EXPRESSION OF IMMUNOGLOBULIN SEQUENCES HOMOLOGOUS TO ANTI-SARS-CoV-2 ANTIBODIES AND HIV IN CHRONIC LYMPHOCYTIC LEUKEMIA CASES

BACKGROUND

Identification of epitopes recognized by leukemic B cells could provide insights into the molecular mechanisms of B cell transformation in chronic lymphocytic leukemia (CLL). The aim of this paper was to compare nucleotide sequences of immunoglobulin heavy chain variable region (IGHV) genes in CLL with known sequences directed against antigens of different origins available in public databases.

MATERIALS AND METHODS

Analysis was performed in the groups of 412 unselected CLL patients with productive IGHV gene using polymerase chain reaction followed by direct sequencing.

RESULTS

Homology between CLL Ig sequences and antibodies directed against autoantigens was found in 12 patients (2.9%), homology between CLL Ig sequences and antiviral antibodies - in 35 patients (8.5%). Most of these sequences belonged to stereotypical clusters. Among the sequences that have homology to antiviral antibodies, the most prevalent were cases homologous with antibodies against HIV (14 cases, 3.4%) and SARS-CoV-2 antigens (10 cases, 2.4%). None of the patients in our cohort was HIV-infected and the study was conducted before the emergence of SARS-CoV-2 virus.

CONCLUSIONS

Suggestions could be made about the possible impact of past infection of SARS-CoV-2 virus on the pathogenesis of CLL. In particular, an increase in the proportion of CLL cases with the expression of some stereotyped BCR and/or an increase of CLL risk in the long-term period after SARS-CoV-2 virus infection is not excluded. This assumption needs to be verified by epidemiological data.

Association of lipoprotein lipase expression with TP53 gene polymorphisms in chronic lymphocytic leukemia cells

BACKGROUND

Expression of lipoprotein lipase (LPL) correlates with unmutated (UM) status of the variable region of the heavy chain of immunoglobulin (IGHV) genes, but the expression level of LPL in UM chronic lymphocytic leukemia (CLL) cases varies significantly.

AIM

To study the association of LPL expression with the genetic variants of the TP53 gene since both genes are involved in lipid metabolism.

MATERIALS AND METHODS

Expression of LPL mRNA was measured in peripheral blood mononuclears of 45 CLL patients with UM IGHV genes by real-time quantitative reverse transcription polymerase chain reaction. Mutational status of IGHV genes and TP53 genotyping (rs1042522, rs1642785, rs17883323, rs2909430, rs145153611, rs113530090, rs12947788, rs12951053, and rs17878362) were performed by polymerase chain reaction amplification followed by direct sequencing.

RESULTS

Observed CLL patients were divided on groups with low (11.17 ± 2.66) and high (275.48 ± 39.37) LPL expression. In CLL patients with UM IGHV genes and low LPL expression we found an increased frequency of rs1042522 G (p = 0.0036), rs1642785 C (p = 0.0001), and rs17878362A2 alleles (p = 0.0091). The possible functional significance of these changes is discussed.

CONCLUSION

Some polymorphic variants of TP53 may be genetic modifiers for LPL expression level in CLL leukemic B-cells. Further research is required in a larger cohort to confirm these findings.

MYC copy number and mRNA expression in chronic lymphocytic leukemia patients exposed to ionizing radiation due to the Chornobyl NPP accident

Some clinical and biological features indicating an unfavorable course of the disease were found in ionizing radiation (IR) - related chronic lymphocytic leukemia (CLL) patients. The MYC proto-oncogene is considered to contribute to CLL pathogenesis. Increased MYC copy number is associated with poor prognosis in CLL.

AIM

To investigate the frequency of MYC gene copy number amplification in IR-exposed CLL patients and relate the findings to the MYC mRNA levels, the presence of unfavourable prognosis mutations (TP53, SF3B1, NOTCH1), and patient`s outcome.

MATERIALS AND METHODS

The analysis of MYC copy number was carried out by real-time quantitative polymerase chain reaction (PCR) in 70 IR-exposed CLL patients. The MYC mRNA expression was measured by real-time quantitative reverse transcription PCR.

RESULTS

Increased MYC gene copy number was present in 5.7% of cases. There was a statistically significant association between increased MYC copy number and increased MYC mRNA (p < 0.014). Additionally, somatic deletion in MYC locus was found in one patient. Most of patients (80%) with detected MYC aberrations were previously untreated, suggesting that these lesions might occur early in the course of the disease. The MYC aberrations were found mutually exclusive with high risk TP53 and SF3B1 mutations, while one case was identified, where MYC amplification and NOTCH1 mutation coincided simultaneously. Regarding clinical outcome, the MYC aberrations were associated with a shorter time to first treatment (3 vs 25 months, p = 0.008) as well as reduced overall survival (60 vs 139 months).

CONCLUSION

Our data suggest that MYC aberrations might be an early event in IR-related CLL and contribute to aggressive disease development in the absence of high risk TP53 and SF3B1 mutations.

Analysis of LPL gene expression in patients with chronic lymphocytic leukemia

AIM

The IGHV mutational status is one of the most important markers for chronic lymphocytic leukemia (CLL) prognostication. Lipoprotein lipase (LPL) gene expression was found to correlate with IGHV status and was suggested as its surrogate marker. Recent data reported that LPL expression might be influenced by pivotal signalling pathways in CLL. This study aimed to assess LPL gene expression in relation to key immunogenetic and molecular markers of CLL, including IGHV mutational status, B-cell receptor (BCR) stereotypy, TP53, NOTCH1, and SF3B1 gene mutations. Materials and Methods: Expression of LPL mRNA was measured in peripheral blood mononuclear cells of 73 CLL patients by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). IGHV, NOTCH1, TP53, and SF3B1 gene mutation analysis was performed by PCR amplification and direct sequencing.

RESULTS

44 of 73 (60%) CLL cases were categorized as LPL-positive based on the cut-off value established by ROC (receiver operating characteristic) curve analysis. LPL expression was significantly associated with IGHV mutation status (r = 0.684; p < 0.0001) and tended to correlate with presence of NOTCH1 gene mutations (p = 0.113). BCR stereotyped cases showed higher LPL expression values in comparison to unstereotyped cases in the LPL-positive group of patients (p = 0.041). LPL expression was associated with a shorter overall survival in the entire СLL group (median 107 vs 143, p = 0.048) as well as in Binet A patients, albeit with borderline significance (median 139 vs not reached, p = 0.086).

CONCLUSION

LPL expression was found to be closely correlated with IGHV gene mutational status and overall survival, proving LPL as prognostic marker in CLL. Our results also indicate a possible relationship between aberrant expression of LPL and BCR- and NOTCH1-dependent signalling pathways.

Structural and functional state of heart left ventricle depending on polymorphism rs966221 phosphodiesterase 4D gene in emergency workers of the Chornobyl NPP suffering from coronary heart disease

OBJECTIVE

This study consisted in examination the features of structural and functional state of the cardiovascular system in emergency workers (EW) of the Chernobyl nuclear power plant (ChNPP) who suffered from coronary heart disease (CHD) and having different genotypes due to polymorphism rs966221 phosphodiesterase 4D (PDE4D) gene.

MATERIALS AND METHODS

The study involved 121 EW and 63 non irradiated patients with CHD. Standardized survey included echo doppler cardiography (EchoCG) that was done by Diagnostic Ultrasound System DS N3 (Mindray). Polymorphism rs966221 PDE4D determined by polymerase chain reaction followed by restriction reaction products.

RESULTS

The distribution of genotypes PDE4D in EW was as follows: CC - 42, CT - 49 and TT - 30 patients. In the con trol group, carriers of the same genotypes were 27, 21 and 15 persons respectively. All echocardiographic parame ters in EW workers and non irradiated patients did not differ significantly. Amongst TT genotype carriers of both groups the proportion of patients with increased myocardial mass index was the highest (82.9%) compared to CC genotype (78.4%) and CT (71.4%). The concentric type of left ventricular (LV) hypertrophy was found in 54.9% of patients with CC genotype, in 51.8% with CT genotype and 45.7% with TT genotype, while the eccentric type in 23.5, 21.4 and 37.1% respectively. The relative number of people with high LV end diastolic volume (EDV) normalized by body surface area (BSA) was 27.5% in CC genotype carriers, 26.8% in CT genotype and 40% in TT genotype carriers (p > 0.05). The increase of BSA indexed LV end systolic volume (ESV) was found in 27.5, 30.4 and 28.6%, and the ejection fraction in 15.7, 23.2 and 22.9% respectively. The largest number of CHD patients with inadequate dias tolic function was in carriers of TT genotype (75%) compared with the data in CC (66.7%) and CT genotypes (42.9%) carriers.

CONCLUSIONS

In patients with the same genotype, both EW and non irradiated persons there were virtually no dif ferences in indicators of the structural and functional status of LV. The analysis of changes of LV structure the fol lowing feature was revealed: eccentric type of LV hypertrophy was more common for patients with TT genotype, but concentric type for CC genotype carriers. In one third of patients with CC and CT genotypes and in 40% of TT geno type carriers it was observed LV systolic function disorders. Diastolic dysfunction manifested as often in patients with TT genotype compared with CC and CT genotypes carriers.

Features of coronary heart disease development in emergency workers of the Chornobyl accident depending on the action of radiation and non radiation risk factors and genotypes of single nucleotide polymorphism rs966221 of phosphodiesterase 4D gene

OBJECTIVE

This study devoted to specific features of coronary heart disease (CHD) development in emergency work ers (EW) of the accident at the Chernobyl nuclear power plant (ChNPP) based on analysis the interaction between radiation and non radiation risk factors and single nucleotide polymorphism (SNP) rs966221 of phosphodiesterase (PDE) 4D gene.

METHODS

It was examined 397 men with CHD, including 274 EW of 1986-1987 and 123 non irradiated persons (con trol group) who were 66±10 and 69±11 years old relatively. The program studies included clinical examination, elec trocardiography (ECG), ECG daily monitoring, ECG stress testing, echo doppler cardiography, analysis of serum lipid spectrum, polymerase chain reaction with restriction of reaction products, retrospective analysis of case histories. Diagnosis of CHD or its approval was carried out in accordance with the standards of diagnosis, accepted in Ukraine. All EW before their taking part in cleaning ChNPP territory did not suffered from CHD.

RESULTS

According to the analysis of contingency tables, carriers of the TT genotype of rs966221 increased the risk of myocardial infarction (MI) in 2.538 times compared with carriers of genotypes CC and CT. The use of Kaplan Meier method showed that a half of EW with the TT genotype developed MI before 64 years old, while with the other geno types up to 78.7 years old. In the control group statistically significant increase of cumulative proportion of patients with MI, carriers of the TT genotype, began from 60 years old. Compared to the non irradiated patients EW fell ill with CHD on 9.4 years earlier. Using proportional hazards analysis (Cox regression), it was found that EW had 3.9 times higher risk of CHD than in non irradiated individuals. Smoking and overweight brought three times less but significant risk - 1.37 and 1.33 respectively. The TT genotype unlike genotypes CC and CT gene PDE4D increased risk of MI in 1.757 times more both in EW and control group.

CONCLUSIONS

The risk of CHD development was determined by radiation factor, such as the involvement in the emer gency works of the accident consequences, as well as non radiation factors, namely smoking and overweight. Only one factor, the TT genotype of rs966221 PDE4D gene, determined the risk of MI occurrence in EW and non irradiated controls. In the post emergency period, CHD developed 6 years earlier in EW with the TT genotype than in patients with genotypes CC and CT.

IGHV3-21 gene expression in patients with B-cell chronic lymphocytic leukemia in Ukraine

THE AIM of the study was to evaluate the frequency of IGHV3-21 gene usage and its clinical significance for patients with B-cell chronic lymphocytic leukemia (CLL) in Ukraine.

PATIENTS AND METHODS

Immunoglobulin variable heavy chain (IGHV) gene repertoire was studied in 189 CLL patients using reverse transcribed polymerase chain reaction and direct sequence of amplified products.

RESULTS

IGHV3-21 gene expression was found in 11 cases (5.8%), and its frequency was intermediate between Scandinavian (11.7%) and Mediterranean CLL (2.9%) cohorts. The most of cases (9 of 11) belonged to subset with heterogeneous HCDR3 (heteroHCDR3 subset), and only 2 cases--to subset with classical short ARDANGMDV motif (homHCDR3 subset). Six IGHV3-21 cases were mutated and 5 cases were unmutated. All unmutated cases (all were from heteroHCDR3 subset) had similarity of their HCDR3s with previously published sequences. The differences in overall (OS), progression-free (PFS) and treatment-free survival (TFS) for IGHV3-21 positive patients in comparison with CLL patients expressing the other IGHV genes were statistically insignificant. These survival parameters were comparable also for CLL patients with mutated IGHV3-21 gene usage and expression the others mutated IGHV genes. But remarkable feature of IGHV3-21 expressing patients was high incidence of solid tumors. They have developed in 4 IGHV3-21 positive cases (36.4%) and in 10 cases with expression of the others IGHV genes (5.6%, p=0.0002). Furthermore, in small group of 6 patients with mutated IGHV3-21 gene expression, 3 patients had solid tumors and one underwent Richter transformation. Unmutated IGHV3-21 gene expressed patients had worse OS and PFS in comparison with CLL patients that expressed the others unmutated IGHV genes.

CONCLUSION

Presented data are in agreement with the opinion about negative prognostic significance of IGHV3-21 gene expression regardless its mutation status. IGHV3-21 expression was associated with development of secondary solid tumors. Revealed high level of homology in heteroHDR3s subset might suggest about possible antigenic influence also, in addition to homHCDR3 subset that was proposed earlier.

Significance of VH genes mutation status for prognosis of CLL patients

AIM

The aim of this study was to evaluate significance of VH mutation status for prognosis of B-cell chronic lymphocytic leukemia (B-CLL) patients in comparison with other prognostic markers.

MATERIALS AND METHODS

The VH mutation status was evaluated in 43 B-CLL patients by RT-PCR amplification and nucleotide sequencing, and CD38 expression - by two-color FACS analysis. The prognostic influence of VH mutation rate and CD38 expression level was tested by different statistical methods.

RESULTS

The increasing number of advanced cases over the follow-up period, shorter median time from diagnosis to start of second line therapy, worse response to fludarabine treatment, poor survival for early stages B-CLL were found in unmutated versus mutated CLL patients. The significance of CD38 expression for CLL prognosis was revealed as predictor for response for fludarabine treatment and time of progression in advanced stages. The correlation between CD38 expression and VH mutation status was not found.

CONCLUSION

Simultaneous determination of VH mutation status and CD38 expression may be helpful for prediction of CLL prognosis.