Biology subjects

Sabbione, F.

Publications and source records attributed to Sabbione, F..

3 recordsLinked to original sources

bioRxiv2024

Ecotin protects Salmonella Typhimurium against the microbicidal activity of host proteases

Salmonella enterica serovar Typhimurium causes acute diarrhea upon oral infection in humans. The harsh and proteolytic environment found in the gastrointestinal tract is the first obstacle that these bacteria face after infection. However, the mechanisms that allow Salmonella to survive the hostile conditions of the gut are poorly understood. The ecotin gene is found in an extensive range of known phyla of bacteria and it encodes a protein that has been shown to inhibit serine proteases. Thus, in the present work we studied the role of ecotin of Salmonella Typhimurium in host-pathogen interactions. We found that Salmonella Typhimurium {Delta}ecotin strain exhibited lower inflammation in a murine model of Salmonella induced colitis. The {Delta}ecotin mutant was more susceptible to the action of pancreatin and purified pancreatic elastase. In addition, the lack of ecotin led to impaired adhesion to Caco-2 and HT-29 cell lines, related to the proteolytic activity of brush border enzymes. Besides, {Delta}ecotin showed higher susceptibility to lysosomal proteolytic content and intracellular replication defects in macrophages. In addition, we found Ecotin to have a crucial role in Salmonella against the microbicide action of granules released and neutrophil extracellular traps from human polymorphonuclear leukocytes. Thus, the work presented here highlights the importance of ecotin in Salmonella as countermeasures against the host proteolytic defense system. IMPORTANCEThe gastrointestinal tract is a very complex and harsh environment. Salmonella is a successful food borne pathogen, but little is known about its capacity to survive against the proteolysis of the gut lumen and intracellular proteases. Here, we show that Ecotin, a serine protease inhibitor, plays an important role in protecting Salmonella against proteases present at different sites encountered during oral infection. Our results indicate that Ecotin is an important virulence factor in Salmonella, adding another tool to the wide range of features this pathogen uses during oral infection.

microbiology↗

bioRxiv2024

CD4+ T cells drive corneal nerve damage but are dispensable for corneal epitheliopathy development in dry eye disease

Dry eye disease (DED) is characterized by a dysfunctional tear film in which the cornea epithelium and its abundant nerves are affected by ocular desiccation and inflammation. Although adaptive immunity and specifically CD4+ T cells play a role in DED pathogenesis, the exact contribution of these cells to corneal epithelial and neural damage remains undetermined. To address this, we explored the progression of a surgical DED model in wild-type (WT) and T cell-deficient mice. We observed that adaptive immune-deficient mice developed all aspects of DED comparably to WT mice except for the absence of functional and morphological corneal nerve changes, nerve damage-associated transcriptomic signature in the trigeminal ganglia, and sustained tear cytokine levels. Adoptive transfer of CD4+ T cells from WT DED mice to T cell-deficient mice reproduced corneal nerve damage but not epitheliopathy. Conversely, T cell-deficient mice reconstituted solely with naive CD4+ T cells developed corneal nerve impairment and epitheliopathy upon DED induction, thus replicating the WT DED phenotype. Collectively, our data show that while corneal neuropathy is driven by CD4+ T cells in DED, corneal epithelia damage develops independently of the adaptive immune response. These findings have implications for T cell-targeting therapies currently in use for DED. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=80 SRC="FIGDIR/small/586336v2_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1138e85org.highwire.dtl.DTLVardef@f1d0c7org.highwire.dtl.DTLVardef@1c1cccaorg.highwire.dtl.DTLVardef@6c09a7_HPS_FORMAT_FIGEXP M_FIG C_FIG Significance StatementDry eye is a frequent ocular disorder in which damage to the corneal epithelium and nerves is triggered by inadequate lubrication. The local CD4+ T cell-predominant immune response aggravates ocular surface impairment but the exact contribution of these cells to corneal epithelial and neural disease remains undetermined. Using adoptive transfer of T cells into T cell-deficient mice, trigeminal transcriptomics, and tear cytokine analysis, we delineate the pathogenic role of CD4+ T cells, revealing that they drive corneal nerve damage but are dispensable for epithelial disease to develop in response to desiccation. CD4+ T cells promote corneal neuropathy possibly by releasing proinflammatory cytokines onto the ocular surface. These findings have implications for T cell-targeting therapies currently used for dry eye.

immunology↗

bioRxiv2023

Ocular TRPV1 deficiency protects from dry eye-induced corneal nerve damage

BackgroundCorneal nerve damage causes the most clinically significant symptoms in dry eye disease (DED) yet its pathophysiology remains poorly understood. Transient receptor potential vanilloid-1 (TRPV1) channels abound in corneal nerve fibers and respond to inflammation-derived ligands, which increase in DED. TRPV1 overactivation promotes axonal degeneration in vitro but whether it contributes to corneal neuropathy is unknown. Therefore, here we explored the role of TRPV1 in DED-associated corneal nerve damage. MethodsSurgical DED was induced in TRPV1-deficient (TRPV1KO) and wild-type (wt) mice. Corneal nerve function was measured on days 0, 5, and 10 by mechanical and capsaicin sensitivity and eye-closing ratio as an indicator of non-evoked pain. Nerve and epithelial morphology was evaluated by confocal microscopy of corneal wholemounts. Pharmacological TRPV1 inhibition in wild-type mice was also evaluated. Resultswt and TRPV1KO mice developed comparable ocular desiccation and corneal epithelial damage. Contrasting with wt mice, corneal mechanosensitivity in TRPV1KO mice did not decrease with disease progression. Capsaicin sensitivity increased in wt mice with DED, and consistently, wt but not TRPV1KO mice with DED displayed signs of non-evoked pain. Wt mice with DED exhibited nerve degeneration throughout the corneal epithelium whereas TRPV1KO mice only developed a reduction in the most superficial nerve endings that failed to propagate to the deeper subbasal corneal nerves. Pharmacological blockade of ocular TRPV1 activity reproduced these findings in wt mice with DED. Although TRPV1KO mice with DED had fewer pathogenic Th1 and Th17 CD4+ T cells in the lymph nodes, conjunctival immune infiltration was comparable between strains. Moreover, CD4+ T cells from wt and TRPV1KO mice with DED were equally pathogenic when transferred into T cell-deficient mice, confirming that TRPV1 activity in T cells is not involved in corneal neuropathy. ConclusionsAlthough ocular desiccation is sufficient to trigger superficial corneal nerve damage in DED, proximal propagation of axonal degeneration requires TRPV1 signaling. Conversely, local inflammation sensitizes ocular TRPV1 channels, which are also involved in ocular pain, a key symptom of the disease. Thus, our findings suggest that ocular TRPV1 overactivation is a driving force in DED-associated corneal neuropathy and a potential therapeutic target. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=63 SRC="FIGDIR/small/554143v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@12d43d7org.highwire.dtl.DTLVardef@c11354org.highwire.dtl.DTLVardef@1dc0098org.highwire.dtl.DTLVardef@ab2e60_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗