Monica Sierra Martinez

Prof. Dr. Monica Sierra Martinez

orcid

Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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2 February 2023 in Pathogens
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JAJudit Alarcón-Millán
Judit Alarcón-Millán
José Bonilla-DelgadoJosé Bonilla-Delgado
José Bonilla-Delgado
GFGloria Fernández-Tilapa
Gloria Fernández-Tilapa
NVNayeli Goreti Nieto Velázquez
Nayeli Goreti Nieto Velázquez
MMMonica Sierra Martinez
Monica Sierra Martinez
ENOC MARIANO CORTÉS MALAGÓNENOC MARIANO CORTÉS MALAGÓN
ENOC MARIANO CORTÉS MALAGÓN
Persistent infection with Helicobacter pylori (H. pylori) is an important factor in gastric diseases. The vacA and cagA virulence factors of H. pylori contribute to the development of these diseases. Triple therapy containing clarithromycin has been used to eradicate this infection. Unfortunately, resistance to this antibiotic is the primary cause of treatment failure. This study aimed to determine the prevalence of clarithromycin resistance-associated mutations and to assess the relationship between virulence factors and Mexican patients infected with H. pylori. The cagA and vacA genotypes were determined by multiplex PCR. Furthermore, a qPCR was used to identify mutations of the 23S rRNA gene. This study reported a prevalence of 84.3% of H. pylori among patients with gastric diseases, and the vacA s1m1/cagA+ genotype was the most frequent (44.8%) in antrum and corpus. Analysis of the 23S rRNA gene revealed a 19.8% prevalence of clarithromycin resistance-associated mutations. The most prevalent mutations were A2143G (56%) and A2142C (25%). A significant association (p < 0.05) between the A2142G and the vacA s1m1/cagA+ genotype was detected. In conclusion, we report a high prevalence (>15%) of clarithromycin resistance-associated mutations, and we found an association between the genotypes of virulence factors and a mutation in the 23S rRNA gene.

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FMFrancisco Alfredo Molina-Pelayo
Francisco Alfredo Molina-Pelayo
David Zárate-LópezDavid Zárate-López
David Zárate-López
RCRosendo García Carrillo
Rosendo García Carrillo
CRCésar Rodríguez-Beas
César Rodríguez-Beas
RIRamón Iñiguez-Palomares
Ramón Iñiguez-Palomares
Luis Castro-SánchezLuis Castro-Sánchez
Luis Castro-Sánchez
Hepatocellular carcinoma (HCC) is the most common primary liver cancer, often diagnosed at advanced stages due to insufficient early screening and monitoring. MicroRNAs (miRNAs) are key regulators of gene expression and potential biomarkers for cancer diagnosis. This study investigated the diagnostic potential of miRNAs in Extracellular Vesicles (EVs) from HCC. miRNA expression in EVs was analyzed using HCC cell lines, circulating EVs from a Diethylnitrosamine (DEN)-induced liver tumor rat model, and plasma samples from HCC patients. Receiver Operating Characteristics (ROCs) were applied to evaluate the diagnostic accuracy of circulating EV miRNAs in patients. Five miRNAs (miR-183-5p, miR-19a-3p, miR-148b-3p, miR-34a-5p, and miR-215-5p) were consistently up-regulated in EVs across in vitro and in vivo HCC models. These miRNAs showed statistically significant differences in HCC patients stratified by TNM staging and Edmondson–Steiner grading compared to healthy controls. They also differentiated HCC patients with various etiologies from the control group and distinguished HCC patients, with or without liver cirrhosis, from cirrhotic and healthy individuals. Individually and as a panel, they demonstrated high sensitivity, specificity, and accuracy in identifying HCC patients. Their consistent upregulation across models and clinical samples highlights their robustness as biomarkers for HCC diagnosis, offering the potential for early disease management and prognosis.

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JMJesús Alejandro Pineda Migranas
Jesús Alejandro Pineda Migranas
JBJuan Carlos Bravata-Alcantara
Juan Carlos Bravata-Alcantara
ICIliana Alejandra Cortés-Ortiz
Iliana Alejandra Cortés-Ortiz
ENOC MARIANO CORTÉS MALAGÓNENOC MARIANO CORTÉS MALAGÓN
ENOC MARIANO CORTÉS MALAGÓN
MRMaria de los Angeles Romero-Tlalolini
Maria de los Angeles Romero-Tlalolini
GAGustavo Acosta-Altamirano
Gustavo Acosta-Altamirano
Cervical cancer remains a significant public health priority, particularly in low- and middle-income countries. In this context, liquid biopsy has emerged as a minimally invasive method for detecting and monitoring molecular biomarkers, offering advantages over traditional screening approaches. This systematic review included 21 studies published between 2015 and 2025 and was conducted in accordance with the PRISMA 2020 statement. The analysis examined the role of serum cytokines, circulating microRNAs (miRNAs), and circulating cell-free HPV DNA (cfHPV-DNA) in patients with cervical cancer or high-grade intraepithelial lesions. Circulating miRNAs—particularly miR-21, miR-29a, and miR-34a—are consistently associated with recurrence, tumor progression, and reduced survival. However, their immediate clinical translation remains limited by methodological variability and the lack of universal normalizers. In contrast, cfHPV-DNA, especially with ddPCR, exhibited the best study-level performance, with a specificity of 100% and a sensitivity of approximately 80–88%, across heterogeneous endpoints and analytic conditions. Consequently, cfHPV-DNA represents a promising tool for post-treatment surveillance and early detection of recurrence. Serum cytokines, such as TNF-α, IL-6, and IL-10, reflect inflammation and the tumor microenvironment. Nevertheless, their lack of standardization and variability across detection platforms restricts their reproducibility, positioning them as complementary rather than stand-alone markers. In conclusion, the evidence supports liquid biopsy as a promising tool in cervical cancer management; nonetheless, only cfHPV-DNA is currently ready for clinical application, whereas miRNAs and cytokines require multicenter validation and technical standardization before implementation.

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FLFrancisco Sierra López
Francisco Sierra López
NINancy Vanessa Iglesias-Vazquez
Nancy Vanessa Iglesias-Vazquez
LBLidia Baylon-Pacheco
Lidia Baylon-Pacheco
Emmanuel Ríos-CastroEmmanuel Ríos-Castro
Emmanuel Ríos-Castro
JOJuan Carlos Osorio-Trujillo
Juan Carlos Osorio-Trujillo
MMMonica Sierra Martinez
Monica Sierra Martinez
Extracellular vesicles (EVs) can transport molecules that combat viruses, such as RNA against SARS-CoV-2. Bacterial coinfections can help establish certain viruses and worsen diseases. Thus, we designed a model to induce the secretion of polydisperse EVs shown with SARS-CoV-2 and bacterial coinfection using macrophages and E. coli fractions as in vitro inducers. We obtained short and large macrophage EVs. The E. coli fraction was designated as SDS-soluble bacterial membrane fraction and its associated proteins (SDS-SBMF). The proteins were identified using a mass spectrometer. SDS-SBMF contained mainly OmpF, OmpA, OmpC, OmpX, and lpp. The SDS-SBMF macrophages induced the secretion of polydisperse EVs at 30 min, reaching optimal secretion at 120 min, as observed via scanning electron microscopy and confocal microscopy. Macrophage EVs contained mainly HSP7C, actin, apolipoprotein, GAPDH, annexin A5, PKM, moesin, and cofilin. We observed an increase in EVs in the bloodstream of patients with SARS-CoV-2 and bacterial coinfection, in addition to the presence of SARS-CoV-2 genes (E, ORF) in EVs. This in vitro method for inducing EVs has the potential to be used to obtain larger samples for study and for the detection of diagnostic and prognostic biomarkers of different diseases.

7 February 2025 in Immunology Letters
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KCKarina Corona-Cervantes
Karina Corona-Cervantes
ESErick Sánchez-Salguero
Erick Sánchez-Salguero
PZPaola Berenice Zárate-Segura
Paola Berenice Zárate-Segura
Aparna KrishnakumarAparna Krishnakumar
Aparna Krishnakumar
APAlberto Piña-Escobedo
Alberto Piña-Escobedo
Jaime García-MenaJaime García-Mena
Jaime García-Mena
In the early days, maternal immunoglobulins are essential for sustaining a balanced gut environment by influencing the interaction between the host and the microbiome. The successional establishment of the pioneer strains is an interesting topic of research where maternal immunoglobulins appear to be important. This proof-of-concept study explored the binding pattern of IgA1, IgA2, IgM, and IgG classes to a commensal bacterial in human colostrum and the stool of breastfed neonates. We used flow cytometry coupled with 16S rRNA gene sequencing in human colostrum and neonatal feces samples to characterize this Ig-microbiota association. We observed that in human colostrum samples, IgA2 and IgM bind alfa and beta Proteobacteria, which can potentially stimulate neonatal immune system development in the gut. Other immunoglobulins like IgG predominantly bind facultative anaerobes belonging to the Firmicutes phylum, reported as part of human milk microbiota and pioneer colonizers of the neonatal gut. Maternal immunoglobulins also bind a wide diversity of bacteria in the neonatal stool. For instance, IgA2 and IgM bound more members of the phylum Bacteroidetes in comparison to IgG, these Bacteroidetes and some firmicutes have been reported as late colonizers of the neonatal gut, and their presence is important due to their ability to produce important short chain fatty acids like propionate and butyrate. Our results support the current view that microbial and immunoglobulin transference is crucial for developing the neonate's immune system and individual gut microbiota.

17 January 2025 in Microorganisms
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ICIliana Alejandra Cortés-Ortiz
Iliana Alejandra Cortés-Ortiz
GAGustavo Acosta-Altamirano
Gustavo Acosta-Altamirano
RNRafael Nambo
Rafael Nambo
JMJesús Alejandro Pineda Migranas
Jesús Alejandro Pineda Migranas
OOscar Giovanni Rios Hernandez
Oscar Giovanni Rios Hernandez
JBJuan Carlos Bravata-Alcantara
Juan Carlos Bravata-Alcantara
Infertility, both primary and secondary, is strongly influenced by microbiological factors, with the vaginal microbiota playing a key role in reproductive health. Objective: The aim of this study was to characterize the vaginal microbiota of 136 Mexican women diagnosed with infertility—primary (n = 58) and secondary (n = 78)—by evaluating the presence of pathogenic bacterial species and their associations with infertility conditions. Methods: Samples were obtained through cervical swabs, and microorganism identification was performed using qPCR techniques. Results: Analysis revealed a positive correlation between increased age and the likelihood of primary infertility, as well as a negative correlation with secondary infertility. Significant differences in microbial composition were also observed between the two infertility groups. Lactobacillus crispatus and Lactobacillus gasseri were dominant in women with primary infertility, in addition to a high prevalence of Gardnerella vaginalis and Fannyhessea vaginae. Additionally, correlations were found between the presence of human papillomavirus (HPV) and sexually transmitted bacteria, as well as Gardnerella vaginalis. Conclusion: Our findings suggest that the composition of the vaginal microbiota may play a decisive role in infertility, highlighting the need for personalized therapeutic strategies based on microbial profiles.