The technology of polychrome glazed ceramics in Ifriqiya: new data from the site of Chimtou

Ifriqiya (roughly Tunisia and eastern Algeria) is believed to have played a significant role in the diffusion of ceramic glazed technologies into other regions of the Western Mediterranean. However, due to limited analysis on North African glazed ceramics, its role in technology transfer remains poorly understood. This paper uses SEM-EDS and petrographic analyses to understand the technology employed in the production of Tunisian ceramics through the study of 30 polychrome glazed ceramics from a medieval settlement at the site of Chimtou (ancient Simitthus), Tunisia, dated to the late ninth-twelfth century. The results show that these are lead-rich glazes with varying contents of alkalis, coloured with copper, iron and manganese oxide and applied over a calcareous body. Opaque glazes were obtained using cassiterite crystals as opacifier or by adding crushed quartz. The use of lead stannate as a colourant and opacifier in one light yellow glaze raises questions about the mechanisms of introduction of tin opacification technology in North Africa. Scrap metal seems to have been used as a source of lead for the glazes; while iron slag was probably used as a source of iron to colour the glaze in one sample, pointing to a cross-craft interaction between glazemaking and metallurgy.

Supplementary information

The online version contains supplementary material available at 10.1007/s12520-024-01974-x.

POS0099 THE CELLULAR METABOLISM OF SLE NK CELLS IS PRIMARILY ALTERED AT THE LEVEL OF MITOCHONDRIAL RESPIRATION

Background

Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease, involving the development of autoreactive cells and autoantibodies. Natural Killer (NK) cells are innate immune cells that mediate the interaction between the innate and adaptive immune system, however their role in SLE is incompletely understood. SLE NK cells are decreased in peripheral blood, exhibit reduced cytotoxicity, and impaired cytokine production (1, 2). Furthermore, SLE NK cells present phenotypic alterations: increased expression of CD38 and altered upregulation of SLAMF7 after activation (3). To date, few studies evaluated the molecular mechanisms underlying NK cell dysfunction in SLE.

Objectives

We examined immunometabolic alterations of SLE NK cells. First, we characterized the cellular metabolism of SLE NK cells by assessing glycolysis and oxidative phosphorylation (OXPHOS) at basal level. Then, we evaluated how cellular metabolism can be manipulated to enhance NK cell function. In this perspective, we examined how the ligation of CD38 with daratumumab (DARA) and SLAMF7 with elotuzumab (ELO) modulate glycolysis and OXPHOS.

Methods

NK cells of cryopreserved PBMC from SLE patients were isolated. Glycolysis and OXPHOS were studied using XFe96 Seahorse. Expression of metabolic receptors (CD71, GLUT-1, CD98), mitochondrial function (mitochondrial membrane potential, mass) and calcium influx were investigated by FACS. Mitochondrial structure was evaluated by electron and confocal microscopy.

Results

First, we examined the cellular metabolism of SLE NK cells compared to healthy cells. We observed that OXPHOS is significantly increased in SLE NK cells (Figure 1A), whereas glycolysis was normal (Figure 1B). Furthermore, the mitochondrial mass and membrane potential (by FACS (Figure 1C) and confocal microscopy) were increased in SLE. Electron microscope imaging showed profound alterations in SLE NK cell mitochondrial ultrastructure (Figure 1D). No significant differences in the expression of key metabolite transporters involved in mitochondrial fueling (CD71, GLUT-1, CD98) was observed in SLE NK cells compared to healthy controls.

Second, we examined how ligation of DARA and ELO influences the metabolism of healthy NK cells. Our data showed that ELO primarily enhances NK cell OXPHOS (Figure 1E), whereas DARA mainly increases glycolysis. Consistently, ELO also increases mitochondrial membrane potential and expression of metabolite transporters CD71, GLUT-1 and CD98. Next, we examined the effect of DARA and ELO on SLE NK cells. While stimulation with DARA adequately increases glycolysis in SLE NK cells, engagement with ELO fails to properly increase OXPHOS (Figure 1F), expression of cell surface transporters, mitochondrial membrane potential and mass.

Conclusion

Our data suggest that SLE NK cells exhibit alterations in cellular metabolism, primarily involving mitochondrial respiration. In contrast, glucose metabolism is similar to that of healthy NK cells. Additionally, ELO and DARA mediate the activation of healthy NK cells through the engagement of different metabolic pathways: OXPHOS and glycolysis, respectively. Therefore, priming SLE NK cells with ELO is unable to adequately engage their dysfunctional mitochondrial respiration. These findings provide important insights on the alteration present in SLE NK cells and contribute to a better understanding of the pathogenesis of the disease.

References

[1]Spada R, Rojas JM, Barber DF. Recent findings on the role of natural killer cells in the pathogenesis of systemic lupus erythematosus. J Leukoc Biol. 2015;98(4):479-87.

[2]Park Y-W, Kee S-J, Cho Y-N, Lee E-H, Lee H-Y, Kim E-M, et al. Impaired differentiation and cytotoxicity of natural killer cells in systemic lupus erythematosus. Arthritis & Rheumatism. 2009;60(6):1753-63.

[3]Humbel M, Bellanger F, Fluder N, Horisberger A, Suffiotti M, Fenwick C, et al. Restoration of NK Cell Cytotoxic Function With Elotuzumab and Daratumumab Promotes Elimination of Circulating Plasma Cells in Patients With SLE. Front Immunol. 2021;12:645478.

Acknowledgements

This study received funding from the Swiss National Science Foundation (Ambizione PZ00P3_173950 to DC).

Disclosure of Interests

None declared

The relationship between microbial community structure and functional stability, tested experimentally in an upland pasture soil

Soil collected from an upland pasture was manipulated experimentally in ways shown previously to alter microbial community structure. One set of soil was subjected to chloroform fumigation for 0, 0.5, 2, or 24 h and the other was sterilised by gamma-irradiation and inoculated with a 10(-2), 10(-4), 10(-6), or 10(-8) dilution of a soil suspension prepared from unsterilized soil. Following incubation for 8 months, to allow for the stabilization of microbial biomass and activity, the resulting microbial community structure (determined by PCR-DGGE of bacterial specific amplification products of total soil DNA) was assessed. In addition, the functional stability (defined here as the resistance and resilience of short-term decomposition of plant residues to a transient heat or a persistent copper perturbation) was determined. Changes in the active bacterial population following perturbation (determined by RT-PCR-DGGE of total soil RNA) were also monitored. The manipulations resulted in distinct shifts in microbial community structure as shown by PCR-DGGE profiles, but no significant decreases in the number of bands. These shifts in microbial community structure were associated with a reduction in functional stability. The clear correlation between altered microbial community structure and functional stability observed in this upland pasture soil was not evident when the same protocols were applied to soils in other studies. RT-PCR-DGGE profiles only detected a shift in the active bacterial population following heat, but not copper, perturbation. We conclude that the functional stability of decomposition is related to specific components of the microbial community.

A subclass of Ras proteins that regulate the degradation of IkappaB

Small guanosine triphosphatases, typified by the mammalian Ras proteins, play major roles in the regulation of numerous cellular pathways. A subclass of evolutionarily conserved Ras-like proteins was identified, members of which differ from other Ras proteins in containing amino acids at positions 12 and 61 that are similar to those present in the oncogenic forms of Ras. These proteins, kappaB-Ras1 and kappaB-Ras2, interact with the PEST domains of IkappaBalpha and IkappaBbeta [inhibitors of the transcription factor nuclear factor kappa B (NF-kappaB)] and decrease their rate of degradation. In cells, kappaB-Ras proteins are associated only with NF-kappaB:IkappaBbeta complexes and therefore may provide an explanation for the slower rate of degradation of IkappaBbeta compared with IkappaBalpha.