Distinct roles for LTalpha3 and LTalpha1beta2 produced by B cells contribute to their multi-faceted impact on ileitis.

B lymphocytes may facilitate chronic inflammation through antibody production or secretion of cytokines, including lymphotoxin (LT)-a1b2 associated with development of lymphoid tissue. Tertiary lymphoid structures (TLS) characterize human and murine ileitis by suppressing outflow from the ileum. Here, we show that B cell-derived secretory IgA protected against ileal inflammation, whereas B cell-derived LTa guarded against ileitis-associated loss of body mass. We initially hypothesized this protection resulted from formation of TLS that suppressed lymphatic outflow and thereby restrained systemic spread of inflammatory signals, but B cell-selective deletion of LTb did not exacerbate weight loss, despite eliminating TLS. Instead, weight loss driven by the cachectic cytokine TNF was exacerbated when LTa3, another ligand for TNF receptors, was selectively neutralized. Thus, B cells' multi-faceted impact on ileitis includes generating secretory IgA, expressing LTa1b2 to drive formation of TLS, and producing LTa3 for protecting against weight loss in the presence of TNF.

Halogen-bonded zigzag mol-ecular network based upon 1,2-di-iodo-perchloro-benzene and the photoproduct rctt-1,3-bis-(pyridin-4-yl)-2,4-di-phenyl-cyclo-butane.

The formation and crystal structure of a zigzag mol-ecular network held together by I⋯N halogen bonds is reported. In particular, the halogen-bond donor is 1,2-di-iodo-perchloro-benzene (1,2-C6I2Cl4 ) while the acceptor is a head-to-tail photoproduct, namely rctt-1,3-bis-(pyridin-4-yl)-2,4-di-phenyl-cyclo-butane ( ht -PP). In this co-crystal (1,2-C6I2Cl4 )·( ht-PP), the donor acts as a bent two-connected node while the acceptor behaves as a linear linker to form the extended solid. Neighbouring chains pack in a tongue-and-groove-like pattern that engage in various Cl⋯π inter-actions to both the phenyl and pyridyl rings resulting in a supra-molecular two-dimensional sheet.

Controlling Topology within Halogen-Bonded Networks by Varying the Regiochemistry of the Cyclobutane-Based Nodes.

The formation of a pair of extended networks sustained by halogen bonds based upon two regioisomers of a photoproduct, namely rctt-1,3-bis(4-pyridyl)-2,4-bis(phenyl)cyclobutane (ht-PP) and rctt-1,2-bis(4-pyridyl)-3,4-bis(phenyl)cyclobutane (hh-PP), that have varied topology is reported. These networks are held together via I⋯N halogen bonds between the photoproduct and the halogen-bond donor 1,4-diiodoperchlorobenzene (C6I2Cl4). The observed topology in each solid is controlled by the regiochemical position of the halogen-bond accepting 4-pyridyl group. This paper demonstrates the ability to vary the topology of molecular networks by altering the position of the halogen bond acceptor within the cyclobutane-based node.