MBL expression in patients with recurrent tonsillitis

Mannose-Binding Lectin: Biologic Characteristics and Role in the Susceptibility to Infections and Ischemia-Reperfusion Related Injury in Critically Ill Neonates

The mannose-binding lectin (MBL) is a member of the collectin family, belonging to the innate immunity system. Genetic, biologic, and clinical properties of MBL have been widely investigated throughout the last decades, although some interesting aspects of its potential clinical relevance are still poorly understood. Low circulating concentrations of MBL have been associated with increased risk of infection and poor neurologic outcome in neonates. On the other hand, an excessive and uncontrolled inflammatory response by the neonatal intestine after the exposure to luminal bacteria, leading to an increased production of MBL, may be involved in the onset of necrotizing enterocolitis. The purpose of the present review is to summarize the current knowledge about genetic and biologic characteristics of MBL and its role in the susceptibility to infections and to ischemia-reperfusion related tissue injuries to better explore its clinical relevance during the perinatal period and the possible future therapeutic applications.

DEFB1 polymorphisms and susceptibility to recurrent tonsillitis in Italian children

INTRODUCTION

The tonsils are secondary lymphoid organs fundamental for immune system response against pathogens within the oral cavity. Tonsillitis refers to inflammation of the pharyngeal tonsils that may include the adenoids and the lingual tonsils and that can be acute, recurrent, and chronic. Viral or bacterial infections, as well as immunologic factors are the main trigger to tonsillitis and disease's chronicity: the host immune responses, especially the innate one, could play an important role in susceptibility to the disease.

OBJECTIVES

The current study aims at investigating the role of functional polymorphisms in the 5'UTR (c.-52G>A, c.-44G>C and c.-20G>A) of DEFB1 gene, encoding for the antimicrobial peptide human beta-defensin 1, in the predisposition to recurrent tonsillitis in children from North Eastern Italy.

RESULTS

No significant correlation was found between DEFB1 allele, genotype and haplotype frequencies and recurrent tonsillitis susceptibility with the exception of an increased risk to disease development in patients carrying DEFB1 rare haplotypes.

CONCLUSION

Our results may suggest that DEFB1 polymorphisms alone may not influence pathology susceptibility, however they could possibly concur, together with other factors involved in the genetic control of innate immune system, in the predisposition towards recurrent tonsillitis.

Manganese-superoxide dismutase and glutathione peroxidase 1 polymorphisms in recurrent tonsillitis and tonsillar hypertrophy

OBJECTIVES

To investigate the association of manganese-superoxide dismutase and glutathione peroxidase 1 polymorphisms with susceptibility to recurrent tonsillitis and tonsillar hypertrophy.

METHODS

The study consisted of 103 patients with recurrent tonsillitis, 105 patients with tonsillar hypertrophy and 106 control subjects with similar age and sex. Genomic DNA was extracted from peripheral leukocytes of whole blood which were obtained from all patients and control subjects. Genotyping was performed to identify MnSOD Ala-9Val and GPx1 Pro198Leu polymorphisms by a method based on PCR amplification and detection of polymorphisms with hybridization probes labeled with fluorescent dyes. Genotype and allele frequencies were compared between patients with recurrent tonsillitis and tonsillar hypertrophy and 106 healthy control subjects.

RESULTS

The genotype distribution of the MnSOD Ala-9Val single nucleotide polymorphism was significantly different for the controls and the recurrent tonsillitis patients (P=0.009). Whereas, no significant difference was found between the patients with tonsillar hypertrophy and the control group (P=0.369). The frequency of the MnSOD CC genotype was lower, and that of the T allele was significantly higher, in recurrent tonsillitis patients than in control subjects. In addition, the frequency of tonsillitis was significantly higher in recurrent tonsillitis patients with the MnSOD Ala-9Val polymorphism than the patients with wild-type (P=0.008). Also, no significant difference was found between patient groups and control subjects in the distribution of the genotype and allele frequency of the GPx1 Pro198Leu single nucleotide polymorphism.

CONCLUSIONS

The MnSOD Ala-9Val polymorphism causes susceptibility to recurrent tonsillitis in Turkish children. And we suggest that there may be a possible relation between local and recurrent infections or inflammation of the tonsillar tissue and the MnSOD Ala-9Val single nucleotide polymorphism in pediatric patients with RT.

Mannose-binding lectin and the balance between immune protection and complication

The innate immune system is evolutionarily ancient and biologically primitive. Historically, it was first identified as an element of the immune system that provides the first-line response to pathogens, and increasingly it is recognized for its central housekeeping role and its essential functions in tissue homeostasis, including coagulation and inflammation, among others. A pivotal link between the innate immune system and other functions is mannose-binding lectin (MBL), a pattern recognition molecule. Multiple studies have demonstrated that MBL deficiency increases susceptibility to infection, and the mechanisms associated with this susceptibility to infection include reduced opsonophagocytic killing and reduced activation of the lectin complement pathway. Results from our laboratory have demonstrated that MBL and MBL-associated serine protease (MASP)-1/3 together mediate coagulation factor-like activities, including thrombin-like activity. MBL and/or MASP-1/3-deficient hosts demonstrate in vivo evidence that MBL and MASP-1/3 are involved with hemostasis following injury. Staphylococcus aureus-infected MBL null mice developed disseminated intravascular coagulation, which was associated with elevated blood IL-6 levels (but not TNF-α) and systemic inflammatory responses. Infected MBL null mice also develop liver injury. These findings suggest that MBL deficiency may manifest as disseminated intravascular coagulation and organ failure with infection. Beginning from these observations, this review focuses on the interaction of innate immunity and other homeostatic systems, the derangement of which may lead to complications in infection and other inflammatory states.

Mannose-binding lectin binds to amyloid β protein and modulates inflammation

Mannose-binding lectin (MBL), a soluble factor of the innate immune system, is a pattern recognition molecule with a number of known ligands, including viruses, bacteria, and molecules from abnormal self tissues. In addition to its role in immunity, MBL also functions in the maintenance of tissue homeostasis. We present evidence here that MBL binds to amyloid β peptides. MBL binding to other known carbohydrate ligands is calcium-dependent and has been attributed to the carbohydrate-recognition domain, a common feature of other C-type lectins. In contrast, we find that the features of MBL binding to Aβ are more similar to the reported binding characteristics of the cysteine-rich domain of the unrelated mannose receptor and therefore may involve the MBL cysteine-rich domain. Differences in MBL ligand binding may contribute to modulation of inflammatory response and may correlate with the function of MBL in processes such as coagulation and tissue homeostasis.