Salum J. Lidenge

Bio: Salum J. Lidenge is an academic researcher from Muhimbili University of Health and Allied Sciences. The author has contributed to research in topics: Medicine & Kaposi's sarcoma. The author has an hindex of 5, co-authored 11 publications receiving 143 citations. Previous affiliations of Salum J. Lidenge include University of Nebraska–Lincoln.

Presence of antibody-dependent cellular cytotoxicity (ADCC) against SARS-CoV-2 in COVID-19 plasma.

Abstract: Background Neutralizing-antibody (nAb) is the major focus of most ongoing COVID-19 vaccine trials. However, nAb response against SARS-CoV-2, when present, decays rapidly. Given the myriad roles of antibodies in immune responses, it is possible that antibodies could also mediate protection against SARS-CoV-2 via effector mechanisms such as antibody-dependent cellular cytotoxicity (ADCC), which we sought to explore here. Methods Plasma of 3 uninfected controls and 20 subjects exposed to, or recovering from, SARS-CoV-2 infection were collected from U.S. and sub-Saharan Africa. Immunofluorescence assay was used to detect the presence of SARS-CoV-2 specific IgG antibodies in the plasma samples. SARS-CoV-2 specific neutralizing capability of these plasmas was assessed with SARS-CoV-2 spike pseudotyped virus. ADCC activity was assessed with a calcein release assay. Results SARS-CoV-2 specific IgG antibodies were detected in all COVID-19 subjects studied. All but three COVID-19 subjects contained nAb at high potency (>80% neutralization). Plasma from 19/20 of COVID-19 subjects also demonstrated strong ADCC activity against SARS-CoV-2 spike glycoprotein, including two individuals without nAb against SARS-CoV-2. Conclusion Both neutralizing and non-neutralizing COVID-19 plasmas can mediate ADCC. Our findings argue that evaluation of potential vaccines against SARS-CoV-2 should include investigation of the magnitude and durability of ADCC, in addition to nAb.

RNA-Seq of Kaposi's sarcoma reveals alterations in glucose and lipid metabolism.

Abstract: Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS). It is endemic in a number of sub-Saharan African countries with infection rate of >50%. The high prevalence of HIV-1 coupled with late presentation of advanced cancer staging make KS the leading cancer in the region with poor prognosis and high mortality. Disease markers and cellular functions associated with KS tumorigenesis remain ill-defined. Several studies have attempted to investigate changes of the gene profile with in vitro infection of monoculture models, which are not likely to reflect the cellular complexity of the in vivo lesion environment. Our approach is to characterize and compare the gene expression profile in KS lesions versus non-cancer tissues from the same individual. Such comparisons could identify pathways critical for KS formation and maintenance. This is the first study that utilized high throughput RNA-seq to characterize the viral and cellular transcriptome in tumor and non-cancer biopsies of African epidemic KS patients. These patients were treated anti-retroviral therapy with undetectable HIV-1 plasma viral load. We found remarkable variability in the viral transcriptome among these patients, with viral latency and immune modulation genes most abundantly expressed. The presence of KSHV also significantly affected the cellular transcriptome profile. Specifically, genes involved in lipid and glucose metabolism disorder pathways were substantially affected. Moreover, infiltration of immune cells into the tumor did not prevent KS formation, suggesting some functional deficits of these cells. Lastly, we found only minimal overlaps between our in vivo cellular transcriptome dataset with those from in vitro studies, reflecting the limitation of in vitro models in representing tumor lesions. These findings could lead to the identification of diagnostic and therapeutic markers for KS, and will provide bases for further mechanistic studies on the functions of both viral and cellular genes that are involved.

Similar Immunological Profiles Between African Endemic and Human Immunodeficiency Virus Type 1-Associated Epidemic Kaposi Sarcoma (KS) Patients Reveal the Primary Role of KS-Associated Herpesvirus in KS Pathogenesis.

Abstract: BACKGROUND Kaposi sarcoma (KS)-associated herpesvirus (KSHV) is etiologically linked to all KS forms, but mechanisms underlying KS development are unclear. The incidence of KS in human immunodeficiency virus type 1-infected (HIV-1+) individuals implicates immune dysregulation; however, the lack of characterization of KSHV immune responses in endemic KS makes the role of HIV-1 unclear. The study objective was to investigate the HIV-1 and KSHV roles in viral nucleic acid detection, antibody responses, and cytokine responses in polymerase chain reaction-confirmed epidemic KS and endemic KS patients and non-cancer controls from sub-Saharan Africa. METHODS KSHV viral DNA (vDNA), total anti-KSHV antibody, KSHV neutralizing antibody (nAb), and cytokines were quantified. RESULTS KSHV vDNA was detectable in tumors but variably in plasma and peripheral blood mononuclear cells. Consistent with elevated antibody-associated cytokines (interleukin [IL] 6, IL-5, and IL-10), nAb titers were higher in epidemic KS and endemic KS patients than in controls (P < .05). Despite HIV-1 coinfection in epidemic KS, nAb titers were similar between epidemic KS and endemic KS patients (P = 0.3). CONCLUSIONS Similarities in antibody and cytokine responses between epidemic and endemic KS patients suggest that KSHV drives KS pathogenesis, whereas HIV-1 exacerbates it.

Lack of CD8 + T-cell co-localization with Kaposi's sarcoma-associated herpesvirus infected cells in Kaposi's sarcoma tumors

Abstract: Despite the close association between Kaposi's sarcoma (KS) and immune dysfunction, it remains unclear whether tumor infiltrating immune cells (TIIC), by their absence, presence, or dysfunction, are mechanistically correlated with KS pathogenesis. Therefore, their potential capacity to serve as prognostic biomarkers of KS disease progression or control is unclear. Because epidemic-KS (EpKS) occurs with HIV-1 co-infection, it is particularly important to compare TIIC between EpKS and HIV-negative African endemic-KS (EnKS) to dissect the roles of HIV-1 and Kaposi Sarcoma-associated herpesvirus (KSHV) in KS pathogenesis. This cross-sectional study of 13 advanced KS (4 EnKS, 9 EpKS) patients and 3 healthy controls utilized single-color immunohistochemistry and dual-color immunofluorescence assays to characterize and quantify KSHV infected cells in relation to various TIIC in KS biopsies. Analysis of variance (ANOVA) and Mann-Whitney tests were used to assess differences between groups where P-values < 0.05 were considered significant. The abundance of KSHV infected cells was heterogeneous in KS biopsies. Despite the presence of T-cell chemoattractant chemokine CxCL-9 in biopsies, CD8+ T-cells were sparsely distributed in regions with evident KSHV infected cells but were readily detectable in regions devoid of KSHV infected cells (P < 0.0001). CD68+ (M1) macrophages were evenly and diffusely distributed in KS biopsies, whereas, the majority of CD163+ (M2) macrophages were localized in regions devoid of KSHV infected cells (P < 0.0001). Overall, the poor immune cell infiltration or co-localization in KS biopsies independent of HIV-1 co-infection suggests a fundamental tumor immune evasion mechanism that warrants further investigation.

Immune determinants of COVID-19 disease presentation and severity.

Abstract: COVID-19, caused by SARS-CoV-2 infection, is mild to moderate in the majority of previously healthy individuals, but can cause life-threatening disease or persistent debilitating symptoms in some cases. The most important determinant of disease severity is age, with individuals over 65 years having the greatest risk of requiring intensive care, and men are more susceptible than women. In contrast to other respiratory viral infections, young children seem to be less severely affected. It is now clear that mild to severe acute infection is not the only outcome of COVID-19, and long-lasting symptoms are also possible. In contrast to severe acute COVID-19, such 'long COVID' is seemingly more likely in women than in men. Also, postinfectious hyperinflammatory disease has been described as an additional outcome after SARS-CoV-2 infection. Here I discuss our current understanding of the immunological determinants of COVID-19 disease presentation and severity and relate this to known immune-system differences between young and old people and between men and women, and other factors associated with different disease presentations and severity.

SARS-CoV-2 variants of concern partially escape humoral but not T-cell responses in COVID-19 convalescent donors and vaccinees.

Abstract: The emergence of SARS-CoV-2 variants harboring mutations in the spike (S) protein has raised concern about potential immune escape. Here, we studied humoral and cellular immune responses to wild type SARS-CoV-2 and the B.1.1.7 and B.1.351 variants of concern in a cohort of 121 BNT162b2 mRNA-vaccinated health care workers (HCW). Twenty-three HCW recovered from mild COVID-19 disease and exhibited a recall response with high levels of SARS-CoV-2-specific functional antibodies and virus-specific T cells after a single vaccination. Specific immune responses were also detected in seronegative HCW after one vaccination, but a second dose was required to reach high levels of functional antibodies and cellular immune responses in all individuals. Vaccination-induced antibodies cross-neutralized the variants B.1.1.7 and B.1.351, but the neutralizing capacity and Fc-mediated functionality against B.1.351 was consistently 2- to 4-fold lower than to the homologous virus. In addition, peripheral blood mononuclear cells were stimulated with peptide pools spanning the mutated S regions of B.1.1.7 and B.1.351 to detect cross-reactivity of SARS-CoV-2-specific T cells with variants. Importantly, we observed no differences in CD4+ T-cell activation in response to variant antigens, indicating that the B.1.1.7 and B.1.351 S proteins do not escape T-cell-mediated immunity elicited by the wild type S protein. In conclusion, this study shows that some variants can partially escape humoral immunity induced by SARS-CoV-2 infection or BNT162b2 vaccination, but S-specific CD4+ T-cell activation is not affected by the mutations in the B.1.1.7 and B.1.351 variants.

Changes in Health Services Use Among Commercially Insured US Populations During the COVID-19 Pandemic.

Abstract: Importance The coronavirus disease 2019 (COVID-19) pandemic has placed unprecedented strain on patients and health care professionals and institutions, but the association of the pandemic with use of preventive, elective, and nonelective care, as well as potential disparities in use of health care, remain unknown. Objective To examine changes in health care use during the first 2 months of the COVID-19 pandemic in March and April of 2020 relative to March and April of 2019 and 2018, and to examine whether changes in use differ by patient’s zip code–level race/ethnicity or income. Design, Setting, and Participants This cross-sectional study analyzed health insurance claims for patients from all 50 US states who receive health insurance through their employers. Changes in use of preventive services, nonelective care, elective procedures, prescription drugs, in-person office visits, and telemedicine visits were examined during the first 2 months of the COVID-19 pandemic in 2020 relative to existing trends in 2019 and 2018. Disparities in the association of the pandemic with health care use based on patient’s zip code–level race and income were also examined. Results Data from 5.6, 6.4, and 6.8 million US individuals with employer-sponsored insurance in 2018, 2019, and 2020, respectively, were analyzed. Patient demographics were similar in all 3 years (mean [SD] age, 34.3 [18.6] years in 2018, 34.3 [18.5] years in 2019, and 34.5 [18.5] years in 2020); 50.0% women in 2018, 49.5% women in 2019, and 49.5% women in 2020). In March and April 2020, regression-adjusted use rate per 10 000 persons changed by −28.2 (95% CI, −30.5 to −25.9) and −64.5 (95% CI, −66.8 to −62.2) for colonoscopies; −149.1 (95% CI, −162.0 to −16.2) and −342.1 (95% CI, −355.0 to −329.2) for mammograms; −60.0 (95% CI, −63.3 to −54.7) and −118.1 (95% CI, −112.4 to −113.9) for hemoglobin A1ctests; −300.5 (95% CI, −346.5 to −254.5) and −369.0 (95% CI, −414.7 to −323.4) for child vaccines; −4.6 (95% CI, −5.3 to −3.9) and −10.9 (95% CI, −11.6 to −10.2) for musculoskeletal surgery; −1.1 (95% CI, −1.4 to −0.7) and −3.4 (95% CI, −3.8 to −3.0) for cataract surgery; −13.4 (95% CI, −14.6 to −12.2) and −31.4 (95% CI, −32.6 to −30.2) for magnetic resonance imaging; and −581.1 (95% CI, −612.9 to −549.3) and −1465 (95% CI, −1496 to −1433) for in-person office visits. Use of telemedicine services increased by 227.9 (95% CI, 221.7 to 234.1) per 10 000 persons and 641.6 (95% CI, 635.5 to 647.8) per 10 000 persons. Patients living in zip codes with lower-income or majority racial/ethnic minority populations experienced smaller reductions in in-person visits (≥80% racial/ethnic minority zip code: 200.0 per 10 000 [95% CI, 128.9-270.1]; 79%-21% racial/ethnic minority zip code: 54.2 per 10 000 [95% CI, 33.6-74.9]) but also had lower rates of adoption of telemedicine (≥80% racial/ethnic minority zip code: −71.6 per 10 000 [95% CI, −87.6 to −55.5]; 79%-21% racial/ethnic minority zip code: −15.1 per 10 000 [95% CI, −19.8 to −10.4]). Conclusions and Relevance In this cross-sectional study of a large US population with employer-sponsored insurance, the first 2 months of the COVID-19 pandemic were associated with dramatic reductions in the use of preventive and elective care. Use of telemedicine increased rapidly but not enough to account for reductions in in-person primary care visits. Race and income disparities at the zip code level exist in use of telemedicine.