Intubation-mediated Intratracheal (IMIT) Instillation: A Noninvasive, Lung-specific Delivery System

Abstract

Respiratory disease studies typically involve the use of murine models as surrogate systems. However, there are significant physiologic differences between the murine and human respiratory systems, especially in their upper respiratory tracts (URT). In some models, these differences in the murine nasal cavity can have a significant impact on disease progression and presentation in the lower respiratory tract (LRT) when using intranasal instillation techniques, potentially limiting the usefulness of the mouse model to study these diseases. For these reasons, it would be advantageous to develop a technique to instill bacteria directly into the mouse lungs in order to study LRT disease in the absence of involvement of the URT. We have termed this lung specific delivery technique intubation-mediated intratracheal (IMIT) instillation. This noninvasive technique minimizes the potential for instillation into the bloodstream, which can occur during more invasive traditional surgical intratracheal infection approaches, and limits the possibility of incidental digestive tract delivery. IMIT is a two-step process in which mice are first intubated, with an intermediate step to ensure correct catheter placement into the trachea, followed by insertion of a blunt needle into the catheter to mediate direct delivery of bacteria into the lung. This approach facilitates a >98% efficacy of delivery into the lungs with excellent distribution of reagent throughout the lung. Thus, IMIT represents a novel approach to study LRT disease and therapeutic delivery directly into the lung, improving upon the ability to use mice as surrogates to study human respiratory disease. Furthermore, the accuracy and reproducibility of this delivery system also makes it amenable to Good Laboratory Practice Standards (GLPS), as well as delivery of a wide range of reagents which require high efficiency delivery to the lung. Video LinkThe video component of this article can be found at

Validation of 2-18F-Fluorodeoxysorbitol as a Potential Radiopharmaceutical for Imaging Bacterial Infection in the Lung

“…Our findings are consistent with those of a published study (12) that also used 18 F-FDS to image lung infection caused by K. pneumoniae, but the strain of bacteria used in that study was the ATCC 700721 strain, better known as MGH 78578, which is relatively avirulent and has a 50% lethal dose of 10 8 CFUs (23). In contrast, we used a highly virulent strain (50% lethal dose, 100 CFUs) called ATCC 43816 (13). This difference explains why the animals in the other study were inoculated with a higher dose of bacteria but developed only mild lung infection on day 5 after inoculation whereas our animals started to develop lung infection on day 2, with a mortality rate of about 10%-20%, and infection was fully developed on day 3, with a survival rate of 30%-40%.…”

“…The rising resistance of K. pneumoniae infections to multiple antibiotics, making the treatment challenging, has emerged as a major concern in hospitals, nursing homes, and other health care settings (13). Therefore, early diagnosis of these infections is critical.…”

“…Female C57 BL mice (8-10 wk old; Charles River) were inoculated with live K. pneumoniae (10 5 CFUs/mL) or dead K. pneumoniae (10 8 CFUs/mL) using a previously published intubation-mediated intratracheal instillation method (13).…”

An Improved Method for Rapid Intubation of the Trachea in Mice

“…In fact, similar methods have already been reported for a multitude of disparate materials in this way 19,25 . Consistent with such protocols, delivery of bleomycin in the manner outlined here resulted in a potent fibrotic response in both lungs, and in all lobes, suggesting a similar level of depth and uniformity in distribution.…”

In vivo monitoring of therapeutic efficacy and virulence profile by bioluminescent Klebsiella pneumoniae.

“…Intubation-mediated intratracheal (IMIT) inoculations were conducted as demonstrated in detail elsewhere [187]. Briefly, isoflurane-anesthetized animals received 10 µl of 2% lidocaine anesthetic to the rear of the throat and were supported supine on a tilting platform raised to a 45 o angle.…”