Cervicovaginal mucus barrier properties during pregnancy are impacted by the vaginal microbiome

Introduction

Mucus in the female reproductive tract acts as a barrier that traps and eliminates pathogens and foreign particles via steric and adhesive interactions. During pregnancy, mucus protects the uterine environment from ascension of pathogens and bacteria from the vagina into the uterus, a potential contributor to intrauterine inflammation and preterm birth. As recent work has demonstrated the benefit of vaginal drug delivery in treating women's health indications, we sought to define the barrier properties of human cervicovaginal mucus (CVM) during pregnancy to inform the design of vaginally delivered therapeutics during pregnancy.

Methods

CVM samples were self-collected by pregnant participants over the course of pregnancy, and barrier properties were quantified using multiple particle tracking. 16S rRNA gene sequencing was performed to analyze the composition of the vaginal microbiome.

Results

Participant demographics differed between term delivery and preterm delivery cohorts, with Black or African American participants being significantly more likely to delivery prematurely. We observed that vaginal microbiota is most predictive of CVM barrier properties and of timing of parturition. Lactobacillus crispatus dominated CVM samples showed increased barrier properties compared to polymicrobial CVM samples.

Discussion

This work informs our understanding of how infections occur during pregnancy, and directs the engineering of targeted drug treatments for indications during pregnancy.

Targeted Contrast Agents for Magnetic Resonance Molecular Imaging of Cancer

Magnetic resonance imaging (MRI) is a clinical imaging modality that provides high-resolution images of soft tissues, including cancerous lesions. Stable gadolinium(III) chelates have been used as contrast agents (CA) in MRI to enhance the contrast between the tissues of interest and surrounding tissues for accurate diagnostic imaging. Magnetic resonance molecular imaging (MRMI) of cancer requires targeted CA to specifically elucidate cancer-associated molecular processes and can provide high-resolution delineation and characterization of cancer for precision medicine. The main challenge for MRMI is the lack of sufficient sensitivity to detect the low concentration of the cellular oncogenic markers. In addition, targeted CA must satisfy regulatory safety requirements prior to clinical development. Up to now, there is no FDA-approved targeted CA for MRMI of cancer.In this Account, we discuss the latest developments in the design and development of clinically translatable targeted CA for MRMI of cancer, with an emphasis on our own research. The primary limitation of MRMI can be overcome by designing small molecular targeted CA to target abundant cancer-specific targets found in the tumor microenvironment (TME). For example, aggressive tumors have a unique extracellular matrix (ECM) composed of oncoproteins, which can be used as targetable markers for MRMI. We have designed and prepared small peptide conjugates of clinical contrast agents, including Gd-DTPA and Gd-DOTA, to target fibrin-fibronectin clots in tumors. These small molecular CA have been effective in enhancing MRMI detection of solid tumors and have demonstrated the ability to detect submillimeter cancer micrometastases in mouse tumor models, exceeding the detection limit of current clinical imaging modalities. We have also identified extradomain B fibronectin (EDB-FN), an oncofetal subtype of fibronectin, as a promising TME target to leverage in the design and development of small peptide targeted CA for clinical translation. The expression level of EDB-FN is correlated with invasiveness of cancer cells and poor patient survival of multiple cancer types. ZD2 peptide with a sequence of seven amino acids (TVRTSAD) was identified to specifically bind to the EDB protein fragment. Several ZD2 conjugates of macrocyclic GBCA, including Gd-DOTA and Gd(HP-DO3A), have been synthesized and tested in mouse tumor models. ZD2-N3-Gd(HP-DO3A) (MT218) with a high r₁ relaxivity was selected as the lead agent for clinical translation. The physicochemical properties and preclinical assessments of MT218 are summarized in this Account. MRMI of EDB-FN with MT218 can effectively detect invasive tumors of multiple cancers with risk-stratification and monitor tumor response to anticancer therapies in mouse models. Currently, MT218 is in clinical trials for precision cancer MRMI. Herein, we will show that using targeted MRI contrast agents specific to abundant TME biomarkers is a pragmatic solution for effective precision cancer imaging in high spatial resolution. And thus, we illustrate a replicable approach for CA development that is vital for cancer MRMI.

Evaluation of Physicochemical Properties, Pharmacokinetics, Biodistribution, Toxicity, and Contrast-Enhanced Cancer MRI of a Cancer-Targeting Contrast Agent, MT218

OBJECTIVES

Preclinical assessments were performed according to the US Food and Drug Administration guidelines to determine the physicochemical properties, pharmacokinetics, clearance, safety, and tumor-specific magnetic resonance (MR) imaging of MT218, a peptidic gadolinium-based MR imaging agent targeting to extradomain B fibronectin for MR molecular imaging of aggressive tumors.

MATERIALS AND METHODS

Relaxivity, chelation stability, binding affinity, safety-related target profiling, and effects on CYP450 enzymes and transporters were evaluated in vitro. Magnetic resonance imaging was performed with rats bearing prostate cancer xenografts, immunocompetent mice bearing murine pancreatic cancer allografts, and mice bearing lung cancer xenografts at different doses of MT218. Pharmacological effects on cardiovascular, respiratory, and central nervous systems were determined in rats and conscious beagle dogs. Pharmacokinetics were tested in rats and dogs. Biodistribution and excretion were studied in rats. Single and repeated dosing toxicity was evaluated in rats and dogs. In vitro and in vivo genotoxicity, in vitro hemolysis, and anaphylactic reactivity were also performed.

RESULTS

At 1.4 T, the r1 and r2 relaxivities of MT218 were 5.43 and 7.40 mM -1 s -1 in pure water, 6.58 and 8.87 mM -1 s -1 in phosphate-buffered saline, and 6.54 and 8.70 mM -1 s -1 in aqueous solution of human serum albumin, respectively. The binding affinity of MT218 to extradomain B fragment is 3.45 μM. MT218 exhibited no dissociation of the Gd(III) chelates under physiological conditions. The peptide degradation half-life ( t1/2 ) of MT218 was 1.63, 5.85, and 2.63 hours in rat, dog, and human plasma, respectively. It had little effect on CYP450 enzymes and transporters. MT218 produced up to 7-fold increase of contrast-to-noise ratios in the extradomain B fibronectin-rich tumors with a dose of 0.04 mmol/kg for at least 30 minutes. MT218 had little pharmacological effect on central nervous, cardiovascular, or respiratory systems. MT218 had a mean plasma elimination half-life ( t1/2 ) of 0.31 and 0.89 hours in rats and dogs at 0.1 mmol/kg, respectively. No detectable Gd deposition was observed in the brain at 6 hours postinjection of MT218 at 0.1 mmol/kg in rats. MT218 was not mutagenic and had no mortality or morbidity in the rats or dogs up to 1.39 and 0.70 mmol/kg/d, respectively. The no observed adverse effect level of MT218 in Sprague-Dawley rats was 1.39 mmol/kg for single dosing and 0.46 mmol/kg/d for repeated dosing. The no observed adverse effect level in dogs was 0.07 mmol/kg/d. MT218 exhibited no genotoxicity, hemolysis, and anaphylactic reactivity.

CONCLUSION

The preclinical assessments showed that the targeted contrast agent MT218 has high r1 and r2 relaxivities, satisfactory physicochemical properties, pharmacokinetic, and safety profiles and produces effective tumor enhancement in multiple cancer types in rats and mice at reduced doses.

Manganese(II) EOB-Pyclen Diacetate for Liver-Specific MRI

MRI is increasingly utilized for the diagnosis of liver disease and focal liver lesions. Although liver-targeted gadolinium-based contrast agents (GBCAs) have high efficacy, there continue to be safety concerns regarding release of toxic Gd(III) ions. Herein, Mn(EOB-PC2A) is synthesized as a nongadolinium alternative for liver-specific MRI. Mn(EOB-PC2A) has an r₁ relaxivity of 2.8 mM^-1 s^-1 in Dulbecco's phosphate-buffered saline (DPBS) and 5.9 mM^-1 s^-1 in saline containing human serum albumin at 1.5 T. It has a strong uptake in hepatocytes with minimal toxicity and demonstrated robust liver-specific enhancement at a dose of 60 μmol/kg. Mn(EOB-PC2A) is a promising liver-specific contrast agent for liver MRI.

Enhanced drug delivery to the reproductive tract using nanomedicine reveals therapeutic options for prevention of preterm birth

Inflammation contributes to nearly 4 million global premature births annually. Here, we used a mouse model of intrauterine inflammation to test clinically used formulations, as well as engineered nanoformulations, for the prevention of preterm birth (PTB). We observed that neither systemic 17a-hydroxyprogesterone caproate (Makena) nor vaginal progesterone gel (Crinone) was sufficient to prevent inflammation-induced PTB, consistent with recent clinical trial failures. However, we found that vaginal delivery of mucoinert nanosuspensions of histone deacetylase (HDAC) inhibitors, in some cases with the addition of progesterone, prevented PTB and resulted in delivery of live pups exhibiting neurotypical development. In human myometrial cells in vitro, the P4/HDAC inhibitor combination both inhibited cell contractility and promoted the anti-inflammatory action of P4 by increasing progesterone receptor B stability. Here, we demonstrate the use of vaginally delivered drugs to prevent intrauterine inflammation-induced PTB resulting in the birth of live offspring in a preclinical animal model.

Characterization of an Adapted Murine Model of Intrauterine Inflammation-Induced Preterm Birth

Preterm birth (PTB) affects nearly 15 million infants each year. Of these PTBs, >25% are a result of inflammation or infection. Animal models have improved our understanding of the mechanisms leading to PTB. Prior work has described induction of intrauterine inflammation in mice with a single injection of lipopolysaccharide (LPS). Herein, we have improved the reproducibility and potency of LPS in the model using two injections distal to the cervix. An in vivo imaging system revealed more uniform distribution of Evans Blue Dye using a double distal injection (DDI) approach compared with a single proximal injection (SPI). Endotoxin concentrations in vaginal lavage fluid from SPI dams were significantly higher than from DDI dams. At equivalent LPS doses, DDI consistently induced more PTB than SPI, and DDI showed a linear dose-response, whereas SPI did not. Gene expression in myometrial tissue revealed increased levels of inflammatory markers in dams that received LPS DDI compared with LPS SPI. The SPI group showed more significant overexpression in cervical remodeling genes, likely due to the leakage of LPS from the uterine horns through the cervix. The more reliable PTB induction and uniform uterine exposure provided by this new model will be useful for further studying fetal outcomes and potential therapeutics for the prevention of inflammation-induced PTB.

Interplay of the physical microenvironment, contact guidance, and intracellular signaling in cell decision making

The peritumoral physical microenvironment consists of complex topographies that influence cell migration. Cell decision making, upon encountering anisotropic, physiologically relevant physical cues, has yet to be elucidated. By integrating microfabrication with cell and molecular biology techniques, we provide a quantitative and mechanistic analysis of cell decision making in a variety of well-defined physical microenvironments. We used MDA-MB-231 breast carcinoma and HT1080 fibrosarcoma as cell models. Cell decision making after lateral confinement in 2-dimensional microcontact printed lines is governed by branch width at bifurcations. Cells confined in narrow feeder microchannels prefer to enter wider branches at bifurcations. In contrast, in feeder channels that are wider than the cell body, cells elongate along one side wall of the channel and are guided by contact with the wall to the contiguous branch channel independent of its width. Knockdown of β1-integrins or inhibition of cellular contractility suppresses contact guidance. Concurrent, but not individual, knockdown of nonmuscle myosin isoforms IIA and IIB also decreases contact guidance, which suggests the existence of a compensatory mechanism between myosin IIA and myosin IIB. Conversely, knockdown or inhibition of cell division control protein 42 homolog promotes contact guidance-mediated decision making. Taken together, the dimensionality, length scales of the physical microenvironment, and intrinsic cell signaling regulate cell decision making at intersections.-Paul, C. D., Shea, D. J., Mahoney, M. R., Chai, A., Laney, V., Hung, W.-C., Konstantopoulos, K. Interplay of the physical microenvironment, contact guidance, and intracellular signaling in cell decision making.