Biology subjects

Castro-Cordova, P.

Publications and source records attributed to Castro-Cordova, P..

6 recordsLinked to original sources

bioRxiv2026

Repurposing nystatin and taurocholate to target intracellular spore persistence during antibiotic treatment to prevent recurrent Clostridioides difficile infection.

Successful treatment of primary Clostridioides difficile infection (CDI) while preventing its recurrence remains a major clinical challenge, with recurrent CDI (R-CDI) affecting 20-30% of treated patients. Persistence of C. difficile spores within the intestinal mucosa is thought to drive R-CDI following antibiotic treatment. Here, we show that intracellular C. difficile spores remain protected from taurocholate-triggered germination, and that nystatin, an FDA-approved antifungal that blocks spore entry into host cells, reduces this protected intracellular population and redirects spores toward an extracellular, germinating population accessible to antibiotics. In a murine model of R-CDI, oral co-administration of taurocholate with nystatin and antibiotics during primary CDI reduced R-CDI incidence from 100% to 44%. When administered during an active R-CDI episode, the same formulation reduced a second R-CDI from 100% to 62%. To improve bioavailability, we encapsulated nystatin and vancomycin in chitosan nanoparticles. Oral administration of nanoparticle-encapsulated vancomycin, alone or combined with nanoparticle-encapsulated nystatin, reduced R-CDI colonization to 33% and 44%, respectively, compared with 100% in mice receiving free vancomycin. Together, these findings support a therapeutic strategy that repurposes nystatin and taurocholate, in combination with antibiotics and nanoparticle-based delivery, to target intracellular spore persistence and reduce the incidence of C. difficile recurrence..

pharmacology and toxicology↗

bioRxiv2026

Gut complement C1q and C3 interact with Clostridioides difficile spores via CdeM and contribute to pathogenesis.

Clostridioides difficile infection (CDI) is characterized by toxin-mediated epithelial injury, intestinal inflammation, and a high frequency of disease recurrence. Although complement components are produced locally within the gastrointestinal tract, their contribution to C. difficile pathogenesis remains poorly understood. Here, we investigated the interaction of the complement proteins C1q and C3 with C. difficile spores and their contribution to spore-host interactions and disease outcome. We found that C1q and C3 are accessible within the healthy ileal mucosa and that TcdB intoxication differentially remodels their spatial availability, decreasing accessible C1q while increasing accessible C3 at higher toxin concentrations. C. difficile spores associated with both complement components in vivo and directly interacted with purified human C1q and C3 in vitro, with immunogold electron microscopy localizing these interactions to the outer exosporium. Although the collagen-like BclA proteins modulated complement binding under some conditions, they were not required for C1q or C3 association. Far-Western analysis coupled to mass spectrometry identified the exosporium proteins CotE and CdeM as candidate complement-interacting proteins, and purified CdeM inclusion bodies directly associated with both C1q and C3. Exposure of spores to human serum promoted their interaction with intestinal epithelial cells, whereas depletion of either C1q or C3 markedly reduced spore internalization and reconstitution with the corresponding purified protein partially restored entry. C3-derived species, including C3dg, were selectively associated with spores but not vegetative cells, without reducing spore viability. Finally, C1q deficiency did not alter the initial onset of CDI but accelerated recovery and markedly attenuated recurrent disease following vancomycin treatment. Together, these findings identify intestinal complement as a previously unrecognized component of the C. difficile spore-host interface and reveal C1q and C3 as modulators of spore epithelial entry, persistence, and recurrent disease.

microbiology↗

bioRxiv2025

Clostridioides difficile major toxins remodel the intestinal epithelia, affecting spore adherence/internalization into intestinal tissue and their association with gut vitronectin.

The most common cause of healthcare-associated diarrhea and colitis in the U.S., is Clostridioides difficile, a spore-forming pathogen. Two toxins, TcdA and TcdB, are major virulence factors essential for disease manifestations, while C. difficile spores are essential for disease transmission and recurrence. Both toxins cause major damage to the epithelial barrier, trigger massive inflammation, and reshape the microbiome and metabolic composition, facilitating C. difficile colonization. C. difficile spores, essential for transmission and recurrence of the disease, persist adhered and internalized in the intestinal epithelia. Studies have suggested that toxin-neutralization in combination with antibiotic during CDI treatment in humans significantly reduces disease recurrence, suggesting a link between toxin-mediated damage and spore persistence. Here, we show that TcdA/TcdB-intoxication of intestinal epithelial Caco-2 cells leads to remodeling of accessible levels of fibronectin (Fn) and vitronectin (Vn) and their cognate alpha-integrin subunits. While TcdB-intoxication of intestinal tissue had no impact in accessible levels of Fn and Vn, but significantly increased levels of intracellular Vn. We observed that Fn and Vn released to the supernatant readily bind to C. difficile spores in vitro, while TcdB-intoxication of intestinal tissue led to increased association of C. difficile spores with gut Vn. Toxin-intoxication of the intestinal tissue also contributes to increased adherence and internalization of C. difficile spores. However, TcdB-intoxicated ligated loops infected of mice treated with Bezlotoxumanb (monoclonal anti- TcdB antibodies) did not prevent TcdB-mediated increased spore adherence and internalization into intestinal tissue. This study highlights the importance of studying the impact of C. difficile toxins of host tissues has in C. difficile interaction with host surfaces that may contribute to increased persistence and disease recurrence.

microbiology↗

bioRxiv2021

E-cadherin redistribution mediated by Clostridioides difficile toxins increases spore-association to adherens junctions

Clostridioides difficile causes antibiotic-associated diseases in humans ranging from mild diarrhea to severe pseudomembranous colitis and death. A major clinical challenge is the prevention of disease recurrence, which affects nearly [~]20 - 30 % of the patients with a primary C. difficile infection (CDI). During CDI, C. difficile forms metabolically dormant spores that are essential for recurrence of CDI (R-CDI). In prior studies, we have shown that C. difficile spores interact with intestinal epithelial cells (IECs), which contributes to R-CDI. However, this interaction remains poorly understood. Here, we provide evidence that C. difficile spores interact with E-cadherin, contributing to spore-adherence and internalization into IECs. C. difficile toxins TcdA/TcdB lead to adherens junctions opening and increase spore-adherence to IECs. Confocal micrographs demonstrate that C. difficile spores associate with accessible E-cadherin; spore-E-cadherin association increases upon TcdA/TcdB intoxication. The presence of anti-E-cadherin antibodies decreased spore adherence and entry into IECs. By ELISA, immunofluorescence, and immunogold labelling, we observed that E-cadherin binds to C. difficile spores, specifically to the hair-like projections of the spore, reducing spore-adherence to IECs. Overall, these results expand our knowledge of how C. difficile spores bind to IECs by providing evidence that E-cadherin acts as a spore-adherence receptor to IECs and by revealing how toxin-mediated damage affects spore interactions with IECs.

microbiology↗

bioRxiv2021

A ligated intestinal loop mouse model protocol to study the interactions of Clostridioides difficile spores with the intestinal mucosa during aging.

The interaction of the Clostridioides difficile spores with the intestinal mucosa contribute to the persistence and recurrence of the infection. Advanced age is one of the main risk factors to manifest C. difficile infection and recurrence. However, the interaction of C. difficile spores with the intestinal mucosa during aging has not been evaluated. In the present work, we provide a detailed protocol with all the critical information to perform an intestinal ligated loop. Using this technique in a mouse model, we evaluated C. difficile spore adherence and internalization to the ileum and colonic mucosa during aging. Consequently, our data suggest that spore internalization in the ileum and colonic mucosa is higher in elderly than in adults or young mice. Also, our data suggest that spore-adherence to the ileum and colonic mucosa decreases with aging.

microbiology↗

bioRxiv2020

Clostridioides difficile spore-entry into intestinal epithelial cells contributes to recurrence of the disease

Clostridioides difficile spores produced during infection are essential for the recurrence of the disease. However, how C. difficile spores persist in the intestinal mucosa to cause recurrent infection remains unknown. Here, we show that C. difficile spores gain entry into the intestinal mucosa via fibronectin-5{beta}1 and vitronectin-v{beta}1 specific-pathways. The spore-surface exosporium BclA3 protein is essential for both spore-entry pathways into intestinal epithelial cells. Furthermore, C. difficile spores of a bclA3 isogenic mutant exhibited reduced entry into the intestinal mucosa and reduced recurrence of the disease in a mouse model of the disease. Inhibition of C. difficile spore-entry led to reduced spore-entry into the intestinal epithelial barrier and recurrence of C. difficile infection in vivo. These findings suggest that C. difficile spore-entry into the intestinal barrier is a novel mechanism of spore-persistence that can contribute to infection recurrence and have implications for the rational design of therapies.

microbiology↗