Systemic DPP4/CD26 is associated with natural HIV-1 control: Implications for COVID-19 susceptibility

A comprehensive review on targeting cluster of differentiation: An attractive strategy for inhibiting viruses through host proteins

Viral infections continue to pose a significant global public health threat. Targeting host proteins, such as cluster of differentiation (CD) macromolecules, may offer a promising alternative approach to developing antiviral treatments. CDs are cell-surface biological macromolecules mainly expressed on leukocytes that viruses can use to enter cells, thereby evading immune detection and promoting their replication. The manipulation of CDs by viruses may represent an effective and clever means of survival through the prolonged co-evolution of hosts and viruses. Targeting of CDs is anticipated to hinder the invasion of related viruses, modulate the body's immune system, and diminish the incidence of subsequent inflammation. They have become crucial for biomedical diagnosis, and some have been used as valuable tools for resisting viral infections. However, a summary of the structures and functions of CDs involved in viral infection is currently lacking. The development of drugs targeting these biological macromolecules is restricted both in terms of their availability and the number of compounds currently identified. This review provides a comprehensive analysis of the critical role of CD proteins in virus invasion and a list of relevant targeted antiviral agents, which will serve as a valuable reference for future research in this field.

Intersecting epidemics: COVID-19 and HIV in sub-Saharan Africa. A systematic review (2020-2022)

There has been significant progress with regards to winning the fight against HIV globally, particularly due to the introduction of antiretroviral therapy (ART). COVID-19 threatened to derail gains in the fight against HIV. As we have started to see with studies on COVID-19 and HIV, there is a need to 'provide an in-depth view' in understanding the dynamics between the two epidemics, especially in sub-Saharan Africa. We, therefore, undertook a systemic review of existing literature to synthesize the effects of COVID-19 on the utilization of HIV services in sub-Saharan Africa, the literature on the risks associated with HIV during the COVID-19 pandemic, and lastly, the innovations and strategies adopted to continue receiving treatment in sub-Saharan Africa. We conducted a systematic review of studies published between 2020 and April 2022. We searched for relevant sub-Saharan studies in the following databases: PubMed, Google Scholar, J-STOR, and Science Direct. The review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search identified 647 papers, and after screening, 41 were in line with the inclusion criteria and were included in the review. There was evidence of the negative effects of COVID-19 on reducing HIV testing, ART treatment, and HIV prevention services. There is evidence pointing to the need for people living with HIV to be prioritized for COVID-19 vaccinations. Innovations and strategies implemented to mitigate the effects of COVID-19 on HIV services include community-based ART distribution, multi-month ART dispensing, the use of digital technologies, and the use of the already existing HIV infrastructure to fight COVID-19. It is still imperative that future studies explore the predictors of utilization of HIV services in the advent of COVID-19.

Effect of DPP4/CD26 expression on SARS‑CoV‑2 susceptibility, immune response, adenosine (derivatives m62A and CD) regulations on patients with cancer and healthy individuals

The worldwide COVID‑19 pandemic was brought on by a new coronavirus (SARS Cov‑2). A marker/receptor called Dipeptidyl peptidase 4/CD26(DPP4/CD26) may be crucial in determining susceptibility to tumors and coronaviruses. However, the regulation of DPP4 in COVID‑invaded cancer patients and its role on small molecule compounds remain unclear. The present study used the Human Protein Atlas, Monaco, and Schmiedel databases to analyze the expression of DPP4 in human tissues and immune cells. The association between DPP4 expression and survival in various tumor tissues was compared using GEPIA 2. The DNMIVD database was used to analyze the correlation between DPP4 expression and promoter methylation in various tumors. On the cBioPortal network, the frequency of DPP4 DNA mutations in various cancers was analyzed. The correlation between DPP4 expression and immunomodulators was analyzed by TISIDB database. The inhibitory effects of cordycepin (CD), N6, N6‑dimethyladenosine (m⁶₂A) and adenosine (AD) on DPP4 in cancer cells were evaluated. DPP4 was mainly expressed in endocrine tissue, followed by gastrointestinal tract, female tissue (mainly in placenta), male tissue (mainly in prostate and seminal vesicle), proximal digestive tract, kidney, bladder, liver, gallbladder and respiratory system. In immune cells, DPP4 mRNA was mainly expressed in T cells, and its expression was upregulated in esophageal carcinoma, kidney renal papillary cell carcinoma (KIRP), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma, pancreatic adenocarcinoma, prostate adenocarcinoma, stomach adenocarcinoma, thyroid carcinoma and thymoma. However, it was downregulated in breast invasive carcinoma, kidney chromophobe, lung squamous cell carcinoma and skin cutaneous melanoma. Thus, DPP4 is involved in viral invasion in most types of cancer. The expression of DPP4 could be inhibited by CD, m⁶₂A and AD in different tumor cells. Moreover, CD significantly inhibited the formation of GFP‑positive syncytial cells. In vivo experiments with AD injection further showed that AD significantly inhibited lymphocyte activating factor 3 expression. These drugs may have potential to treat COVID‑19 by targeting DPP4. Thus, DPP4 may be medically significant for SARS‑CoV‑2‑infected cancer patients, providing prospective novel targets and concepts for the creation of drugs against COVID‑19.

The number of circulating CD26 expressing cells is decreased in critical COVID-19 illness

We evaluated the number of CD26 expressing cells in peripheral blood of patients with COVID-19 within 72 h of admission and on day 4 and day 7 after enrollment. The majority of CD26 expressing cells were presented by CD3+ CD4+ lymphocytes. A low number of CD26 expressing cells were found to be associated with critical-severity COVID-19 disease. Conversely, increasing numbers of CD26 expressing T cells over the first week of standard treatment was associated with good outcomes. Clinically, the number of circulating CD26 cells might be a marker of recovery or the therapeutic efficacy of anti-COVID-19 treatment. New therapies aimed at preserving and increasing the level of CD26 expressing T cells may prove useful in the treatment of COVID-19 disease.

DPP4 as a Potential Candidate in Cardiovascular Disease

The rising prevalence of cardiovascular disease has become a global health concern. The occurrence of cardiovascular disease is the result of long-term interaction of many risk factors, one of which is diabetes. As a novel anti-diabetic drug, DPP4 inhibitor has been proven to be cardiovascular safe in five recently completed cardiovascular outcome trials. Accumulating studies suggest that DPP4 inhibitor has potential benefits in a variety of cardiovascular diseases, including hypertension, calcified aortic valve disease, coronary atherosclerosis, and heart failure. On the one hand, in addition to improving blood glucose control, DPP4 inhibitor is involved in controlling cardiovascular risk factors. On the other hand, DPP4 inhibitor directly regulates the occurrence and progression of cardiovascular diseases through a variety of mechanisms. In this review, we summarize the recent advances of DPP4 in cardiovascular disease, aiming to discuss DPP4 inhibitor as a potential option for cardiovascular therapy.

Reduced CCR5 Expression and Immune Quiescence in Black South African HIV-1 Controllers

Unique Individuals who exhibit either suppressive HIV-1 control, or the ability to maintain low viral load set-points and preserve their CD4+ T cell counts for extended time periods in the absence of antiretroviral therapy, are broadly termed HIV-1 controllers. We assessed the extent to which black South African controllers (n=9), differ from uninfected healthy controls (HCs, n=22) in terms of lymphocyte and monocyte CCR5 expression (density and frequency of CCR5-expressing cells), immune activation as well as peripheral blood mononuclear cell (PBMC) mitogen-induced chemokine/cytokine production. In addition, relative CD4+ T cell CCR5 mRNA expression was assessed in a larger group of controllers (n=20) compared to HCs (n=10) and HIV-1 progressors (n=12). Despite controllers having significantly higher frequencies of activated CD4+ and CD8+ T cells (HLA-DR+) compared to HCs, CCR5 density was significantly lower in these T cell populations (P=0.039 and P=0.064, respectively). This lower CCR5 density was largely attributable to controllers with higher VLs (>400 RNA copies/ml). Significantly lower CD4+ T cell CCR5 density in controllers was maintained (P=0.036) when HCs (n=12) and controllers (n=9) were matched for age. CD4+ T cell CCR5 mRNA expression was significantly less in controllers compared to HCs (P=0.007) and progressors (P=0.002), whereas HCs and progressors were similar (P=0.223). The levels of soluble CD14 in plasma did not differ between controllers and HCs, suggesting no demonstrable monocyte activation. While controllers had lower monocyte CCR5 density compared to the HCs (P=0.02), significance was lost when groups were age-matched (P=0.804). However, when groups were matched for both CCR5 promoter haplotype and age (n=6 for both) reduced CCR5 density on monocytes in controllers relative to HCs was highly significant (P=0.009). Phytohemagglutinin-stimulated PBMCs from the controllers produced significantly less CCL3 (P=0.029), CCL4 (P=0.008) and IL-10 (P=0.028) compared to the HCs, which was largely attributable to the controllers with lower VLs (<400 RNA copies/ml). Our findings support a hypothesis of an inherent (genetic) predisposition to lower CCR5 expression in individuals who naturally control HIV-1, as has been suggested for Caucasian controllers, and thus, likely involves a mechanism shared between ethnically divergent population groups.