Skewed intracellular cytokine production of iNKT cells toward Th2-related responses in alloimmunized thalassemia patients.

INTRODUCTION: Red blood cell alloimmunization is a challenging issue in thalassemia patients. Several studies have investigated the role of different immune system compartment in alloimmunization, but the exact mechanism remains unclear. Considering the immunoregulatory function of iNKT cells and their subsets, in this study, we evaluated the possible role of these cells in alloimmunization status of thalassemia patients. METHODS: 78 ß-thalassemia major patients (41 alloimmunized and 37 non-alloimmunized) and 17 healthy controls were engaged in this study. Mononuclear cells were isolated from peripheral blood samples and stimulated for cytokine production. Samples were subjected to flow cytometry for enumeration of iNKT cells and characterized based on their cytokine production pattern. Finally, the results correlated with alloimmunization status, clinical and laboratory data. RESULTS: Results demonstrated that the number of iNKT, iNKT+IFN-ɤ+, and iNKT+IL-4+ cells in thalassemia group was significantly higher than healthy controls while no significant change was observed in the number of these cells between alloimmunized and non-alloimmunized thalassemia patients. Interestingly, the ratio of iNKT+IL-4+: iNKT+IFN-γ+ cells in alloimmunized thalassemia group represent a considerable increase in comparison to both non-alloimmunized thalassemia group and healthy controls. However, evaluating this value in non-alloimmunized group represents an approximately equal ratio of 0.94, which was almost similar to this ratio in the control group (0.99). CONCLUSION: Our results illustrated a noteworthy imbalance in the ratio of iNKT cell subsets in favour of IL-4 producing iNKT cells in alloimmunized thalassemia patients. Regarding the role of IL-4 in stimulating the Th2-related immune responses, this imbalance could consider as a possible mechanism in alloantibody responses of thalassemia patients.

High-yield production of recombinant platelet factor 4 by harnessing and honing the gram-negative bacterial secretory apparatus.

Platelet factor 4 is a cytokine released into the bloodstream by activated platelets where it plays a pivotal role in etiology and diagnosis of heparin-induced thrombocytopenia. Therefore, a sustainable source of recombinant PF4 with structural and functional similarity to its native form is urgently needed to be used in diagnostic procedures. To this end, a three-in-one primary construct was designed from which three secondary constructs can be derived each capable of employing either type I, type II secretory or cytoplasmic pathways. Protein expression and secretion were performed in Escherichia coli BL21 (DE3) and confirmed by SDS-PAGE and Western blotting. To further enhance protein secretion, the effect of several controllable chemical factors including IPTG, Triton X-100, sucrose, and glycine were individually investigated at the outset. In the next step, according to a fractional factorial approach, the synergistic effects of IPTG, Triton X-100, and glycine on secretion were further investigated. To ascertain the structure and function of the secreted recombinant proteins, dynamic light scattering was utilized to confirm the rPF4 tetramerization and heparin-mediated ultra-large complex formation. Moreover, Raman spectroscopy and Western blotting were exploited to evaluate the secondary and quaternary structures, respectively. The type II secretory pathway was proven to be superior to type I in the case of rPF4 secretion. Supplementation with chemical enhancers improved the protein secretion mediated by the Type II system to approximately more than 500 µg/mL. Large quantities of native rPF4 up to 20 mg were purified as the culture medium was scaled up to 40 mL. Western blotting confirmed the formation of dimers and tetramers in the secreted rPF4 proteins. Dynamic light scattering revealed the rPF4 oligomerization into of larger complexes of approximately 100-1200 nm in size following heparin supplementation, implying proper protein folding and tetramerization. Moreover, the rPF4 secondary structure was found to be 43.5% Random coil, 32.5% ß-sheet, 18.6% α-helix and 4.9% Turn, which is in perfect agreement with the native structure. Our results indicate that the gram-negative type II bacterial secretory system holds a great promise as a reliable protein production strategy with industrial applications. However, further efforts are required to realize the full potential of secretory pathways regarding their application to proteins with distinct characteristics.

Evaluation of regulatory T cells frequency and FoxP3/GDF-15 gene expression in ß-thalassemia major patients with and without alloantibody; correlation with serum ferritin and folate levels.

ß-thalassemia major is one of the most common hematologic disorders in the world. It causes severe anemia and patients require regular blood transfusions, which causes different complications such as iron overload and alloimmunization. Regulatory T cells (Tregs) have an important role in regulation of immune responses. FoxP3 is the major marker of Tregs and its expression can be influenced by different factors. GDF-15 is another gene that plays a role in iron homeostasis and regulation of immune system in different diseases. The aim of this study was to assess the frequency of Tregs and FoxP3/GDF-15 gene expression in ß-thalassemia major patients with and without alloantibody as well as its correlation with different factors such as serum ferritin and folate levels. This study was conducted on 68 ß-thalassemia major patients with and without alloantibodies in comparison with 20 healthy individuals with matched age and sex as control group. Enzyme-linked immunosorbent assay (ELISA), flow cytometry, and real-time PCR were performed in order to evaluate serum ferritin and folate levels, frequency of Tregs, and the expression of FoxP3 and GDF-15 genes, respectively. The percentage and absolute count of Tregs were increased in patients compared with controls (P = 0.0003), but there was no difference between responders and non-responders (P > 0.05). The Tregs count correlated positively with serum ferritin. No correlation was observed between target genes and serum ferritin and folate, but there was a positive significant correlation between the expression of FoxP3 and GDF-15 genes, which shows the immunosuppressive role of GDF-15.