Department of Microbiology/Immunology

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    The distribution of reproductive risk factors disclosed the heterogeneity of receptor-defined breast cancer subtypes among Tanzanian women
    (SPRINGER, 2021-12-20) Rweyemamu, Linus Paul; Akan, Gokce; Adolf, Ismael C; Magorosa, Erick; Mosha, Innocent; Dharsee, Nazma; Namkinga, Lucy; Lyantagaye, Sylvester L; Nateri, Abdolrahman S; Atalar, Fatmahan
    Background Recent epidemiological studies suggest that reproductive factors are associated with breast cancer (BC) molecular subtypes. However, these associations have not been thoroughly studied in the African populations. The present study aimed to investigate the prevalence of BC molecular subtypes and assess their association with reproductive factors in Tanzanian BC patients. Methods This hospital-based case-only cross-sectional study consisted of 263 histologically confirmed BC patients in Tanzania. Clinico-pathological data, socio-demographic characteristics, anthropometric measurements, and reproductive risk factors were examined using the Chi-square test and one-way ANOVA. The association among reproductive factors and BC molecular subtypes was analyzed using multinomial logistic regression. The heterogeneity of the associations was assessed using the Wald test. Results We found evident subtype heterogeneity for reproductive factors. We observed that post-menopausal status was more prevalent in luminal-A subtype, while compared to luminal-A subtype, luminal-B and HER-2 enriched subtypes were less likely to be found in post-menopausal women (OR: 0.21, 95%CI 0.10–0.41, p = 0.001; OR: 0.39, 95%CI 0.17–0.89, p = 0.026, respectively). Also, the luminal-B subtype was more likely to be diagnosed in patients aged ≤ 40 years than the luminal-A subtype (OR: 2.80, 95%CI 1.46–5.32, p = 0.002). Women who had their first full-term pregnancy at < 30 years were more likely to be of luminal-B (OR: 2.71, 95%CI 1.18–4.17, p = 0.018), and triple-negative (OR: 2.28, 95%CI 1.02–4.07, p = 0.044) subtypes relative to luminal-A subtype. Furthermore, we observed that breastfeeding might have reduced odds of developing luminal-A, luminal-B and triple-negative subtypes. Women who never breastfed were more likely to be diagnosed with luminal-B and triple-negative subtypes when compared to luminal-A subtype (OR: 0.46, 95%CI 0.22–0.95, p = 0.035; OR: 0.41, 95%CI 0.20–0.85, p = 0.017, respectively). Conclusion Our results are the first data reporting reproductive factors heterogeneity among BC molecular subtypes in Tanzania. Our findings suggest that breast-feeding may reduce the likelihood of developing luminal-A, luminal-B, and triple-negative subtypes. Meanwhile, the first full-term pregnancy after 30 years of age could increase the chance of developing luminal-A subtype, a highly prevalent subtype in Tanzania. More interventions to promote modifiable risk factors across multiple levels may most successfully reduce BC incidence in Africa.
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    Absence of Germline BRCA1 c. 68_69delAG and c. 5266dupC Mutations among Hormone Receptor-negative Breast Cancer Patients: A First Impression at a Tertiary Cancer-care Facility in Tanzania
    (AJOL, 2021-12-29) Rweyemamu, Linus Paul; Akan, Gokce; Mbotwa, Christopher H; Dharsee, Nazma; Namkinga, Lucy; Lyantagaye, Sylvester L; Mselle, Ted F; Atalar, Fatmahan
    The germline BRCA1 c.68_69delAG (185delAG) and c.5266dupC (5382insC) mutations are associated with hormone receptor-negative breast cancer (BC). Limited studies have examined their contribution to alarming BC incidence in Sub Saharan Africa (SSA). Our study aimed to examine the contribution of germline BRCA1 c.68_69delAG and c.5266dupC mutations to BC incidence among hormone receptor-negative BC patients admitted to Ocean Road Cancer Institute in Tanzania. Face-to-face interviews were conducted to capture socio-demographic characteristics, anthropometric measurements, family history of cancer and reproductive information from each patient. Their histopathological data were extracted from the hospital medical records. The germline BRCA1 founder mutations were analyzed on blood samples using Sanger sequencing technology. The patients mean age at diagnosis was 47.05 ± 12.82 years. A family history of cancer was observed in 13.6% of patients. The germline BRCA1 c.68_69delAG and c.5266dupC mutations were not detected in the study group. Our findings indicate that the germline BRCA1 c.68_69delAG and c.5266dupC mutations do not contribute to BC manifestation in hormone receptor-negative BC patients in Tanzania. Thus, screening BC patients for these mutations has no clinical relevance. Our data further suggest that the c.68_69delAG and the c.5266dupC mutations should not be considered when developing genetic testing guidelines in Tanzania.
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    The interplay between XPG-Asp1104His polymorphism and reproductive risk factors elevates risk of breast cancer in Tanzanian women: A multiple interaction analysis
    (WILEY, 2022-06-12) Rweyemamu, Linus Paul; Adolf, Ismael C; Akan, Gokce; Mselle, Ted F; Dharsee, Nazma; Namkinga, Lucy; Lyantagaye, Sylvester L; Atalar, Fatmahan
    Background Reproductive history and genetics are well-known risk factors of breast cancer (BC). Little is known about how these factors interact to effect BC. This study investigated the association of ten polymorphisms in DNA repair genes with BC susceptibility in the Tanzanian samples and further analyzed the association between reproductive risk factors and disease risk Methods A hospital-based case–control study in 263 histopathological confirmed BC patients and 250 age-matched cancer-free controls was carried out. Allelic, genotypic, and haplotype association analyses were executed. Also, multifactor dimensionality reduction (MDR), and interaction dendrogram approaches were performed. Results The frequency of genotypic and allelic variants of XRCC1-Arg399Gln (rs25487), XRCC2-Arg188His (rs3218536), XRCC3-Thr241Met (rs861539), XPG-Asp1104His (rs17655), and MSH2-Gly322Asp (rs4987188) were significantly different between the groups (p < 0.05). Moreover, XRCC1-Arg399Gln (rs25487), XRCC3-Thr241Met (rs861539), and XPG-Asp1104His (rs17655) were associated with the increased risk of BC in co-dominant, dominant, recessive, and additive genetic-inheritance models (p < 0.05). XRCC1-Arg/Gln genotype indicated a 3.1-fold increased risk of BC in pre-menopausal patients (p = 0.001) while XPG-His/His genotype showed a 1.2-fold increased risk in younger BC patients (<40 years) (p = 0.028). Asp/His+His/His genotypes indicated a 1.3-fold increased risk of BC in PR+ patients and a 1.1-fold decreased risk of BC in luminal-A patients (p = 0.014, p = 0.020, respectively). MDR analysis revealed a positive interaction between BC and the XPG-Asp1104His (rs17655) together with family history of cancer in the first-degree relatives. Dendrogram analysis indicated that the XPG-Asp1104His (rs17655) and family history of cancer in first-degree relatives were significantly synergistic and might be associated with an elevated risk of BC in Tanzania. Conclusions The XPG-Asp1104His (rs17655) might exert both independent and interactive effects on BC development in the Tanzanian women.
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    Breast cancer in East Africa: Prevalence and spectrum of germline SNV/indel and CNVs in BRCA1 and BRCA2 genes among breast cancer patients in Tanzania
    (WILEY, 2022-07-19) Rweyemamu, Linus Paul; Gültaşlar, Busra K; Akan, Gokce; Dharsee, Nazma; Namkinga, Lucy; Lyantagaye, Sylvester L; Yazici, Hulya; Atalar, Fatmahan
    Background Growing prevalence and aggressiveness of breast cancer (BC) among East African women strongly indicate that the genetic risk factor implicated in the etiology of the disease may have a key role. Germline pathogenic variants in BRCA1 and BRCA2 (BRCA1/2) are known to increase the lifetime risk of BC. This study investigated the prevalence and spectrum of germline single nucleotide variant/insertion and deletion (SNV/indel), and copy number variations (CNVs) in BRCA1/2 among Tanzanian BC patients, and evaluated the associations of identified variants with patient's socio-demographic and histopathological characteristics. Methods One hundred BC patients were examined for BRCA1/2 variants using next-generation sequencing (NGS). Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) assay were performed for the confirmation of SNV/indel and CNVs, respectively. Results Six germline SNV/indel pathogenic variants were detected from six unrelated patients. Five of these variants were identified in BRCA1, and one in BRCA2. We also identified, in one patient, one variant of uncertain clinical significance (VUS). CNV was not detected in any of the BC patients. Furthermore, we found that in our cohort, BRCA1/2 variant carriers were triple-negative BC patients (p = 0.019). Conclusions Our study provides first insight into BC genetic landscape by the use of NGS in the under-represented East African Tanzanian populations. Our findings support the importance of genetic risk factors in BC etiology in Tanzania and showed a relatively high overall prevalence (6%) of germline BRCA1/2 pathogenic variants in BC patients. Therefore, our results indicate that BRCA1/2 pathogenic variants may well contribute to BC incidence in Tanzania. Thus, the identification of frequent variants in BRCA1/2 genes will enable implementation of rapid, inexpensive population-specific BRCA1/2 genetic testing, particularly for triple-negative BC patients known for their high prevalence in Tanzania. This will, in turn, greatly contributes to provide effective therapeutic strategies.
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    Distinct Immune Profiles of Exhausted Effector and Memory CD8+ T Cells in Individuals With Filarial Lymphedema
    (Frontiers Media S.A., 2021-08-11) Horn, Sacha; Borrero-Wolff, Dennis; Ritter, Manuel; Arndts, Kathrin; Wiszniewsky, Anna; Debrah, Linda Batsa; Debrah, Alexander Y.; Osei-Mensah, Jubin; Chachage, Mkunde; Hoerauf, Achim; Kroidl, Inge; Layland, Laura E.
    CD8+ T cells are crucial for the clearance of viral infections, and current research begins to highlight their importance in parasitic diseases too. In-depth research about characteristics of CD8+ T-cell subsets and exhaustion remains uncertain, especially during filariasis, a chronic helminth infection. Lymphatic filariasis, elicited by Wuchereria bancrofti, remains a serious health problem in endemic areas in Ghana, especially in those suffering from morbidity due to lymphedema (LE). In this observational study, the characteristics and profiles of CD8+ T cells were compared between asymptomatic Wuchereria bancrofti-infected individuals, uninfected endemic normals, and those with LE (grades 2–6). Focusing on exhausted memory (CD8+exmem: CD8+ T-betdimEomeshi) and effector (CD8+exeff: CD8+T-bethiEomesdim) CD8+ T-cell subsets, advanced flow cytometry revealed that LE individuals presented reduced frequencies of IFN-γ+CD8+exmem T cells expressing Tim-3 or LAG-3 which negatively correlated to the presence of LE. Moreover, the LE cohort further showed significantly higher frequencies of IL-10+CD8+exeff T cells expressing either Tim-3, LAG-3, CD39, KLRG-1, or PD-1, all associated markers of exhaustion, and that these frequencies positively correlated with the presence of LE. In summary, this study shows that distinct exhausted CD8+ T-cell subsets are prominent in individuals suffering from LE, suggesting that enhanced inflammation and constant immune activation might drive exhaustion of CD8+ T cells. Since T-cell exhaustion is known to be associated with insufficient control of persisting antigen, the data presented here reveals that these CD8+ T-cell exhaustion patterns in filarial LE should be taken into consideration for prevention and control management of LE.
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    Altered Lipid Profiles and Vaccine Induced-Humoral Responses in Children Living With HIV on Antiretroviral Therapy in Tanzania
    (Frontiers Media S.A., 2021-11-09) Mbuya, Wilbert; Mwakyula, Issakwisa; Olomi, Willyelimina; Agrea, Peter; Nicoli, Francesco; Ngatunga, Cecilia; Mujwahuzi, Leodegard; Mwanyika, Paul; Chachage, Mkunde
    People living with HIV, even under therapy, have a high burden of age-related co-morbidities including an increased risk of dyslipidemia (which often predisposes to cardiovascular diseases) and immune-aging. In this study, lipid profiles and antibody responses to measles and pertussis toxin vaccines were compared between ART experienced HIV+ children (n=64) aged 5-10 years, and their age- and sex-matched HIV- controls (n=47). Prevalence of high-density lipoprotein cholesterol (HDL-c) and triglyceride-driven dyslipidemia was higher among treated HIV+ children than in controls (51.6% vs 27.7% respectively, p < 0.019). In a multivariate Poisson regression model adjusted for age, sex and BMI, the association between low HDL-c, hypertriglyceridemia and HIV remained significantly high (for HDL-c: ARR: 0.89, 95% CI: 0.82 – 0.96, p = 0.003; for triglycerides: ARR: 1.54, 95% CI: 1.31 – 1.81, p < 0.001). Among HIV+ children, the use of lopinavir/ritonavir, a protease-based antiretroviral therapy was also associated elevation of triglyceride levels (p = 0.032). Also, HIV+ children had a 2.8-fold reduction of anti-measles IgG titers and 17.1-fold reduction of anti-pertussis toxin IgG levels when compared to HIV- children. Our findings suggest that dyslipidemia and inadequate vaccine-induced antibody responses observed in this population of young African HIV+ children might increase their risk for premature onset of cardiovascular illnesses and acquisition of preventable diseases.
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    HPV Type Distribution in HIV Positive and Negative Women With or Without Cervical Dysplasia or Cancer in East Africa
    (Frontiers Media S.A., 2021-11-30) Mcharo, Ruby; Lennemann, Tessa; France, John; Torres, Liset; Gari, Mercè; Mbuya, Wilbert; Mwalongo, Wolfram; Mahenge, Anifrid; Bauer, Asli; Mnkai, Jonathan; Glasmeyer, Laura; Judick, Mona; Paul, Matilda; Schroeder, Nicolas; Msomba, Bareke; Sembo, Magreth; Chiwerengo, Nhamo; Hoelscher, Michael; Geisenberger, Otto; Lelle, Ralph J.; Saathoff, Elmar; Maboko, Leonard; Chachage, Mkunde; Kroidl, Arne; Geldmacher, Christof
    Background: Women living with HIV in sub-Saharan Africa are at increased risk to develop cervical cancer (CC), which is caused by persistent infection with 13 oncogenic human papilloma viruses (HR-HPVs). It is important to accurately identify and target HIV-positive women at highest risk to develop CC for early therapeutic intervention. Methods: A total of 2,134 HIV+ and HIV− women from South-West Tanzania were prospectively screened for cervical cancer and precancerous lesions. Women with cervical cancer (n=236), high- and low-grade squamous intraepithelial lesions (HSIL: n=68, LSIL: n=74), and without lesion (n=426) underwent high-resolution HPV genotyping. Results: Eighty percent of women who were diagnosed with HSIL or LSIL were living with HIV. Any lesion, young age, HIV status, and depleted CD4 T cell counts were independent risk factors for HPV infections, which were predominantly caused by HR-HPV types. While multiple HR-HPV type infections were predominant in HIV+ women with HSIL, single-type infections predominated in HIV+ CC cases (p=0.0006). HPV16, 18, and 45 accounted for 85% (68/80) and 75% (82/110) of HIV+ and HIV− CC cases, respectively. Of note, HPV35, the most frequent HPV type in HSIL-positive women living with HIV, was rarely detected as a single-type infection in HSIL and cancer cases. Conclusion: HPV16, 18, and 45 should receive special attention for molecular diagnostic algorithms during CC prevention programs for HIV+ women from sub-Saharan Africa. HPV35 may have a high potential to induce HSIL in women living with HIV, but less potential to cause cervical cancer in single-type infections.
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    Depletion of Human Papilloma Virus E6- and E7-Oncoprotein-Specific T-Cell Responses in Women Living With HIV
    (Frontiers Media S.A., 2021-10-25) Mbuya, Wilbert; Mcharo, Ruby; Mhizde, Jacklina; Mnkai, Jonathan; Mahenge, Anifrid; Mwakatima, Maria; Mwalongo, Wolfram; Hoelscher, Michael; Saathoff, Elmar; Rwegoshora, France; Torres, Liset; Kroidl, Arne; Geldmacher, Christof; Held, Kathrin; Chachage, Mkunde; Sembo, Margareth; Haule, Antelmo; Maboko, Leonard; Geisenberger, Otto; Agrea, Peter; Koup, Richard A.
    Background: Cervical cancer - caused by persistent High Risk Human Papilloma Virus (HR HPV) infections - is the second most common cancer affecting women globally. HIV infection increases the risk for HPV persistence, associated disease progression and malignant cell transformation. We therefore hypothesized that this risk increase is directly linked to HIV infection associated dysfunction or depletion of HPV-oncoprotein-specific T-cell responses. Methods: The 2H study specifically included HIV+ and HIV- women with and without cervical lesions and cancer to analyze HPV oncogene-specific T cell responses in relation to HPV infection, cervical lesion status and HIV status. Oncoprotein E6 and E7 specific T-cell responses were quantified for the most relevant types HPV16, 18 and 45 and control antigens (CMV-pp65) and M.tb-PPD in 373 women, using fresh peripheral blood mononuclear cells in an IFN-γ release ELISpot assay. Results: Overall, systemic E6- and E7-oncoprotein-specific T-cell responses were infrequent and of low magnitude, when compared to CMV-pp65 and M.tb-PPD (p < 0.001 for all HR HPV types). Within HIV negative women infected with either HPV16, 18 or 45, HPV16 infected women had lowest frequency of autologous-type-E6/E7-specific T-cell responses (33%, 16/49), as compared to HPV18 (46% (6/13), p = 0.516) and HPV45 (69% (9/13), p = 0.026) infected women. Prevalent HPV18 and 45, but not HPV16 infections were linked to detectable oncoprotein-specific T-cell responses, and for these infections, HIV infection significantly diminished T-cell responses targeting the autologous infecting genotype. Within women living with HIV, low CD4 T-cell counts, detectable HIV viremia as well as cancerous and precancerous lesions were significantly associated with depletion of HPV oncoprotein-specific T-cell responses. Discussion: Depletion of HPV-oncoprotein-specific T-cell responses likely contributes to the increased risk for HR HPV persistence and associated cancerogenesis in women living with HIV. The low inherent immunogenicity of HPV16 oncoproteins may contribute to the exceptional potential for cancerogenesis associated with HPV16 infections.
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    The gut-microbiome contribution to HIV-associated cardiovascular disease and metabolic disorders
    (Elsevier, 2021-12) Chachage, Mkunde
    During the past decade, there has been a great effort in characterizing the gut microbiome of individuals living with HIV and its influence on HIV-metabolic disorders. Herein, the current understanding of the changes in the composition and function of the gut microbiome in the context of HIV infection, cardiovascular disease, and HIV-associated metabolic disorders is reviewed. A focus is especially given to bacteria gut microbiome and their produced metabolites, including tryptophan, short-chain fatty acids, and trimethylamine-N-oxide, and discuss current literatures that have investigated their role in HIV pathogenesis and HIV metabolic disorders. This review finally calls for future studies to focus on interrogating the mechanism of host-gut microbiome interaction in relation to HIV and HIV comorbidities by using multiomics approaches and on geographically diverse populations.