Baseflow significantly contributes to river floods in Peninsular India.

Extreme rainfall prior to a flood event is often a necessary condition for its occurrence; however, rainfall alone is not always an indicator of flood severity. Antecedent wetness condition of a catchment is another important factor which strongly influences the flood magnitudes. The key role of soil moisture in driving floods is widely recognized; however, antecedent conditions of deeper saturated zone may contribute to river floods. Here, we assess how closely the flood magnitudes are associated to extreme rainfall, soil moisture and baseflow in 70 catchments of Peninsular India for the period 1979-2018. Annual flood magnitudes have declined across most of the catchments. Effect of flow regulations is also assessed to understand the impact of human interventions on flood characteristics. Reservoir regulation has positive effect by reducing the flood peak and volume, whereas the duration of flood events has increased after the construction of dams. Baseflow exhibits similar patterns of trends as floods, whereas trends in rainfall and soil moisture extremes are weakly correlated with trends in flood magnitudes. Baseflow is found to be more strongly influencing the flood magnitudes than soil moisture at various time lags. Further analysis with event coincidence analysis confirms that baseflow has stronger triggering effect on river floods in Peninsular India.

Role of Extracellular Vesicles in the Propagation of Lung Fibrosis in Systemic Sclerosis.

OBJECTIVES: Systemic sclerosis (SSc) has the highest mortality rate among the rheumatic diseases, with lung fibrosis leading as the cause of death. A characteristic of severe SSc-related lung fibrosis is its progressive nature. Although most research has focused on the pathology of the fibrosis, the mechanism mediating the fibrotic spread remains unclear. We hypothesized that extracellular vesicle (EV) communication drives the propagation of SSc lung fibrosis. METHODS: EVs were isolated from normal (NL) or SSc-derived human lungs and primary lung fibroblasts (pLFs). EVs were also isolated from human fibrotic lungs and pLFs induced experimentally with transforming growth factor-ß (TGFß). Fibrotic potency of EVs was assessed using functional assays in vitro and in vivo. Transmission electron microscopy, nanoparticle tracking analysis, real-time quantitative polymerase chain reaction (RT-qPCR), immunoblotting, and immunofluorescence were used to analyze EVs, their cargo, extracellular matrix (ECM) fractions, and conditioned media. RESULTS: SSc lungs and pLFs released significantly more EVs than NL lungs, and their EVs showed increased fibrotic content and activity. TGFß-stimulated NL lung cores and pLFs increased packaging of fibrotic proteins, including fibronectin, collagens, and TGFß, into released EVs. The EVs induced a fibrotic phenotype in recipient pLFs and in vivo in mouse lungs. Furthermore, EVs interacted with and contributed to the ECM. Finally, suppressing EV release in vivo reduced severity of murine lung fibrosis. CONCLUSIONS: Our findings highlight EV communication as a novel mechanism for propagation of SSc lung fibrosis. Identifying therapies that reduce EV release, activity, and/or fibrotic cargo in SSc patient lungs may be a viable therapeutic strategy to improve fibrosis.

Reduced Cathepsin L expression and secretion into the extracellular milieu contribute to lung fibrosis in systemic sclerosis.

OBJECTIVES: Lung fibrosis is the leading cause of death in SSc, with no cure currently available. Antifibrotic Endostatin (ES) production does not reach therapeutic levels in SSc patients, suggesting a deficit in its release from Collagen XVIII by the main cleavage enzyme, Cathepsin L (CTSL). Thus, elucidating a potential deficit in CTSL expression and activity unravels an underlying molecular cause for SSc-driven lung fibrosis. METHODS: Fibrosis was induced experimentally using TGF-ß in vitro, in primary human lung fibroblasts (pLFs), and ex vivo, in human lung tissues. ES and CTSL expression was quantified using ELISA, RT-qPCR, immunoblotting or immunofluorescence. Recombinant NC1-FLAG peptide was used to assess CTSL cleavage activity. CTSL expression was also compared between SSc vs normal (NL)-derived pLFs and lung tissues. RESULTS: ES levels were significantly reduced in media conditioned by TGF-ß-induced pLFs. TGF-ß-stimulated pLFs significantly reduced expression and secretion of CTSL into the extracellular matrix (ECM). CTSL was also sequestered in its inactive form into extracellular vesicles, further reducing its availability in the ECM. Media conditioned by TGF-ß-induced pLFs showed reduced cleavage of NC1-Flag and reduced release of the antifibrotic ES fragment. SSc-derived pLFs and lung tissues expressed significantly lower levels of CTSL compared with NL. CONCLUSIONS: Our findings identify CTSL as a protein protective against lung fibrosis via its activation of antifibrotic ES, and whose expression in SSc pLFs and lung tissues is suppressed. Identifying strategies to boost CTSL endogenous levels in SSc patients could serve as a viable therapeutic strategy.

E4 engages uPAR and enolase-1 and activates urokinase to exert antifibrotic effects.

Fibroproliferative disorders such as systemic sclerosis (SSc) have no effective therapies and result in significant morbidity and mortality. We recently demonstrated that the C-terminal domain of endostatin, known as E4, prevented and reversed both dermal and pulmonary fibrosis. Our goal was to identify the mechanism by which E4 abrogates fibrosis and its cell surface binding partner(s). Our findings show that E4 activated the urokinase pathway and increased the urokinase plasminogen activator (uPA) to type 1 plasminogen activator inhibitor (PAI-1) ratio. In addition, E4 substantially increased MMP-1 and MMP-3 expression and activity. In vivo, E4 reversed bleomycin induction of PAI-1 and increased uPA activity. In patients with SSc, the uPA/PAI-1 ratio was decreased in both lung tissues and pulmonary fibroblasts compared with normal donors. Proteins bound to biotinylated-E4 were identified as enolase-1 (ENO) and uPA receptor (uPAR). The antifibrotic effects of E4 required uPAR. Further, ENO mediated the fibrotic effects of TGF-ß1 and exerted TGF-ß1-independent fibrotic effects. Our findings suggest that the antifibrotic effect of E4 is mediated, in part, by regulation of the urokinase pathway and induction of MMP-1 and MMP-3 levels and activity in a uPAR-dependent manner, thus promoting extracellular matrix degradation. Further, our findings identify a moonlighting function for the glycolytic enzyme ENO in fibrosis.

Amino acid residues important for D-galactose recognition by the F-type lectin, Ranaspumin-4.

F-type lectins are typically L-fucose binding proteins with characteristic L-fucose-binding and calcium-binding sequence motifs, and an F-type lectin fold. An exception is Ranaspumin-4, an F-type lectin of the Tungra frog, Engystomops pustulosus. Ranaspumin-4 is D-galactose specific and does not bind to L-fucose although it has the conserved L-fucose binding sequence motif and shares overall sequence similarity with other F-type lectins. Here, we report the detailed glycan-binding profile of wild-type Ranaspumin-4 using hemagglutination inhibition assays, flow cytometry assays and enzyme-linked lectin assays, and identify residues important for D-galactose recognition using rational site-directed mutagenesis. We demonstrate that Ranaspumin-4 binds to terminal D-galactose in α or ß linkage with preference for α1-3, α1-4, ß1-3, and ß1-4 linkages. Further, we find that a methionine residue (M31) in Ranaspumin-4 that occurs in place of a conserved Gln residue (in other F-type lectins), supports D-galactose recognition. Resides Q42 and F156 also likely aid in D-galactose recognition.

Mutations in KIRREL1, a slit diaphragm component, cause steroid-resistant nephrotic syndrome.

Steroid-resistant nephrotic syndrome is a frequent cause of chronic kidney disease almost inevitably progressing to end-stage renal disease. More than 58 monogenic causes of SRNS have been discovered and majority of known steroid-resistant nephrotic syndrome causing genes are predominantly expressed in glomerular podocytes, placing them at the center of disease pathogenesis. Herein, we describe two unrelated families with steroid-resistant nephrotic syndrome with homozygous mutations in the KIRREL1 gene. One mutation showed high frequency in the European population (minor allele frequency 0.0011) and this patient achieved complete remission following treatment, but later progressed to chronic kidney disease. We found that mutant KIRREL1 proteins failed to localize to the podocyte cell membrane, indicating defective trafficking and impaired podocytes function. Thus, the KIRREL1 gene product has an important role in modulating the integrity of the slit diaphragm and maintaining glomerular filtration function.

Effect of naturally occurring variations of the F-type lectin sequence motif on glycan binding: studies on F-type lectin domains with typical and atypical sequence motifs.

The typical F-type lectin domain (FLD) has an L-fucose-binding motif [HX(26)RXDX(4)R/K] with conserved basic residues that mediate hydrogen bonding with alpha-L-fucose. About one-third of the nonredundant FLD sequences in the publicly available databases are "atypical"; they have motifs with substitutions of these critical residues and/or variations in motif length. We addressed the question if atypical FLDs with substitutions of the critical residues retain lectin activity by performing site-directed mutagenesis and assessing the glycan-binding functions of typical and atypical FLDs. Site directed mutagenesis of an L-fucose-binding FLD from Streptosporangium roseum indicated that the critical His residue could be replaced by Ser and the second Arg by Lys without complete loss of lectin activity. Mutagenesis of His to other naturally substituting residues and mutagenesis of the first Arg to the naturally substituting residues, Lys, Ile, Ser, or Cys, resulted in loss of lectin activity. Glycan binding analysis and site-directed mutagenesis of atypical FLDs from Actinomyces turicensis, and Saccharomonospora cyanea confirmed that Ser and Thr can assume the L-fucose-binding role of the critical His, and further suggested that the residue in this position is dispensable in certain FLDs. We identified, by sequence and structural analysis of atypical FLDs, a Glu residue in the complementarity determining region, CDR5 that compensates for a lack of the critical His or other appropriate polar residue in this position. We propose that FLDs lacking a typical FLD sequence motif might nevertheless retain lectin activity through the recruitment of other strategically positioned polar residues in the CDR loops. © 2018 IUBMB Life, 71(3):385-397, 2019.

Saccharide binding by intelectins.

This communication probes ligand binding by human Intelectin-1 with several saccharides. Human Intelectin-1 was previously reported to bind to microbial glycans via ribofuranoside or galactofuranoside residues, whereas subsequently, a crystal structure of ligand bound hITLN1 indicated that hITLN1 does not bind to ribofuranoside but distinguishes between microbial and human glycans through a glycan motif - a terminal, acyclic 1,2-diol, which is present on galactofuranose and other microbial saccharides. Here, we demonstrate that besides glycerol and glycerol derivatives (which have an acyclic 1,2-diol), and 2-deoxy-d-galactose, d-ribose and 2-deoxy-d-ribose, which have been previously reported as human Intelectin-1 ligands, 2-C-hydroxymethyl-d-ribose, d-talose, d-idose, d-altrose and sorbitol also elute human Intelectin-1 from Sepharose CL-6B. Interestingly, Sepharose, 2-deoxy-d-galactose (in its pyranose form), 2-C-hydroxymethyl-d-ribose, d-ribose and 2-deoxy d-ribose lack a terminal, acyclic 1,2-diol. We discuss the implications of these observations and rationalize the discrepancies in the apparent affinity of saccharide ligands for hITLN1 with different assay formats. We also report the distinct saccharide binding profiles of the hITLN1 homologues, HaloITLN and XL35ITLN, and demonstrate that hITLN1 binding to a saccharide ligand may modulate binding to its protein ligand, lactoferrin and vice versa.

Increasing frequency and spatial extent of concurrent meteorological droughts and heatwaves in India.

The impacts of concurrent droughts and heatwaves could be more serious compared to their individual occurrence. Meteorological drought condition is generally characterized by low rainfall, but impact of such an event is amplified with simultaneous occurrence of heatwaves. Positive feedback between these two extremes can worsen the rainfall deficit situation to serious soil moisture depletion due to enhanced evapotranspiration. In this study, the concurrence of meteorological droughts and heatwaves is investigated in India using Indian Meteorological Department (IMD) high resolution gridded data over a period of 60 years. Significant changes are observed in concurrent meteorological droughts and heatwaves defined at different percentile based thresholds and durations during the period 1981-2010 relative to the base period 1951-1980. There is substantial increase in the frequency of concurrent meteorological droughts and heatwaves across whole India. Statistically significant trends in the spatial extent of droughts are observed in Central Northeast India and West Central India; however, the spatial extent affected by concurrent droughts and heatwaves is increasing across whole India. Significant shifts are identified in the distribution of spatial extent of concurrent drought and heatwaves in India compared to the base period.

Complete Genomes of Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, Two Phylogenetically Distinct Probiotics.

Several spore-forming strains of Bacillus are marketed as probiotics due to their ability to survive harsh gastrointestinal conditions and confer health benefits to the host. We report the complete genomes of two commercially available probiotics, Bacillus coagulans S-lac and Bacillus subtilis TO-A JPC, and compare them with the genomes of other Bacillus and Lactobacillus. The taxonomic position of both organisms was established with a maximum-likelihood tree based on twenty six housekeeping proteins. Analysis of all probiotic strains of Bacillus and Lactobacillus reveal that the essential sporulation proteins are conserved in all Bacillus probiotic strains while they are absent in Lactobacillus spp. We identified various antibiotic resistance, stress-related, and adhesion-related domains in these organisms, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival during antibiotic treatment and harsh conditions.