Evolutionary stalling and a limit on the power of natural selection to improve a cellular module.

Cells consist of molecular modules which perform vital biological functions. Cellular modules are key units of adaptive evolution because organismal fitness depends on their performance. Theory shows that in rapidly evolving populations, such as those of many microbes, adaptation is driven primarily by common beneficial mutations with large effects, while other mutations behave as if they are effectively neutral. As a consequence, if a module can be improved only by rare and/or weak beneficial mutations, its adaptive evolution would stall. However, such evolutionary stalling has not been empirically demonstrated, and it is unclear to what extent stalling may limit the power of natural selection to improve modules. Here we empirically characterize how natural selection improves the translation machinery (TM), an essential cellular module. We experimentally evolved populations of Escherichia coli with genetically perturbed TMs for 1,000 generations. Populations with severe TM defects initially adapted via mutations in the TM, but TM adaptation stalled within about 300 generations. We estimate that the genetic load in our populations incurred by residual TM defects ranges from 0.5 to 19%. Finally, we found evidence that both epistasis and the depletion of the pool of beneficial mutations contributed to evolutionary stalling. Our results suggest that cellular modules may not be fully optimized by natural selection despite the availability of adaptive mutations.

A chimeric antigen receptor uniquely recognizing MICA/B stress proteins provides an effective approach to target solid tumors.

BACKGROUND: The advent of chimeric antigen receptor (CAR) T cell therapies has transformed the treatment of hematological malignancies; however, broader therapeutic success of CAR T cells has been limited in solid tumors because of their frequently heterogeneous composition. Stress proteins in the MICA and MICB (MICA/B) family are broadly expressed by tumor cells following DNA damage but are rapidly shed to evade immune detection. METHODS: We have developed a novel CAR targeting the conserved α3 domain of MICA/B (3MICA/B CAR) and incorporated it into a multiplexed-engineered induced pluripotent stem cell (iPSC)-derived natural killer (NK) cell (3MICA/B CAR iNK) that expressed a shedding-resistant form of the CD16 Fc receptor to enable tumor recognition through two major targeting receptors. FINDINGS: We demonstrated that 3MICA/B CAR mitigates MICA/B shedding and inhibition via soluble MICA/B while simultaneously exhibiting antigen-specific anti-tumor reactivity across an expansive library of human cancer cell lines. Pre-clinical assessment of 3MICA/B CAR iNK cells demonstrated potent antigen-specific in vivo cytolytic activity against both solid and hematological xenograft models, which was further enhanced in combination with tumor-targeted therapeutic antibodies that activate the CD16 Fc receptor. CONCLUSIONS: Our work demonstrated 3MICA/B CAR iNK cells to be a promising multi-antigen-targeting cancer immunotherapy approach intended for solid tumors. FUNDING: Funded by Fate Therapeutics and NIH (R01CA238039).

Three common CARD15 mutations are not responsible for the pathogenesis of Crohn's disease in Iranians.

BACKGROUND/AIMS: Crohn's disease frequency has increased in recent years in Iran. Genetic and environmental factors predispose people to this disease. Mutation in Caspase Recruitment Domain 15 (CARD15) gene is the most well known genetic predisposing factor to this disease. Frequency of three common CARD15 mutations has been studied in different ethnic groups. We aimed to study the frequency of these mutations in Iranian patients affected with Crohn's Disease. METHODOLOGY: One hundred fifteen proved cases of Crohn Disease and 115 age and sex matched normal controls were recruited in this study. Lf1007fs, R702W and G908R mutations were studied by Polymerase Chain Reaction-Restriction Fragment Length Polymorphims (PCR-RFLP) followed by sequencing the positive cases. RESULTS: Lf1007fs and G908R mutations were not found in either patients or age-sex matched controls. Just in two patients, R702W mutation was proved by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and sequencing. None of these patients had illeal or fibrostenotic type of disease while 14.7% of total patients had stricturing type of disease. No complication was seen in these two patients while 50.4% of patients had acquired complications during the course of disease. CONCLUSION: The three mutations described are not responsible for the pathogenesis of Crohn's Disease in Iranians. The results are in accordance with other Asian nations' studies on IBD Patients.

Lentiviral Mediating Genetic Engineered Mesenchymal Stem Cells for Releasing IL-27 as a Gene Therapy Approach for Autoimmune Diseases.

OBJECTIVE: Autoimmune diseases precede a complex dysregulation of the immune system. T helper17 (Th17) and interleukin (IL)-17 have central roles in initiation of inflammation and subsequent autoimmune diseases. IL-27 significantly controls autoimmune diseases by Th17 and IL-17 suppression. In the present study we have created genetic engineered mesenchymal stem cells (MSCs) that mediate with lentiviral vectors to release IL-27 as an adequate vehicle for ex vivo gene therapy in the reduction of inflammation and autoimmune diseases. MATERIALS AND METHODS: In this experimental study, we isolated adipose-derived MSCs (AD-MSCs) from lipoaspirate and subsequently characterized them by differentiation. Two subunits of IL-27 (p28 and EBI3) were cloned in a pCDH-513B-1 lentiviral vector. Expressions of p28 and EBI3 (Epstein-Barr virus induced gene 3) were determined by real time polymerase chain reaction (PCR). MSCs were transduced by a pCDH-CMV-p28-IRES- EBI3-EF-copGFP-Pur lentiviral vector and the bioassay of IL-27 was evaluated by IL-10 expression. RESULTS: Cell differentiation confirmed true isolation of MSCs from lipoaspirate. Restriction enzyme digestion and sequencing verified successful cloning of both p28 and EBI3 in the pCDH-513B-1 lentiviral vector. Real time PCR showed high expressions level of IL-27 and IL-10 as well as accurate activity of IL-27. CONCLUSION: The results showed transduction of functional IL-27 to AD-MSCs by means of a lentiviral vector. The lentiviral vector did not impact MSC characteristics.