Samuel Darkwah

Dr. Samuel Darkwah

Mie University Graduate School of Medicine, Dept. of Molecular Pathobiology and Cell Adhesion Biology
orcid

Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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17 August 2023 in Antibiotics
Verified
Journal Article
Open access
PDF file
AOAbdul-Halim Osman
Abdul-Halim Osman
Fleischer C. N. KoteyFleischer C. N. Kotey
Fleischer C. N. Kotey
AOAlex Odoom
Alex Odoom
SDSamuel Darkwah
Samuel Darkwah
RYRaphael K. Yeboah
Raphael K. Yeboah
EDEric Donkor
Eric Donkor
The growing threat of antibiotic resistance is a significant global health challenge that has intensified in recent years. The burden of antibiotic resistance on public health is augmented due to its multifaceted nature, as well as the slow-paced and limited development of new antibiotics. The threat posed by resistance is now existential in phage therapy, which had long been touted as a promising replacement for antibiotics. Consequently, it is imperative to explore the potential of combination therapies involving antibiotics and phages as a feasible alternative for treating infections with multidrug-resistant bacteria. Although either bacteriophage or antibiotics can potentially treat bacterial infections, they are each fraught with resistance. Combination therapies, however, yielded positive outcomes in most cases; nonetheless, a few combinations did not show any benefit. Combination therapies comprising the synergistic activity of phages and antibiotics and combinations of phages with other treatments such as probiotics hold promise in the treatment of drug-resistant bacterial infections.

26 October 2020 in Frontiers in Cell and Developmental Biology
Verified
Journal Article
Open access
PDF file
Eun Jeong ParkEun Jeong Park
Eun Jeong Park
PMPhyoe Kyawe Myint
Phyoe Kyawe Myint
AIAtsushi Ito
Atsushi Ito
MAMichael G. Appiah
Michael G. Appiah
SDSamuel Darkwah
Samuel Darkwah
MSMotomu Shimaoka
Motomu Shimaoka
Integrins are transmembrane proteins that mediate cellular adhesion and migration to neighboring cells or the extracellular matrix, which is essential for cells to undertake diverse physiological and pathological pathways. For integrin activation and ligand binding, bidirectional signaling across the cell membrane is needed. Integrins aberrantly activated under pathologic conditions facilitate cellular infiltration into tissues, thereby causing inflammatory or tumorigenic progressions. Thus, integrins have emerged to the forefront as promising targets for developing therapeutics to treat autoimmune and cancer diseases. In contrast, it remains a fact that integrin-ligand interactions are beneficial for improving the health status of different tissues. Among these ligands, irisin, a myokine produced mainly by skeletal muscles in an exercise-dependent manner, has been shown to bind to integrin αVβ5, alleviating symptoms under unfavorable conditions. These findings may provide insights into some of the underlying mechanisms by which exercise improves quality of life. This review will discuss the current understanding of integrin-ligand interactions in both health and disease. Likewise, we not only explain how diverse ligands play different roles in mediating cellular functions under both conditions via their interactions with integrins, but also specifically highlight the potential roles of the emerging ligand irisin in inflammation, cancer, and metabolic disease.

27 December 2018 in Blood Advances
Verified
Journal Article
Open access
PDF file
Eun Jeong ParkEun Jeong Park
Eun Jeong Park
OPOnmanee Prajuabjinda
Onmanee Prajuabjinda
ZSZay Yar Soe
Zay Yar Soe
SDSamuel Darkwah
Samuel Darkwah
MAMichael G. Appiah
Michael G. Appiah
MSMotomu Shimaoka
Motomu Shimaoka
Exosomes secreted from T cells have been shown to affect dendritic cells, cancer cells, and other T cells. However, little is known about how T-cell exosomes (T exosomes) modulate endothelial cell functions in the context of tissue-specific homing. Here, we study the roles of T exosomes in the regulation of gut-specific T-cell homing. The gut-tropic T cells induced by retinoic acid secrete the exosomes that upregulate integrin α4β7 binding to the MAdCAM-1 expressed on high endothelial venules in the gut. T exosomes were preferentially distributed to the villi of the small intestine in an α4β7-dependent manner. Exosomes from gut-tropic T cells suppressed the expression of MAdCAM-1 in the small intestine, thereby inhibiting T-cell homing to the gut. Moreover, microRNA (miRNA) profiling analysis has shown that exosomes from gut-tropic T cells were enriched with miRNAs targeting NKX2.3, a transcription factor critical to MAdCAM-1 expression. Taken together, our study proposes that α4β7-expressing T exosomes distribute themselves to the small intestine and modify the expression of microenvironmental tissues such that any subsequent lymphocyte homing is precluded. This may represent a novel mechanism by which excessive lymphocyte homing to the intestinal tissues is downsized.

17 July 2024 in Antibiotics
Verified
Journal Article
Open access
PDF file
EDEric Donkor
Eric Donkor
AOAlex Odoom
Alex Odoom
AOAbdul-Halim Osman
Abdul-Halim Osman
SDSamuel Darkwah
Samuel Darkwah
Fleischer C. N. KoteyFleischer C. N. Kotey
Fleischer C. N. Kotey
Background: Antimicrobial resistance (AMR) poses a global health threat, with lower-middle-income countries bearing a disproportionate burden. Surveillance of AMR under a One Health framework is needed to elucidate the associations among clinical, animal, and environmental AMR. This review aimed to describe the state of AMR in Ghana, focusing on One Health. Method: This review utilized the PRISMA guidelines and major databases to systematically search and analyze AMR in Ghana published from 1 January 2014 to 1 May 2023. Results: Out of the 48 articles that met the inclusion criteria, 28 studies were conducted on humans, 14 studies involved animals, and 6 studies focused on the environment. A total of 48 different pathogens were identified across the human, animal, and environmental sectors, with the most common being Escherichia coli (67%, n = 32), Klebsiella spp. (52%, n = 25), Pseudomonas spp. (40%, n = 19), and Salmonella spp. (38%, n = 18). Generally, a high prevalence of antibiotic resistance was observed among various bacterial species across the sectors. These bacteria exhibited resistance to commonly used antibiotics, with resistance to ampicillin and tetracycline exceeding 80%, and multidrug resistance (MDR) ranging from 17.6% in Shigella spp. to 100% in Acinetobacter spp. Conclusion: This review reaffirms the significant challenge of AMR in Ghana, with a high prevalence observed in the human, animal, and environmental sectors. Key pathogens (e.g., Staphylococcus aureus and Escherichia coli) found across the sectors emphasize the urgent need for a One Health approach to tackle AMR in Ghana.

Verified
Journal Article
Open access
PDF file
MAMichael Gyasi Appiah
Michael Gyasi Appiah
Eun Jeong ParkEun Jeong Park
Eun Jeong Park
SDSamuel Darkwah
Samuel Darkwah
Eiji KawamotoEiji Kawamoto
Eiji Kawamoto
Yuichi AkamaYuichi Akama
Yuichi Akama
MSMotomu Shimaoka
Motomu Shimaoka
Sepsis is a systemic inflammatory disorder induced by a dysregulated immune response to infection resulting in dysfunction of multiple critical organs, including the intestines. Previous studies have reported contrasting results regarding the abilities of exosomes circulating in the blood of sepsis mice and patients to either promote or suppress inflammation. Little is known about how the gut epithelial cell-derived exosomes released in the intestinal luminal space during sepsis affect mucosal inflammation. To study this question, we isolated extracellular vesicles (EVs) from intestinal lavage of septic mice. The EVs expressed typical exosomal (CD63 and CD9) and epithelial (EpCAM) markers, which were further increased by sepsis. Moreover, septic-EV injection into inflamed gut induced a significant reduction in the messaging of pro-inflammatory cytokines TNF-α and IL-17A. MicroRNA (miRNA) profiling and reverse transcription and quantitative polymerase chain reaction (RT-qPCR) revealed a sepsis-induced exosomal increase in multiple miRNAs, which putatively target TNF-α and IL-17A. These results imply that intestinal epithelial cell (IEC)-derived luminal EVs carry miRNAs that mitigate pro-inflammatory responses. Taken together, our study proposes a novel mechanism by which IEC EVs released during sepsis transfer regulatory miRNAs to cells, possibly contributing to the amelioration of gut inflammation.

9 April 2021 in Viruses
Verified
Journal Article
Open access
PDF file
Eun Jeong ParkEun Jeong Park
Eun Jeong Park
PMPhyoe Kyawe Myint
Phyoe Kyawe Myint
MAMichael Gyasi Appiah
Michael Gyasi Appiah
SDSamuel Darkwah
Samuel Darkwah
SCSiqingaowa Caidengbate
Siqingaowa Caidengbate
MSMotomu Shimaoka
Motomu Shimaoka
The spike glycoprotein attached to the envelope of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to and exploits angiotensin-converting enzyme 2 (ACE2) as an entry receptor to infect pulmonary epithelial cells. A subset of integrins that recognize the arginyl–glycyl–aspartic acid (RGD) sequence in the cognate ligands has been predicted in silico to bind the spike glycoprotein and, thereby, to be exploited for viral infection. Here, we show experimental evidence that the β1 integrins predominantly expressed on human pulmonary epithelial cell lines and primary mouse alveolar epithelial cells bind to this spike protein. The cellular β1 integrins support adhesive interactions with the spike protein independently of ACE2, suggesting the possibility that the β1 integrins may function as an alternative receptor for SARS-CoV-2, which could be targeted for the prevention of viral infections.