Developmental expression of Toll‑like receptors in the guinea pig lung

Expression of Toll-Like Receptors in the Lung Tissue of Mouse Fetuses Generated by in vitro Embryo Culture and Embryo Transfer

Mouse fetuses generated by in vitro embryo culture and embryo transfer exhibit impaired lung development, altered composition of pulmonary epithelial cells associated with downregulation of several genes involved in lung development and toll-like receptor (TLR) signaling pathway. The aims of the present study were to determine the expression of all TLRs and to examine if the expression of TLRs, along with genes involved in TLR signaling pathway, is altered in the lung tissue of mouse fetuses generated through embryo culture and embryo transfer. Two experimental (EGs) and one control (CG) group were included in the study. Embryos cultured at 5% CO2-95% air for 95 h or less than 24 h were transferred to pseudo-pregnant females to obtain fetuses comprising EGin vitro (n = 18) and EGin vivo (n = 18), respectively. Fetuses obtained from naturally ovulating females on day 18 of pregnancy served as the CG (n = 18). Western blot and immunohistochemistry were used to determine the expression of TLR proteins. The expression of transcripts encoding TLRs, and the genes involved in TLR signaling pathway (Lbp, Pik3r1, Pik3cb, Nfkbia, and Fos), was determined using qRT-PCR. While all TLRs were expressed by cells lining the bronchial/bronchiolar epithelium of lung tissues in all groups, some of the TLRs were expressed in a specific pattern. When compared to CG, the expression of transcripts encoding TLR-2, -3, -4, -5, -7, -8, -9, -12, -13, Lbp, Pik3r1, Pik3cb, Nfkbia, and Fos was significantly downregulated in both EGs. It appears that stress imposed on embryos at preimplantation stages of development is associated with downregulation of TLRs, along with some of the genes involved in TLR signaling pathway, in the lung tissue during the perinatal period. It remains to be determined if downregulation of TLRs, along with the genes involved in TLR signaling pathway, has any functional consequences in the adult lung tissue.

Targeting the Toll-like receptor pathway as a therapeutic strategy for neonatal infection

Toll-like receptors (TLRs) are crucial transmembrane receptors that form part of the innate immune response. They play a role in the recognition of various microorganisms and their elimination from the host. TLRs have been proposed as vital immunomodulators in the regulation of multiple neonatal stressors that extend beyond infection such as oxidative stress and pain. The immune system is immature at birth and takes some time to become fully established. As such, babies are especially vulnerable to sepsis at this early stage of life. Findings suggest a gestational age-dependent increase in TLR expression. TLRs engage with accessory and adaptor proteins to facilitate recognition of pathogens and their activation of the receptor. TLRs are generally upregulated during infection and promote the transcription and release of proinflammatory cytokines. Several studies report that TLRs are epigenetically modulated by chromatin changes and promoter methylation upon bacterial infection that have long-term influences on immune responses. TLR activation is reported to modulate cardiorespiratory responses during infection and may play a key role in driving homeostatic instability observed during sepsis. Although complex, TLR signaling and downstream pathways are potential therapeutic targets in the treatment of neonatal diseases. By reviewing the expression and function of key Toll-like receptors, we aim to provide an important framework to understand the functional role of these receptors in response to stress and infection in premature infants.

Therapeutic effects and mechanisms study of Hanchuan Zupa Granule in a Guinea pig model of cough variant asthma

ETHNOPHARMACOLOGICAL RELEVANCE

Hanchuan Zupa Granule (HCZP), a traditional Chinese ethnodrug, has the functions of supressing a cough, resolving phlegm, warming the lungs, and relieving asthma. In clinical practice employing traditional Chinese medicine (TCM), HCZP is commonly used to treat acute colds, cough and abnormal mucous asthma caused by a cold, or "Nai-Zi-Lai" in the Uygur language. Studies have confirmed the use of HCZP to treat cough variant asthma (CVA) and other respiratory diseases. However, the pharmacological mechanisms of HCZP remain unrevealed.

AIM OF THE STUDY

To investigate the anti-tussive and anti-asthmatic effects and the possible pharmacological mechanisms of HCZP in the treatment of CVA.

MATERIALS AND METHODS

A guinea pig CVA animal model was established by intraperitoneal injection of ovalbumin (OVA) combined with intraperitoneal injection of aluminium hydroxide adjuvant and atomized OVA. Meanwhile, guinea pigs with CVA received oral HCZP (at dosages of 0.571, 0.285 and 0.143 g/kg bodyweight). The number of coughs induced by aerosol capsaicin was recorded, and the airway hyperresponsiveness (AHR) of CVA guinea pigs was detected with the FinePointe series RC system. H&E staining of lung tissues was performed to observe pathological changes. ELISA was used to detect inflammatory cytokines. qRT-PCR and western blotting analyses were used to detect the expression of Th1-specific transcription factor (T-bet), Th2-specific transcription factor (GATA3), and Toll-like receptor 4 (TLR4) signal transduction elements. These methods were performed to assess the protective effects and the potential mechanisms of HCZP on CVA.

RESULTS

Great changes were found in the CVA guinea pig model after HCZP treatment. The number of coughs induced by capsaicin in guinea pigs decreased, the body weights of guinea pigs increased, and inflammation of the eosinophilic airway and AHR were reduced simultaneously. These results indicate that HCZP has a significant protective effect on CVA. A pharmacological study of HCZP showed that the levels of interleukin-4 (IL-4) and IL-5 and tumour necrosis factor-α (TNF-α) in serum decreased. The amount of interferon-γ (IFN-γ) increased, mRNA and protein expression of TLR4 and GATA3 weakened, and mRNA and protein expression of T-bet increased.

CONCLUSIONS

HCZP ameliorated the symptoms of guinea pigs with CVA induced by OVA by regulating the Th1/Th2 imbalance and TLR4 receptors.