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Immnunity – session 3/3 : why immunization can help to prevent respiratory infections?

Oct 20, 2020


Recurrent respiratory infections, chronic respiratory conditions and allergic respiratory diseases are linked to the immune system responses and the regulation of Th1 and Th2 activity.  If we cannot do anything about our age or genetics, immunization is recommended as a safe and effective preventive method against respiratory tract infections.

Alternative immunization approaches such as oral immunostimulants may also be efficient. Bacterial lysates have a broad spectrum of action and stimulate both innate and adaptive immunity. This reinforces their rationale of use in prevention of infections, as complementary approach to vaccination.

The first discovery about Polyvalent Mechanical Bacterial lysates was its ability to activate and mature the dendritic cells at the level of oral mucosa, a major step of the innate immunity allowing an efficient immune answer.In 2019, Pr Guido Ferlazzo (Professor of General Pathology and Immunology – University of Messina, Italy) shared his latest discoveries on bacterial lysates, more specifically PMBL® (Polyvalent Mechanical Bacterial Lysates), and its action on the reinforcement of the airway epithelial barrier in a paper titled «Mucosal Immunity In The Infections Of Airways»:

In order to investigate whether the bacterial lysate obtained mechanically can improve the inducible barrier function, they analyzed the expression of the adhesion molecules involved in the cell-cell junctions.

« Following the culture of human bronchial epithelial cells in the presence of the bacterial lysate, we observed a significant increase in the expression of ICAM-1 and E-cadherin on epithelial cells of the respiratory mucosa. The epithelial cells, particularly those of the mucous membranes, are considered as an integral part of the immune response, precisely due to the barrier properties that are readily increased when stimulated by the presence of microorganisms.

(…) Among these anti-microbial peptides, β-defensins are released in high quantities from the respiratory epithelium but not, ad example, from the intestinal one. We then analyzed whether, in the experimental model of respiratory mucosa cells human, it is possible to induce the production of β-defensin a following stimulation by the bacterial lysate obtained for mechanical lysis.  The gene expression of this peptide is induced after only 6 hours of stimulation with the PMBL lysate, indicating that, in the case of sublingual administration (and not swallowing the lysate tablet), the epithelia of the oropharynx they would release peptides with a high anti-microbial action, such as the β-defensin, which would therefore concentrate precisely in the main one entry region of airway pathogens, precisely the oropharyngeal region.

(…) In conclusion, The ability of PMBL to maintain the integrity of the respiratory epithelial barrier, counteracting microbial colonization and, at the same time, stimulate the regeneration of mucous tissue during chronic phlogosis can play an important role in prophylaxis of respiratory airway infections and their recurrence in patients with chronic inflammatory diseases of the respiratory tract.

In a publication from the Department of Biotechnology Development, Institute of Hygiene, Faculty of Medicine in Uruguay, a paper entitled “Characterization of Bacterial Lysates by Use of Matrix-Assisted Laser Desorption–Ionization Time of Flight Mass Spectrometry Fingerprinting” , presents a new analytical method for bacterial lysates characterization is introduced: MALDI-TOF MS (Matrix-Assisted Laser Desorption-Ionization Time of Flight Mass Spectrometry Mass).

The technique allows to obtain a unique mass fingerprint for each microorganism, and is thus ideal for the analysis of monovalent but also polyvalent bacterial lysates products. This reliable and reproducible method is useful to produce protein profiles after cellular extraction and purification.

Polyvalent bacterial lysates obtained by mechanical lysis, PMBL, resulted in a more defined fingerprints, so a more precise characterization as compared to those obtained by chemical alkaline lysis. This result corroborates our precedent findings on PMBL, showing that mechanical lysis allows a better preservation of the proteins/antigens structure as compared to chemical lysis Morandi et al, demonstrated that the better preservation of the antigens structure are 10-100 times more powerful in triggering immune response.1



COVID-19 has led to renewed interest in how to support immunity. Taking care of our immune system is not only important during a pandemic, but also for every stage of life.

The understanding of the human immune system is increasing at an unprecedented scale. Cutting edge new technologies allow us to analyze human immune responses in a comprehensive and cohesive manner.



1 Morandi et al (2011), A mixture of bacterial mechanical lysates is more efficient than signle strain lysate and of bacterial-derived soluble product for the induction of an activating phenotype in human dendritic cells.  Immunol Lett