Gut microbial dysbiosis in the pathogenesis of leukemia: an immune-based perspective

Leukemias are a set of clonal hematopoietic malignant diseases that develop in the bone marrow. Several factors influence leukemia development and progression. Among these, the gut microbiota is a major factor influencing a wide array of its processes. The gut microbial composition is linked to the risk of tumor development and the host's ability to respond to treatment, mostly due to the immune-modulatory effects of their metabolites. Despite such strong evidence, its role in the development of hematologic malignancies still requires attention of investigators worldwide. In this review, we make an effort to discuss the role of host gut microbiota-immune crosstalk in leukemia development and progression. Additionally, we highlight certain recently developed strategies to modify the gut microbial composition that may help to overcome dysbiosis in leukemia patients in the near future.

Aberrations in the progesterone pathway and the Th1/Th2 cytokine dichotomy - An evaluation of RPL predisposition in the northeast Indian population

PROBLEM

Recurrent pregnancy loss (RPL) is the spontaneous loss of two or more consecutive pregnancies prior to 20 weeks of gestation, occurring in 1% of the reproductive-age population. It is a major cause of infertility in India with a staggering 7.46% prevalence rate.

METHOD OF STUDY

Blood and product of conception (POCs) from RPL cases (n = 65) were enrolled for this study, along with cases of medically terminated pregnancy (MTP, n = 80) and term delivery cases (n = 90) as control. ELISA for progesterone and progesterone induced blocking factor (PIBF) levels was carried out, followed by mRNA expression analysis of progesterone receptor isoform B (PR-B) and its downstream immunomodulatory effectors, namely, PIBF, IL-10 and IL-12. Screening of PROGINS haplotype of PR gene and PIBF polymorphism were also conducted to correlate with their respective gene expression profiles.

RESULTS

Serum progesterone level was found to be comparable in the RPL and MTP cases. Although the mRNA expression of PR-B was found to be downregulated in the RPL cases, no significant PROGINS haplotype was observed. Presence of a single nucleotide polymorphism (SNP) in the PIBF gene (rs1372000) was more in healthy controls compared to RPL cases. Serum PIBF levels were found to be lower in the RPL cases with a resultant increase in IL-12 and a decrease in IL-10 mRNA expression in these cases.

CONCLUSIONS

This study indicates that progesterone, acting through PIBF, modulates the immunological state of pregnancy to be Th1-biased in RPL, indicative of a pro-inflammatory, labour-like state not desired for a healthy pregnancy.

Oxidative stress-A key determinant of complications and negative outcome in hepatitis E virus infected pregnancies: A comprehensive account involving cases from northeast India

Regulated oxidative stress (OS) is important during pregnancy. Sporadic studies suggest the significance of deregulated OS in hepatitis E virus (HEV) infected pregnancy, but with limited reactive oxygen species (ROS) or antioxidant markers. The present novel study, therefore, aimed to evaluate the significance of ROS-antioxidant imbalance and resulting altered OS in HEV infected pregnancy complications like preterm delivery (PTD) and outcome. Difference in serum levels of ROS and antioxidant panel of markers were evaluated by ELISA for HEV immunoglobulin M RNA positive genotype 1 cases (including acute [acute viral hepatitis, AVH] and fulminant [fulminant hepatic failure, FHF] cases) and healthy term delivery subjects, and analyzed statistically. Direct ROS marker H₂ O₂ levels and indirect OS marker for DNA damage 8-hydroxy-2'-deoxyguanosine was significantly increased in HEV-cases compared to controls, and was associated and prognostic factor for PTD and fetal death in HEV cases. A comparatively lower total serum antioxidant capacity was observed in the FHF cases compared to the control subjects and the AVH cases. Glutathione (GSH) levels and superoxide dismutase (SOD) activity were significantly associated with PTD in the FHF sub-cohorts (p = 0.017) and AVH sub-cohorts (p < 0.001), respectively, and was associated with poor prognosis in HEV cases. The serum H₂ O₂ levels were found to be negatively correlated with SOD activity (p = 0.016) and GSH levels (p = 0.001) in the HEV-AVH cases; and positively correlated with the viral load in HEV cases (p = 0.023). The ROS-antioxidant imbalance resulting OS plays a detrimental associative role in HEV infected pregnancy complications like PTD and adverse pregnancy outcomes; and holds therapeutic significance.

Impact of TNF-α profile in recurrent pregnancy loss pathogenesis: A patient based study from Assam

BACKGROUND

Lacunae exist in understanding the underlying etiology in majority of recurrent pregnancy loss (RPL) cases. Given the significance of regulated immune-modulation in pregnancy, and the central role of pro-inflammatory TNF-α plays in it; this study targeted to appraise the significance of TNF-α profile in RPL pathogenesis in an ethnically distinct population from Assam, India.

METHODS

Term delivery, medically terminated pregnancy (MTP) and RPL cases (based on ASRM criteria) were enrolled with no anatomical and chromosomal abnormalities or pathological infections; and blood and/or placenta/product of conceptus (POC) tissue samples were collected with informed consent. Serum level and tissue level TNF-α expression profile were screened using specific molecular tools, and was correlated with TNF-α -308 G/A genotype; for its association with RPL predisposition.

RESULTS

A significant gestation specific increase in serum TNF-α levels was observed in MTP cases (19.932 ± 4.407 pg/mL) compared to term delivery subjects (p = 0.001), while a comparable levels were observed with RPL cases (22.709 ± 5.833 pg/mL) (p = 0.646). A site specific (POC) increased expression was observed in RPL compared to MTP cases at both at transcript (6.37 ± 3.714 folds) and protein levels. The TNF-α -308 variant genotype was associated with increased predisposition to RPL (OR = 1.721) compared to MTP as well as significantly increased serum TNF-α levels (p = 0.017); especially in subjects with a homozygous TNF-α -308 A/A genotype.

CONCLUSION

Our data emphasizes on the importance of site specific TNF-α expression levels in RPL pathogenesis in the studied population, and underlines its importance in screening, clinical stratification, and therapeutics by molecular targeting using TNF-α inhibitors.

Increased homocysteine mediated oxidative stress as key determinant of hepatitis E virus (HEV) infected pregnancy complication and outcome: A study from Northeast India

With the background of association of oxidative stress and Hepatitis E virus (HEV) infection in pregnancy complications the present novel study aimed to evaluate the significance of changes in maternal homocysteine levels and the related mechanism(s) in the pathophysiology of HEV related pregnancy complications and negative outcomes. Term delivery (TD, N = 194) and HEV-IgM positive pregnancy cases [N = 109] were enrolled. Serum and placental homocysteine levels were evaluated by ELISA and immunofluorescence and in turn correlated with serum Vitamin B12 levels. Distribution of variant MTHFR C➔T and TYMS1494del6bp genotyping were studied by PCR-RFLP. Differential folate receptor alpha (FR-α) expression in placenta was evaluated by real-time PCR and immunofluorescence respectively. The HEV viral load was significantly higher in both FHF and AVH cases. Higher serum homocysteine levels was associated with preterm delivery (PTD) and fetal death in HEV infected cases and was significantly inversely correlated with serum VitaminB12 levels in HEV cases. Placental homocysteine expression was upregulated in HEV cases, and in cases with negative pregnancy outcome. A Homocysteine level was associated with MTHFR C677T status. Genetic alterations in folate pathway was associated with increased risk of PTD in HEV infected pregnancy cases, disease severity, and negative pregnancy outcome in AVH and FHF groups. FR-α expression was downregulated in placental tissues of HEV infected pregnancy.Placental stress caused by HEV inflicted increased homocysteine due to alterations in maternal vitamin B12 levels and folate pathway components is detrimental mechanism in PTD and negative pregnancy outcome in HEV infected pregnancy cases and holds prognostic and therapeutic significance.

Exploring the p53 connection of cervical cancer pathogenesis involving north-east Indian patients

BACKGROUND

As per WHO, Cervical cancer (CaCx) is a global issue, being the fourth common cancer in women with incidence rate of 13.1 per 1 lakh women globally and accounting for 311000 deaths in the year 2018 itself globally. The molecular pathogenesis in Human papillomavirus (HPV) infected cases is inconclusive. The detection of molecular factors leading to progression of CaCx can be important in the diagnosis and management of the disease. p53 a known tumor suppressor gene having a regulative role in cell cycle has been highlighted as key factor in the prevention of cancer but its significance in CaCx cases has been variably documented. The present study therefore targeted to evaluate the significance of p53 profile in CaCx cases in ethnically distinct northeast Indian population.

METHODS

Blood and Tissue samples (N = 85) of cervical cancer patients were collected and screening for HPV was performed using PCR. Thereafter the differential mRNA expression(qPCR), Immunohistochemistry, Mutation (PCR direct sequencing method) of p53 was studied. Further p53 epigenetic profiling was done by Methylation specific PCR (MS-PCR) and western blotting by using p53 acetylation specific antibodies.

RESULTS

Our findings revealed that the downregulation of p53 was associated with the progression of disease and the variation in downregulation based on p53 polymorphism was observed. Further hypermethylation and deacetylation of p53 was also found to be associated with the pathogenesis of CaCx. The downregulated expression and hypermethylation of p53 in lower grade of CaCx, together established its association with the progression of CaCx from lower to severe grade.

CONCLUSION

Therefore, in CaCx patients of northeast Indian population, malfunctioning of p53 is found to have significant role in cervical cancer progression.

Impact of modulation of telomerase and cancer stem-cell marker OCT4 axis in cervical cancer pathogenesis with underlying HPV16 infection

Lacunae exist in the molecular event(s) specificity associated with cervical cancer (CaCx) pathogenesis. The present study aimed to evaluate the significance of telomerase-cervical cancer stem cells (CSCs) modulation in CaCx pathogenesis with underlying HPV16 infection. The study included HPV16 positive cases only (N = 65) of the total enrolled cases from Northeast India. The analysis of viral load and the differential messenger RNA expression of E6, E7, hTERT, hTR, and cancer stem-cell markers was studied by real-time polymerase chain reaction. Further the protein and colocalization study for E6, hTERT, and oct4 was performed by immunofluorescence. The real-time polymerase chain reaction based analysis showed an upregulation of HPV16 viral oncoprotein E6 and E7, and telomerase component hTERT and hTR expression and their correlation in CaCx susceptibility and severity. The hTERT expression correlated with viral load; while the E6 and telomerase protein expression colocalized in the nucleus. The CSCs marker octamer-binding transcription factor 4 (OCT4) was significantly upregulated in CaCx cases, was associated with CaCx susceptibility and severity, and colocalized with E6 expression in the nucleus as revealed from the immunofluorescence studies. To conclude, the telomerase-OCT4 axis modulation holds key in HPV16 CaCx pathogenesis mediated by HPV16 E6 viral oncoprotein expression, and underlines its potential for therapeutic targeting.

Associative role of TYMS6bpdel polymorphism and resulting hyperhomocysteinemia in the pathogenesis of preterm delivery and associated complications: A study from Northeast India

Aberrations including genetic alterations in folate pathway are detrimental in multiple disease pathogenesis, including pregnancy. The present study is based on the screening of the associative role of TYMS 14946bp deletion(del) polymorphism and associated hyperhomocysteinemia in susceptibility to preterm delivery (PTD), which is strongly associated with neonatal mortality and morbidity.

METHODS

A total of 209 PTD cases {extremely preterm (n=22), very preterm (n=43) and moderately preterm (n=144)} and 194 term delivery cases were evaluated for TYMS 14946bp deletion and its association with preterm delivery, pregnancy outcome, baby birth weight and homocysteine estimation.

RESULTS

The results showed that the distribution of TYMS 14946bp del/del genotype significantly increased the risk of PTD [OR=2.801, p=0.002] and is associated with fetal death. The TYMS 6bp ins/del and 6bp del/del genotype was associated with low birth weight (LBW) compared to 6bp ins/ins genotype in both term and PTD groups, and in case of very (p=0.024) and moderately (p=0.045) sub-cohorts of PTD significantly. Elevated serum homocysteine levels were significantly associated with PTD (p<0.001) and fetal death (p=0.013); and was also found to significantly correlate with TYMS 14946bp del/del genotype in all the pregnancy cases (p=0.008). TYMS 6bp del/del genotype was associated with higher homocysteine levels compared to ins/ins (p=0.005) and ins/del (p=0.062) genotypes within the PTD group.

CONCLUSION

The study provides crucial information regarding the importance of TYMS6bpdel/del genotype and associated hyperhomocysteinemia in susceptibility to PTD, fetal death and LBW; and thus indicating their prognostic significance of TYMS 6bp del/del genotype in PTD which is of clinical importance.

Preterm delivery and associated negative pregnancy outcome - A tale of faulty progesterone receptor signalling pathway and linked derailed immunomodulation: A study from Northeast India

Preterm delivery (PTD) is one of the potent contributor of neonatal mortality and morbidity, and the underlying cause in some situation is elusive. This study attempts to delineate the association of deregulation in progesterone receptor (PR) pathway and deleterious immune responses in predisposing patients to PTD in Northeast India, a region with high rate of PTD cases. A total of 109 cases of PTD and 100 term delivery cases were enrolled with all clinical details. The PTD cases were stratified based on gestation age at delivery. The differential expression of PR and key downstream effectors and cytokines were evaluated for correlation with PTD susceptibility, gestational period, and pregnancy outcome. The results indicated a sharp downregulation in PR expression is associated with PTD susceptibility, lower gestational period and negative pregnancy outcome. The PR downstream effector PIBF was also found to be downregulated in PTD, and is associated with gestational period and negative pregnancy outcome. The downregulation of PR and PIBF expression was found to correlate with a predominant Th1 state with higher CD56+NK cell counts and pro-inflammatory burst lead by hyper TNF-α, NF-kB and IFNγ expression, and complicated by lower IL10 expression, contributing to PTD as well as negative pregnancy outcome in the PTD cases. TNF-α expression in placenta inversely correlated with placental PR expression. To conclude, deregulation in PR pathway is a hallmark of preterm delivery and negative pregnancy outcome. Differential expression of several markers such as PR, PIBF and TNF-α has prognostic significance, and hence is of clinical significance.

Evidence of extrahepatic replication of hepatitis E virus in human placenta

The incidence and severity of hepatitis E virus (HEV) infection in pregnant women is high in developing countries. Transplacental transmission of HEV in the third trimester of pregnancy has been found to be associated with high fetal mortality. Based on this evidence and in the absence of reports on HEV replication in extrahepatic sites, this study was carried out to investigate if HEV replication occurs in the placenta of infected mothers. The study included 68 acute viral hepatitis (AVH) and 22 acute liver failure (ALF) pregnant patients. Viral RNA was extracted from blood and placenta. HEV replication in placenta was confirmed by a replicative negative-strand-specific reverse transcriptase PCR. Viral load was estimated by real-time PCR. Immunohistochemical studies were also carried out for in situ detection of HEV in placental tissue sections. Replicative HEV RNA was detectable only in the placenta in ALF and AVH cases and not in blood samples. Positive staining of placental tissue sections with HEV antibody against the viral structural protein ORF3 was observed. HEV replication in placenta also correlated with fetal and maternal mortality in ALF patients. It is demonstrated for the first time that HEV replication occurs in human placenta and that placenta may be a site of extrahepatic replication of HEV in humans.

High viral load and deregulation of the progesterone receptor signaling pathway: association with hepatitis E-related poor pregnancy outcome

BACKGROUND & AIMS

Hepatitis E virus (HEV) infection is associated with high maternal and fetal mortalities. A prospective study was undertaken to evaluate the role of viral and host factors in HEV related pregnancy outcomes.

METHODS

The study included HEV infected pregnancy cases; acute viral hepatitis (AVH), n=100 and fulminant hepatic failure (FHF), n=43, and healthy pregnancy cases, n=50. HEV genotypes and viremia were studied by nucleotide sequencing and real time PCR, respectively. Progesterone receptor (PR) gene mutations (PROGINS) were studied by PCR, PR expression at the mRNA and protein levels in the placenta were studied by semi-quantitative RT-PCR and immunohistochemistry, respectively. Progesterone induced blocking factor (PIBF) expression was studied by RT-PCR in blood. Serum interleukin-10 (IL-10) and interleukin-12 (IL-12) levels were assayed by ELISA.

RESULTS

HEV viral load was significantly higher in FHF than AVH (p<0.001) and in cases with fetal mortality in AVH (p=0.001) and FHF (p=0.018). PROGINS were predominant in FHF compared to AVH (p=0.26) and showed reduced mRNA and protein expression. The risk of fetal mortality in AVH was two times higher (OR, 2.190; CI, 0.303-15.85) and maternal and fetal mortalities in FHF were 4-fold (OR, 4.0; CI, 0.363-44.113) increased in PROGINS carriers. PR and PIBF expression was lower in AVH and even lower in FHF compared to healthy controls. The higher IL-12/IL-10 ratio observed in FHF compared to other groups correlated with fetal mortality in AVH and FHF (p<0.001).

CONCLUSIONS

In conclusion, reduced expression of PR and PIBF, a higher IL-12/IL-10 ratio, and a high viral load results in poor pregnancy outcome in Hepatitis E.

Role of polymorphic N-acetyl transferase2 and cytochrome P4502E1 gene in antituberculosis treatment-induced hepatitis

BACKGROUND AND AIM

Antituberculosis drugs, isoniazid and rifampicin, in combination, are known to develop drug-induced hepatotoxicity (DIH). A higher risk of DIH during antituberculosis treatment (ATT) has been reported in the Indian subcontinent compared to its Western counterparts. The role of genetic factors in a higher incidence of ATT hepatotoxicity in the Indian population is still unclear. The present study was aimed at investigating the role of the N-acetyltransferase2 (NAT2) and cytochrome P4502E1 (CYP2E1) gene polymorphisms in ATT hepatotoxicity.

METHODS

The study population included 218 pulmonary tuberculosis patients who were started on ATT and followed up for the occurrence of ATT-induced hepatitis. The genetic polymorphisms of the NAT2 and CYP2E1 genes were studied by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

The occurrence of DIH was 18.8% (41/218). There was a higher prevalence of NAT2 slow-acetylator genotypes in DIH (70.73%) compared to non-DIH (44.63%; P < 0.05). The frequency of the NAT2*5/*7 and NAT2*6/*7 genotypes was significantly higher in DIH than non-DIH (19.51% vs 6.78%, and 19.51% vs 5.08%). No association of the CYP2E1 RsaI polymorphism could be demonstrated with DIH. However, the DraI C/D genotype of the CYP2E1 gene was mostly prevalent in DIH (85.37%), compared to non-DIH (64.41%) (P < 0.05). Slow-acetylator status and the CYP2E1 C/D or C/C genotype together showed a higher frequency in DIH (65.85%) compared to non-DIH (28.81%) (P < 0.0001).

CONCLUSION

The study demonstrates for the first time a possible association between the DraI polymorphism of the CYP2E1 gene and the risk of ATT hepatotoxicity. The genotyping of the NAT2 and CYP2E1 genes could possibly identify the groups at highest risk of developing ATT-induced hepatitis prior to medication.

Role of CYP2E1 gene polymorphisms association with hepatitis risk in Northeast India

AIM

To investigate hepatitis virus, genetic and environmental factors, and their interactions in predisposing patients to liver diseases in Northeast India.

METHODS

A total of 104 jaundice patients and 124 community controls were included. Serological analysis was performed by routine enzyme-linked immunosorbent assay, and nucleic acid testing for hepatitis viruses was done by polymerase chain reaction (PCR), followed by PCR direct sequencing for viral genotyping. Cytochrome P450 2E1 (CYP2E1) polymorphism was studied by PCR-restriction fragment length polymorphism. Nitrite and volatile nitrosamines in indigenous foods consumed routinely by the Northeast Indian ethnic population were estimated by Griess's reagent and GC-MS, respectively.

RESULTS

Hepatitis A virus (HAV) infection was predominantly prevalent (36.5%) in our cohort, followed by hepatitis B virus (HBV), hepatitis E virus (HEV) and hepatitis C virus. HBV genotype D and HEV genotype 1 were the most dominant. CYP2E1 c1/c2 genotype frequency was comparatively higher in alcoholic (P < 0.0001, OR = 30.5) and cryptogenic (P = 0.014, OR = 8.714) patients, and was associated with significantly higher hepatitis risk (P = 0.0.007, OR = 6.489). Mutant C allele of Cyp2E1 DraI frequency was comparatively higher in HAV (P = 0.006), alcoholic (P = 0.003) and cryptogenic (P = 0.014) cases, and was associated with overall hepatitis risk (P = 0.026, OR = 5.083). Indigenous foods, Gundruk, Kharoli, betel leaf and nuts were found to have the highest nitrite content.

CONCLUSION

Apart from viral factors, CYP2E1 polymorphism might be associated with increased risk of liver diseases in Northeast India. Indigenous foods that contain nitrite and nitrosamine might be an associated risk factor.