Preventing Respiratory Viral Diseases with Antimicrobial Peptide Master Regulators in the Lung Airway Habitat

Epithelial Antimicrobial Peptide/Protein and Cytokine Expression Profiles Obtained from Nasopharyngeal Swabs of SARS-CoV-2-Infected and Non-Infected Subjects

Immune responses of the epithelia of the upper respiratory tract are likely crucial in early inhibition of the viral replication and finally clearance of SARS-CoV-2. We aimed to compare the expression profiles of antimicrobial peptides/proteins (AMPs) and related cytokines observed in the nasopharynx of SARS-CoV-2-infected patients and non-infected controls and to assess the associations between these parameters and COVID-19 patients' outcomes. We included 45 subjects who had tested positive for SARS-CoV-2 and 22 control subjects who had tested negative for SARS-CoV-2. Biomaterial for SARS-CoV-2 detection, as well as gene and protein expression studies, was obtained from all subjects using nasopharyngeal swabs which were performed a maximum of 7 days before inclusion in the study. Univariable and multivariable statistics were performed. When compared to the controls, the mRNA expression levels of human β-defensin 1 (hBD-1), LL-37, and trappin-2 were significantly higher in specimens of nasopharyngeal swabs from COVID-19 patients. Protein expression of hBD-1 was also increased in the COVID-19 group. mRNA expression levels of interferon-ɣ (IFN-ɣ), tumor necrosis factor- ɑ (TNF-ɑ), and interleukin-6 (IL-6) measured in SARS-CoV-2-infected patients were significantly higher than those observed in the controls, which could also be confirmed in the protein levels of IFN-ɣ and IL-6. A significant correlation between mRNA and protein levels could be observed only for IL-6. Univariable analysis revealed that low IFN-ɣ mRNA levels were associated with severe/fatal outcomes. The occurrence of COVID-19 pneumonia was significantly associated with lower expression levels of IL-6 mRNA, IFN-ɣ mRNA, and TNF-ɑ mRNA. Concerning the severe/fatal outcomes, the multivariable logistic regression model revealed that none of the aforementioned parameters remained significant in the model. However, the logistic regression model revealed that higher TNF-ɑ mRNA expression was a significant independent predictor of absence of pneumonia [odds ratio: 0.35 (95% CI 0.14 to 0.88, p = 0.024)]. In conclusion, nasopharyngeal expression of AMPs (hBD-1, LL-37, and trappin-2) and cytokines (IL-6, IFN-ɣ, and TNF-ɑ) is upregulated in response to early SARS-CoV-2 infection, indicating that these AMPs and cytokines play a role in the local host defense against the virus. Upregulated nasopharyngeal TNF-ɑ mRNA expression during the early phase of SARS-CoV-2 infection was a significant independent predictor of the absence of COVID-19 pneumonia. Hence, high TNF-ɑ mRNA expression in the nasopharynx appears to be a protective factor for lung complications in COVID-19 patients.

Antimicrobial Peptides (AMPs) and the Microbiome in Preterm Infants: Consequences and Opportunities for Future Therapeutics

Antimicrobial peptides (AMPs) are crucial components of the innate immune system in various organisms, including humans. Beyond their direct antimicrobial effects, AMPs play essential roles in various physiological processes. They induce angiogenesis, promote wound healing, modulate immune responses, and serve as chemoattractants for immune cells. AMPs regulate the microbiome and combat microbial infections on the skin, lungs, and gastrointestinal tract. Produced in response to microbial signals, AMPs help maintain a balanced microbial community and provide a first line of defense against infection. In preterm infants, alterations in microbiome composition have been linked to various health outcomes, including sepsis, necrotizing enterocolitis, atopic dermatitis, and respiratory infections. Dysbiosis, or an imbalance in the microbiome, can alter AMP profiles and potentially lead to inflammation-mediated diseases such as chronic lung disease and obesity. In the following review, we summarize what is known about the vital role of AMPs as multifunctional peptides in protecting newborn infants against infections and modulating the microbiome and immune response. Understanding their roles in preterm infants and high-risk populations offers the potential for innovative approaches to disease prevention and treatment.

Lysozyme: A Natural Product with Multiple and Useful Antiviral Properties

Lysozyme, especially the one obtained from hen's egg white, continues to show new pharmacological properties. The fact that only a few of these properties can be translated into therapeutic applications is due to the lack of suitable clinical studies. However, this lack cannot hide the evidence that is emerging from scientific research. This review for the first time examines, from a pharmacological point of view, all the relevant studies on the antiviral properties of lysozyme, analyzing its possible mechanism of action and its ability to block viral infections and, in some cases, inhibit viral replication. Lysozyme can interact with nucleic acids and alter their function, but this effect is uncoupled from the catalytic activity that determines its antibacterial activity; it is present in intact lysozyme but is equally potent in a heat-degraded lysozyme or in a nonapeptide isolated by proteolytic digestion. An analysis of the literature shows that lysozyme can be used both as a disinfectant for raw and processed foods and as a drug to combat viral infections in animals and humans. To summarize, it can be said that lysozyme has important antiviral properties, as already suspected in the initial studies conducted over 50 years ago, and it should be explored in suitable clinical studies on humans.

Mucosal Immunity against SARS-CoV-2 in the Respiratory Tract

The respiratory tract, the first-line defense, is constantly exposed to inhaled allergens, pollutants, and pathogens such as respiratory viruses. Emerging evidence has demonstrated that the coordination of innate and adaptive immune responses in the respiratory tract plays a crucial role in the protection against invading respiratory pathogens. Therefore, a better understanding of mucosal immunity in the airways is critical for the development of novel therapeutics and next-generation vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and other respiratory viruses. Since the coronavirus disease 2019 pandemic, our knowledge of mucosal immune responses in the airways has expanded. In this review, we describe the latest knowledge regarding the key components of the mucosal immune system in the respiratory tract. In addition, we summarize the host immune responses in the upper and lower airways following SARS-CoV-2 infection and vaccination, and discuss the impact of allergic airway inflammation on mucosal immune responses against SARS-CoV-2.

Cathelicidin-derived antiviral peptide inhibits herpes simplex virus 1 infection

Herpes simplex virus 1 (HSV-1) is a widely distributed virus. HSV-1 is a growing public health concern due to the emergence of drug-resistant strains and the current lack of a clinically specific drug for treatment. In recent years, increasing attention has been paid to the development of peptide antivirals. Natural host-defense peptides which have uniquely evolved to protect the host have been reported to have antiviral properties. Cathelicidins are a family of multi-functional antimicrobial peptides found in almost all vertebrate species and play a vital role in the immune system. In this study, we demonstrated the anti-HSV-1 effect of an antiviral peptide named WL-1 derived from human cathelicidin. We found that WL-1 inhibited HSV-1 infection in epithelial and neuronal cells. Furthermore, the administration of WL-1 improved the survival rate and reduced viral load and inflammation during HSV-1 infection via ocular scarification. Moreover, facial nerve dysfunction, involving the abnormal blink reflex, nose position, and vibrissae movement, and pathological injury were prevented when HSV-1 ear inoculation-infected mice were treated with WL-1. Together, our findings demonstrate that WL-1 may be a potential novel antiviral agent against HSV-1 infection-induced facial palsy.