation but impaired granuloma expansion, cellular organization, and leukocyte accumulation. This response required Caspase-1/11 and IL-18, but was independent of IL-1{beta}. Loss of NLRP3 also impaired parasite control despite reducing hepatic inflammation and histopathological alterations. Together, our findings identify NLRP3-Caspase-1/11-IL-18 signaling as a mechanism that coordinates the cellular and spatial organization of protective hepatic granulomas, revealing granuloma architecture as a previously unrecognized function of inflammasome-mediated immunity and providing mechanistic insight into host resistance in visceral leishmaniasis, a potentially fatal neglected tropical disease.

immunology↗

bioRxiv2023

The unique Legionella longbeachae capsule favors intracellular replication and immune evasion

Legionella longbeachae and Legionella pneumophila cause Legionnaires disease despite species-specific differences in environmental niches, disease epidemiology, and genomic content. Here, we characterized a new L. longbeachae virulence factor, a capsule that is expressed in post-exponential growth phase as shown by electron microscopy. Analysis of the capsule composition via HLPC revealed the presence of a highly anionic polysaccharide absent in a capsule mutant. The capsule is crucial for replication and virulence in vivo in a mouse model of infection and in the natural host Acanthamoeba castellanii. It has anti-phagocytic function when encountering innate immune cells, it is involved in a low cytokine responses in mice and in human monocyte derived macrophages and helps to dampen the innate immune response. The L. longbeachae capsule is a novel virulence factor, unique among known Legionella species, that aids L. longbeachae to survive in specific niches and partly confers L. longbeachae its unique infection characteristics.

microbiology↗

bioRxiv2022

In Vitro Inhibition of SARS-CoV-2 Infection by Bromhexine hydrochloride

The world is enduring the SARS CoV-2 pandemic, and although extensive research has been conducted on the issue, only a few antivirals have been approved to treat patients with COVID-19. Bromhexine hydrochloride was previously identified as a potent inhibitor of TMPRSS2, an essential protease for ACE-2 virus receptor interactions. In the present study, we investigated whether bromhexine treatment could reduce SARS CoV-2 replication in vitro. To evaluate bromhexines effectiveness against SARS COV-2 infection, viral load was measured using Caco-2 cell lines expressing TMPRSS2. Our molecular docking results indicate that bromhexine displays an affinity with the active site of TMPRSS2. The drug significantly inhibited SARS CoV-2, both parental and P1 variant strains, infection in the Caco-2 cell line, reducing about 40% of SARS-CoV-2 entrance and about 90% of viral progeny in the supernatant 48h post-infection. Furthermore, bromhexine did not exhibit any direct virucidal activity on SARS CoV-2. In conclusion, bromhexine hydrochloride efficiently disrupts SARS CoV-2 infection in vitro and has the potential to become an effective antiviral agent in COVID-19 treatment.

pharmacology and toxicology↗

bioRxiv2022

Targeting C5aR1 signaling reduced neutrophil extracellular traps and ameliorates COVID-19 pathology

Patients with severe COVID-19 develop acute respiratory distress syndrome (ARDS) that may progress to cytokine storm syndrome, organ dysfunction, and death. Considering that complement component 5a (C5a), through its cellular receptor C5aR1, has potent proinflammatory actions, and plays immunopathological roles in inflammatory diseases, we investigated whether C5a/C5aR1 pathway could be involved in COVID-19 pathophysiology. C5a/C5aR1 signaling increased locally in the lung, especially in neutrophils of critically ill COVID-19 patients compared to patients with influenza infection, as well as in the lung tissue of K18-hACE2 Tg mice (Tg mice) infected with SARS-CoV-2. Genetic and pharmacological inhibition of C5aR1 signaling ameliorated lung immunopathology in Tg-infected mice. Mechanistically, we found that C5aR1 signaling drives neutrophil extracellular trap (NET)s-dependent immunopathology. These data confirm the immunopathological role of C5a/C5aR1 signaling in COVID-19 and indicate that antagonist of C5aR1 could be useful for COVID-19 treatment.

immunology↗

bioRxiv2020

Infection of human lymphomononuclear cells by SARS-CoV-2

Although SARS-CoV-2 severe infection is associated with a hyperinflammatory state, lymphopenia is an immunological hallmark, and correlates with poor prognosis in COVID-19. However, it remains unknown if circulating human lymphocytes and monocytes are susceptible to SARS-CoV-2 infection. In this study, SARS-CoV-2 infection of human peripheral blood mononuclear cells (PBMCs) was investigated both in vitro and in vivo. We found that in vitro infection of whole PBMCs from healthy donors was productive of virus progeny. Results revealed that monocytes, as well as B and T lymphocytes, are susceptible to SARS-CoV-2 active infection and viral replication was indicated by detection of double-stranded RNA. Moreover, flow cytometry and immunofluorescence analysis revealed that SARS-CoV-2 was frequently detected in monocytes and B lymphocytes from COVID-19 patients, and less frequently in CD4+T lymphocytes. The rates of SARS-CoV-2-infected monocytes in PBMCs from COVID-19 patients increased over time from symptom onset. Additionally, SARS-CoV-2-positive monocytes and B and CD4+T lymphocytes were detected by immunohistochemistry in post mortem lung tissue. SARS-CoV-2 infection of blood circulating leukocytes in COVID-19 patients may have important implications for disease pathogenesis, immune dysfunction, and virus spread within the host.

microbiology↗

bioRxiv2020

Role of the transcriptional regulator SP140 in resistance to bacterial infections via repression of type I interferons

Type I interferons (IFNs) are essential for anti-viral immunity, but often impair protective immune responses during bacterial infections. An important question is how type I IFNs are strongly induced during viral infections, and yet are appropriately restrained during bacterial infections. The Super susceptibility to tuberculosis 1 (Sst1) locus in mice confers resistance to diverse bacterial infections. Here we provide evidence that Sp140 is a gene encoded within the Sst1 locus that represses type I IFN transcription during bacterial infections. We generated Sp140-/- mice and find they are susceptible to infection by Legionella pneumophila and Mycobacterium tuberculosis. Susceptibility of Sp140-/- mice to bacterial infection was rescued by crosses to mice lacking the type I IFN receptor (Ifnar-/-). Our results implicate Sp140 as an important negative regulator of type I IFNs that is essential for resistance to bacterial infections. Impact StatementRepression of type I interferons by SP140 is essential for resistance to Legionella pneumophila and Mycobacterium tuberculosis.

immunology↗

bioRxiv2019

Systems Analysis of Subjects Acutely Infected with Chikungunya Virus

The largest ever recorded epidemic of the chikungunya virus (CHIKV) began in 2004 and affected four continents. Acute symptomatic infections are typically associated with the onset of fever and often debilitating polyarthralgia/polyarthritis. In this study, a systems biology approach was used to analyze the blood transcriptomes of adults acutely infected with CHIKV. Gene signatures that were associated with viral RNA amounts and to the onset of symptoms were identified. Among those genes, the putative role of Eukaryotic Initiation Factor (eIF) family genes and apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC3A) in the CHIKV replication process were displayed. We further compared these signatures with those induced by dengue virus infection and rheumatoid arthritis. Finally, we demonstrated that CHIKV infection in mice induced IL-1 beta production in a mechanism highly dependent on the inflammasome NLRP3 activation. The findings provided valuable insights into the virus-host interactions during the acute phase and could be useful in the investigation of new and effective therapeutic interventions.

immunology↗